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MP4657AGS-Z
LED Driver, AC / DC, 1A, -40 to 125 °C, Flyback, 4 Outputs, 80V, SOIC-16
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- Manufacturer: MONOLITHIC POWER SYSTEMS (MPS)
- Product type: AC / DC LED Driver ICs
- MSL: MSL 2 - 1 year
- SVHC: No SVHC (19-Jan-2021)
- Topology: Flyback
- IC Mounting: Surface Mount
- No. of Pins: 16Pins
- Product Range: -
- Qualification: -
- No. of Outputs: 4Outputs
- Device Topology: Flyback
- LED Driver Type: Isolated
- Driver Case Style: SOIC
- IC Case / Package: SOIC
- Input Voltage Max: 16V
- Input Voltage Min: 4V
- Output Current Max: 1A
- Output Voltage Max: 80V
- Switching Frequency: 350kHz
- Switching Frequency Typ: 350kHz
- Operating Temperature Max: 125°C
- Operating Temperature Min: -40°C
- Automotive Qualification Standard: -
| Delivery and price | |
|---|---|
| Units per pack | 2500 |
| Price | 1.17 € |
| Current stock | 10+ |
| Lead time | 30 days |
Datasheet
## _**MP4657A**_ **Single-Stage Flyback, 4-String LED Driver and System Voltage Controller** mes **DESCRIPTION FEATURES**
The MP4657A is a single-stage flyback, 4-string LED driver and system voltage controller for LED backlighting on the secondary side. The device controls the flyback power stage and an external N-channel MOSFET to regulate system output voltage and the LED current loop with integrated 4-string LED current balancing. With a 4V to 16V input voltage, the device outputs a direct driving signal to control the N- channel MOSFET for regulating the system output voltage. The device also outputs a compensation signal to control the primary-side flyback (or other power stage) through an optocoupler.
The MP4657A induces PWM dimming or analog dimming to the LED current through the ADIMP/PWM pin. Apply a pulse signal with a >5kHz frequency on this pin for analog dimming. Apply a pulse signal with a <5kHz frequency on this pin for PWM dimming.
The device uses an individual control method for the LED current and system voltage. When the PWM signal is effective, the MP4657A regulates the LED current loop through the flyback power stage and further regulates the system voltage by controlling the N-channel MOSFET. Soft switching for the N-channel MOSFET can be achieved to reduce voltage spikes. When the PWM signal is ineffective, the device directly controls the system voltage through the flyback power stage.
The MP4657A features rich protections to increase system reliability. Protections are utilized for both the system voltage stage and the LED driver stage. LED driver stage protections include LED open protection, LED short protection and LEDx pin short to ground protection. The system voltage stage protections include over-voltage protection (OVP) and feedback open loop protection. The device also has thermal protection.
- Single-Stage Flyback for High Efficiency LED Current and System Voltage Regulation
- Individual Control Method for the LED Driver Stage and System Voltage Stage
- 4V to 16V Supply Voltage
- 4-String, 80V LED Current Balancing
- 1.5% System Voltage Accuracy
- 1.5% LED Current Accuracy and 2% LED Current Balancing
- Low LEDx Regulation Voltage, High Efficiency
- Fast Dynamic Control, Fast Response
- System Supply Over-Voltage Protection (OVP)
- System Supply Short Protection
- LED Open, LED Short Protection
- LEDx Pin Short to Ground Protection
- Feedback Open Loop Protection for System Voltage
- Soft Switching for the External N-Channel MOSFET
- Thermal Protection
- Available in an SOIC-16 Package
## **APPLICATIONS**
- LCD Monitors and TVs
- Desktop LCD Flat Panel Displays
- Flat Panel Video Displays
All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS”, the MPS logo, and “Simple, Easy Solutions” are trademarks of Monolithic Power Systems, Inc. or its subsidiaries.
The MP4657A is available in an SOIC-16 package.
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MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2021 MPS. All Rights Reserved.
**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS
## **TYPICAL APPLICATION**
**==> picture [476 x 281] intentionally omitted <==**
**----- Start of picture text -----**<br>
TM D1<br>Flyback<br>R1<br>AC 100V to NP N LED C1<br>85V to 265V 380V Bus R2<br>M1<br>NSYS<br>Flyback D2 VSYS<br>Controller<br>C2 M2 R3<br>C3<br>D3 R11 R4<br>R8 MP4657A<br>1 SYNC GATE 16<br>D4<br>R9<br>2 OPT VDRV 15<br>C6<br>3 VFB VIN/SOURCE 14<br>R10<br>C4<br>R7 4 DCOMP ADIMP/PWM 13 PWM or ADIM Pulse<br>C5 R6 5 ICOMP ISET/FAULT 12 R5<br>al 6 OVP LED3 11<br>7 LED1 LED4 10<br>8 LED2 GND 9<br>**----- End of picture text -----**<br>
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS
## **ORDERING INFORMATION**
|**Part Number***<br>~~——~~|**Package**<br>~~——~~|**Top Marking**<br>~~——~~|**MSL Rating**<br>~~——~~|
|---|---|---|---|
|MP4657AGS<br>~~——~~|SOIC-16<br>~~——~~|_See Below_<br>~~——~~|2<br>~~——~~|
* For Tape & Reel, add suffix -Z (e.g. MP4657AGS-Z).
## **TOP MARKING**
MPS: MPS prefix YY: Year code WW: Week code MP4657A: Part number LLLLLLLLL: Lot number
## **PACKAGE REFERENCE**
**==> picture [246 x 245] intentionally omitted <==**
**----- Start of picture text -----**<br>
TOP VIEW<br>SYNC [| 1 [|__| 16 GATE<br>OPT [| 2 [|__| 15 VDRV<br>VFB [| 3 [|__| 14 VIN/SOURCE<br>DCOMP [| 4 |__| 13 ADIMP/PWM<br>ICOMP [| 5 |__| 12 ISET/FAULT<br>OVP [| 6 [| 11 LED3<br>LED1 [| 7 [_ 10 LED4<br>LED2 8 9 GND<br>[| |<br>SOIC-16<br>pO<br>**----- End of picture text -----**<br>
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS
## **PIN FUNCTIONS**
|**Pin #**<br>~~aa~~|**Name**<br>~~aa~~|**Description**<br>~~aa~~|
|---|---|---|
|1<br>~~a~~|SYNC<br>~~a~~|**Synchronization pin.**This pin synchronizes the GATE signal to the input signal of the<br>pin. Connect this pin to the secondary side winding of the flyback transformer through a<br>voltage divider. Its fallingedge synchronizes thegate signal’s shutdown.<br>~~ee~~|
|2<br>~~a~~|OPT<br>~~a~~|**Optical coupler.**This pin outputs the compensation signal. Connect this pin to the<br>external optical coupler to control the flyback.|
|3<br>~~oe~~|VFB<br>~~oe~~|**System voltage feedback.**Connect this pin to the system voltage through a voltage<br>divider.|
|4<br>~~oe~~|DCOMP<br>~~oe~~|**Compensation for the system voltage.**When PWM is effective, the DCOMP pin<br>compensates the system voltage control loop and controls the duty cycle of the<br>external N-channel MOSFET. When PWM is ineffective, this pin compensates the<br>system voltage control loopwith a differentgain and controls the flybackpower stage.|
|5<br>~~i~~|ICOMP<br>~~i~~|**Compensation for the LED driver stage.**The ICOMP pin compensates the LED<br>driver loop and controls the flyback power stage when PWM is effective. This pin holds<br>its voltage value when PWM is ineffective.|
|6<br>~~i~~<br>~~a~~|OVP<br>~~i~~<br>~~a~~|**Over-voltage protection for the LED driver stage.**Connect this pin to the output of<br>the LED voltage through a voltage divider.|
|7<br>~~a~~<br>~~eG~~<br>~~———~~|LED1<br>~~a~~<br>~~eG~~<br>~~———~~|**LED string 1 cathode.**<br>~~eG~~|
|8<br>~~———~~|LED2<br>~~———~~|**LED string 2 cathode.**|
|9<br>~~———~~<br>~~———~~|GND<br>~~———~~<br>~~———~~|**Ground.**|
|10<br>~~———~~<br>~~———~~|LED4<br>~~———~~<br>~~———~~|**LED string 4 cathode.**|
|11<br>~~———~~<br>~~———~~|LED3<br>~~———~~<br>~~———~~|**LED string 3 cathode.**|
|12<br>~~———~~<br>~~———~~|ISET/FAULT<br>~~———~~<br>~~———~~|**LED current setting pin and fault indicator.**This pin sets the LED current under<br>normal conditions. Connect a resistor from ISET/FAULT to ground to set the LED<br>current. Thispin ispulled low if a fault occurs.|
|13<br>~~———~~|ADIMP/PWM<br>~~———~~|**Dimming signal inputpin.**|
|14<br>~~———~~<br>~~eG~~|VIN/SOURCE<br>~~———~~<br>~~eG~~|**Power supply inputpin.**The GATE signal is also referred to thispin.<br>~~eG~~|
|15<br>~~———~~<br>~~a~~|VDRV<br>~~———~~<br>~~a~~|**Supply voltage for the gate driver.**Bypass this pin to VIN/SOURCE with a ceramic<br>capacitor.|
|16<br>~~a~~|GATE<br>~~a~~|**Gate driver pin.**The GATE signal is referred to the VIN/SOURCE pin. This pin’s<br>maximum voltage is limited below 6V(referred to VIN/SOURCE).|
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS
## **ABSOLUTE MAXIMUM RATINGS**[(1)]
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|||
|---|---|
|VIN/SOURCE .............................. -0.3V to +18V|
|VDRV .......................................... -0.3V to +53V|
|LEDx ............................................ -0.3V to +80V|
|GATE-VIN/SOURCE ................... -0.3V to +12V|
|SYNC ............................................ -6.5V to +6V|
|OPT ............................................... -0.3V to +5V|
|Other pins ................................... -0.3V to +6.5V|
|Junction temperature ............................... 150°C|
|Lead temperature .................................... 260°C|
|Storage temperature ................ -65°C to +150°C|
|Continuous power dissipation (TA = 25°C)|[(2)]|
|SOIC-16 .................................................. 1.56W|
|Operating frequency ............... 20kHz to 350kHz|
**----- End of picture text -----**<br>
## _**Thermal Resistance**_[(4)] _**θJA θJC**_ SOIC-16 ................................ 80 ...... 35 ... °C/W
## **Notes:**
- 1) Exceeding these ratings may damage the device.
- 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX) - TA) / θJA. Exceeding the maximum allowable power dissipation can cause excessive die temperature, and the device may go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage.
- 3) The device is not guaranteed to function outside of its operating conditions.
- 4) Measured on JESD51-7, 4-layer PCB.
_**ESD Ratings**_ Human body model (HBM) .................... ±2000V Charged device model (CDM) ................ ±1500V _**Recommended Operating Conditions**_[(3)] Supply voltage (VIN) ........................... 4V to 16V Operating frequency ............... 20kHz to 350kHz Operating junction temp (TJ) .... -40°C to +125°C
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS **ELECTRICAL CHARACTERISTICS VIN = 13V, TJ = 25°C, unless otherwise noted. IN = 13V, TJ = 25°C, unless otherwise noted. = 13V, TJ = 25°C, unless otherwise noted. J = 25°C, unless otherwise noted. = 25°C, unless otherwise noted.** ~~a~~ **Parameter Symbol Condition Min Typ Max Units**
## **ELECTRICAL CHARACTERISTICS**
## **VIN = 13V, TJ = 25°C, unless otherwise noted. IN = 13V, TJ = 25°C, unless otherwise noted. = 13V, TJ = 25°C, unless otherwise noted. J = 25°C, unless otherwise noted. = 25°C, unless otherwise noted.**
|**Parameter**<br>~~a~~|**Symbolymbolmbol**<br>~~a~~|**Condition**<br>~~a~~|**Min**<br>~~a~~|**Typyp**<br>~~a~~|**Max**<br>~~a~~|**Units**<br>~~a~~|
|---|---|---|---|---|---|---|
|**VIN Supply**<br>~~es~~|||||||
|VIN supplyrange<br>~~es~~|VIN<br>~~es~~|~~es~~|4<br>~~es~~|~~es~~|16<br>~~es~~|V<br>~~es~~|
|VIN UVLO<br>~~>~~|VUVLO_VIN<br>~~>~~|~~>~~|3.3<br>~~>~~|3.6<br>~~>~~|3.9<br>~~>~~|V<br>~~>~~|
|VIN UVLO hysteresis<br>~~>~~<br>~~ee~~|VHYS_UVLO_VIN<br>~~>~~|~~>~~|~~>~~|350<br>~~>~~|~~>~~|mV<br>~~>~~|
|Quiescent current<br>~~ee~~|IQ|PWM = 0, GATE = high, VIN= 5V,<br>no load|||0.5|mA|
|**Gate Driver Supply Voltage (VDRV, Referred to VIN/SOURCE, Unless Otherwise Noted)**<br>~~ee~~<br>~~es~~|||||||
|Voltage range<br>~~es~~|VDRV<br>~~es~~|Refer to GND<br>~~es~~|6.5<br>~~es~~|~~es~~|48<br>~~es~~|V<br>~~es~~|
|VDRV UVLO<br>~~a~~|~~a~~<br>~~a~~<br>~~ee~~|VIN= 5V<br>~~a~~<br>~~a~~<br>~~a~~<br>~~ee~~|5.3<br>~~a~~<br>~~a~~|5.8<br>~~a~~<br>~~a~~|6.3<br>~~a~~<br>~~a~~|V<br>~~a~~<br>~~a~~|
|Hysteresis for VDRV<br>UVLO<br>~~a~~|~~a~~<br>~~ee~~|~~a~~<br>~~ee~~||210||mV|
|**Gate Driver(Gate for External MOSFET on VSYS)**<br>~~a~~<br>~~ee~~<br>~~ee~~<br>~~**a**~~<br>~~ee~~<br>~~ee~~|||||||
|GATE voltage (refer to<br>VIN/SOURCE)<br>~~**a**~~|VGATE<br>~~ee~~|VDRV - VIN/SOURCE = 14V<br>~~ee~~||5.7||V|
|Output source current<br>~~**a**~~|ISOURCE_GATENWith 1nF load<br>~~ee~~|With 1nF load<br>~~ee~~||0.5(5)||A|
|Output sink current<br>~~oo~~|ISINK_GATEN<br>~~oo~~|With 1nF load<br>~~oo~~|~~oo~~|1(5)<br>~~oo~~|~~oo~~|A<br>~~oo~~|
|**Analog and PWM Dimming (ADIMP/PWM)**<br>~~oo~~<br>~~es~~|||||||
|ADIMP/PWM logic high<br>~~es~~|VADIMP_HI<br>~~es~~|~~es~~|1.5<br>~~es~~|~~es~~|6<br>~~es~~|V<br>~~es~~|
|ADIMP/PWM logic low<br>~~>~~<br>~~a~~|VADIMP_LO<br>~~>~~<br>~~ee~~|~~>~~<br>~~ee~~|~~>~~<br>~~ee~~|~~>~~<br>~~ee~~|0.7<br>~~>~~<br>~~ee~~|V<br>~~>~~<br>~~ee~~|
|ADIMP/PWM pull-down<br>resistor<br>~~a~~<br>~~a~~<br>~~ee~~|RADIMP_DOWN<br>~~a~~<br>~~ee~~<br>~~**ee**~~|~~a~~<br>~~ee~~<br>~~**ee**~~|~~a~~<br>~~ee~~<br>~~**ee**~~|1.6<br>~~a~~<br>~~ee~~<br>~~**ee**~~|~~a~~<br>~~ee~~<br>~~**ee**~~|MΩ<br>~~a~~<br>~~ee~~<br>~~**ee**~~|
|Analog dimming input<br>frequencyrange<br>~~a~~<br>~~ee~~|~~ee~~<br>~~**ee**~~|~~ee~~<br>~~**ee**~~|5<br>~~ee~~<br>~~**ee**~~|~~ee~~<br>~~**ee**~~|100<br>~~ee~~<br>~~**ee**~~|kHz<br>~~ee~~<br>~~**ee**~~|
|Duration time to disable<br>LED loop<br>~~ee~~|~~**ee**~~|EN LED<br>~~**ee**~~|~~**ee**~~|25<br>~~**ee**~~|~~**ee**~~|ms<br>~~**ee**~~|
|**SYNC**<br>~~**ee**~~<br>~~**eeee**~~<br>~~ee~~<br>~~es~~|||||||
|SYNC logic high threshold<br>~~es~~|VSYNC_HI<br>~~es~~|~~es~~|~~es~~|~~es~~|1.3<br>~~es~~|V<br>~~es~~|
|SYNC logic low threshold<br>~~>~~|VSYNC_LOW<br>~~>~~|~~>~~<br>~~ee~~|0.1<br>~~>~~<br>~~ee~~|~~>~~<br>~~ee~~|~~>~~|V<br>~~>~~|
|SYNC input frequency<br>range<br>~~a~~|~~a~~|~~a~~<br>~~ee~~|20<br>~~a~~<br>~~ee~~|~~a~~<br>~~ee~~|350<br>~~a~~|kHz<br>~~a~~|
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|**Parameter**<br>~~a~~|**Symbol**<br>~~a~~|**Condition**<br>~~a~~|**Min**<br>~~a~~|**Typ**<br>~~a~~|**Max**<br>~~a~~|**Units**<br>~~a~~|
|---|---|---|---|---|---|---|
|**OPT**|||||||
|OPT output voltage range<br>~~|~~<br>~~ee~~|~~|~~<br>~~ee~~|Normal<br>operation<br>H<br>(typical<br>maximum output voltage during<br>normal operation)<br>~~|~~<br>~~er~~|~~|~~<br>~~er~~|2.3<br>~~|~~<br>~~er~~|~~|~~<br>~~er~~|V<br>~~|~~<br>~~er~~<br>~~ee~~|
|||Normal<br>operation<br>L<br>(typical<br>minimum output voltage during<br>normal operation)<br>~~|~~<br>~~er~~<br>~~Po~~<br>~~ee~~|~~|~~<br>~~er~~<br>~~Po~~<br>~~ee~~|0.8<br>~~|~~<br>~~er~~<br>~~Po~~<br>~~ee~~|~~|~~<br>~~er~~<br>~~Po~~<br>~~ee~~||
|OPT output voltage when<br>latched off<br>~~ee~~|~~ee~~|~~Po~~<br>~~ee~~|~~Po~~<br>~~ee~~|3.3<br>~~Po~~<br>~~ee~~|~~Po~~<br>~~ee~~|V<br>~~ee~~|
|Source current capability<br>~~ee~~<br>~~I~~|IOPT<br>~~ee~~<br>~~I~~|~~Po~~<br>~~ee~~<br>~~I~~|20<br>~~Po~~<br>~~ee~~<br>~~I~~|~~Po~~<br>~~ee~~<br>~~I~~|~~Po~~<br>~~ee~~<br>~~I~~|mA<br>~~ee~~<br>~~I~~|
|**Compensation Loop for LED Driver(ICOMP)**<br>~~ee~~|||||||
|Gain bandwidthproduct<br>~~ee~~|GB_I<br>~~ee~~|75pF on ICOMP<br>~~ee~~|~~ee~~|1.0(5)<br>~~ee~~|~~ee~~|MHz<br>~~ee~~|
|Open loopDCgain<br>~~>~~|AV_I<br>~~>~~|ICOMP open<br>~~>~~|~~>~~|70(5)<br>~~>~~|~~>~~|dB<br>~~>~~|
|Input common-mode range<br>~~a~~|VCM_I<br>~~a~~|For design<br>~~a~~|-0.3(5)<br>~~a~~|~~a~~|+4(5)<br>~~a~~|V<br>~~a~~|
|Transconductance<br>~~a~~<br>~~a~~|GM_I<br>~~a~~<br>~~a~~|PWM = high<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|720<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|μA/V<br>~~a~~<br>~~a~~|
|Saturated output current<br>~~a~~<br>~~a~~|ISAT_I<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|~~a~~<br>~~a~~|90<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|μA<br>~~a~~<br>~~a~~|
|Low level clampvoltage<br>~~a~~<br>~~a~~|VICOMP_L<br>~~a~~<br>~~a~~|Normal operation<br>~~a~~<br>~~a~~|0.93<br>~~a~~<br>~~a~~|0.98<br>~~a~~<br>~~a~~|1.03<br>~~a~~<br>~~a~~|V<br>~~a~~<br>~~a~~|
|High level clampvoltage<br>~~a~~<br>~~a~~|VICOMP_H<br>~~a~~<br>~~a~~|Normal operation<br>~~a~~<br>~~a~~|2.35<br>~~a~~<br>~~a~~|2.47<br>~~a~~<br>~~a~~|2.6<br>~~a~~<br>~~a~~|V<br>~~a~~<br>~~a~~|
|**Output for System Voltage Feedback(VFB)**<br>~~a~~<br>~~a~~|||||||
|Reference voltage<br>~~a~~|VREF_VFB<br>~~a~~|~~a~~|1.182<br>~~a~~|1.2<br>~~a~~|1.218<br>~~a~~|V<br>~~a~~|
|Leakage current<br>~~a~~<br>~~a~~<br>~~ee~~<br>~~a~~|ILKG_VFB<br>~~a~~<br>~~a~~<br>~~a~~<br>~~ee~~<br>|Normal operation<br>~~a~~<br>~~a~~<br>~~ee~~<br>|~~a~~<br>~~a~~<br>~~ee~~<br>|~~a~~<br>~~a~~<br>~~ee~~<br>|0.2<br>~~a~~<br>~~a~~<br>~~ee~~<br>|μA<br>~~a~~<br>~~a~~<br>~~ee~~<br>|
|System over-voltage<br>protection threshold<br>~~ee~~<br>~~a~~|VOVP_VFB<br>~~a~~<br>~~ee~~<br>|~~ee~~<br>|~~ee~~<br>|124%<br>~~ee~~<br>|~~ee~~<br>|VREF_VFB<br>~~ee~~<br>|
|System open feedback<br>protection threshold<br>~~ee ~~<br>~~a ee~~<br>~~es~~|~~a~~<br> ~~ee~~<br>~~ee~~|DCOMP saturated<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|50%<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|VREF_VFB<br>~~ee~~<br>~~ee~~|
|System open feedback<br>protection delaytime<br>~~ee~~<br>~~es~~|~~ee~~|DCOMP saturated<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|1024<br>~~ee~~<br>~~ee~~|~~ee~~|cycles<br>~~ee~~|
|**Compensation Loop for System Voltage and Duty Cycle of the External MOSFET(DCOMP)**<br>~~ee~~<br>~~es~~<br>~~ee~~|||||||
|Gain bandwidthproduct<br>~~ee~~|GB_V<br>~~ee~~|75pF on DCOMP<br>~~ee~~|~~ee~~|1.0(5)<br>~~ee~~|~~ee~~|MHz<br>~~ee~~|
|Open loopDCgain<br>~~>~~|AV_V<br>~~>~~|DCOMP open<br>~~>~~|~~>~~|70(5)<br>~~>~~|~~>~~|dB<br>~~>~~|
|Low level clampvoltage<br>~~>~~|VDCOMP_L<br>~~>~~|Normal operation<br>~~>~~|0.93<br>~~>~~|0.98<br>~~>~~|1.03<br>~~>~~|V<br>~~>~~|
|High level clampvoltage<br>~~>~~|VDCOMP_H<br>~~>~~|Normal operation<br>~~>~~|2.35<br>~~>~~|2.48<br>~~>~~|2.6<br>~~>~~|V<br>~~>~~|
|Transconductance when<br>PWM is on<br>~~a~~<br>~~ae~~<br>~~ae~~|GM_DCOMP_ON<br>~~a~~<br>~~ee~~<br>~~ee~~<br>|PWM = high<br>~~a~~<br>~~ee~~<br>~~ee~~<br>|~~a~~<br>~~ee~~<br>~~ee~~<br>|680<br>~~a~~<br>~~ee~~<br>~~ee~~<br>|~~a~~<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>|μA/V<br>~~a~~<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>|
|Transconductance when<br>PWM is off<br>~~ae~~<br>~~ae~~<br>~~a~~|GM_DCOMP_OFFPWM = low<br>~~ee~~<br>~~ee~~<br>~~ee~~|PWM = low<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|~~ee~~<br>~~ee~~<br>~~**ee**~~|260<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|~~ee~~<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|μA/V<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|
|Saturated output current<br>when PWM is on<br>~~ae~~<br>~~ae~~<br>~~a~~|ISAT_DCOMP_ON<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~**ee**~~|~~ee~~<br>~~ee~~<br>~~**ee**~~|90<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|~~ee~~<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|μA<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>~~**ee**~~|
|Saturated output current<br>when PWM is off<br>~~ae ~~<br>~~a~~|ISAT_DCOMP_OFF<br> ~~ee~~<br>~~ee~~|~~**ee**~~|~~**ee**~~|45<br>~~**ee**~~|~~ee~~<br>~~**ee**~~|μA<br>~~ee~~<br>~~**ee**~~|
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2021 MPS. All Rights Reserved.
