IS32LT3953-GRLA3-TR ISSI

IS32LT3953 CONSTANT-CURRENT 3-AMPERE PWM DIMMABLE BUCK REGULATOR LED DRIVER WITH FAULT PROTECTION July 2021 GENERAL DESCRIPTION FEATURES The IS32LT3953 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 multi ple 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 direct logic input or power supply to be automatically adjusted for a variety of LED voltage configurations. Internal control loop compensation The IS32LT3953 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 Robust fault protection: operation which will spread the electromagnetic - Pin-to-GND short energy into a wider frequency band. This function is - Component open/short faults helpful for optimizing EMI performance. - Adjacent pin-to-pin short A logic input PWM signal applied to the enable (EN) - LED open/short pin will adjust the average LED current. The LED - Thermal shutdown brightness is proportional to the duty cycle of the PWM AEC-Q100 Qualified signal. APPLICATIONS True average output current operation is achieved with fast transient response by using cycle-by-cycle, Automotive and avionic lighting controlled on-time method. Daytime running lights The IS32LT3953 is available in an SOP-8-EP package Turn/stop lights with an exposed pad for enhanced thermal dissipation. Front and rear fog lights It operates from 4.5V to 38V over the temperature Matrix headlight range of -40C to +125C. Motorcycle headlight TYPICAL APPLICATION CIRCUIT Figure 1 Typical Application Circuit Lumissil Microsystems www.lumissil.com 1 Rev. E, 07/13/2021 IS32LT3953 PIN CONFIGURATION Package Pin Configuration (Top View) SOP-8-EP PIN DESCRIPTION No. Pin Description Power supply input. Connect a bypass capacitor CIN to ground. 1 VCC The path from CIN to GND and VCC pins should be as short as possible. On-time setting. Connect a resister from this pin to VCC pin to 2 TON set the regulator controlled on-time. Logic input for enable and PWM dimming. Pull up above 1.4V 3 EN/PWM to enable and below 0.4V to disable. Input a 100Hz~20kHz PWM signal to dim the LED brightness. Drive output current sense feedback. Set the output current by 4 FB connecting a resister from this pin to the ground. 5, 6 GND Ground. Both pins must be grounded. Internal MOSFET gate driver bootstrap. Connect a 0.1F X7R 7 BOOT ceramic capacitor from this pin to LX pin. Internal high-side MOSFET switch output. Connect this pin to 8 LX the inductor and Schottky diode. Thermal Pad Connect to GND. Lumissil Microsystems www.lumissil.com 2 Rev. E, 07/13/2021