概觀
The IS31LT3353 is a continuous mode inductive
step-down converter, designed for driving a single
LED or multiple series connected LEDs efficiently
from a voltage source higher than the LED voltage.
The chip operates from an input supply between 6V
and 40V and provides an externally adjustable output
current of up to 1A.
The IS31LT3353 includes an integrated output
switch and a high-side output current sensing circuit,
which uses an external resistor to set the nominal
average output current.
The output current can be dynamically adjusted by
adding either a digital PWM or analog voltage level
signal to the ADJ pin. A PWM signal will provide a
gated output current while a voltage signal will
generate a continuously linear output current.
Applying a voltage less than 0.2V to the ADJ pin
turns the output off and switches the chip into a low
current standby state.
The chip is assembled in SOT23-5 and SOT89-5
packages. It operates from 6V to 40V over the
temperature range of -40°C to +125°C.
APPLICATION CIRCUIT.