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MP4657BGS-P
LED Driver, AC / DC, -40 to 125 °C, 4 Outputs, Flyback, 350 kHz, SMD, 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: -
- Output Voltage Max: -
- 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 | 500 |
| Price | 1.18 € |
| Current stock | 500+ |
| Lead time | 30 days |
Datasheet
## _**MP4657B**_ **Single-Stage Flyback, 4-String LED Driver and System Voltage Controller** mes **DESCRIPTION FEATURES**
The MP4657B 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 the system supply 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 for regulating the system supply voltage. The device also outputs a compensation signal to control the primary-side flyback (or other power stage) through an optocoupler.
The MP4657B induces pulse-width modulation (PWM) dimming and analog dimming to the LED current through the ADIMP/PWM pin. For analog dimming, apply a pulse signal with a >5kHz frequency to this pin. For PWM dimming, apply a pulse signal with a <5kHz frequency.
The device uses an individual control method for the LED current (ILED) and system voltage (VSYS). When the PWM signal is effective, the MP4657B regulates the ILED loop through the flyback power stage and further regulates VSYS 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 VSYS through the flyback power stage.
The MP4657B features numerous 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. System voltage stage protections include over-voltage protection (OVP) and feedback open-loop protection. The device also offers 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
- High-Efficiency, Low LEDx Regulation Voltage
- 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 the 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 MP4657B is available in an SOIC-16 package.
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MP4657B Rev. 1.0 11/11/2021
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **TYPICAL APPLICATION**
**==> picture [466 x 305] intentionally omitted <==**
**----- Start of picture text -----**<br>
TM D1<br>Flyback<br>R1<br>AC 100V to NP NLED C1<br>85V to 265V 380V Bus R2<br>M1 7 bts<br>NSYS Hy fy<br>Flyback D2 VSYS<br>Controller<br>C2 M2 C3 R3<br>D3 R11 R4<br>R8<br>1 SYNC GATE 16<br>D4<br>R9<br>; 2 OPT : VDRV 15 a<br>: MP4657B F E C6 Ff<br>3 VFB VIN/SOURCE 14<br>R10<br>C4 R7 4 DCOMP ADIMP/PWM 13 PWM or ADIM_Pulse<br>C5 R6 5 ICOMP ISET/FAULT 12 R5<br>6 OVP LED3 11<br>7 LED1 LED4 10<br>8 LED2 GND 9<br>E |<br>**----- End of picture text -----**<br>
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MP4657B Rev. 1.0 11/11/2021
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **ORDERING INFORMATION**
|**Part**<br>**Number***|**Package**|**Top Marking**|**MSL Rating**|
|---|---|---|---|
|MP4657BGS|SOIC-16|_See Below_|2|
* For Tape & Reel, add suffix -Z (e.g. MP4657BGS-Z).
## **TOP MARKING**
MPS: MPS prefix YY: Year code WW: Week code MP4657B: Part number LLLLLLLLL: Lot number
## **PACKAGE REFERENCE**
**==> picture [210 x 217] 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>**----- End of picture text -----**<br>
**SOIC-16**
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MP4657B Rev. 1.0 11/11/2021
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **PIN FUNCTIONS**
|**Pin #**<br>~~a ~~<br>~~ee~~|**Name**<br> ~~a ee~~<br>~~ee~~|**Description**<br>~~ee~~<br>~~ee~~|
|---|---|---|
|1<br>~~ee~~|SYNC<br>~~ee~~|**Synchronization pin.**This pin synchronizes the gate signal to the input signal of SYNC<br>pin. Connect this pin to the secondary-side winding of the flyback transformer through a<br>voltage divider. Its fallingedge synchronizes thegate signal turningoff.<br>~~ee~~|
|2<br>~~ee~~<br>~~a~~|OPT<br>~~ee~~<br>~~a~~|**Optocoupler.**This pin outputs the compensation signal. Connect this pin to the external<br>optocoupler to control the flyback.<br>~~ee~~|
|3<br>~~i~~|VFB<br>~~i~~|**System voltage feedback.**Connect this pin to the system voltage (VSYS) through a<br>voltage divider.|
|4<br>~~i~~|DCOMP<br>~~i~~|**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 external<br>N-channel MOSFET. When PWM is ineffective, this pin compensates the system voltage<br>control loop with a differential gain and controls the flyback power stage.|
|5<br>~~i~~|ICOMP<br>~~i~~|**Compensation for the LED driver stage.**The ICOMP pin compensates the LED driver<br>loop and controls the flyback power stage when the PWM signal is effective. This pin<br>holds its voltage value when the PWM signal is ineffective.|
|6<br>~~a~~<br>~~pe~~|OVP<br>~~a~~<br>|**Over-voltage protection (OVP) for the LED stage.**Connect this pin to the output of the<br>LED voltage through a voltage divider.|
