Overview
The IS31LT3352 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 required LED voltage. The chip
operates from an input supply between 6V and 40V and
provides an externally adjustable output current of up to
750mA. Depending upon supply voltage and external
components, this can provide up to 30 watts of output
power.
The IS31LT3352 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 IS31LT3352 integrates temperature compensation
function in order to maintain LEDs’ stable and reliable
operation. The IS31LT3352 measures the thermistance
mounted close to LEDs. When ambient temperature near
LEDs goes too high and the Negative Temperature
Coefficient thermistors reach the value of threshold
resistance connected at RTH pin, output current starts to
reduce automatically. After the ambient temperature falls
down to a safe temperature，the current will return to the
set value.
The IS31LT3352 can be connected as LED drivers’ chain
with the same temperature compensation percentage. In
this chain, every IS31LT3352’s ADJO output pin drives
next stage’s IS31LT3352 ADJI input pin with temperature
compensation information. So, only one thermistor is
needed in the whole IS31LT3352 system.