**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS **ELECTRICAL CHARACTERISTICS** _**(continued)**_ **VIN = 13V, TJ = 25°C, unless otherwise noted. IN = 13V, TJ = 25°C, unless otherwise noted. = 13V, TJ = 25°C, unless otherwise noted. J = 25°C, unless otherwise noted. = 25°C, unless otherwise noted. Parameter Symbol Condition Min Typ Max Units** ~~a~~ **LED Driver Protection (OVP, LED Short)**
**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER**
## **ELECTRICAL CHARACTERISTICS** _**(continued)**_
## **VIN = 13V, TJ = 25°C, unless otherwise noted. IN = 13V, TJ = 25°C, unless otherwise noted. = 13V, TJ = 25°C, unless otherwise noted. J = 25°C, unless otherwise noted. = 25°C, unless otherwise noted.**
|**Parameter**<br>~~a~~|**Symbolymbolmbol**<br>~~a~~|**Condition**<br>~~a~~|**Min**<br>~~a~~|**Typyp**<br>~~a~~|**Max**<br>~~a~~|**Units**<br>~~a~~|
|---|---|---|---|---|---|---|
|**LED Driver Protection (OVP, LED Short)(OVP, LED Short)OVP, LED Short), LED Short) LED Short))**<br>~~a~~|||||||
|LED over voltage protection<br>(OVP)threshold<br>~~a~~|VTH_OVP<br>~~a~~|~~a~~|2.25<br>~~a~~|2.40<br>~~a~~|2.55<br>~~a~~|V<br>~~a~~|
|OVP threshold hysteresis<br>~~GGG~~|~~GGG~~|~~GGG~~|~~GGG~~|200<br>~~GGG~~|~~GGG~~|mV<br>~~GGG~~|
|OVP to latch IC threshold<br>~~GGG~~|~~GGG~~|~~GGG~~|~~GGG~~|3<br>~~GGG~~|~~GGG~~|V<br>~~GGG~~|
|LEDx threshold for open<br>LED stringmark off<br>~~a~~<br>|~~ee~~|OVP triggered (test mode<br>required)<br>~~ee~~||100||mV|
|LEDx slow over voltage<br>threshold (for short LED<br>protection)<br>~~a~~|VTH_LEDxOV_SLOW<br> ~~ee~~|~~ee~~||4.9||V|
|LED short delaytime slow<br> <br>~~Ge~~|tD_LEDxOV_SLOW<br> ~~ee ~~<br>~~Ge ~~|~~ee~~<br> ~~GG~~|~~GG~~|5.8<br>~~GG~~||ms|
|LEDx fast over voltage<br>threshold|VTH_LEDxOV_FAST|||20||V|
|All LED strings short delay<br>time at low voltage||||200||ms|
|All LED strings short delay<br>time at high voltage||||12||ms|
|Thermalprotection threshold<br>~~Ge~~|~~Ge ~~|Risingedge<br> ~~GD~~|~~GD~~|150(5)<br>~~GD~~||°C|
|Thermal protection<br>hysteresis<br>~~a~~||||25(5)||°C|
|**LED Current Regulation(VLEDx, ISET)**|||||||
|ISET voltage<br>~~GG~~<br>~~pe~~|VISET<br>~~GG~~|~~GG~~<br>~~—————~~|1.53<br>~~GG~~<br>~~—————~~|1.58<br>~~GG~~<br>~~—————~~|1.63<br>~~GG~~<br>~~—————~~|V<br>~~GG~~<br>~~—————~~|
|LEDx average current<br>~~GG~~<br>~~pe~~<br>~~pe~~|ILED<br>~~GG~~|RISET= 320kΩ(trim),50mA<br>~~GG~~<br>~~—————~~|-1.5%<br>~~GG~~<br>~~—————~~|50<br>~~GG~~<br>~~—————~~|+1.5%<br>~~GG~~<br>~~—————~~|mA<br>~~GG~~<br>~~—————~~|
|||40% dimming20mA<br>~~—————~~<br>~~——————~~|-3%<br>~~—————~~<br>~~——————~~|20.3<br>~~—————~~<br>~~——————~~|+3%<br>~~—————~~<br>~~——————~~|mA<br>~~—————~~<br>~~——————~~|
|Current matching<br>~~pe~~<br>~~pe~~<br>~~pe~~|~~——————~~|ILED= 50mA<br>~~—————~~<br>~~——————~~|~~—————~~<br>~~——————~~|0.3<br>~~—————~~<br>~~——————~~|2<br>~~—————~~<br>~~——————~~|%<br>~~—————~~<br>~~——————~~|
|||ILED= 20mA(40%)<br>~~——————~~<br>~~——————~~|~~——————~~<br>~~——————~~|0.6<br>~~——————~~<br>~~——————~~|2.5<br>~~——————~~<br>~~——————~~|%<br>~~——————~~<br>~~——————~~|
|Minimum LEDx regulation<br>voltage<br>~~pe~~<br>~~pe~~|VLEDx<br>~~——————~~|ILED= 200mA<br>~~——————~~<br>~~——————~~|~~——————~~<br>~~——————~~|560<br>~~——————~~<br>~~——————~~|~~——————~~<br>~~——————~~|mV<br>~~——————~~<br>~~——————~~|
|||ILED= 60mA<br>~~——————~~|~~——————~~|176<br>~~——————~~|~~——————~~|mV<br>~~——————~~|
|Fault voltage (ISET/FAULT<br>pin voltage if a fault occurs)<br>~~pe~~<br>~~a~~|~~——————~~<br>~~a~~|Fault condition occurs<br>~~——————~~<br>~~a~~|~~——————~~<br>~~a~~|~~——————~~<br>~~a~~|0.2<br>~~——————~~<br>~~a~~|V<br>~~——————~~<br>~~a~~|
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER**
## **TYPICAL CHARACTERISTICS**
**VFB Reference vs. Temperature**
**==> picture [190 x 343] intentionally omitted <==**
**----- Start of picture text -----**<br>
1.21<br>1.205<br>1.2<br>1.195<br>1.19<br>1.185<br>-50 0 50 100<br>TEMPERATURE (°C)<br>VIN Rising Voltage vs.<br>Temperature<br>3.65<br>3.64<br>3.63<br>3.62<br>3.61<br>3.6<br>-50 0 50 100<br>TEMPERATURE ( C)<br>VIN RISING VOLTAGE (V)<br>VFB REFERENCE (V)<br>**----- End of picture text -----**<br>
**==> picture [186 x 169] intentionally omitted <==**
**----- Start of picture text -----**<br>
SYNC Rising Voltage vs.<br>Temperature<br>1.184<br>1.18<br>1.176<br>1.172<br>1.168<br>1.164<br>-50 0 50 100<br>TEMPERATURE ( C)<br>SYNC RISINING VOLTAGE (V)<br>**----- End of picture text -----**<br>
**VFB OVP vs. Temperature**
**==> picture [188 x 342] intentionally omitted <==**
**----- Start of picture text -----**<br>
1.5<br>1.495<br>1.49<br>1.485<br>1.48<br>1.475<br>-50 0 50 100<br>TEMPERATURE ( C)<br>VLED OVP Threshold vs.<br>Temperature<br>2.4<br>2.39<br>2.38<br>2.37<br>2.36<br>2.35<br>-50 0 50 100<br>TEMPERATURE ( C)<br>VLED OVP THRESHOLD (V)<br>VFB OVP (V)<br>**----- End of picture text -----**<br>
**==> picture [188 x 169] intentionally omitted <==**
**----- Start of picture text -----**<br>
SYNC Falling Voltage vs.<br>Temperature<br>0.22<br>0.21<br>0.2<br>0.19<br>0.18<br>0.17<br>-50 0 50 100<br>TEMPERATURE ( C)<br>SYNC FALLING VOLTAGE (V)<br>**----- End of picture text -----**<br>
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER**
## **TYPICAL CHARACTERISTICS** _**(continued)**_
## **ISET Voltage vs. Temperature**
**Quiescent Current vs. Temperature**
**==> picture [451 x 342] intentionally omitted <==**
**----- Start of picture text -----**<br>
1.65 430<br>1.64 420<br>1.63 410<br>1.62 400<br>1.61 390<br>a a<br>1.6 Mii| 380 in<br>-50 0 50 100 -50 0 50 100<br>TEMPERATURE ( C) TEMPERATURE ( C)<br>OPT High Level Voltage vs. OPT Low Level Voltage vs.<br>Temperature Temperature<br>2.275 0.79<br>2.27 0.78<br>2.265 0.77<br>2.26 0.76<br>2.255 0.75<br>aime ici<br>2.25 0.74<br>-50 0 50 100 -50 0 50 100<br>TEMPERATURE ( C) TEMPERATURE ( C)<br>OPT HIGH LEVEL VOLTAGE (V)<br>ISET VOLTAGE (V)<br>QUIESCENT CURRENT (mA)<br>OPT LOW LEVEL VOLTAGE (V)<br>**----- End of picture text -----**<br>