|7<br>~~pe~~|LED1<br>|**LED string 1 cathode.**|
|8<br>~~pea~~|LED2<br>~~a~~|**LED string 2 cathode.**|
|9<br>~~a~~|GND<br>~~a~~|**Ground.**|
|10<br>~~a~~|LED4<br>~~a~~|**LED string 4 cathode.**|
|11<br>~~a~~|LED3<br>~~a~~|**LED string 3 cathode.**|
|12<br>~~—————EE~~|ISET/FAULT<br>~~—————EE~~|**LED current setting pin and fault indicator.**This pin sets the LED current (ILED) under<br>normal conditions. Connect a resistor from the ISET/FAULT pin to ground to set ILED.<br>Thispin ispulled low if a fault occurs.<br>~~—————EE~~|
|13<br>~~—————EE~~|ADIMP/PWM**Dimmin**<br>~~—————EE~~|**Dimming signal inputpin.**<br>~~—————EE~~|
|14<br>~~a~~|VIN/SOURCE**Power supply input pin.**<br>~~a~~|**Power supply input pin.**The gate signal is also referred to this pin.|
|15<br>~~a~~<br>~~a~~|VDRV<br>~~a~~<br>~~a~~|**Supply voltage for the gate driver.**Bypass this pin to VIN/SOURCE with a ceramic<br>capacitor.|
|16<br>~~a~~<br>~~a~~|GATE<br>~~a~~<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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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **ABSOLUTE MAXIMUM RATINGS**[(1)]
**==> picture [238 x 163] intentionally omitted <==**
**----- Start of picture text -----**<br>
|||
|---|---|
|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 regulator 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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MP4657B Rev. 1.0 11/11/2021
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/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**
**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **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>~~a~~|||||||
|VINsupply range<br>~~a~~|~~a~~|~~a~~|4<br>~~a~~|~~a~~|16<br>~~a~~|V<br>~~a~~|
|VINUVLO|VUVLO_VIN||3.3|3.6|3.9|V|
|VINUVLO hysteresis<br>~~a~~|VHYS_UVLO_VIN<br>|||350<br>~~tt~~<br>|~~tt~~<br>|mV<br>~~tt~~<br>|
|Quiescent current<br>~~ttt~~<br>~~a~~|IQ<br>~~ttt~~<br>|PWM = 0, GATE = high,<br>VIN= 5V,no load<br>~~ttt~~<br>|~~ttt~~<br>|~~ttt~~<br>~~tt~~<br>|0.5<br>~~ttt~~<br>~~tt~~<br>|mA<br>~~ttt~~<br>~~tt~~<br>|
|**Gate Driver Supply Voltage (VDRV, Referred to VIN/SOURCE, Unless Otherwise Noted)**<br>~~ttt~~<br>~~tt~~<br>~~a~~<br>~~ee~~|||||||
|Voltage range<br>~~a ~~|VDRV<br> ~~ee~~|Refer to GND<br>~~ee~~|6.5<br>~~ee~~|~~tt~~<br>~~ee~~<br>~~ee~~|48<br>~~tt~~<br>~~ee~~|V<br>~~tt~~<br>~~ee~~|
|VDRV UVLO||VIN = 5V|5.3|5.8<br>~~ee~~|6.3|V|
|Hysteresis for VDRV UVLO<br>~~Oe~~|~~Oe~~|~~Oe~~|~~Oe~~|210<br>~~Oe~~|~~Oe~~|mV<br>~~Oe~~|
|**Gate Driver(GATE, for External MOSFET on VSYSTEM)**<br>~~Oe~~<br>~~aeeeee ee~~|||||||
|GATE voltage (refer to<br>VIN/SOURCE)<br>~~ae~~<br>|VGATE<br>~~ee~~<br>|VDRV - VIN/SOURCE = 14V<br>~~ee~~<br>|~~ee ee~~<br>|5.7<br>~~ee~~<br>|~~ee~~<br>|V<br>~~ee~~<br>~~—~~|
|Output source current<br>~~ae ~~<br>~~ye~~|ISOURCE_GATENWith 1nF load<br> ~~ee~~<br>~~ye~~|With 1nF load<br>~~ee ~~<br>~~ye~~|~~ee ee~~<br>~~ye~~|0.5(5)<br>~~ee~~<br>~~ye~~|~~ee~~<br>~~ye~~|A<br>~~ee~~<br>~~ye—~~|
|Output sink current<br>~~ye~~|ISINK_GATEN<br>~~ye~~|With 1nF load<br>~~ye~~|~~ye~~|1(5)<br>~~ye~~|~~ye~~|A<br>~~ye—~~|
|**Analog and PWM Dimming (ADIMP/PWM)**<br>~~—~~<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>~~a~~|VADIMP_LO||||0.7|V|
|ADIMP/PWMpull-down resistor R<br>~~a~~<br>~~a~~|ull-down resistor RADIMP_DOWN<br>~~ee~~|~~ee~~|~~ee~~|1.6||MΩ|
|Analog dimming input<br>frequencyrange<br>~~a~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee ee~~|5<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|100<br>~~ee~~<br>~~ee~~|kHz<br>~~ee~~<br>~~ee~~|
|Duration time to disable the<br>LED loop<br>~~ee~~<br>~~a~~|~~ee~~<br>~~ee~~<br>~~a~~<br>~~ee~~|EN LED<br>~~ee~~<br>~~ee ~~<br>~~a~~<br>~~ee ee~~|~~ee~~<br> ~~ee~~<br>~~a~~<br>~~ee~~|25<br>~~ee~~<br>~~a~~<br>~~ee~~|~~ee~~<br>~~a~~<br>~~ee~~|ms<br>~~ee~~<br>~~a~~<br>~~ee~~|
|**SYNC**<br>~~a~~<br>~~ee~~<br>~~ee ee~~|||||||
|SYNC logic high threshold<br>~~a~~<br>|VSYNC_HI<br>||||1.3<br>|V<br>~~—~~|
|SYNC logic low threshold<br>~~ye~~|VSYNC_LOW<br>~~ye~~|~~ye~~|0.1<br>~~ye~~|~~ye~~|~~ye~~|V<br>~~ye—~~|
|SYNC input frequencyrange<br>~~ye~~|~~ye~~|~~ye~~|20<br>~~ye~~|~~ye~~|350<br>~~ye~~|kHz<br>~~ye—~~|
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **ELECTRICAL CHARACTERISTICS** _**(continued)**_
**VIN = 13V, TJ = 25°C, unless otherwise noted.**
|**Parameter**<br>~~eG~~|**Symbol**<br>~~eG~~|**Condition**<br>~~eG~~<br>~~Cs~~|**Min**<br>~~eG~~<br>~~Cs~~|**Typ**<br>~~eG~~|**Max**<br>~~eG~~|**Units**<br>~~eG~~|
|---|---|---|---|---|---|---|
|**OPT**<br>~~Cs~~|||||||
|OPT output voltage range<br>~~a~~|~~ee~~|Normal operation H (typical<br>maximum output voltage<br>during normal operation)<br>~~ee~~|~~ee~~|2.3<br>~~ee~~|~~ee~~|V<br>~~ee~~|
|~~a~~|~~ee~~|Normal operation L (typical<br>minimum output voltage<br>duringnormal operation)<br>~~ee~~|~~ee~~|0.8<br>~~ee~~|~~ee~~|V<br>~~ee~~|
|OPT output voltage when<br>latched off<br>~~a~~<br>~~a~~|~~ee~~|~~ee~~|~~ee~~|3.3<br>~~ee~~|~~ee~~|V<br>~~ee~~|
|Source current capability<br>~~GD~~|IOPT<br>~~GD~~|~~GD~~|20<br>~~GD~~|~~GD~~|~~GD~~|mA<br>~~GD~~|
|**Compensation Loop for LED Driver(ICOMP)**|||||||
|Gain bandwidthproduct<br>~~se~~|GB_I<br>~~se~~|75pF on ICOMP<br>~~GO~~<br>~~ee~~|~~GO~~<br>~~ee~~|1(5)<br>~~GO~~<br>~~ee~~|~~ee~~|MHz|
|Open-loopDCgain<br>~~se~~<br>~~ee~~|AV_I<br>~~se ~~<br>~~ee~~|ICOMP open<br> ~~GO~~<br>~~ee~~<br>~~ee~~|~~GO~~<br>~~ee~~<br>~~ee~~|70(5)<br>~~GO~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|dB<br>~~ee~~|
|Input common-mode range<br>~~ee~~|VCM_I<br>~~ee~~|For design<br>~~ee~~<br>~~ee~~<br>~~ee~~|-0.3(5)<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|+4(5)<br>~~ee~~<br>~~ee~~<br>~~ee~~|V<br>~~ee~~|
|Transconductance<br>~~ee~~<br>~~ee~~|GM_I<br>~~ee~~<br>~~ee~~|PWM=High<br>~~ee~~<br>~~ee ~~<br>~~ee~~<br>~~ee~~|~~ee~~<br> ~~ee ~~<br>~~ee~~<br>~~ee~~|720<br>~~ee~~<br> ~~ee ~~<br>~~ee~~<br>~~ee~~|~~ee~~<br> ~~ee~~<br>~~ee~~<br>~~ee~~|μA/V<br>~~ee~~<br>~~ee~~|
|Saturated output current<br>~~ee~~|ISAT_I<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|90<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|μA<br>~~ee~~|
|Low-level clampvoltage<br>~~ee~~<br>~~ee~~|VICOMP_L<br>~~ee~~<br>~~ee~~<br>~~ee~~|Normal operation<br>~~ee~~<br>~~ee ~~<br>~~ee~~<br>~~De~~|~~ee~~<br> ~~ee ~~<br>~~ee~~<br>~~De~~|1<br>~~ee~~<br> ~~ee ~~<br>~~ee~~<br>~~De~~|~~ee~~<br> ~~ee~~<br>~~ee~~|V<br>~~ee~~<br>~~ee~~|
|High-level clampvoltage<br>~~eG~~|VICOMP_H<br>~~ee~~<br>~~eG~~|Normal operation<br>~~eG~~<br>~~De~~|~~eG~~<br>~~De~~|2.5<br>~~eG~~<br>~~De~~|~~eG~~|V<br>~~eG~~|
|**Output for System Voltage Feedback(VFB)**<br>~~De~~<br>~~ve~~|||||||
|Reference voltage<br>~~ve~~|VREF_VFB<br>~~ve~~|~~ve~~|1.182<br>~~ve~~<br>~~GO~~|1.2<br>~~ve~~<br>~~GO~~|1.218<br>~~ve~~<br>~~GO~~|V<br>~~ve~~|
|Leakage current<br>~~eG~~|ILKG_VFB<br>~~eG~~|Normal operation<br>~~eG~~|~~eG~~<br>~~GO~~|~~eG~~<br>~~GO~~|0.2<br>~~eG~~<br>~~GO~~|μA<br>~~eG~~|
|System over-voltage<br>protection(OVP)threshold<br>~~eG~~<br>~~a~~|VOVP_VFB<br>~~eG~~<br>~~a~~|~~eG~~<br>~~a~~|~~eG~~<br>~~GO~~<br>~~a~~|1.24<br>~~eG~~<br>~~GO~~<br>~~a~~|~~eG~~<br>~~GO~~<br>~~a~~|VREF_VFB<br>~~eG~~<br>~~a~~|
|System open feedback<br>protection threshold<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|DCOMP saturated<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|0.5<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|VREF_VFB<br>~~a~~<br>~~a~~|
|System open feedback<br>protection delaytime<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|DCOMP saturated<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|1024<br>~~a~~<br>~~a~~|~~a~~<br>~~a~~|cycles<br>~~a~~<br>~~a~~|
|**Compensation Loop for System Voltage and Duty Cycle of the Extra MOSFET(DCOMP)**<br>~~a~~<br>~~ve~~|||||||
|Gain bandwidthproduct<br>~~ve~~|GB_V<br>~~ve~~|75pF on DCOMP<br>~~ve~~|~~ve~~|1(5)<br>~~ve~~|~~ve~~|MHz<br>~~ve~~|
|Open-loopDCgain<br>~~ve~~<br>~~se~~|AV_V<br>~~ve~~<br>~~se~~|DCOMP open<br>~~ve~~<br>~~se~~<br>~~ee~~|~~ve~~<br>~~se~~<br>~~ee~~|70(5)<br>~~ve~~<br>~~se~~<br>~~ee~~|~~ve~~<br>~~se~~<br>~~ee~~|dB<br>~~ve~~<br>~~se~~|
|Low-level clampvoltage<br>~~se~~<br>~~ee~~|VDCOMP_L<br>~~se~~<br>~~ee~~|Normal operation<br>~~se~~<br>~~ee~~<br>~~ee~~|~~se~~<br>~~ee~~<br>~~ee~~|1<br>~~se~~<br>~~ee~~<br>~~ee~~|~~se~~<br>~~ee~~<br>~~ee~~|V<br>~~se~~<br>~~ee~~|
|High-level clampvoltage<br>~~ee~~|VDCOMP_H<br>~~ee~~|Normal operation<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|2.5<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|V<br>~~ee~~|
|Transconductance when the<br>PWM is on<br>~~a~~|GM_DCOMP_ONPWM = high<br>~~a~~|PWM = high<br>~~ee ~~<br>~~a~~|~~ee ~~<br>~~a~~|680<br> ~~ee ~~<br>~~a~~|~~ee~~<br>~~a~~|μA/V<br>~~a~~|
|Transconductance when the<br>PWM is off<br>~~a~~|GM_DCOMP_OFFPWM = low<br>~~a~~|PWM = low<br>~~a~~|~~a~~|260<br>~~a~~|~~a~~|μA/V<br>~~a~~|
|Saturated output current when<br>the PWM is on<br>~~a~~|ISAT_DCOMP_ON<br>~~a~~|~~a~~|~~a~~|90<br>~~a~~|~~a~~|μA<br>~~a~~|
|Saturated output current when<br>the PWM is off<br>~~a~~|ISAT_DCOMP_OFF<br>~~a~~|~~a~~|~~a~~|45<br>~~a~~|~~a~~|μA<br>~~a~~|
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
|**Parameter**<br>~~a~~|**Symbol**<br>~~a~~|**Symbol**<br>~~a~~|**Condition**<br>~~a~~|**Min**<br>~~a~~|**Typ**<br>~~a~~|**Max**<br>~~a~~|**Units**<br>~~a~~|
|---|---|---|---|---|---|---|---|
|**LED Driver Protection(OVP, LED Short)**||||||||
|LED over-voltage protection (OVP)<br>threshold<br>~~a~~|VTH_OVP<br>~~a~~||~~a~~|2.25<br>~~a~~<br>~~ee~~|2.40<br>~~a~~<br>~~ee~~|2.55<br>~~a~~<br>~~ee~~|V<br>~~a~~|
|OVP threshold hysteresis<br>~~ee~~|~~ee~~||~~ee~~|~~ee~~<br>~~ee~~|200<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|mV<br>~~ee~~|
|OVP to latch IC threshold<br>~~ee~~|~~ee~~||~~ee~~|~~ee~~<br>~~ee~~|3<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|V<br>~~ee~~|
|LEDx UVLO threshold<br>~~ee~~|VLEDX_UVLO<br>~~ee~~||OVP triggered (test mode<br>required)<br>~~ee~~|~~ee ~~<br>~~ee~~|100<br> ~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|mV<br>~~ee~~|
|LEDX slow over-voltage (OV)<br>threshold(for LED shortprotection) <br>~~ee~~<br>~~ee~~|VTH_LEDxOV_SLOW<br>~~ee~~||~~ee~~<br>~~ae~~|~~ee~~<br>~~ae~~|4.9<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~|V<br>~~ee~~|
|LED short delaytime slow<br>~~ee~~|tD_LEDxOV_SLOW||~~ae~~|~~ae~~|5.8<br>~~ee~~|~~ee~~|ms|
|LEDx fast OV threshold<br>~~ee~~|VTH_LEDxOV_FAST||~~ae~~|~~ae~~|20<br>~~ee~~|~~ee~~|V|
|All LED strings short delay time at<br>low voltages<br>~~ee~~<br>~~ee~~|~~ee~~||~~ae~~<br>~~ee~~|~~ae ~~<br>~~ee~~|200<br> ~~ee ~~<br>~~ee~~|~~ee~~<br>~~ee~~|ms<br>~~ee~~|
|All LED strings short delay time at<br>high voltages<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~||~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|12<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|ms<br>~~ee~~<br>~~ee~~|
|Thermalprotection threshold<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~||Risingedge<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|150(5)<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|°C<br>~~ee~~<br>~~ee~~|
|Thermalprotection hysteresis<br>~~ee~~|~~ee~~||~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|25(5)<br>~~ee~~<br>~~ee~~<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~|°C<br>~~ee~~|
|**LED Current Regulation(VLEDx, ISET)**<br>~~ee~~<br>~~ee ee ee~~<br>~~ee~~<br>~~eeeeee~~||||||||
|ISET voltage<br>~~ee~~|VISET<br>~~ee~~|~~ee~~<br>~~ee~~<br>~~ee~~||1.53<br>~~ee~~<br>~~ee~~<br>~~ee~~|1.58<br>~~ee~~<br>~~ee~~<br>~~ae~~|1.63<br>~~ee~~<br>~~ee~~<br>~~ee~~|V<br>~~ee~~|
|LEDx average current<br>~~ee~~<br>~~ee~~|ILED<br>~~ee~~<br>~~ee~~|RISET= 320kΩ(trim),50mA -1.5%<br>~~ee~~<br>~~ee ~~<br>~~ee~~<br>~~ee~~||50mA -1.5%<br>~~ee~~<br> ~~ee ~~<br>~~ee~~<br>~~ee~~|50<br>~~ee~~<br> ~~ee~~<br>~~ee~~<br>~~ae~~|+1.5%<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>~~ee~~|mA<br>~~ee~~<br>~~ee~~|
|~~ee~~<br>~~pe~~|~~ee~~<br>|40% dimming,20mA<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>||-3%<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>|19.2<br>~~ee~~<br>~~ae~~<br>~~ee~~<br>|+3%<br>~~ee~~<br>~~ee~~<br>~~ee~~<br>|mA<br>~~ee~~<br>|
|Current matching<br>~~ee~~<br>~~pe~~|~~ee~~<br>|ILED= 50mA<br>~~ee ~~<br>~~ee~~<br>~~ee~~<br>||~~ee ~~<br>~~ee~~<br>~~ee~~<br>|0.3<br> ~~ae ~~<br>~~ee~~<br>~~ee~~<br>|2<br> ~~ee~~<br>~~ee~~<br>~~ee~~<br>|%<br>~~ee~~<br>|
|~~ee~~<br>~~pe~~|~~ee~~<br>|ILED= 20mA(40%)<br>~~ee~~<br>~~ee~~<br>||~~ee~~<br>~~ee~~<br>|0.6<br>~~ee~~<br>~~ee~~<br>|2.5<br>~~ee~~<br>~~ee~~<br>|%<br>~~ee~~<br>|
|Minimum LEDx regulation voltage<br>~~pe ~~|VLEDx<br> ~~—————t—~~|ILED= 200mA<br>~~ee~~<br>~~—————t—~~||~~ee~~<br>~~—————t—~~|560<br>~~ee~~<br>~~—————t—~~|~~ee~~<br>~~—————t—~~|mV<br>~~—————t—~~|
|||ILED= 60mA<br>~~ee~~<br>~~—————t—~~||~~ee~~<br>~~—————t—~~|176<br>~~ee~~<br>~~—————t—~~|~~ee~~<br>~~—————t—~~|mV<br>~~—————t—~~|
|Fault voltage (ISET/FAULT pin<br>voltage if a fault occurs)<br>~~pe ~~<br>~~ee~~|<br>~~ee~~|Fault condition occurs<br>~~ee ~~<br><br>~~ee~~||~~ee ~~<br><br>~~ee~~|~~ee ~~<br><br>~~ee~~|0.2<br> ~~ee~~<br><br>~~ee~~|V<br><br>~~ee~~|
## **Note:**
5) Not tested in production. Guaranteed by characterization.
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **TYPICAL CHARACTERISTICS**
## **VFB Reference vs. Temperature**
**==> picture [194 x 145] 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> (V)<br>FB_REF<br>V<br>**----- End of picture text -----**<br>
**==> picture [186 x 170] intentionally omitted <==**
**----- Start of picture text -----**<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> RISING VOLTAGE (V)<br>IN<br>V<br>**----- End of picture text -----**<br>
**==> picture [185 x 168] 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 [191 x 147] 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> OVP (V)<br>FB<br>V<br>**----- End of picture text -----**<br>
**==> picture [187 x 168] intentionally omitted <==**
**----- Start of picture text -----**<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> OVP THRESHOLD (V)<br>LED<br>V<br>**----- End of picture text -----**<br>
**==> picture [187 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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## **TYPICAL CHARACTERISTICS** _**(continued)**_
**==> picture [456 x 363] intentionally omitted <==**
**----- Start of picture text -----**<br>
Quiescent Current vs.<br>ISET Voltage vs. Temperature<br>Temperature<br>1.65 430<br>1.64 420<br>1.63 410<br>1.62 400<br>1.61 390<br>cee eelita<br>1.6 380<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>2.25 0.74<br>cia a cca<br>-50 0 50 100 -50 0 50 100<br>TEMPERATURE ( C) TEMPERATURE ( C)<br>QUIESCENT CURRENT (mA)<br>OPT HIGH-LEVEL VOLTAGE (V)<br>(V)<br>ISET<br>V<br>OPT LOW-LEVEL VOLTAGE (V)<br>**----- End of picture text -----**<br>
