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AL1666S-13
LED, AC/DC DRIVER, SOIC, SMD
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- Manufacturer: DIODES INC.
- Product type: AC / DC LED Driver ICs
- SVHC: No SVHC (25-Jun-2025)
- Topology: Buck-Boost, Flyback
- IC Mounting: Surface Mount
- No. of Pins: 8Pins
- Product Range: -
- Qualification: -
- No. of Outputs: 1Outputs
- Device Topology: Buck-Boost, Flyback
- LED Driver Type: Isolated
- Driver Case Style: SOIC
- IC Case / Package: SOIC
- Input Voltage Max: 305V
- Input Voltage Min: 85V
- Output Current Max: -
- Output Voltage Max: 20V
- Switching Frequency: -
- Switching Frequency Typ: 150kHz
- Operating Temperature Max: 105°C
- Operating Temperature Min: -40°C
- Automotive Qualification Standard: -
| Delivery and price | |
|---|---|
| Units per pack | 5000 |
| Price | 0.17 € |
| Current stock | 1000+ |
| Lead time | 30 days |
Datasheet
**AL1666** Co CT **HIGH PERFORMANCE DIMMABLE LED CONTROLLER**
## **Description**
The AL1666 is a high performance single stage Flyback and Buckboost controller, targeting dimmable LED lighting application. It is a primary side regulation (PSR) controller which can provide accurate Constant Current (CC) regulation without opto-coupler and secondary control circuitry. It is operating at BCM mode which results in good EMI and efficiency, and keeps high PF and low THD under universal input voltage.
The AL1666 can support analog/PWM dimming modes. When a 0 to 2.4V DC signal is applied on ADIM pin, the device will operate in analog dimming mode; when a digital signal is applied on PWMD pin and the ADIM pin is connected with hundreds of nF capacitors, the device will work at PWM-to-DC dimming mode. The dimming range is 1% to 100%.
## **Pin Assignments**
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**----- Start of picture text -----**<br>
(Top View)<br>ADIM | 1 || 8 | FB<br>PWMD | 2 | 7 VCC<br>COMP | 3 || 6 | OUT<br>CS | 4 | | 5 | GND<br>**----- End of picture text -----**<br>
The AL1666 has rich protection features. It integrates multiple protections including Under Voltage Lock Out (UVLO), Output Over Voltage Protection (OVP), Output Short Circuit Protection (OSP), Over Current Protection (OCP), Winding Short Circuit, Secondary Diode Short, Internal Thermal Fold-Back Protection (TFP) and Over Temperature Protection (OTP).
The AL1666 is available in SO-8 (Standard) package.
**==> picture [82 x 9] intentionally omitted <==**
**----- Start of picture text -----**<br>
SO-8 (Standard)<br>**----- End of picture text -----**<br>
## **Applications**
- General LED Lighting Driver with Dimming Function
- 0 to 10V Dimming Luminaires
- General Purpose Constant Current Source
- Smart LED Lighting
## **Features**
- Primary Side Regulation without Opto-Coupler
- Valley Switching for Low Switching Loss
- Support Analog and PWM-to-DC Dimming
- Analog/PWM-to-DC Dimming Range: 1% to 100%
- Tight CS Reference Voltage 0.4V±1.5%
- High PF>0.9 and Low THD<20%
- High Efficiency
- Internal Protections
- Under Voltage Lock Out (UVLO)
- Output Over Voltage Protection (OVP)
- Output Short Protection (OSP)
- Over Current Protection (OCP)
- Winding Short Circuit Protection
- Secondary Diode Short Protection
- Internal Thermal Fold-back Protection (TFP)
- Over Temperature Protection (OTP)
- Tight LED Current Variation Range
- LED Current Line Regulation: ±2% (90VAC to 305VAC)
- LED Current Load Regulation: ±2% Full Load to Half Load
- Package: SO-8 (Standard)
- **Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)**
- **Halogen and Antimony Free. “Green” Device (Note 3** )
- **For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/**
Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant.