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER**
## **TYPICAL PERFORMANCE CHARACTERISTICS**
**VIN_AC = 220VAC, VLED = 44V, 150mA/string, 4 strings, analog dimming, VSYS = 5V, ISYS = 3A, TA = 25°C, unless otherwise noted.**
## **Standby Mode**
Constant voltage mode, ISYS = 0mA
## **Steady State**
Constant voltage mode
**==> picture [289 x 58] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VSYS RE | SE RE || ARI LU ||SE CH1: VSYS<br>CH2: VGATE CH2: VGATE<br>CH4: VSW<br>CH4: VSW<br>**----- End of picture text -----**<br>
**Load Transient** Constant voltage mode, ISYS = 0.2A to 3A
## **Start-Up**
Constant voltage mode
**==> picture [295 x 97] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH4: VS-SW<br>CH1: VSYS CH1: VSYS<br>CH2: VDCOMP CH2: VGATE<br>CH4:<br>VDCOMP<br>CH3: IPRI CH3: IPRI<br>**----- End of picture text -----**<br>
## **Shutdown**
Constant voltage mode
**LED Enabled**
**==> picture [293 x 78] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VSYS CH1: VSYS<br>CH4:<br>CH2: VGATE VICOMP<br>CH4: VDCOMP<br>CH3: IPRI ——— CH2: VLED<br>CH3: ILED<br>**----- End of picture text -----**<br>
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER**
## **TYPICAL PERFORMANCE CHARACTERISTICS** _**(continued)**_
**VIN_AC = 220VAC, VLED = 44V, 150mA/string, 4 strings, analog dimming, VSYS = 5V, ISYS = 3A, TA = 25°C, unless otherwise noted.**
## **Start-Up**
**==> picture [295 x 124] intentionally omitted <==**
**----- Start of picture text -----**<br>
LED Disabled<br>CH1: VSYS OT LO SO,——<br>|<br>SORE: qqqq<br>| CH1: VSYS<br>CH4: VICOMP q CH4: VICOMP<br>q<br>CH2: VDCOMP 2 | CH2:<br>qqq VDCOMP<br>|<br>|<br>CH3: ILED q CH3: ILED<br>**----- End of picture text -----**<br>
Constant current mode, duty = 80%
## **Shutdown**
Constant current mode, duty = 80%
## **Steady State**
Constant current mode, duty = 50%
**==> picture [293 x 98] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH4: VS-SW<br>CH4: VCH1: VICOMPSYS P CH1: VSYS<br>CH2: VGATE<br>CH2: VDCOMP 2<br>CH3: ILED CH3: ILED<br>**----- End of picture text -----**<br>
## **Load Transient**
Duty = 50%, ISYS = 0A to 3A
**One-String LED Open Fault** Constant current mode, duty = 50%
**==> picture [288 x 82] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH2: VGATE<br>CH3: ILED<br>CH1: VLED<br>CH1: VSYS CH2: VSYS<br>CH4: ISYS CH3: ILED<br>CH4: VICOMP<br>**----- End of picture text -----**<br>
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER**
## **TYPICAL PERFORMANCE CHARACTERISTICS** _**(continued)**_
**VIN_AC = 220VAC, VLED = 44V, 150mA/string, 4 strings, analog dimming, VSYS = 5V, ISYS = 3A, TA = 25°C, unless otherwise noted.**
## **LED String Open Fault (All)**
Constant current mode, duty = 25%
## **One-String Short Fault (2 LEDs)**
Constant current mode, duty = 25%
**==> picture [305 x 82] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VLED ] CH1: VLED<br>CH4: VGATE Sh i eeRk |<br>CH2: VSYS f ]|]| CH2: VSYS<br>CH3: ILED |]] CH3: ILED<br>CH4: VLEDx<br>**----- End of picture text -----**<br>
## **One-String Short Fault (LED+ to LED-)**
Constant current mode, duty = 25%
**==> picture [37 x 82] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VLED<br>CH2: VSYS<br>CH3: ILED<br>CH4: VLEDx<br>**----- End of picture text -----**<br>
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**==> picture [505 x 550] intentionally omitted <==**
**----- Start of picture text -----**<br>
MP4657A – 1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER<br>MPS<br>FUNCTIONAL BLOCK DIAGRAM<br>D2 VSYS<br>C2 M2<br>D3 R11 C3<br>R8<br>:<br>1 Voltage Limit<br>D4 SYNC Duty Cycle<br>L R9 o Gate m GATE - 16<br>Control<br>PWM 5 9<br>GND<br>——s UVLO_VDR VDRV 15<br>UVLO_VIN 6V (Refer to VIN/SOURCE) C6<br>VIN/ SOURCE 14<br>Delay UVLO_VIN<br>| | <] 3.6V<br>2 OPT<br>Level Adjust<br>R10<br>V SYS PWM PWM _N<br>1.24 * VREF 10µs OV_SYS<br>! R3 =<br>4\ 4 —<br>VREF G M_DCOMP_ON Duty Cycle<br>3 Ramp<br>VFB<br>core R4 G M_DCOMP_OFF . Ramp SYNC<br>Generator<br>L. C4 R7 4 DCOMP in<br>PWM _N LED1 7<br>IREF GM<br>ISET<br>PWM IREF<br>PWM<br>—— C5 R6 5 ICOMP S1 < G j M_I VMin VLED_REFLEDx 7 Min LED 1LED 2LED 3LED 4 . . . | ip ... LED2LED3 118<br>EN_CH1<br>R5 12 ISET/FAULT ISET Voltage Adjust DC_ ADIM Fault 200msdelay . .. LED4 10<br>LEDx<br>“ 13 ADIMP/PWM TS Dimming Control Dimming PWM DimminAnalog g DC_ADIMPWM LED Protection Management 6 5.8ms 12 ms delay ... All LEDx4.9V<br>3V = 10µs OV_SYS delay ... 20V<br>6 OVP 100mV<br>ae OV_LED S<br>2.4V/2.2V > 10µs .. < LEDx<br>.<br>**----- End of picture text -----**<br>
**Figure 1: Functional Block Diagram**
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** mpc
## **OPERATION**
The MP4657A is a single-stage flyback, 4-string LED driver and system voltage controller for LED backlighting on the secondary side. It controls the flyback power stage and an external N-channel MOSFET to regulate the system output voltage and LED current loop with integrated 4-string LED current balancing. With a 4V to 16V input voltage (VIN), the device outputs a direct driving signal to control the N- channel MOSFET to regulate the system output voltage. The device also outputs a compensation signal to control the primary-side flyback (or other power stage) through an optocoupler.
