LTC3218

6

3218fa

BLOCK DIAGRAM

The LTC3218 uses a switched capacitor charge pump to

power a high current LED with a programmed regulated

current. Current regulation is achieved using an internal

current sense resistor connected between the CPO and

switches, the strengths of which are modulated to achieve

the desired LED current. This mode provides maximum

efficiency and minimum noise. The LTC3218 will remain in

–

+

CPO

GND

ENT

CP

CM

3218 BD

CURRENT

SOURCE

CONTROL

VOLTAGE

CLAMP

106

Ω

220m

Ω

OSCILLATOR

MODE

CONTROL

1

9

2

3

8

GND

11

6

5

4

ENF

7

10

CONTROL

LOGIC

OPERATION

the maximum CPO voltage possible in this mode. When

this dropout condition occurs, the LTC3218 will switch to

2x mode after a soft-start period.

The current delivered to the LED load is controlled by the

internal programmable current source. The current is