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/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**
**==> picture [135 x 10] intentionally omitted <==**
**----- Start of picture text -----**<br>
Constant voltage mode, ISYS = 0A<br>**----- End of picture text -----**<br>
**==> picture [94 x 22] intentionally omitted <==**
**----- Start of picture text -----**<br>
Steady State<br>Constant voltage mode<br>**----- End of picture text -----**<br>
**==> picture [288 x 55] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VSYS CH1: VSYS<br>CH2: VGATE RE | SE RE || ARI LU ||SE 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 [309 x 111] intentionally omitted <==**
**----- Start of picture text -----**<br>
I<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 Enable**
**==> picture [293 x 77] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VSYS CH1: VSYS<br>a CH4:<br>CH2: VGATE VICOMP<br>CH4: VDCOMP<br>CH2: VLED<br>CH3: IPRI<br>CH3: ILED<br>**----- End of picture text -----**<br>
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/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 Disable**
## **Start-Up**
Constant current mode, duty = 80%
**==> picture [293 x 74] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VSYS q CH1: VSYS<br>CH4: VICOMP q CH4:<br>CH2: VDCOMP 2 | VICOMP<br>qqq| VDCOMP CH2:<br>|<br>CH3: ILED q|q CH3: ILED<br>**----- End of picture text -----**<br>
## **Shutdown**
Constant current mode, duty = 80%
## **Steady State**
Constant current mode, duty = 50%
**==> picture [292 x 96] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VSYS i" { CH4: VCH1: VS-SWSYS<br>CH4:VICOMP<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 [289 x 89] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH2: VGATE<br>CH1: VLED<br>CH3: ILED<br>CH1: VSYS CH2: VSYS<br>CH4: ISYS CH3: ILED<br>CH4:<br>VICOMP<br>**----- End of picture text -----**<br>
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/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%
**Short One String, 2 LEDs** Constant current mode, duty = 25%
**==> picture [289 x 74] intentionally omitted <==**
**----- Start of picture text -----**<br>
CH1: VLED CH1: VLED<br>CH4: VGATE<br>CH2: VSYS CH2: VSYS<br>CH3: ILED CH4: VCH3: ILEDxLED<br>**----- End of picture text -----**<br>
## **One-String Short Fault (LED+ to LED-)**
Constant current mode, duty = 25%
**==> picture [37 x 74] 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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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **FUNCTIONAL BLOCK DIAGRAM**
**==> picture [470 x 485] intentionally omitted <==**
**----- Start of picture text -----**<br>
D2<br>VSYS<br>C2 M2<br>D3 R11 C3<br>R8<br>1 Voltage Limit<br>D4 SYNC Duty Cycle GATE<br>R9 Gate 16<br>Control<br>PWM<br>9<br>GND<br>UVLO_VDR 15 VDRV<br>6V (Refer to<br>UVLO_VIN VIN/SOURCE) C1<br>14<br>Delay UVLO_VIN<br>CT <}-— < 3.6V VIN/SOURCE<br>2 OPT<br>Level Adjust<br>R10 —_<br>VSYS PWM PWM_N<br>1.24VREF 10µs OV_SYS<br>R3 Se<br>VREF GM_DCOMP_ON Duty Cycle<br>Ramp<br>3<br>VFB<br>t R4 GM_DCOMP_OFF . Ramp SYNC<br>Generator<br>C4 R7 4 DCOMP<br>PWM_N LED1 7<br>IREF GM<br>ISET<br>PWM IREF<br>C5 R6 5 PWM ael VLED_REF LED1 = . LED2 8<br>ICOMP S1 GM_I Min VLEDx Min LED2LED3LED4 .. LED3 11<br>—— < i 7 . Y<br>ISET/FAULT EN_CH1<br>R5 12 ISET Voltage Adjust DC_ADIM Fault 200ms Delay . .. LED4 10<br>LEDx<br>PWM 5.8ms<br>TS 13 ADIMP/PWM Dimming Control Dimming Dimming Analog DC_ADIMPWM LED Protection Management ale 12ms Delay ... All LEDx4.9V<br>6 OVP 3V 10µs OV_SYS Delay ... 100m20VV<br>OV_LED<br>2.4V/2.2V 10µs .. LEDx<br>.<br>. . .<br>**----- End of picture text -----**<br>
**Figure 1: Functional Block Diagram**
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **OPERATION**