The device uses an individual control method for both the LED current and system voltage. When the PWM signal is effective, the MP4657A regulates the LED current loop through the flyback power stage and further regulates the system voltage by controlling the turning on and off of the external N-channel MOSFET. Soft switching can be achieved for the N-channel MOSFET to reduce voltage spikes. When the PWM signal is ineffective, the device directly controls the system voltage through the flyback power stage.
## **Gate Driver and System Start Up**
Figure 2 shows the MP4657A’s gate driver start-up. VDRV supplies the GATE driver, and the GATE signal’s amplitude (refer to VIN/SOURCE) is limited to 6V.
**==> picture [226 x 142] intentionally omitted <==**
**----- Start of picture text -----**<br>
D2 VSYS<br>C2 D3 R11 M2 | C3<br>R8 MP4657A<br>SYNC Voltage Limit<br>D4 R9 Gate GATE 16<br>Control<br>GND 9<br>UVLO_VDR 15 VDRV<br>6V (Refer to<br>VIN/SOURCE)<br>nl UVLO_VIN 14<br>3.6V VIN/SOURCE<br>SignalDuty PWM<br>**----- End of picture text -----**<br>
**Figure 2: MP4657A Gate Driver and Start Up**
Before start-up, the VIN/SOURCE voltage is below the under-voltage lockout (UVLO) threshold, and the MP4657A monitors the
VDRV voltage. After VDRV reaches its UVLO threshold, the MP4657A turns on the external N-channel MOSFET to regulate VSYS. The VIN/SOURCE voltage is charged until it reaches its UVLO threshold. Then the system logic starts to work. Next, the duty cycle signal and the PWM signal determine whether the external N-channel MOSFET should be turned on or off.
## **Switching Sequence and Soft-Switching**
Figure 3 shows the MP4657A’s operating sequence. The device GATE signal’s falling edge is synchronized to the primary flyback gate signal’s rising edge through the SYNC pin.
**==> picture [145 x 154] intentionally omitted <==**
**----- Start of picture text -----**<br>
GATE_ FLYBAC K<br>IPRI ISEC<br>I TRANS<br>SYNC SYNC<br>Edge Edge<br>SYNC<br>ID_LED<br>GATE<br>(VSYS<br>MOSFET)<br>IMOS<br>(VSYS<br>MOSFET) t1 t2 t3 t4<br>**----- End of picture text -----**<br>
**Figure 3: MP4657A Switching Sequence**
The falling edge of the SYNC signal synchronizes the falling edge of the GATE signal. This means that the N-channel MOSFET turns off when the primary-side flyback switch turns on. For most applications, the N-channel MOSFET turns off when the secondary side winding current is as low as 0A, thus voltage spikes are less likely to occur. The GATE signal’s turning on and duty cycle are controlled by the DCOMP. Before the N-channel MOSFET turns on, the secondary-side current goes through the LED winding. When the N-channel MOSFET turns on, the secondary-side current starts to transfer from the LED winding to the system voltage winding. Because there is leakage inductance, the N-channel MOSFET can turn on with zero current. Therefore, the switching loss for the N-channel MOSFET is very small.
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS
## **LED Current and System Voltage Regulation**
The MP4657A accurately regulates both the LED current loop and the system voltage with a single flyback power stage.
When the PWM signal is ineffective and the LED stage is disabled, the MP4657A regulates the system output voltage by controlling the flyback power stage and the N-channel MOSFET is fully on (see Figure 4).
**==> picture [229 x 58] intentionally omitted <==**
**----- Start of picture text -----**<br>
EA_V<br>VFB DCOMP_PWM OFF<br>VREF Total VN-Channel SYS Power VSYS<br>Power MOSFET Fully On<br>Flyback<br>VLEDxMin EA_I ICOMP Control OFF LED Stage Power<br>V —. LED_REF L I a nn<br>**----- End of picture text -----**<br>
## **Figure 4: MP4657A Control Scheme when PWM Signal is Ineffective**
When the PWM signal is effective, the MP4657A regulates the LED current loop through the flyback power stage (see Figure 5). The system voltage is regulated through the duty cycle control of the N-channel MOSFET. The integrated, individual control for the N- channel MOSFET achieves soft switching without voltage spikes.
**==> picture [232 x 91] intentionally omitted <==**
**----- Start of picture text -----**<br>
EA_D<br>VFB DCOMP_PWM ON N-Channel VSYS<br>VREF 7 MOSFET Control Duty<br>Total<br>Flyback Power<br>VLEDxMin EA_I ICOMP Control LED Power Stage VLEDx BalanceCurrent ILED1–4<br>VLED_REF<br>Figure 5: MP4657A Control Scheme when PWM pe [a] }<br>**----- End of picture text -----**<br>
## **Figure 5: MP4657A Control Scheme when PWM Signal is Effective** _**LED Current Loop Regulation when PWM Signal is Effective (ICOMP Loop)**_
In the LED current regulation loop, the minimum VLEDx is fed back and compared to the internal reference VLED_REF (this reference changes with the set current). The internal error amplifier (EA) regulates the average value of the minimum VLEDx to the VLED_REF. EA’s output is connected to the external current-loop compensation network on the ICOMP pin through an inner switch (S1).
When PWM signal is effective, S1 is on, and the output of the error amplifier is connected to the external compensation network on the ICOMP pin. The minimum VLEDx is regulated by this control loop and the flyback power is configured by the ICOMP voltage. When PWM
signal is ineffective, S1 turns off and the compensation network on ICOMP is disconnected from the error amplifier. ICOMP holds its voltage value until the PWM signal is effective again. The error amplifier output is pulled low when PWM is ineffective. _**System Output Voltage Regulation (DCOMP Loop)**_
The system voltage is fed back to the VFB pin through a voltage divider. When PWM signal is ineffective, the MP4657A regulates the system voltage by controlling the flyback power stage while the N-channel MOSFET is fully on. The internal voltage loop error amplifier regulates the average value of the VFB voltage to the reference voltage. The error amplifier output is connected to the external voltage loop compensation network on the DCOMP pin. The system voltage is regulated by this control loop, and the flyback power is configured by the DCOMP voltage.
