The IS32LT3954 is a DC-to-DC switching converter,
which integrate an N-channel MOSFET to operate in
a buck configuration. The device supply a wide input
voltage between 4.5V and 40V and provides a
constant current of up to 3A for driving a single LED or
multiple series connected LEDs.
The external resistor, RSET, is used to adjust LED
output current, which allowing the output voltage to be
automatically adjusted for a variety of LED
The IS32LT3954 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
feature to spread the electromagnetic emitting energy
into a wider frequency band. It is helpful to optimize
the EMI performance.
A logic input PWM signal to the enable (EN) pin is
applied to adjust the LED current. The brightness of
LED is proportional to the duty cycle of the PWM
True average output current operation is achieved
with fast transient response by using cycle-by-cycle,
controlled on-time method.
IS32LT3954 is available in an SOP-8-EP package
with an exposed pad for enhanced thermal dissipation.
It operates from 4.5V to 40V over the temperature
range of -40°C to +125°C.