The MP4657B 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 plus an external N-channel MOSFET to regulate the LED current loop and system supply voltage, and includes 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 supply 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 (ILED) and system voltage (VSYS). When the PWM signal is effective, the MP4657B regulates the ILED loop through the flyback power stage and further regulates VSYS by controlling the N-channel MOSFET’s turning on and off functionality. Soft switching for the N- channel MOSFET can be achieved to reduce voltage spikes. When the PWM signal is ineffective, the device directly controls VSYS through the flyback power stage.
## **Gate Driver and System Start-Up**
Figure 2 shows the MP4657B’s gate driver startup. The VDRV pin supplies the gate driver. The GATE signal’s amplitude (refer to VIN/SOURCE) is limited to 6V.
**==> picture [229 x 144] intentionally omitted <==**
**----- Start of picture text -----**<br>
D2 VSYS<br>C2 D3 R11 M2 C3<br>R8 MP4657B<br>SYNC Voltage Limit<br>D4 R9 Gate GATE 16<br>Control<br>GND 9<br>UVLO_VDR 15 VDRV<br>6V (refer to VIN/<br>SOURCE)<br>UVLO_VIN 14<br>3.6V VIN/SOURCE<br>SignalDuty PWM<br>**----- End of picture text -----**<br>
**Figure 2: MP4657B Gate Driver and Start-Up**
Before start-up, the VIN/SOURCE voltage is below the under-voltage lockout (UVLO) threshold, and the MP4657B monitors the VDRV
voltage (VDRV). After VDRV reaches its UVLO threshold, the MP4657B turns on the external N- channel MOSFET. 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 MP4657B’s operating sequence. The device’s GATE signal’s falling edge is synchronized to the primary flyback gate signal’s rising edge through the SYNC pin.
**==> picture [136 x 166] intentionally omitted <==**
**----- Start of picture text -----**<br>
GATE<br>Flyback<br>IPRI ISEC<br>ITRANS<br>Sync Sync<br>Edge Edge<br>Sync ee<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: MP4657B Switching Sequence** The falling edge of the SYNC signal synchronizes to the falling edge of the GATE signal. This means that the N-channel MOSFET turns off when the MOSFET of primary-side flyback turns on. For most applications, the N- channel MOSFET turns off when the secondaryside winding current reaches 0A, since voltage spikes are less likely to occur.
The GATE signal’s turning on and duty cycle is 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 VSYS 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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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **LED Current and System Voltage (VSYS) Regulation**
The MP4657B accurately regulates both the ILED and the VSYS with a single flyback power stage.
When the PWM signal is ineffective and the LED stage is disabled, the MP4657B regulates VSYS by controlling the flyback power stage, and the N-channel MOSFET is fully on (see Figure 4).
**==> picture [227 x 94] intentionally omitted <==**
**----- Start of picture text -----**<br>
VFBVREF EA_V DCOMP_PWM Off PowerTotal NMOS Fully OnVSYS Power VSYS<br>Flyback<br>VMin LEDx EA_I ICOMP Control OFF LED Stage Power<br>Ref<br>py 7 —<br>Figure 4: MP4657B Control Scheme when the<br>PWM Signal Is Ineffective<br>**----- End of picture text -----**<br>
When the PWM signal is effective, the MP4657B regulates the ILED loop through the flyback power stage (see Figure 5). VSYS 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 [226 x 75] intentionally omitted <==**
## **Figure 5: MP4657B Control Scheme when the PWM Signal Is Effective** _**LED Current Loop Regulation when PWM Signal Is On (ICOMP Loop)**_
In the ILED regulation loop, the minimum VLEDx is fed back and compared to the internal reference voltage (VLED_REF, which changes with the set current). The internal error amplifier (EA) regulates the average value of the minimum LEDx voltage (VLEDx) signal to this VLED_REF. The EA’s output is connected to the external current-loop compensation network on the ICOMP pin through an inner switch (S1).
compensation network on the ICOMP pin. The minimum VLEDx is regulated by this control loop, and the flyback power is programmed by ICOMP voltage (VICOMP). When the PWM signal is ineffective, S1 turns off. Then the compensation network on ICOMP is disconnected from the EA and holds its voltage value until the PWM signal is effective again. _**System Output Voltage Regulation (DCOMP Loop)**_
VSYS is fed back to the VFB pin through a voltage divider. When the PWM signal is ineffective, the MP4657B regulates VSYS by controlling the flyback power stage while the N- channel MOSFET is fully on. The internal voltage loop EA regulates the average value of the VFB pin’s voltage (VFB) to VREF. EA’s output is connected to the external voltage-loop compensation network on the DCOMP pin. VSYS is regulated by this control loop, and the flyback power is determined by the DCOMP voltage.
