LTC3201

4

3201f

PI FU CTIO S

ceramic capacitor to GND.

CP (Pin 2): Flying Capacitor Positive Terminal.

FILTER (Pin 3): Input Noise Filter Terminal. Bypass with a

0.22

µF high resonant frequency ceramic capacitor to

GND. Place filter capacitor less than 1/8" from device.

CM (Pin 4): Flying Capacitor Negative Terminal.

GND (Pin 5): Ground. Connect to a ground plane for best

performance.

D0 (Pin 6): Current Control DAC LSB Input.

D1 (Pin 7): Current Control DAC Bit 1 Input.

D2 (Pin 8): Current Control DAC MSB Input. Inputs D0 to

D2 program a 3-bit DAC output which is used as the

internal reference voltage. The DAC output reference volt-

age is used to regulate amount of current flowing through

the LEDs. An internal control loop adjusts the charge

pump output such that the voltage drop across an external

sense resistor connected from FB to GND equals the

internal DAC output reference voltage. See Truth Table in

Applications Information section for internal reference

settings vs DAC code. When D0 to D2 are low, the part

enters a low current shutdown mode and the load is

FB (Pin 10): Charge Pump Feedback Input. This pin acts

SI

PLIFIED BLOCK DIAGRA

3201 BD

CHARGE

PUMP

3-BIT

DAC

LPF

3

1

10

9

5

2

4

8

7

6

SOFT-START

AND

SWITCH CONTROL

1.8MHz

OSCILLATOR

GND

FILTER

FB

CP

CM

D1

D2

D0

1.2V