ISSI IS32LT3953B

Description

The IS32LT3953B is a DC-to-DC switching converter that integrates an N-channel MOSFET to operate in a buck configuration. The device can operate from a wide input voltage between 4.5V and 38V and provides a constant current of up to 3A for driving a single LED or multiple series connected LEDs. The external resistor, RISET, is used to set a constant LED output current, while allowing the output voltage to be automatically adjusted for a variety of LED configurations. The IS32LT3953B operates in a fixed frequency mode during switching. There is an external resistor connected between the VCC and TON pins used to configure the on-time (switching frequency). The switching frequency is dithered for spread spectrum operation which will spread the electromagnetic energy into a wider frequency band. This function is helpful for optimizing EMI performance. A logic input PWM signal applied to the enable (EN) pin will adjust the average LED current. The LED brightness is proportional to the duty cycle of the PWM signal. True average output current operation is achieved with fast transient response by using cycle-by-cycle, controlled on-time method. The IS32LT3953B is available in an SOP-8-EP package with an exposed pad for enhanced thermal dissipation. It operates from 4.5V to 38V over the temperature range of -40°C to +125°C.

Features

• Wide input voltage supply from 4.5V to 38V
  • Withstand 40V load dump
• True average output current control
• 3A maximum output over operating temperature range
• Cycle-by-cycle current limit
• Integrated high-side MOSFET switch
• Dimming via analog input, direct logic input or power supply voltage
• Internal control loop compensation
• Under-voltage lockout (UVLO) and thermal shutdown protection
• 2μA low power shutdown
• Spread spectrum to optimize EMI
• Internal linear regulator output (VDD) to bias the external circuit
• Robust fault protection:
  • Pin-to-GND short
  • Component open/short faults
  • Adjacent pin-to-pin short
  • LED open/short
  • Thermal shutdown
• AEC-Q100 Qualified

Typical applications

• Automotive and avionic lighting, Daytime running lights, Turn/stop lights, Front and rear fog lights, Matrix headlight, Motorcycle headlight

More information

• Datasheet
• IC product information