When the PWM signal is effective, the flyback power is controlled by ICOMP, and VSYS is regulated by the DCOMP pin controlling the duty cycle of the N-channel MOSFET. The VFB is compared to the internal VREF. The EA outputs an error signal to DCOMP pin. The EA’s gain with an effective PWM signal is different from that with an ineffective PWM signal. The DCOMP pin’s voltage determines the duty cycle of the N-channel MOSFET (see Figure 6).
**==> picture [218 x 131] intentionally omitted <==**
**----- Start of picture text -----**<br>
OPT Level Adjust<br>R10 VSYS PWM PWM_N Driver GATE<br>R8 VREF GM_V_ON Duty<br>VFB Ramp Cycle<br>R9 GM_V_F Ramp SYNC<br>Generator<br>Ale DCOMP tte<br>C7 R7 PWM_N<br>PWM IREF — GM LED1<br>PWM<br>C5 R6 ICOMP S1 GM_I Min VVLED_REFLEDx Min LED1LED2LED3LED4 ... LED2LED3<br>LED4<br>**----- End of picture text -----**<br>
**Figure 6: MP4657B Control Diagram**
When the PWM signal is effective, S1 is on and the EA’s output is connected to the external
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **Dimming Control**
The MP4657B provides analog dimming and PWM dimming for LED current through the ADIMP/PWM pin. For analog dimming, apply a pulse signal with a >5kHz frequency to this pin. In this mode, the PWM signal is always effective unless the pulse signal is removed. For PWM dimming, apply a pulse signal with a <5kHz frequency. In this mode, ILED is chopped by the pulse signal. During PWM dimming, the PWM signal is effective when the pulse is high, and is ineffective when the pulse is low.
## **Protection Features**
The MP4657B integrates sufficient protections for the system voltage stage and the LED driver stage.
## **System Voltage Stage Protections**
The protections for the VSYS stage, include system over-voltage protection (OVP) and open-loop feedback protection.
## _**System Over-Voltage Protection (OVP)**_
The VFB pin senses VSYS for regulation and over-voltage protection (OVP). If the VFB exceeds VREF by 24%, system OVP is triggered. The OPT pin is clamped to 3.3V to stop primary switching when the PWM signal is ineffective. If system OVP is triggered when PWM is effective, the GATE signal turns off. If the OVP pin’s voltage exceeds 3V, the IC latches off. This function protects VSYS from damaging the device.
## _**Feedback Open-Loop Protection (VSYS Stage)**_
If VFB is below 50% of VREF and DCOMP is saturated for 1024 consecutive 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 stage (VLED) 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 (VLEDx) is pulled to ground while VLED
continue increasing until the OVP pin’s 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 MP4657B regulates VSYS as an ineffective PWM signal condition. The IC marks off the open LED strings that have VLEDx below 100mV. The remaining LED strings discharge VLED, and the OVP pin voltage decreases until it drops below the OVP threshold. Then the LED control loop recovers, and the minimum VLEDx of the remaining LED strings are 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. VSYS is also regulated as an ineffective PWM signal condition, and the fault indicator is pulled low.
## _**LED Short Protection**_
VLEDx is monitored for LED short conditions. If an LED string is shorted, the respective VLEDx rises. If VLEDx exceeds 4.9V for 5.8ms, the IC marks off the string that has 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 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 Pin Short-to-Ground Protection**_
If ICOMP is saturated and VLEDx 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 resets, and the ISET pin sets ILED.
## **Thermal Protection**
Thermal protection is integrated into the MP4657B. If the die temperature exceeds the over-temperature (OT) threshold, the IC stops working until the die temperature is reduced. Once the temperature returns to within its safe range, the IC resumes normal operation.
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER** MPS
## **APPLICATION INFORMATION**
## **Gate Signal Synchronization (SYNC)**
The SYNC pin synchronizes the GATE signal. Its falling edge synchronizes the GATE signal turning off. Connect a voltage divider from the secondary winding to this pin to indicate the primary-side MOSFET turning on.
## **System Voltage Feedback (VFB)**
The VFB pin feeds back the system voltage (VSYS). Connect this pin to VSYS with a voltage divider. This voltage divider determines VSYS, calculated with Equation (1):
**==> picture [183 x 28] intentionally omitted <==**
Where RVFBH and RVFBL are the high-side and low-side resistors of the voltage divider, respectively.
The VFB pin is monitored for system OVP. If VFB exceeds VREF by 24% for 10µs, system OVP is triggered.
## **LED Open Protection**
The OVP pin monitors the output LED voltage (VLED) and can trigger LED open protection. Connect this pin to VLED through a voltage divider and set the OVP point (VOV_LED) using Equation (2):
**==> picture [195 x 31] intentionally omitted <==**
Where ROVPH and ROVPL are the voltage dividers’ high-side and low-side resistors, 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 1.6V, and its source current determines each channel’s ILED. 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, VDRV can typically be supplied by the secondary-side winding of the power transformer.
Connect the GATE signal directly to the N- channel MOSFET, or use 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:
Design the turn ratio between the primary-side winding and the secondary LED winding (NP:NLED).
