Datasheet A80601, A80601-1 (Allegro) - 9
| Manufacturer | Allegro |
| Description | High Power LED Driver with Pre-Emptive Boost for Ultra-High Dimming Ratio and Low Output Ripple |
| Pages / Page | 37 / 9 — A80601 and. High Power LED Driver with Pre-Emptive Boost. A80601-1 for … |
| File Format / Size | PDF / 5.0 Mb |
| Document Language | English |
A80601 and. High Power LED Driver with Pre-Emptive Boost. A80601-1 for Ultra-High Dimming Ratio and Low Output Ripple
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A80601 and High Power LED Driver with Pre-Emptive Boost A80601-1 for Ultra-High Dimming Ratio and Low Output Ripple APPLICATION EXAMPLES
VIN *optional D1 VOUT > 40 V R L1 SENSE C Q2 IN Q1 ROVP C COUT VDRV GATE VDRV GDRV CS PGND VSENSE VC VIN OVP VDRV R C PU VDD VDD VT LED1 FAULT
A80601
LED2 Cascode Enable EN Transistors LED3 PWM Q3..Q6 LED4 PWM ton ≥ 0.3 µs ADIM iLED Max. LEDx pin voltage CLKOUT 100% COMP limited to VDRV - VT ADIM AGND ISET FSET DITH PEB RZ CP RM APWM 100 kHz 0-90% RISET RFSET CZ CM RD
Figure 4: Cascode transistors can be used in case VOUT needs to be higher than 40 V
To drive an output load with more than 11 white LEDs in series, the above application circuit can be used. The cascode transistors Q3..Q6 limits LED1-4 pin voltages to VDRV – VT, even in case of LED string direct short. (VT = threshold voltage of transistor, typically under 3 V). The cascode transistors can be any small-signal N-channel MOSFET, rated for the maximum output voltage and LED current per channel. As an example: consider T2N7002BK in SOT23 package. It is rated for 60 V breakdown and 400 mA continuous current. Allegro MicroSystems, LLC 9 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com Document Outline Features and Benefits Description Applications Package Selection Guide Absolute Maximum Ratings Thermal Characteristics Typical Application – SEPIC Functional Block Diagram Pinout Diagram and Terminal List Electrical Characteristics Functional Description Enabling the IC Powering Up: LED Detection Phase Powering Up: Boost Output Undervoltage Soft Start Function Frequency Selection Synchronization Loss of External Sync Signal Switching Frequency Dithering Clock Out Function LED Current Setting PWM Dimming Pre-Emptive Boost (PEB) Analog Dimming ADIM Mode APWM Mode Extending LED Dimming Ratio Analog Dimming with External Voltage VDD VDRV Shutdown Fault Detection and Protection FAULT Status LED String Partial-Short Detect Overvoltage Protection Boost Switch Overcurrent Protection Input Overcurrent Protection and Disconnect Switch Setting the Input Current Sense Resistor Input UVLO Fault Protection During Operation Package Outline Drawing Appendix: External MOSFET Selection Guide
VIN *optional D1 VOUT > 40 V R L1 SENSE C Q2 IN Q1 ROVP C COUT VDRV GATE VDRV GDRV CS PGND VSENSE VC VIN OVP VDRV R C PU VDD VDD VT LED1 FAULT
A80601
LED2 Cascode Enable EN Transistors LED3 PWM Q3..Q6 LED4 PWM ton ≥ 0.3 µs ADIM iLED Max. LEDx pin voltage CLKOUT 100% COMP limited to VDRV - VT ADIM AGND ISET FSET DITH PEB RZ CP RM APWM 100 kHz 0-90% RISET RFSET CZ CM RD
Figure 4: Cascode transistors can be used in case VOUT needs to be higher than 40 V
To drive an output load with more than 11 white LEDs in series, the above application circuit can be used. The cascode transistors Q3..Q6 limits LED1-4 pin voltages to VDRV – VT, even in case of LED string direct short. (VT = threshold voltage of transistor, typically under 3 V). The cascode transistors can be any small-signal N-channel MOSFET, rated for the maximum output voltage and LED current per channel. As an example: consider T2N7002BK in SOT23 package. It is rated for 60 V breakdown and 400 mA continuous current. Allegro MicroSystems, LLC 9 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com Document Outline Features and Benefits Description Applications Package Selection Guide Absolute Maximum Ratings Thermal Characteristics Typical Application – SEPIC Functional Block Diagram Pinout Diagram and Terminal List Electrical Characteristics Functional Description Enabling the IC Powering Up: LED Detection Phase Powering Up: Boost Output Undervoltage Soft Start Function Frequency Selection Synchronization Loss of External Sync Signal Switching Frequency Dithering Clock Out Function LED Current Setting PWM Dimming Pre-Emptive Boost (PEB) Analog Dimming ADIM Mode APWM Mode Extending LED Dimming Ratio Analog Dimming with External Voltage VDD VDRV Shutdown Fault Detection and Protection FAULT Status LED String Partial-Short Detect Overvoltage Protection Boost Switch Overcurrent Protection Input Overcurrent Protection and Disconnect Switch Setting the Input Current Sense Resistor Input UVLO Fault Protection During Operation Package Outline Drawing Appendix: External MOSFET Selection Guide