When PWM signal is effective, the flyback power is controlled by ICOMP, and the system voltage is regulated by DCOMP controlling the N-channel MOSFET’s duty cycle. The VFB pin feeds back the system voltage, which is compared to the internal reference voltage. The error amplifier outputs an error signal to the DCOMP pin. The error amplifier’s gain when PWM is effective is different from that when PWM is ineffective. The DCOMP voltage determines the duty cycle of the N-channel MOSFET (see Figure 6).
**==> picture [215 x 152] intentionally omitted <==**
**----- Start of picture text -----**<br>
OPT<br>Level Adjust GATE<br>R10 V SYS PWM PWM _N Driver<br>R3 V REF GM_DCOMP_ON Duty<br>VFB Cycle<br>Ramp<br>{ > B S<br>SSF R4 GM_DCOMP_OFF Ramp SYNC<br>eae _ DCOMP en e l Generator<br>C4 R7 PWM _N<br>PWM IREF GM LED 1<br>av a l<br>PWM<br>— C5 R6 ICOMP S1 T GM_I VLEMin VD_REF y LEDx Min LED 1LED 2LED 3LED 4 ... Y LED 2LED 3<br>LED 4<br>**----- End of picture text -----**<br>
**Figure 6: MP4657A Control Diagram**
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** MPS
## **Dimming Control**
The MP4657A provides analog dimming and PWM dimming for the LED current through the ADIMP/PWM pin. For analog dimming, apply a pulse signal with frequency exceeding 5kHz to this pin. In this mode, the PWM signal is always effective unless it is removed. The duty cycle of the PWM signal configures the LED current amplitude. For PWM dimming, apply a pulse signal with frequency below 5kHz to this pin. In this mode, the PWM signal is effective when the pulse is high and is ineffective when the pulse is low. The LED current is chopped by the PWM signal.
## **Protections**
The MP4657A integrates rich protections for the system voltage stage and the LED driver stage.
## **System Voltage Stage Protections**
The protections for the system voltage stage include system over-voltage protection (OVP) and feedback open loop protection.
## _**System Over-Voltage Protection (OVP)**_
The VFB pin senses the system voltage for regulation and over-voltage protection (OVP). If the VFB voltage exceeds the reference voltage by 24%, system OVP is triggered. In this case, if PWM signal is ineffective, the OPT pin is clamped to 3.3V to stop primary switching. If system OVP is triggered when PWM signal is effective, the GATE signal turns off. If OVP pin voltage exceeds 3V, the IC latches off. This function protects the system voltage from damaging the device.
## _**Feedback Open Loop Protection**_
If the VFB voltage drops below 50% of the reference voltage and DCOMP is saturated for 1024 switching cycles, the IC latches off and the fault indicator is pulled low.
## **LED Driver Stage Protections**
Fault protections for the LED driver stage include LED open protection, LED short protection and LEDx pin short to ground protection.
## _**LED Open Protection**_
The output voltage of the LED strings is sensed on the OVP pin. LED open protection is achieved by monitoring the OVP pin and LEDx (x = 1~4) voltages. If one or more LED strings
have an open condition, the respective LEDx voltage is pulled to ground while the LED voltage keeps increasing until the OVP pin voltage reaches the OVP threshold (about 2.4V). When the OVP pin voltage exceeds 2.4V for 10μs, LED open protection is triggered. The control loop for the LED stage is disabled, and the MP4657A regulates the system voltage as in PWM ineffective condition. The IC marks off the open LED strings that have a VLEDx below 100mV. The remaining LED strings discharge the LED stage output voltage, so the OVP pin voltage decreases. After the voltage drops below the OVP threshold, the LED control loop recovers, and the minimum LEDx voltage of the remaining LED strings is regulated. The fault indicator does not function in this condition when there are functional LED strings.
If all LED strings have an open condition, they are all marked off, and the LED control loop is disabled. The system voltage is regulated as in PWM ineffective condition and the fault indicator is pulled low.
## _**LED Short Protection**_
The LEDx voltage is monitored for LED short conditions. If an LED string is shorted, the respective LEDx voltage rises. If this voltage exceeds 4.9V for 5.8ms, the IC marks off the string for having a short condition. Meanwhile, all other strings continue working.
If all of the LEDx voltages (except the marked off strings) exceed 4.9V, it takes 200ms to trigger LED short protection. This prevents mistriggering short protection if OVP is triggered or if the duty cycle of analog dimming changes. If all of the LEDx voltages (except the marked off strings) exceed 20V for 12ms, all LED strings short protection is triggered.
## _**LEDx Short to Ground Protection**_
If ICOMP is saturated and the LEDx voltage is low for 100ms, the IC triggers LEDx short to ground protection. The LED control loop is disabled and the fault indicator is pulled low.
To recover the LED loop from this fault, toggle the ADIMP/PWM pin. Pull ADIMP/PWM low for longer than 25ms, then pull it high. The fault indictor is reset and the ISET pin sets the LED current.
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## **Thermal Protection**
Thermal protection is integrated in the MP4657A. If the die temperature exceeds the over-temperature threshold, the IC stops working until the die temperature drops to its safe range. Then the IC returns to normal operation.
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## **APPLICATION INFORMATION**
## **Gate Signal Synchronization (SYNC)**
The SYNC pin synchronizes the GATE signal. Its falling edge synchronizes the GATE signal’s turning off. Connect a voltage divider from the secondary winding to this pin to indicate the turning on of the primary-side MOSFET.
## **System Voltage Feedback (VFB)**
The VFB pin feeds back the system voltage. Connect this pin to the system voltage with a voltage divider. This voltage divider determines the system voltage, calculated with Equation (1):
**==> picture [181 x 28] intentionally omitted <==**
Where RVFBH and RVFBL are the high-side and low-side resistor of the voltage divider, respectively.
The VFB pin is monitored for system overvoltage protection. If the VFB voltage exceeds the reference voltage by 24% for 10µs, system OVP is triggered.
## **LED Open Protection**
The OVP pin monitors the output LED voltage and can trigger LED open protection. Connect this pin to the output LED voltage through a voltage divider. The over-voltage protection threshold can be estimated with Equation (2):
**==> picture [195 x 28] intentionally omitted <==**
Where ROVPH and ROVPL are the high-side and low-side resistors of the voltage divider, respectively.
## **LED Current Setting (ISET/FAULT)**
The LED current (ILED) is set by the resistor on the ISET/FAULT pin. The ISET/FAULT pin outputs a 1.6V voltage and its sourcing current determines each channel’s LED current. ILED can be estimated with Equation (3):
**==> picture [193 x 28] intentionally omitted <==**
## **Gate Driver Supply and GATE (VDRV, GATE)**
The VDRV pin supplies power to the gate driver (refer to the VIN/SOURCE pin). Connect a sufficient voltage source to this pin to supply the gate driver, and bypass this supply to the VIN/SOURCE pin with a 1μF ceramic capacitor. The VDRV pin can handle a maximum 53V voltage (refer to GND), and the GATE signal is limited to 6V (refer to VIN/SOURCE).
In primary flyback power stage applications, the VDRV can generally be supplied from the secondary side winding of the power transformer.
Connect the GATE signal to the N-channel MOSFET directly or using a driving resistor.
