LP5526

SNVS431D – FEBRUARY 2006 – REVISED MARCH 2013

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LED ON/OFF CONTROL WITH RGB CONTROL REGISTER

Each LED output can be set ON by writing the corresponding bit high in the Control register (00H). RSW controls

RLED, GSW controls GLED and BSW controls BLED output. Note that EN_RGB bit must be high and

RGB_PWM bit low. In this mode, the RGB register (01H) does not have any effect. CC_SW bit in Control register

defines the LED output mode.

Switch Mode / Constant Current Mode

Each RGB LED output can be set to act as a switch or a constant current sink. Selection of mode is done with

the CC_SW bit in the Control Register. If bit is set high, then the switch mode is selected. Default is switch mode.

SWITCH MODE

In switch mode, the RGB LED outputs are low ohmic switches to ground. Resistance is typically 3.2

Ω. External

ballast resistors must be used to limit the current through the LED.

CONSTANT CURRENT MODE

maximum current control register (address 02H).

Table 5. RGB MAX CURRENT REGISTER (02H)

Name

Bit

Description

IR[1:0]

5:4

RLED maximum current

IG[1:0]

3:2

GLED maximum current

IB[1:0]

1:0

BLED maximum current

Maximum current for each LED output is adjusted with the RGB max current register in following way:

IR[1:0], IG[1:0], IB[1:0]

Maximum Current / Output

00

01

10

11

External ballast resistors are not needed in this mode. The maximum current for all RGB LED drivers is set with

(3)

where

1.23V = reference voltage

100 = internal current mirror multiplier

50

Table with example resistance values and corresponding output currents:

(mA)

2.4

50.2

2.7

44.7

3.0

40.3

3.3

36.7

3.6

33.7

3.9

31.1.

16

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