High-Voltage, 3-Channel Linear High-Brightness

LED Driver with Open LED Detection

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7

Pulse-Dimming Inputs (DIM_)

The MAX16823 features pulsed or chopped-current

dimming inputs (DIM_) to chop the LED current and to

adjust the brightness. DIM_ also serves as an active-

high enable input. A logic-low at DIM_ turns off OUT_

and a logic-high turns on OUT_. If the signal at DIM

stays low more than the programmed LEDGOOD delay

time, LEDGOOD goes low (Figure 1).

Two Brightness Levels for

TAIL/STOP Lights

Figure 2 shows the PWM dimming operation for the

MAX16823 with an ICM7555 timer. The ICM7555 pro-

vides an adjustable duty cycle using two external resis-

tors and a capacitor. In TAIL operation, the output of

the ICM7555 feeds into DIM and lights up the LEDs.

The LED’s brightness depends on the duty cycle of the

I_REG

MAX16823

I_REG

I_REG

IN

IN

IN

OUT1

CS1

OUT2

OUT3

UVLO

THERMAL

SHUTDOWN

LGC

LEDGGOOD

DIM3

DIM2

DIM1

GND

IN

IN

IN

BANDGAP

LEDGOOD

DETECTOR

CS2

CS3

REG

Block Diagram