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LT3593ES6

1MHz White LED Driver with Output Disconnect and One Pin Current Programming

Linear Technology 

LT3593

PIN FUNCTIONS (DFN/TSOT)

VIN (Pin 1/Pin 3): Input Supply Pin. Must be locally by-

passed with a 1μF X5R or X7R type ceramic capacitor.

GND (Pin 2/Pin 2): Ground Pin. Connect directly to local

ground plane.

SW (Pin 6/Pin 4): Switch Pin. Connect inductor between

this pin and the VIN pin. Minimize inductance at this pin

to minimize EMI.

CAP (Pin 5/Pin 5): Output Pin. Connect to output capaci-

tor. Minimize trace between this pin and output capacitor

to reduce EMI.

CTRL (Pin 3/Pin 1): Current Control and Shutdown Pin.

This pin is used to program the LED output current. This

pin is strobed up to 32 times to decrement the internal

5-bit DACs from full-scale to 1LSB. The counter will stop

at 1LSB if the strobing continues beyond 32 counts.

The pin must be held high after the final desired positive

strobe edge. The data is transferred after a 128μs (typ)

delay. The part can be reprogrammed to a different value

after it has been enabled, however the current will change

to the new value after 128μs. If CTRL is held low for longer

than 128μs (typ), the part will go into shutdown.

LED (Pin 4/Pin 6): LED Pin. An internal switch connects

this pin to CAP. The top of the LED string is connected

to this pin. When the part is in shutdown, the LED pin is

switched off from CAP so no current runs through the

LEDs. The switch is also used to sense the LED current

when the part is on.

Exposed Pad (Pin 7/NA): Ground. The Exposed Pad must

be soldered to the PCB.

BLOCK DIAGRAM

1

VIN

SHDN

VREF

1.24V

–

PWM

COMP

A2

+

RSQ

6

SW

DRIVER

Q1

OVERVOLTAGE

PROTECTION

CAP

5

+–

RAMP

GENERATOR

OSCILLATOR

RC

CC

A3

A1

R

M2

M1

SHDN

5-BIT

LINEAR DAC

LED

4

5-BIT

COUNTER

SHDN

GND

7

2

PIN NUMBERS REFER TO DFN PACKAGE. REFER TO PIN CONFIGURATION FOR TSOT PIN NUMBERS

Figure 1. Block Diagram

CTRL

3

3593 F01

3593f

6

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