LTC3206

6

3206f

BLOCK DIAGRA

11

5

4

6

3

14

25

–

+

15

960kHz

OSCILLATOR

1x AND 1.5x CHARGE PUMP

–

+

SGND 13

ENRGB/S 10

SCL

9

SDA

8

19 MAIN4

20 MAIN3

24 AUX2

23 AUX1

2 SUB2

1 SUB1

21 MAIN2

18 BLUE

3206 BD

17 GREEN

16 RED

22 MAIN1

2

2

2

CONTROL

LOGIC

4

4

4

24

4

4

PWM

COMMAND LATCH

–

+

PGND

CPO

ENABLECP

STOP

OPERATIO

Power Management

To optimize efficiency, the power management section of

the LTC3206 provides two methods of supplying power to

the CPO pin: 1x direct connect mode or 1.5x boost mode.

When any display of the LTC3206 is enabled, the power

is high enough to power all of the LEDs with the pro-

grammed current, the system will remain in this “direct

connect” mode providing maximum efficiency. Internal

circuits monitor all current sources for the onset of “drop-

out,” the point at which the current sources can no longer

supply programmed current. As the battery voltage falls,

the LED with the largest forward voltage will reach the drop-

out threshold first. When any of the LED pins reach the drop-

out threshold, the LTC3206 will switch to boost mode and

automatically soft-start the 1.5x boost charge pump. The

constant frequency charge pump is designed to minimize