概觀
The IS32LT3956 is a DC-to-DC switching converter,
which integrates an N-channel MOSFET to operate in
a buck configuration. The device supplies 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
configurations. True average output current operation
is achieved with fast transient response by using
cycle-by-cycle, controlled on-time method.
The IS32LT3956 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).
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
signal. The embedded high-side NMOS can be used
to bypass some LEDs in the LED string to achieve
different amount LEDs output. Such as high/low beam
application.
IS32LT3956 is available in an eTSSOP-16 package
with an exposed pad for enhanced thermal
dissipation.