2. See https://www.diodes.com/quality/lead-free/ for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds.
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
**Typical Applications Circuit**
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C7 R14<br>L1 T1<br>C1 C2 RTH R10 C5 D3 R11 C6 + OUT<br>F1<br>AC D2<br>VR1<br>Input i f Aux R4 D1 1 ; am ie<br>DB1 PWM Signal<br>CVCC<br>R5 D4<br>VCC PWMD<br>Q1<br>FB OUT<br>AL1666 R9<br>R6 COMP<br>RCOMP ADIM GND CS<br>U1<br>CCOMP CDIM RCS<br>| fag<br>Flyback Application Circuit<br>L1<br>T1<br>C1 C2 RTH R11 C6 OUT<br>F1<br>D3<br>AC<br>VR1<br>Input Aux<br>R4 D1<br>DB1 PWM Signal<br>CVCC<br>D4<br>R5<br>VCC PWMD<br>Q1<br>i _ ie my FB ie OUT l i ,<br>AL1666<br>R9<br>R6 COMP<br>RCOMP ADIM GND CS<br>CCOMP CDIM RCS<br>~ fe<br>Buck-Boost Application Circuit<br>Pin Descriptions<br>+<br>**----- End of picture text -----**<br>
|**Pin Descriptionsptionstions**|||
|---|---|---|
|**Pin Number**|**Pin Name**|**Function**|
|1|ADIM|Analog dimming input pin|
|2|PWMD|PWM signal input pin|
|3|COMP|Loop compensation pin|
|4|CS|Current sense pin, connect this pin to the source of the primary switch|
|5|GND|Ground|
|6|OUT|Gate driver output|
|7|VCC|Supply voltage of gate driver and control circuits of the IC|
|8|FB|The feedback voltage sensing from the auxiliary winding|
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Functional Block Diagram**
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|||||
|---|---|---|---|
|ADIM|VCC|
|1|7|
|2|
|Analog|VREF|
|PWMD|PWM to DC|Dim|
|Dimming|Control|UVLO|VREF|
|&Bias|
|OVP|
|6|
|Driver|OUT|
|8|Logical|
|Valley|
|FB|Control|
|Detector|
|OTP|
|2V|
|-|
|OCP|
|+|Internal|
|OTP|
|Temperature|
|4|Sense|
|CS|-|
|Gm|
|+|
|VREF|
|3|5|
|eae|
|COMP|GND|
|Absolute Maximum Ratings gs s|(@TA = +25°C, unless otherwise specified.) (Note 4) A = +25°C, unless otherwise specified.) (Note 4) = +25°C, unless otherwise specified.) (Note 4)|
|Symbol|Parameter|Rating|Unit|
|VCC|Power Supply Voltage|-0.3 to 30|V|
|ss|
|VCS|Voltage at CS to GND|-0.3 to 7|V|
|VFB|FB Input|-0.3 to 7|V|
|ss|
|VCOMP|Loop Compensation Pin|-0.3 to 7|V|
|VOUT|Driver Output Voltage|-0.3 to 20|V|
|ss|
|VPWMD|Voltage at PWMD to GND|-0.3 to 7|V|
|VADIM|Voltage at ADIM to GND|-0.3 to 7|V|
|ss|
|TJ|Operating Junction Temperature|-40 to +150|°C|
|TSTG|Storage Temperature|-65 to +150|°C|
|ss|
|TLEAD|Lead Temperature (Soldering, 10s)|+300|°C|
|PD|Power Dissipation at TA = +50°C|0.65|W|
|a|
|θJA|Thermal Resistance (Junction to Ambient)|136|°C/W|
|θJC|Thermal Resistance (Junction to Case)|30|°C/W|
|a|
|ESD (Human Body Model)|2000|V|
|—|
|ESD (Charged-Device Model)|1000|V|
|—|
|Note:|4. Stresses greater than those listed under|Absolute Maximum Ratings|can cause permanent damage to the device. These are stress ratings only, and|
|functional operation of the device at these or any other conditions beyond those indicated under|Recommended Operating Conditions|is not implied.|
|Exposure to|Absolute Maximum Ratings|for extended periods can affect device reliability. All voltages unless otherwise stated and measured with|
|respect to GND.|
**----- End of picture text -----**<br>
## **Absolute Maximum Ratings gs s** (@TA = +25°C, unless otherwise specified.) (Note 4) A = +25°C, unless otherwise specified.) (Note 4) = +25°C, unless otherwise specified.) (Note 4)
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
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TA<br>V<br> 6. ICC<br>Symbol<br>UVLO Section<br>VCC_TH<br>ee<br>VOPR_MIN<br>VCC_OVP<br>| a<br>NEW PRODUCT<br>**----- End of picture text -----**<br>