The maximum voltage stress (VDS_PRI) on the primary-side MOSFET, which occurs at the 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 OVP point of VLED.
Consider the leakage inductance of the flyback transformer, and assume there is a 60V spike voltage on the primary-side MOSFET, as well as a 10% derating of the switch voltage capability. VDS_PRI can be estimated with Equation (5):
**==> picture [188 x 14] intentionally omitted <==**
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
Where VRATING_PRI is the rating voltage of the primary-side MOSFET.
Calculate NP:NLED with Equation (6):
**==> picture [235 x 25] intentionally omitted <==**
Design the turn ratio between the LED winding and the VSYS winding (NLED:NSYS).
Ensure that VSYS is below the reflecting voltage from the LED winding under the minimum VLED. This relationship can be estimated with Equation (7):
**==> picture [181 x 41] intentionally omitted <==**
Where VLED_MIN is the minimum output LED voltage. Choose a 15% margin for production design, calculated with Equation (8):
**==> picture [195 x 28] intentionally omitted <==**
## **Selecting the External N-Channel MOSFET**
The voltage stress on the external N-channel MOSFET can be estimated with Equation (9):
**==> picture [183 x 28] intentionally omitted <==**
The maximum voltage stress occurs at VIN_AC_MAX. Considering the small voltage spike and the MOSFET voltage derating, it is recommended to choose a 20% margin. Estimate the voltage rating (VRATING_EXT) with Equation (10):
**==> picture [199 x 28] intentionally omitted <==**
The average current flowing through the N- channel MOSFET is equal to the output current of VSYS. This flowing current is a pulse waveform, and its RMS current is much greater than the average value. Assume that the RMS current (IRMS_EXT) is 1.5 to 2 times greater than the average current; estimate this value using Equation (11):
Where IRMS_EXT is the RMS current through the N-channel MOSFET, and ISYS is the output current of VSYS.
The switching loss from the N-channel MOFET’s soft switching is typically low. The rating current for the N-channel MOSFET should be 2 to 3 times that 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 good thermal performance. For the best results, refer to Figure 7 and 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. Separate the output loop GND and control circuit GND, and only connect them at the GND pin.
3. Place peripheral electronic components (such as those for VIN/SOURCE, VFB, SYNC, DCOMP, and ICOMP) close to the IC to decouple noise.
**==> picture [182 x 139] intentionally omitted <==**
**----- Start of picture text -----**<br>
R1 C3<br>SYNC 1 16 GATE<br>C1<br>OPT 2 15 VDRV<br>VFB 3 14 VIN/ SOURCE<br>R2 C2<br>DCOMP 4 13 ADIMP/ PWM<br>C4 C5<br>ICOMP 5 12 ISET/ FAULT<br>C6 R3<br>C7 OVP 6 11 LED3<br>LED1 7 10 LED4<br>LED2 8 9 GND<br>**----- End of picture text -----**<br>
**Figure 7: Recommended PCB Layout for a 1- Layer Board**
**==> picture [162 x 14] intentionally omitted <==**
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **TYPICAL APPLICATION CIRCUIT**
**==> picture [471 x 278] intentionally omitted <==**
**----- Start of picture text -----**<br>
D1<br>TM MUR340T3G<br>Flyback<br>R1<br>750kΩ<br>85V265VACAC to 100V380VBUSBUS to NP NLED C133µF/100V R230kΩ<br>M1<br>NSYS<br>M2<br>Flyback D2 AM7432<br>Controller<br>C2 C3 R3<br>47nF 470µF/25V 31.6kΩ<br>R11<br>D3 1N4148 100Ω R4<br>10kΩ<br>Ce 1<br>R8<br>100kΩ<br>D4 1 SYNC GATE 16<br>1N4148 R9<br>10kΩ 2 OPT VDRV 15<br>MP4657B C6<br>1µF<br>1kΩR10 C4 R7 3 VFB VIN/SOURCE 14<br>PC817 220nF 20kΩ 4 DCOMP ADIMP/PWM 13 PWM or ADIM Pulse<br>R6 R5<br>750Ω 5 ICOMP ISET/FAULT 12 200kΩ<br>C5<br>2.2µF 6 OVP LED3 11<br>7 LED1 LED4 10<br>8 LED2 GND 9<br>**----- End of picture text -----**<br>
**Figure 8: Typical Application Circuit (MP4657B Flyback 4-String LED Driver and System Voltage Regulation Scheme)**
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **PACKAGE INFORMATION**
## **SOIC-16**
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER**
## **CARRIER INFORMATION**
|a\|a\|Pin1|1<br>O|1<br>O|1<br>1<br>OO O<br>OO<br>OO|1<br>1<br>OO O<br>OO<br>OO|1<br>1<br>OO O<br>OO<br>OO|1<br>1<br>OO O<br>OO<br>OO|1<br>1<br>OO O<br>OO<br>OO|1<br>1<br>OO O<br>OO<br>OO|O|1<br> 0|1<br> 0||O|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|Van,|||||ABCD||||ABCD||ABCD|||ABCD||
||||||||||——>|||||||
||||||||||**Feed Direction**|||||||
|**Part Number**|**Package**<br>**Description**|**Quantity/**<br>**Reel**|**Quantity/**<br>**Tube**||**Quantity/**<br>**Tray**||**Quantity/**||**Reel**<br>**Diameter**|**Carrier**<br>**Tape Width**||||**Carrier**<br>**Tape Pitch**||
|MP4657BGS-Z|SOIC-16|2500|50||N/A||||13in||16mm||||8mm|
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**MP4657B – 1-STAGE FLYBACK 4-STRING LED DRIVER/VOLTAGE CONTROLLER REVISION HISTORY Revision # Revision Date Description Pages Updated** 1.0 11/11/2021 Initial Release - ~~pp~~[MPS]
**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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