Overview
The IS32LT3129A is a triple channel linear
programmable current regulator capable of up to
150mA of each LED channel and up to 30mA for the
backlight LED. It integrates a debounce and latch
circuit on the channel enable pin (EN) to facilitate the
use of a low cost momentary contact switch or a
regular latched switch. The I2C interface can
communicate with a MCU to either configure or drive
the LED channels. The I2C interface has higher priority
over the EN input. In additional, the I2C interface
supports reading function for MCU to get the state of
device and the fault flag of open/short circuit and
thermal shutdown.
The device can operate as a stand-alone LED driver
configurable with external resistors; no microcontroller
is required. A single external resistor programs the
current level, while two separate resistors
independently program the fade in and fade out ramp
rate for the channel.
The device integrates a 63 steps fade in and fade out
algorithm (Gamma correction) which causes the output
LED current to gradually ramp up to the full source
value after the EN pin is triggered. The same controller
causes the LED current to gradually ramp down to
zero if the EN pin is triggered while the output channel
is ON. The fade ramp can be interrupted mid-cycle
before completion of the ramp cycle.
The IS32LT3129A is targeted at the automotive market
with end applications to include map and dome lighting
as well as exterior accent lighting. For 12V automotive
applications the low dropout driver can support 1 to 3
LEDs (VF = 3.2V) per channel. It is offered in a small
thermally enhanced eTSSOP-20 package.