Datasheet LT3476 (Analog Devices)
| Fabricante | Analog Devices |
| Descripción | High Current Quad Output LED Driver |
| Páginas / Página | 14 / 1 — FeAtures. Description. True Color PWMTM Dimming Delivers Up to 5000:1. … |
| Formato / tamaño de archivo | PDF / 245 Kb |
| Idioma del documento | Inglés |
FeAtures. Description. True Color PWMTM Dimming Delivers Up to 5000:1. Dimming Ratio (In Boost Configuration)
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LT3476 High Current Quad Output LED Driver
FeAtures Description
n
True Color PWMTM Dimming Delivers Up to 5000:1
The LT®3476 is a quad output DC/DC converter designed
Dimming Ratio (In Boost Configuration)
to operate as a constant-current source for driving high n
LED Current Regulation with High-Side Sense
current LEDs. A fixed frequency, current mode architecture n
VADJ Pin Accurately Sets LED Current Sense
results in stable operation over a wide range of supply and
Threshold Over Range 10mV to 120mV
output voltages. A frequency adjust pin allows the user to n Four Independent Driver Channels with 1.5A, 36V program switching frequency between 200kHz and 2MHz Internal NPN Switches to optimize efficiency and external component size. n Frequency Adjust Pin: 200kHz to 2MHz The LT3476 senses output current at the high side of n High Efficiency Conversion = Up to 96% the LED. High side current sensing is the most flexible n Open LED Protection scheme for driving LEDs, allowing buck, boost or buck- n Low Shutdown Current < 10µA boost configurations. Each current monitor threshold is n Wide VIN Range: 2.8V to 16V trimmed to within 2.5% at the full scale of 105mV. With n Thermally Enhanced, 38-Lead, 5mm × 7mm an external sense resistor, the user programs the output QFN Package current range of each channel. Each of the four regulators is independently operated by that channel’s PWM signal.
ApplicAtions
This PWM feature allows precise adjustment of the color mixing or dimming ratio of the LED source. Dimming n RGGB Lighting ratios up to 1000:1 can be achieved. n Automotive and Avionic Lighting L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and True n TFT LCD Backlighting Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Constant-Current Sources
typicAl ApplicAtion 100W Quad 1A × 8 LED Driver 1000:1 PWM Dimming at 100Hz
PVIN 33V CAP1 CAP2 CAP3 CAP4 100mΩ 100mΩ 100mΩ 100mΩ PWM LED1 LED2 LED3 LED4 5V/DIV 2.2µF × 4 UP TO 1A 1A 1A 1A 8 LEDS 0.22µF 0.22µF 0.22µF 0.22µF ILED 500mA/DIV 5µs/DIV 3476 TA02 10µH 10µH 10µH 10µH 1.05V SW1 SW2 SW3 SW4 CAP1-4 REF 4.99k VIN LED1-4 2.8V TO 16V LT3476 VADJ1-4 VIN VC1-4 100k PWM1-4 PWM1-4 RT SHDN SHDN GND 2.2µF 21k 3476 TA01 1nF 3476fb 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FeAtures Description
n
True Color PWMTM Dimming Delivers Up to 5000:1
The LT®3476 is a quad output DC/DC converter designed
Dimming Ratio (In Boost Configuration)
to operate as a constant-current source for driving high n
LED Current Regulation with High-Side Sense
current LEDs. A fixed frequency, current mode architecture n
VADJ Pin Accurately Sets LED Current Sense
results in stable operation over a wide range of supply and
Threshold Over Range 10mV to 120mV
output voltages. A frequency adjust pin allows the user to n Four Independent Driver Channels with 1.5A, 36V program switching frequency between 200kHz and 2MHz Internal NPN Switches to optimize efficiency and external component size. n Frequency Adjust Pin: 200kHz to 2MHz The LT3476 senses output current at the high side of n High Efficiency Conversion = Up to 96% the LED. High side current sensing is the most flexible n Open LED Protection scheme for driving LEDs, allowing buck, boost or buck- n Low Shutdown Current < 10µA boost configurations. Each current monitor threshold is n Wide VIN Range: 2.8V to 16V trimmed to within 2.5% at the full scale of 105mV. With n Thermally Enhanced, 38-Lead, 5mm × 7mm an external sense resistor, the user programs the output QFN Package current range of each channel. Each of the four regulators is independently operated by that channel’s PWM signal.
ApplicAtions
This PWM feature allows precise adjustment of the color mixing or dimming ratio of the LED source. Dimming n RGGB Lighting ratios up to 1000:1 can be achieved. n Automotive and Avionic Lighting L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and True n TFT LCD Backlighting Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Constant-Current Sources
typicAl ApplicAtion 100W Quad 1A × 8 LED Driver 1000:1 PWM Dimming at 100Hz
PVIN 33V CAP1 CAP2 CAP3 CAP4 100mΩ 100mΩ 100mΩ 100mΩ PWM LED1 LED2 LED3 LED4 5V/DIV 2.2µF × 4 UP TO 1A 1A 1A 1A 8 LEDS 0.22µF 0.22µF 0.22µF 0.22µF ILED 500mA/DIV 5µs/DIV 3476 TA02 10µH 10µH 10µH 10µH 1.05V SW1 SW2 SW3 SW4 CAP1-4 REF 4.99k VIN LED1-4 2.8V TO 16V LT3476 VADJ1-4 VIN VC1-4 100k PWM1-4 PWM1-4 RT SHDN SHDN GND 2.2µF 21k 3476 TA01 1nF 3476fb 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts