Datasheet LT3932, LT3932-1 (Analog Devices)
| Fabricante | Analog Devices |
| Descripción | 36V, 2A Synchronous Step-Down LED Driver |
| Páginas / Página | 30 / 1 — FEATURES. DESCRIPTION. ±1.5% LED Current Regulation. ±1.2% Output Voltage … |
| Revisión | B |
| Formato / tamaño de archivo | PDF / 4.7 Mb |
| Idioma del documento | Inglés |
FEATURES. DESCRIPTION. ±1.5% LED Current Regulation. ±1.2% Output Voltage Regulation. 5000:1/10000+:1 PWM Dimming at 100Hz
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LT3932/LT3932-1 36V, 2A Synchronous Step-Down LED Driver
FEATURES DESCRIPTION
n
±1.5% LED Current Regulation
The LT®3932 , featuring the Silent Switcher®architecture n
±1.2% Output Voltage Regulation
to minimize EMI/EMC emissions, utilizes fixed-frequency, n
5000:1/10000+:1 PWM Dimming at 100Hz
peak current control and provides PWM dimming for a
(LT3932/LT3932-1)
string of LEDs. The LED current is programmed by an ana- n
128:1 Internal PWM Dimming
log voltage or the duty cycle of pulses at the CTRL pin. An n
Spread-Spectrum Frequency Modulation
output voltage limit can be set with a resistor divider to n
Silent Switcher
®
Architecture for Low EMI
the FB pin. n 3.6V to 36V Input Voltage Range The switching frequency is programmable from 200kHz to n 0V to 36V LED String Voltage 2MHz by an external resistor at the RT pin or by an exter- n 200kHz to 2MHz with SYNC Function nal clock at the SYNC/SPRD pin. With the optional spread n 99.9% Maximum Duty Cycle spectrum frequency modulation enabled, the frequency n 20:1 Analog or Duty Cycle LED Current Control varies from 100% to 125% to reduce EMI. The LT3932 n Open/Short LED Protection and Fault Indication also includes a driver for an external, high side PMOS for n Accurate LED Current Sense with Monitor Output PWM dimming and an internal PWM signal generator for n Programmable UVLO analog control of PWM dimming when an external signal is n Thermally Enhanced 28-Pin (4mm × 5mm) QFN not available. The LT3932-1 permits higher dimming ratios. Additional features include an LED current monitor, an
APPLICATIONS
accurate EN/UVLO pin threshold, open-drain fault report- n Automotive Lighting ing for open-circuit and short-circuit load conditions, and n Industrial and General Purpose Lighting thermal shutdown. n Machine Vision Systems All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents including 7199560, 7321203, 9596728, 9642200 and other patents pending.
TYPICAL APPLICATION 2A LED Driver with Internal PWM Dimming
INTVCC
Internal PWM Dimming
VIN VIN BST 20V 22nF 8.2µH 274k SW 10µF 2x1µF EN/UVLO V SW 30.1k OUT 20V/DIV 110k COUT LT3932 FB 100µF PWMTG VREF 10k 2A MAX 10V/DIV IL 100k CTRL GND 2.2µF 1A/DIV 100k PWM ISP ILED 50mΩ 1A/DIV INTV 3932 TA01b CC ISN PWM = 1.078V 2µs/DIV 100k (8% PWM DUTY RATIO) 2.2µF PWMTG FAULT FAULT ISMON ISMON SYNC/SPRD SS RT RP VC 45.3k 28.7k 9V 162k 2MHz 7.8kHz 100nF 10nF 3932 TA01a Rev B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
±1.5% LED Current Regulation
The LT®3932 , featuring the Silent Switcher®architecture n
±1.2% Output Voltage Regulation
to minimize EMI/EMC emissions, utilizes fixed-frequency, n
5000:1/10000+:1 PWM Dimming at 100Hz
peak current control and provides PWM dimming for a
(LT3932/LT3932-1)
string of LEDs. The LED current is programmed by an ana- n
128:1 Internal PWM Dimming
log voltage or the duty cycle of pulses at the CTRL pin. An n
Spread-Spectrum Frequency Modulation
output voltage limit can be set with a resistor divider to n
Silent Switcher
®
Architecture for Low EMI
the FB pin. n 3.6V to 36V Input Voltage Range The switching frequency is programmable from 200kHz to n 0V to 36V LED String Voltage 2MHz by an external resistor at the RT pin or by an exter- n 200kHz to 2MHz with SYNC Function nal clock at the SYNC/SPRD pin. With the optional spread n 99.9% Maximum Duty Cycle spectrum frequency modulation enabled, the frequency n 20:1 Analog or Duty Cycle LED Current Control varies from 100% to 125% to reduce EMI. The LT3932 n Open/Short LED Protection and Fault Indication also includes a driver for an external, high side PMOS for n Accurate LED Current Sense with Monitor Output PWM dimming and an internal PWM signal generator for n Programmable UVLO analog control of PWM dimming when an external signal is n Thermally Enhanced 28-Pin (4mm × 5mm) QFN not available. The LT3932-1 permits higher dimming ratios. Additional features include an LED current monitor, an
APPLICATIONS
accurate EN/UVLO pin threshold, open-drain fault report- n Automotive Lighting ing for open-circuit and short-circuit load conditions, and n Industrial and General Purpose Lighting thermal shutdown. n Machine Vision Systems All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents including 7199560, 7321203, 9596728, 9642200 and other patents pending.
TYPICAL APPLICATION 2A LED Driver with Internal PWM Dimming
INTVCC
Internal PWM Dimming
VIN VIN BST 20V 22nF 8.2µH 274k SW 10µF 2x1µF EN/UVLO V SW 30.1k OUT 20V/DIV 110k COUT LT3932 FB 100µF PWMTG VREF 10k 2A MAX 10V/DIV IL 100k CTRL GND 2.2µF 1A/DIV 100k PWM ISP ILED 50mΩ 1A/DIV INTV 3932 TA01b CC ISN PWM = 1.078V 2µs/DIV 100k (8% PWM DUTY RATIO) 2.2µF PWMTG FAULT FAULT ISMON ISMON SYNC/SPRD SS RT RP VC 45.3k 28.7k 9V 162k 2MHz 7.8kHz 100nF 10nF 3932 TA01a Rev B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts