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LP55281

SNVS458D – JUNE 2007 – REVISED OCTOBER 2016

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Table 1. LED Current Level Adjust

Rx_IPLS[7:6], Gx_IPLS[7:6], Bx_IPLS[7:6]

SINK CURRENT PULSE (IMAX = 100 × 1.23 / RRGB) – IPLS

00

0.25 × IMAX

01

0.50 × IMAX

10

0.75 × IMAX

11

1.00 × IMAX

Table 2. LED PWM Control

Rx_PWM[5:0], Gx_PWM[5:0], Bx_PWM[5:0]

AVERAGE SINK CURRENT

PULSE RATIO (%)

000 000

0

0

000 001

1/63 × IPLS

1.6

000 010

2/63 × IPLS

3.2

...

...

...

111 110

62/63 × IPLS

98.4

111 111

63/63 × IPLS

100

Each RGB set must be enabled separately by setting EN_RGBx bit to 1. The device must be enabled (NSTBY =

1) before the RGB outputs can be activated.

When any of EN_RGBx bits are set to 1 and NSTBY = 1, the RGB driver takes a certain quiescent current from

battery even if all PWM control bits are 0. The quiescent current is dependent on RRGB resistor, and can be

calculated from formula IR_RGB = 1.23 V / RRGB.

7.3.2.1 PWM Control Timing

PWM frequency can be selected from 3 predefined values: 10 kHz, 20 kHz, and 40 kHz. The frequency is

selected with FPWM1 and FPWM0 bits, see Table 3.

Table 3. PWM Frequency

FPWM1

FPWM0

PWM FREQUENCY (fPWM)

0

0

9.92 kHz

0

1

19.84 kHz

1

0

39.68 kHz

1

1

39.68 kHz