ISSI IS32LT3953

Description

The IS31LT3953_IS32LT3953 is a DC-to-DC switchingconverter, which integrate an N-channel MOSFET tooperate in a buck configuration. The device supply awide input voltage between 4.5V and 38V andprovides a constant current of up to 3A for driving asingle LED or multiple series connected LEDs.The external resistor, RSET, is used to adjust LEDoutput current, which allowing the output voltage to beautomatically adjusted for a variety of LEDconfigurations.The IS31LT3953_IS32LT3953 operates in a fixedfrequency mode during switching. There is an externalresistor connected between the VCC and TON pinsused to configure the on-time (switching frequency).The switching frequency is dithered for spreadspectrum feature to spread the electromagneticemitting energy into a wider frequency band. It ishelpful to optimize the EMI performance.A logic input PWM signal to the enable (EN) pin isapplied to adjust the LED current. The brightness ofLED is proportional to the duty cycle of the PWMsignal.True average output current operation is achieved withfast transient response by using cycle-by-cycle,controlled on-time method.IS31LT3953_IS32LT3953 is available in an SOP-8-EPpackage with an exposed pad for enhanced thermaldissipation. It operates from 4.5V to 38V over thetemperature range of -40°C to +125°C.

Features

• Wide input voltage supply from 4.5V to 38V
• Withstand 40V load dump
• ±5% true average output current control
• 3A maximum output over operating temperaturerange
• Cycle-by-cycle current limit
• Integrated high-side MOSFET switch
• Dimming via direct logic input or power supplyvoltage
• Internal control loop compensation
• Under-voltage lockout (UVLO) and thermalshutdown protection
• 2μA low power shutdown
• Spread spectrum to optimize EMI
• Robust fault protection:
• Pin-to-GND short
• Component open/short faults
• Adjacent pin-to-pin short
• LED open/short
• AEC-Q100 qualification
• IS32LT3953 only