IS32LT3953B-GRLA3-TR ISSI

IS32LT3953B CONSTANT-CURRENT 3-AMPERE PWM DIMMABLE BUCK REGULATOR LED DRIVER WITH FAULT PROTECTION April 2021 GENERAL DESCRIPTION FEATURES The IS32LT3953B is a DC-to-DC switching converter Wide input voltage supply from 4.5V to 38V that integrates an N-channel MOSFET to operate in a - Withstand 40V load dump buck configuration. The device can operate from a True average output current control wide input voltage between 4.5V and 38V and 3A maximum output over operating temperature provides a constant current of up to 3A for driving a range single LED or multiple series connected LEDs. Cycle-by-cycle current limit The external resistor, R , is used to set a constant ISET Integrated high-side MOSFET switch LED output current, while allowing the output voltage Dimming via analog input, direct logic input or to be automatically adjusted for a variety of LED power supply voltage configurations. Internal control loop compensation The IS32LT3953B operates in a fixed frequency mode Under-voltage lockout (UVLO) and thermal during switching. There is an external resistor shutdown protection connected between the VCC and TON pins used to 2A low power shutdown configure the on-time (switching frequency). The Spread spectrum to optimize EMI switching frequency is dithered for spread spectrum Internal linear regulator output (VDD) to bias the operation which will spread the electromagnetic external circuit energy into a wider frequency band. This function is Robust fault protection: helpful for optimizing EMI performance. - Pin-to-GND short A logic input PWM signal applied to the enable (EN) - Component open/short faults pin will adjust the average LED current. The LED - Adjacent pin-to-pin short brightness is proportional to the duty cycle of the PWM - LED open/short signal. - Thermal shutdown True average output current operation is achieved with AEC-Q100 Qualified fast transient response by using cycle-by-cycle, controlled on-time method. APPLICATIONS The IS32LT3953B is available in an SOP-8-EP Automotive and avionic lighting package with an exposed pad for enhanced thermal Daytime running lights dissipation. It operates from 4.5V to 38V over the Turn/stop lights temperature range of -40C to +125C. Front and rear fog lights Matrix headlight Motorcycle headlight TYPICAL APPLICATION CIRCUIT V CC L 1 1 8 Optional VCC LX C IN R TON 4.7F 7 D 1 2 BOOT C TON BOOT C OUT 0.1F IS32LT3953B PWM 3 EN/PWM 4 100Hz ~ 20kHz FB 5 VDD 6 R ISET C VDD GND 0.47F Figure 1 Typical Application Circuit Lumissil Microsystems www.lumissil.com 1 Rev. C, 03/25/2021 IS32LT3953B TYPICAL APPLICATION CIRCUIT (CONTINUE) V CC L 1 1 8 Optional VCC LX C IN R TON 4.7F 7 D 1 2 BOOT C TON BOOT C OUT 0.1F IS32LT3953B PWM 3 R DIM2 EN/PWM 4 100Hz ~ 20kHz FB 5 VDD 6 R ISET C VDD GND 0.47F R DIM1 V ADIM Figure 2 Typical Application Circuit of Analog Dimming V CC L 1 1 8 Optional VCC LX C IN R TON 4.7F D 7 1 2 BOOT C TON BOOT C OUT 0.1F IS32LT3953B PWM 3 R EN/PWM 4 DIM2 100Hz ~ 20kHz FB 5 VDD 6 R ISET C VDD GND 0.47F NTC R DIM1 Placed close to LEDs Figure 3 Typical Application Circuit Of Thermal Rolloff with External NTC Lumissil Microsystems www.lumissil.com 2 Rev. C, 03/25/2021