## **Recommended Operating Conditions** (@TA = +25°C, unless otherwise specified.)
|**Symbol**<br>~~a~~|**Parameter**|**Min**|**Max**|**Unit**|
|---|---|---|---|---|
|TAA<br>~~a~~|Ambient Temperature (Note 5)|-40|+105|°C|
|VCC<br>~~a~~|Operating VCC Voltage (Note 6)|8.5|VCC_OVP(Min)|V|
## **Electrical Characteristics** (@TA = +25°C, unless otherwise specified.)
|**Symbol**<br>~~a~~<br>~~ee~~|**Parameter**<br>|**Conditions**<br>|**Min**<br>|**Typ**<br>|**Max**<br>|**Unit**<br>|
|---|---|---|---|---|---|---|
|**UVLO Section**<br>~~a~~<br>~~ee~~|||||||
|VCC_THCC_THC_THH<br>~~a~~<br>~~ee~~|Startup Threshold Voltage<br>|—<br>|15.8<br>|18.5<br><br>~~EE~~|19.5<br><br>~~EE~~|V<br><br>~~EE~~|
|VOPR_MINOPR_MINR_MININ<br>~~a~~<br>~~eeooo~~|Minimal Operating Voltage<br>~~ooo~~|After Turn On<br>~~ooo~~|5.8<br>~~ooo~~|7.8<br>~~ooo~~<br>~~EE~~|9<br>~~ooo~~<br>~~EE~~|V<br>~~ooo~~<br>~~EE~~|
|VCC_OVPCC_OVPC_OVPVP<br>~~a~~<br>~~tt~~|VCCOVP Voltage<br>~~tt~~|—<br>~~tt~~|21.8<br>~~tt~~|25<br>~~EE~~<br>~~tt~~|29.5<br>~~EE~~<br>~~tt~~|V<br>~~EE~~<br>~~tt~~|
|**Standby Current Section**<br>~~a~~<br>~~tt~~|||||||
|IST<br>~~a~~<br>~~ee~~|Startup Current<br>~~a~~<br>~~es~~|VCC=VCC_TH-0.5V, before start up<br>~~a~~<br>~~rs~~|-0.5V, before start up<br>—<br>~~a~~<br>~~es~~|120<br>~~a~~<br>~~ee~~|300<br>~~a~~<br>~~es~~|µA<br>~~a~~|
|ICC<br>~~ee~~|Operating Current @4kHz<br>~~es~~|VCC=20V, VDIM=3V,<br>VFB=VCS=VCOMP=1V,COUT=1nF<br>~~rs~~|—<br>~~es~~|2<br>~~ee~~|4<br>~~es~~|mA|
|ICC_OVP<br>~~ee~~<br>~~a~~<br>~~ee~~|Shunt Current in OVP Mode<br>~~es~~<br>|VCC> VCC_OVP<br>~~rs ~~<br>|3.1<br> ~~es ~~<br>|—<br> ~~ee~~<br>|—<br>~~es~~<br>|mA<br>|
|**Drive Output Section**<br>~~ee~~|||||||
|tR<br>~~ee~~|Output Voltage Rise Time (Note 7)<br>|CL= 1nF<br>|—<br>|100<br>|—<br>|ns<br>|
|tF<br>~~eea~~|Output Voltage Fall Time (Note 7)<br>~~a~~|CL= 1nF<br>~~a~~|—<br>~~a~~|100<br>~~a~~|—<br>~~a~~|ns<br>~~a~~|
|VOUT_CLAMP<br>~~a~~|Output Clamp Voltage<br>~~a~~<br>~~a~~|VCC= 20V<br>~~a~~<br>~~a~~|9.8<br>~~a~~<br>~~a~~|12<br>~~a~~<br>~~a~~|15.5<br>~~a~~<br>~~a~~|V<br>~~a~~<br>~~a~~|
|tON_MIN<br>~~a~~|Minimum On Time (Note 7)<br>~~a~~|—<br>~~a~~|—<br>~~a~~|1000<br>~~a~~|2010<br>~~a~~|ns<br>~~a~~|
|tON_MAX<br>~~a~~<br>~~ooo~~|Maximum On Time<br>~~a~~<br>~~ooo~~|—<br>~~a~~<br>~~ooo~~|—<br>~~a~~<br>~~EE~~|15<br>~~a~~<br>~~EE~~|—<br>~~a~~<br>~~EE~~|µs<br>~~a~~<br>~~EE~~|
|tOFF_MAX<br>~~ooo~~|Maximum Off Time<br>~~ooo~~|—<br>~~ooo~~|—<br>~~EE~~|290<br>~~EE~~|405<br>~~EE~~|µs<br>~~EE~~|
|fMAX<br>~~ooo~~<br>~~tt~~|Maximum Frequency<br>~~ooo~~<br>~~tt~~|—<br>~~ooo~~<br>~~tt~~|—<br>~~EE~~<br>~~tt~~|150<br>~~EE~~<br>~~tt~~|—<br>~~EE~~<br>~~tt~~|kHz<br>~~EE~~<br>~~tt~~|
|**Internal CS Reference**<br>~~tt~~|||||||
|VREF<br>~~a~~|Internal Reference Voltage<br>~~a~~|—<br>~~a~~|0.394<br>~~a~~|0.4<br>~~a~~|0.406<br>~~a~~|V<br>~~a~~|
|VCS_CLAMP<br>~~a~~|Primary Current Clamp Voltage<br>~~a~~|—<br>~~a~~|—<br>~~a~~|2<br>~~a~~|—<br>~~a~~|V<br>~~a~~|
|VCS_OCP<br>~~a~~|Primary Over Current Voltage<br>~~a~~|—<br>~~a~~|—<br>~~a~~|3<br>~~a~~|—<br>~~a~~|V<br>~~a~~|
|**Error Amplifier**<br>~~a~~|||||||
|Gm<br>~~a~~|Trans-Conductance<br>~~a~~|—<br>~~a~~|—<br>~~a~~|27<br>~~a~~|—<br>~~a~~|µA/V<br>~~a~~|
|ISOURCE<br>~~a~~|Amplifier Source Current<br>~~a~~|—<br>~~a~~|—<br>~~a~~|7.2<br>~~a~~|—<br>~~a~~|µA<br>~~a~~|
|**Feedback Input Section**<br>~~ye~~|||||||
|VFB_CV<br>~~ye~~|FB CV Threshold<br>~~ye~~|—<br>~~ye~~|2.86<br>~~ye~~|3.0<br>~~ye~~|3.26<br>~~ye~~|V<br>~~ye~~|
|**PWMD Section**<br>~~ye~~|||||||
|VPWM_L<br>~~ye~~|PWM Signal Low Threshold Voltage<br>~~ye~~|—<br>~~ye~~|—<br>~~ye~~|—<br>~~ye~~|0.4<br>~~ye~~|V<br>~~ye~~|
|VPWM_H<br>~~a~~|PWM Signal High Threshold Voltage —<br><br>~~ees~~|PWM Signal High Threshold Voltage —<br><br>~~ees~~<br>~~ttt~~|2.0<br><br>~~ttt~~|—<br><br>~~ttt~~|—<br><br>~~ttt~~|V<br><br>~~ttt~~|
|fPWM<br>~~li~~|PWM Frequency for PWM to DC<br>Dimming<br>~~li~~<br>~~ees~~|—<br>~~li~~<br>~~ees~~<br>~~ttt~~|0.5<br>~~li~~<br>~~ttt~~|—<br>~~li~~<br>~~ttt~~|20<br>~~li~~<br>~~ttt~~|kHz<br>~~li~~<br>~~ttt~~|
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666 Unit** 2.4 V 2.45 V 100 % — °C — °C |__|
|NEW PRODUCT<br>**AL1666**<br>**Electrical Characteristics**(@TA= +25°C, unless otherwise specified.) (continued)<br>**Symbol**<br>**Parameter**<br>**Conditions**<br>**Min**<br>**Typ**<br>**Max**<br>**Unit**<br>**ADIM Section**<br>—<br>Analog Dimming Range on ADIM<br>—<br>0.05<br>—<br>2.4<br>V<br>—<br>Analog Dimming High Level<br>—<br>2.35<br>2.4<br>2.45<br>V<br>—<br>Analog Dimming Range Ratio<br>—<br>1<br>—<br>100<br>%<br>**Thermal Fold-Back Section**<br>TREG<br>Overheating Temperature Regulation (Note 7) —<br>—<br>+150<br>—<br>°C<br>**Over Temperature Protection Section**<br>—<br>Shutdown Temperature (Notes 7, 8)<br>—<br>—<br>+180<br>—<br>°C<br>Notes:<br>7. These parameters, although guaranteed by design, are not 100% tested in production.<br>8. At startup, when VCCreaches VCC_TH, the controller blanks OTP for more than 250s to avoid detecting an OTP fault by allowing the<br>PWMD pin voltage to reach its nominal value if a filtering capacitor is connected to the PWMD pin.<br> ~~E~~<br>|__||
|---|
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Performance Characteristics** (Note 9)
## **Startup Threshold Voltage vs. Ambient Temperature Minimum Operating Voltage vs. Ambient Temperature**
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22 9.0<br>8.7 T_T<br>21 Y LT<br>| | | ft | ft yt 8.4 po<br>20 P| | | | ft ft tf 8.1 eeeeee<br>HH el<br>7.8<br>19 | | | | | [pees ee=>=><br>7.5<br>18 |—| [tery | | 7.2 > ee aeaa ee<br>17 + | | | | | df ld 6.9 mToeoe<br>6.6<br>16<br>P| | | | | ft ff 6.3 pp<br>15 Ft | ft | ft ff i 6.0 ee<br>-40 -20 0 20 40 60 80 100 120 -40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC) Ambient Temperature (oC)oC)C)<br>VCC OVP Voltage vs. Ambient Temperature Startup Current vs. Ambient Temperature<br>32 250<br>31 ToT 230 i<br>30 fe a 210 a i<br>2928 a 190170<br>27 es 150 ee ee<br>26 > ee 130 el<br>25 a ee 110 Toe<br>24 fe 90 ee<br>23 Oe 70 a<br>22 a 50 a<br>-40 -20 0 20 40 60 80 100 120 -40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC) Ambient Temperature (oC)oC)C)<br>A)<br><br> (<br>ICC_STCC_ST<br> (V)<br>CC_OVP<br>V<br> (V)<br>CC_TH<br>V<br> (V)<br>OPR_MIN<br>V<br>**----- End of picture text -----**<br>
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9.0<br>8.7 T_T<br>LT<br>ft yt 8.4 po<br>ft tf 8.1 eeeeee<br>HH el<br>7.8<br>ee=>=><br>7.5<br>| | 7.2 > ee aeaa ee<br>| df ld 6.9 mToeoe<br>6.6<br>ft ff 6.3 pp<br>ff i 6.0 ee<br>80 100 120 -40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC)oC)C)<br>250<br>230 i<br>210 a i<br>170190170<br>150 ee ee<br>130 el<br>110 Toe<br>90 ee<br>70 a<br>50 a<br>80 100 120 -40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC)oC)C)<br>0.430<br>0.425<br>n a<br>0.420<br>0.415 EEE<br>ae 0.410 a ,<br>0.405<br>0.400 EEEen<br>0.395<br>0.390<br>| jd 0.385 eeee<br>[ ft 0.380 es<br>80 100 120 -40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC)<br>A)<br><br> (<br>ICC_STCC_ST<br> (V)<br>OPR_MIN<br>V<br> (V)<br>CS_REF<br>V<br>**----- End of picture text -----**<br>
**Operating Current vs. Ambient Temperature CS Reference Voltage vs. Ambient Temperature**
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1.00<br>0.95 TT on<br>0.90<br>Seer<br>0.85 ee ae<br>0.80<br>0.75 pZOope<br>0.70<br>0.65 P| | | | | | jd<br>0.60 | | | | | | [ ft<br>-40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC)<br> (mA)<br>ICC_OPR<br>**----- End of picture text -----**<br>
Note: 9. These electrical characteristics are tested under DC condition. The ambient temperature is equal to the junction temperature of the device.
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Performance Characteristics** (continued)
## **CS Clamp Reference Voltage vs. Ambient Temperature FB CV Threshold vs. Ambient Temperature**
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2.20<br>2.15 P| | | | ft | ft<br>2.10<br>PERSE<br>2.05<br>pj ft ttt<br>2.00 P| [ | [ft<br>1.95 i ee a<br>1.90<br>1.85<br>| | | | | | | ft |<br>1.80 | | | | | | ft ft<br>-40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC)<br>(V)<br>CS_CLAMP<br>V<br>**----- End of picture text -----**<br>
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3.5<br>3.4<br>ee eeeee<br>3.3<br>3.2 EERE<br>3.1<br>a<br>3.0 ee<br>2.9<br>po<br>2.8<br>2.7<br>2.6 es ee<br>2.5 ee<br>-40 -20 0 20 40 60 80 100 120<br>Ambient Temperature (oC)<br>(V)<br>FB_CV<br>V<br>**----- End of picture text -----**<br>
**FB CV Threshold vs. VCC Voltage CS Reference Voltage vs. VCC Voltage**
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3.5 0.430<br>3.4 a 0.425 a<br>0.420<br>3.3<br>So 0.415 ER<br>3.2<br>0.410<br>3.1 0.405<br>3.0 0.400<br>2.9 SoSfT 0.395 ee<br>2.8 ee 0.390<br>0.385<br>2.7<br>0.380<br>2.6 FEES 0.375 EEEEEEES<br>2.5 0.370 -—} +} +} +} J<br>8 10 12 14 16 18 20 22 24 8 10 12 14 16 18 20 22 24<br>VCC Voltage (V) VCC Voltage (V)<br>Analog Dimming Curve Analog Dimming Curve (Zoomed in 0 to 10%)<br>1009080 OOA 1098 TLL2LLL<br>70 PEPE EE 7 a<br>6050 aa 65<br>40 HEEL 4 fe<br>30 aD 4a 3 a<br>20 POAT CEE Cee 2 TE<br>10 TPAC EEE EEE 1 i,ALLL<br>0 PCELEELEEELLE 0 rTFL<br>0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 0.00 0.03 0.06 0.09 0.12 0.15 0.18 0.21 0.24 0.27<br>VADIM (V) VADIM (V)<br>Dimming Percentage (%)<br>(V)<br>FB_CV<br>V<br>Dimming Percentage (%)<br> (V)<br>CS_REF<br>V<br>**----- End of picture text -----**<br>
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Application Information**
The AL1666 is a constant current high PF Flyback and Buck-boost controller with Primary Side Regulation (PSR), targeting LED lighting applications. The device eliminates the opto-couplers or the secondary feedback circuits, which will help to minimize the whole system BOM cost. High power factor is achieved by constant on-time operation. In order to reduce the switching losses and improve EMI performance, quasiresonant switching mode is applied. The AL1666 integrates multiple protections including UVLO protection, VCC over voltage protection, output open voltage protection, over current protection, thermal fold-back protection and over temperature protection. The AL1666 can support analog dimming mode and PWM dimming.
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C7 R14<br>L1 T1<br>C1 C2 RTH R10 C5 D3 R11 C6 + OUT<br>F1<br>AC VR1 D2<br>Input hi © Aux R4 D1 1 am ie<br>DB1 PWM Signal<br>CVCC<br>R5 VCC PWMD D4<br>Q1<br>FB OUT<br>AL1666 R9<br>R6 COMP<br>RCOMP ADIM GND CS<br>U1<br>CCOMP CDIM RCS<br>| fag<br>Figure 1. Flyback Application Circuit<br>L1<br>T1<br>C1 C2 RTH R11 C6 OUT<br>F1<br>D3<br>AC<br>VR1<br>Input ie Aux R4 D1<br>DB1 PWM Signal<br>CVCC<br>D4<br>R5<br>VCC PWMD<br>Q1<br>i _ ° oh FB pe OUT w e a l :<br>AL1666 R9<br>R6 COMP<br>RCOMP ADIM GND CS<br>CCOMP CDIM RCS<br>eS<br>Figure 2. Buck-Boost Application Circuit<br>+<br>**----- End of picture text -----**<br>
## **Start-Up**
After AC supply is powered on, the capacitor CVCC across VCC pin and GND pin will be charged up by BUS voltage through a start-up resistor RTH. Once VCC reaches VCC_TH, the internal blocks start to work. VCC is supplied by VBUS until the auxiliary winding of Flyback transformer could supply enough energy to maintain VCC above VOPR_MIN. If VCC voltage is lower than VOPR_MIN, the switch will be turned off.
After VCC exceeds VCC_TH, the drive blocks don’t start to switch on/off signals until VCOMP is higher than the initial voltage VCOMP_ST which can be programmed by RCOMP. The formula is shown as below. Such design can program startup on time to reduce the startup time or reduce the output overshoot current.
**==> picture [152 x 12] intentionally omitted <==**
Where VCOMP_ST is the pre-charged voltage of COMP pin, RCOMP is shown as Figure 1.
Generally, a big capacitance of CCOMP is necessary to achieve high power factor and stabilize the system loop (1μF to 2μF is recommended). The pre-charged voltage in start-up procedure can be programmed by RCOMP.
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**==> picture [564 x 436] intentionally omitted <==**
## **4. Secondary Diode/Primary Windings/Secondary Windings Short Protection**
The CS voltage will be high when Secondary Diodes/Primary windings/Secondary windings are Shorted. If CS is higher than VCS_OCP, the protection will be triggered, switch will be turned off and VCC will be latched for 16s, then VCC will be discharged. Once VCC is below VOPR_MIN, the IC will shut down and power on again by the BUS voltage through the startup resistor. Power dissipation is low when output short protection happens.
## **5. Thermal Fold-Back Protection (TFP)**
The AL1666 has thermal fold-back function: it adopts self-adaptive control method which can prevent the system from breaking down caused by over temperature. The overheating temperature is set at +150°C. When the temperature of the IC is higher than this point; the device will decrease the voltage reference of the CS linearly till OTP happens. By this way, the device can limit system’s input power at high ambient temperature, preventing system’s temperature increases further.
## **6. Over Temperature Protection (OTP)**
The AL1666 has built-in Over Temperature Protection (OTP) function. When the temperature goes up to +180°C, the over temperature protection is triggered, which leads to VCC UVLO. When OTP recovers, the system can be restarted.
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Application Information** (continued)
## **Output Constant-Current Control**
According to the definition of mean output current, the mean output current can be obtained as below.
**==> picture [137 x 30] intentionally omitted <==**
Where IO_MEAN is the mean output current; ISP is secondary peak current of transformer; tONS is discharge time of secondary side of transformer; tSW is the switch period.
According to the principle of AL1666 close loop control, the voltage of RCS will be sampled when switch is turned off and the value will be held until discharge time tONS is over. It can be described by following formula:
**==> picture [110 x 37] intentionally omitted <==**
Where IP is primary peak current of transformer; RCS is current sense resister which is shown as Figure 1.
tONS is discharge time of secondary side of transformer; tSW is the switch period. VREF is internal reference voltage that is equal to 0.4V.
The peak current at secondary side has following relationship with primary side peak current, if the effect of the leakage inductor is neglected.
_I_ _N_ _I SP PS P_
Where NPS is the turns ratio of Flyback transformer (NPS=1 for Buck-boost); IP is the primary peak current of the transformer.
According to these above formulas, the mean output current can be induced finally by below expressions.
**==> picture [95 x 29] intentionally omitted <==**
Where IO_MEAN is the mean output current; RCS is current sense resister which is shown as Figure 1 and Figure 2;
VREF is internal reference voltage that is equal to 0.4V; NPS is the turns ratio of Flyback transformer (NPS=1 for Buck-boost); Therefore, the constant output current control can be realized with appropriate parameter design.
## **PF and THD Compensation Circuit**
In typical application, the AL1666 can provide PF>0.9 and THD <20%. It can improve PF>0.95 and THD<10% by adding the below compensation circuit. VBUS is connected to bus line which is after rectifier bridge. COMP pin voltage will add an offset that almost follows with bus line voltage in the circuit. Due to COMP voltage controls switch-on time, thus phase difference between input voltage and input current will be reduced that can optimize PF and THD. In the circuit, range of resister value R12 is from 800kΩ to 1.5MΩ, range of resistor value R13 is from 500Ω resistor to 5.1kΩ. Range of capacitance C11 is 1F to 2F. PF and THD can be improved by fine tuning these components.
**==> picture [187 x 146] intentionally omitted <==**
**----- Start of picture text -----**<br>
VBUS<br>COMP<br>R12 CCOMP<br>C11 R13 RCOMP<br> Figure 3. PF and THD Optimization Circuit<br>[a][n]<br>**----- End of picture text -----**<br>
Figure 3. PF and THD Optimization Circuit
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Application Information** (continued)
## **Line Regulation Compensation Function**
The AL1666 can achieve good line regulation by adjusting the FB pull-up resistor RFB1 and the CS external horizontal resistor RCS1. RFB2 is the FB pull-down resistor. Figure 4 shows this circuit. As RFB2 is far larger than RFB3, during tONP, the VFB can be calculated approximately as:
And the VCS_OFFSET can be got:
**==> picture [234 x 69] intentionally omitted <==**
Where:
- K is conversion coefficient of IFB3 that is equal to 0.013*10[-3]
- VIN_RMS is the input RMS voltage
- NAP is the turns’ ratio of auxiliary winding and primary winding
- RFB3 is the internal FB pulldown resistor that is connected to the system during tONP time and equals to 184Ω
- RCS2 is the internal horizontal resistor that is 6kΩ
The output current can be calculated as:
**==> picture [425 x 32] intentionally omitted <==**
Where:
-
VREF is the internal reference voltage that is equal to 0.4V
**==> picture [264 x 144] intentionally omitted <==**
**----- Start of picture text -----**<br>
Q1 AL1666 FB RFB1<br>_|<br>VREF K tONP<br>CS IFB3<br>V→I RFB2<br>RCS1 RCS2 RFB3<br>RCS<br>bee<br>Figure 4. Line Regulation Compensation Circuit<br>**----- End of picture text -----**<br>
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
**Application Information** (continued) **Dimming Mode** The AL1666 can support two dimming modes: analog dimming and PWM-to-DC dimming. **1. Analog Dimming Mode** In analog dimming mode, the dimming signal is added to ADIM pin directly to realize dimming function. The setting circuit is shown as Figure 5. When VADIM is higher than 2.4V, the driver will output 100% of rated current; when the voltage VADIM is in the range from 0mv to 2.4V, the output current will change linearly with the voltage VADIM. The dimming curve is shown as Figure 6 and the dimming range is from 1% to 100%. 50mV to 2.4V 100% Dimming Signal ADIM CADIM AL1666 1% 0 2.4V VADIM Figure 5. Analog Dimming Setting Circuit Figure 6. Analog Dimming Curve ~~pa~~ **2. PWM-to-DC Dimming Mode** In PWM-to-DC dimming mode, PWM dimming signal is added to PWMD pin. The setting circuit is shown as below. A capacitance of hundreds nF is recommended for CADIM. The duty cycle of the dimming signal DDIM is reflected by the voltage on ADIM pin VADIM. _VADIM=DDIM×2.4V_
Where DDIM is duty of PWM signal; VADIM is the voltage of ADIM pin.
**==> picture [163 x 113] intentionally omitted <==**
**----- Start of picture text -----**<br>
ADIM<br>AL1666<br>PWMD<br>f o<br>C<br>ADIM<br>**----- End of picture text -----**<br>
**==> picture [170 x 126] intentionally omitted <==**
**----- Start of picture text -----**<br>
100%<br>1% Le<br>0 PWM Duty (%) 100<br>Dimming Range<br>**----- End of picture text -----**<br>
Figure 7. PWM Dimming Setting Circuit
Figure 8. PWM Dimming Curve (PWM Frequency is 1kHz)
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666**
## **Application Information** (continued)
## **Operation Parameters Design**
## **Setting the Current Sense Resistor RCS**
The current sense resistance can be calculated as following:
**==> picture [79 x 30] intentionally omitted <==**
Where IO_MEAN is the mean output current; RCS is current sense resister which is shown as Figure 1;
VREF is internal reference voltage that is equal to 0.4V; NPS is the turns ratio of Flyback transformer (NPS=1 for Buck-boost).