## **Selecting the Turn Ratios of the Power Transformer**
The power transformer includes three power windings: the primary-side winding (NP), the secondary LED winding (NLED) and the secondary system voltage winding (NSYS). To design the turn ratios of the power transformer, follow the instructions below:
1. Design the turn ratio between the primaryside winding and the secondary LED winding (NP:NLED).
The maximum voltage stress on the primary-side switch which occurs at maximum input AC voltage and the maximum output LED voltage can be calculated with Equation (4):
**==> picture [230 x 23] intentionally omitted <==**
Where VIN_AC_MAX is the maximum input AC voltage, VDIODE is the forward voltage of the rectifier diode, and VOV_LED is over-voltage protection point of the output LED voltage.
Consider the leakage inductance of the flyback transformer, and assume there is a 60V spike voltage on the primary-side switch, as well as a 10% derating of the switch voltage capability. VDS_PRI can be estimated with Equation (5):
**==> picture [191 x 14] intentionally omitted <==**
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Where VRATING_PRI is the rating voltage of the primary switch.
Calculate NP:NLED with Equation (6):
**==> picture [235 x 25] intentionally omitted <==**
2. Design the turn ratio between the LED winding and the system voltage winding (NLED:NSYS).
Ensure that the system voltage is below the reflecting voltage from the LED winding under the minimum output LED voltage. This relationship can be estimated with Equation (7):
**==> picture [189 x 44] intentionally omitted <==**
Where VLED_MIN is the minimum output LED voltage. Choose a 15% margin for production design, calculated with Equation (8):
**==> picture [202 x 29] intentionally omitted <==**
## **Selecting the External N-Channel MOSFET**
The voltage stress on the external N-channel MOSFET can be estimated with Equation (9):
**==> picture [223 x 31] intentionally omitted <==**
The maximum voltage stress occurs at the maximum input AC voltage. Considering the small voltage spike and the derating of the MOSFET voltage, choose a 20% margin. Estimate the voltage rating of the external N- channel MOSFET with Equation (10):
The average current flowing through the N- channel MOSFET is equal to the output current of the system voltage. This flowing current is a pulse waveform, and its RMS current is much greater than the average value. Assume that the RMS current is 1.5 to 2 times greater than the average current, estimated with Equation (11):
**==> picture [162 x 15] intentionally omitted <==**
Where IRMS_EXT is the RMS current through the N-channel MOSFET, and ISYS is the output current of the system output voltage.
The switching loss from the N-channel MOFET’s soft switching is generally low. The rating current for the N-channel MOSFET should be 2 to 3 times of the RMS current. Consider thermal loss and power loss when selecting the RDS(ON) and package size for the N-channel MOSFET.
## **PCB Layout Guidelines**
Efficient PCB layout is important to achieve reliable operation, good EMI performance and excellent thermal performance. For the best results, follow the guidelines below:
1. Minimize the power stage loop area. This includes the primary loop (input capacitor, transformer, and MOSFET-sense resistor), as well as the secondary winding loop (transformer, rectifier, and diode-output capacitor).
2. The output loop GND and control circuit GND should be separated, and only connected at GND pin.
3. Place the peripheral electronic components (such as those for VIN/SOURCE, VFB, SYNC, DCOMP, and ICOMP) close to the IC to decouple noise.
**==> picture [234 x 25] intentionally omitted <==**
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## **TYPICAL APPLICATION CIRCUT**
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D 1<br>TM MUR340T3G<br>Flyback<br>R1<br>750kΩ<br>85 V to 265VAC 380V Bus100 V to NP NLED C133µF/ 100V 30kΩR2<br>M1<br>NSYS<br>D2 M2<br>Flyback MBR20150FCT AM7432N VSYS<br>Controller<br>C2 R3<br>47nF C3 31.6kΩ<br>D3 R11 470µF/ 25V<br>1N4148 100Ω R4<br>10kΩ<br>R8<br>100kΩ MP4657A<br>1 16<br>D4 SYNC GATE<br>1N4148 R9<br>10kΩ 2 15<br>OPT VDRV<br>C6<br>R10 3 VFB VIN/ SOURCE 14 1µF<br>1kΩ C4 R7<br>PC817 220nF 20kΩ 4 DCOMP ADIMP/ PWM 13 PWM or ADIM Pulse<br>R6 R5<br>750Ω 5 12 200kΩ<br>ICOMP ISET/ FAULT<br>C5<br>2.2µF 6 11<br>OVP LED3<br>7 LED1 LED4 10<br>8 9<br>LED2 GND<br>**----- End of picture text -----**<br>
**Figure 7: Typical Application Circuit (MP4657A Flyback 4-String LED Driver and System Voltage Regulation Scheme)**
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**MP4657A** _**–**_ **1-STAGE FLYBACK, 4-STRING LED DRIVER AND VOLTAGE CONTROLLER** ee
## **PACKAGE INFORMATION**
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SOIC-16<br>0 . 386( 9 . 80)<br>0 . 394(10 . 00) 0 . 024(0 . 61) 0 . 050(1 . 27)<br>16 9<br>0 . 063<br>(1 . 60 )<br>HAA A'A AA EF Et Ent EH<br>0 . 150 0 . 228<br>( 3 . 80 ) (5 . 80) 0 . 213<br>PIN 1 ID 0 . 157 0 . 244 (5 . 40)<br>(4 . 00) (6 . 20)<br>arsepessens ge| Hhailag atin<br>1 8<br>ol e HOGBHgd<br>TOP VIEW RECOMMENDED LAND PATTERN<br>0 . 053(1 . 35)<br>0 . 069(1 . 75)<br>SEATING PLANE 0 . 0075(0 . 19 )<br>0 . 0098(0 . 25)<br>0 . 013(0 . 33) 0 . 050(1 . 27) 0 . 004(0 . 10 )<br>0 . 020(0 . 51) BSC 0 . 010(0 . 25) SEE DETAIL "A"<br>**----- End of picture text -----**<br>
**==> picture [55 x 8] intentionally omitted <==**
**----- Start of picture text -----**<br>
FRONT VIEW<br>**----- End of picture text -----**<br>
**==> picture [45 x 8] intentionally omitted <==**
**----- Start of picture text -----**<br>
SIDE VIEW<br>**----- End of picture text -----**<br>
**0 . 010(0 . 25) x 45 o 0 . 020(0 . 50) GAUGE PLANE 0 . 010(0 . 25) BSC** ~~S~~ s **0o- 8o 0 . 016(0 . 41)** ~~re~~ **0 . 050(1 . 27)** | **DETAIL A**
- **NOTE: 1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN BRACKET IS IN MILLIMETERS. 2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURR.**
- 7 **3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH**
- **2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,**
- **3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.**
- **4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.004'' INCHES MAX.**
- **5) DRAWING CONFORMS TO JEDEC MS-012, VARIATION AC.**
- **6) DRAWING IS NOT TO SCALE.**
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## **CARRIER INFORMATION**
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Pin1 1 1 1 1<br>——><br>Feed Direction<br>ABCD ABCD ABCD ABCD<br>**----- End of picture text -----**<br>
|**Part Number**|**Package**<br>**Description**|**Quantity/**<br>**Reel**|**Quantity/**<br>**Tube**|**Quantity/**<br>**Tray**|**Reel**<br>**Diameter**|**Carrier**<br>**Tape**<br>**Width**|**Carrier**<br>**Tape**<br>**Pitch**|
|---|---|---|---|---|---|---|---|
|MP4657AGS-Z|SOIC-16|2500|50|N/A|13in|16mm|8mm|
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## **REVISION HISTORY**
|**Revision #**<br>~~pp~~|**Revision Date**<br>~~pp~~|**Description**<br>~~pp~~|**Pages Updated**<br>~~pp~~|
|---|---|---|---|
|1.0<br>~~pp~~|11/03/2021<br>~~pp~~|Initial Release<br>~~pp~~|-<br>~~pp~~|
**Notice:** The information in this document is subject to change without notice. Please contact MPS for current specifications. Users should warrant and guarantee that third-party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications.
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Updated at June 3, 2026
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