## **Setting Transformer Selection (T1)**
NPS is limited by the electrical stress of the switch MOSFET, can be calculated by below formula.
**==> picture [205 x 37] intentionally omitted <==**
Where VMOS_(BR)DS is the breakdown voltage of the switch MOSFET. VIN_MAX is the max rated input voltage. ∆VS is the overshoot voltage clamped by RCD snobbier during OFF time. VO is the output voltage. VD_F is the forward voltage of secondary diode. NPS is the turns ratio of Flyback transformer (NPS=1 for Buck-boost).
For boundary conduction mode and constant on time method, the peak current of primary inductance can be calculated as below.
**==> picture [182 x 40] intentionally omitted <==**
Where VIN_RMS is the rate input voltage; IP is the primary inductance current. NPS is the turns ratio of Flyback transformer (NPS=1 for Buck-boost); IO_MEAN is the mean output current; VO is the output voltage.
The switching frequency is not constant for AL1666 due to boundary conduction mode. To set the minimum switching frequency fMIN at the crest of the minimum AC input, primary inductance can be obtained by below formula.
**==> picture [136 x 29] intentionally omitted <==**
Where VIN_RMS is the rate input voltage; IP is the primary inductance current. NPS is the turns ratio of Flyback transformer (NPS=1 for Buck-boost);
IO_MEAN is the mean output current; VO is the output voltage; fMIN is the minimum switching frequency at the crest of the minimum AC input.
According to the Faraday’s Law, the winding number of the inductance can be calculated by:
**==> picture [50 x 65] intentionally omitted <==**
Where,
Ae is the core effective area.
Bm is the maximum magnetic flux density.
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AL1666 Document number: DS42417 Rev. 1 - 2
December 2019 © Diodes Incorporated
**AL1666 Ordering Information AL1666 X - X** Product Name Package Packing S : SO-8 (Standard) 13 : 13" Tape & Reel **13” Tape and Reel Part Number Package Code Package Quantity Part Number Suffix** AL1666S-13 S SO-8 (Standard) 4000/Tape & Reel -13 | **Marking Information** ~~ae ee~~ **(Top View)** 8 7 6 5 | LL Logo YY : Year : 19, 20, 21~ Marking ID **AL1666** WW : Week : 01~52; 52 represents 52 and 53 week **YY WW X X** X X : Internal Code ~~ae~~ 1 2 3 4
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**AL1666**
## **Package Outline Dimensions**
Please see http://www.diodes.com/package-outlines.html for the latest version.
## **SO-8 (Standard)**
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**----- Start of picture text -----**<br>
E1<br>h<br>A3<br>c<br>E A2 A SO-8 (Standard)<br>Ø GS eating Planeauge Plane Dim Min Max Typ<br>1 L A -- 1.75 --<br>e A1 A1 0.10 0.25 --<br>D A EE A2 1.25 1.65 --<br>A3 0.50 0.70 --<br>b<br>b 0.30 0.51 --<br>c 0.15 0.25 --<br>D 4.80 5.00 --<br>E 5.80 6.20 6.00<br>E1 3.80 4.00 --<br>e -- -- 1.27<br>h 0.25 0.50 --<br>L 0.45 0.82 --<br>Ø 0° 8° --<br>All Dimensions in mm<br> OPTION A OPTION B<br>(TOP VIEW) (TOP VIEW)<br>45°<br>**----- End of picture text -----**<br>
## **Suggested Pad Layout**
Please see http://www.diodes.com/package-outlines.html for the latest version.
## **SO-8 (Standard)**
**==> picture [322 x 141] intentionally omitted <==**
**----- Start of picture text -----**<br>
X1<br>Dimensions Value (in mm)<br>ood C 1.27<br>Y1 X 0.802<br>X1 4.612<br>Y 1.505<br>Y1 6.50<br>Y<br>agen C X ==<br>**----- End of picture text -----**<br>
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AL1666 Document number: DS42417 Rev. 1 - 2
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**AL1666 IMPORTANT NOTICE** DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated website, harmless against all damages. Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel. Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings noted herein may also be covered by one or more United States, international or foreign trademarks. This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the final and determinative format released by Diodes Incorporated. **LIFE SUPPORT** Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: |__| A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2019, Diodes Incorporated **www.diodes.com**[i] AL1666 16 of 16 December 2019 Document number: DS42417 Rev. 1 - 2 **www.diodes.com** © Diodes Incorporated
Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems.
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Updated at April 29, 2026
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