RT4539A

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DS4539A-01

December 2022

24

Table 10

I2C Code

PWMI Duty (%)

ILED current

Don't care

0

0%

I2C code

1

6.105uA×I2C code×4095×PWM duty

I2C code

50

I2C code

99

Don't care

100

100%

Fade IN / OUT Time Control

The fade in / out time control can be set by the I2C interface. More setting details are shown in Table 11.

Table 11. Fade In / Out Time Control

Address Bit

Name

Default Value

Description

R/W

06h

[2:

0]

Fade IN / OUT Time

Control

0.5µs

(B000)

DC mode fade time control

B000: 0.5µs

B001: 1µs

B010: 2µs

B011: 4µs

B100: 8µs

B101: 16µs

B110: 32µs

B111: 64µs

R/W

Fade in / out time can be controlled by address 06h [2: 0]. There are eight brightness times that adjust range from

0.5µs to 64µs. When the fade in/out command is B000, the brightness time of per step will be at 0.5µs. This function

can guarantee the highest of fade in/out time is 64µs. Figure 9 shows the fade in time at 10-bit resolution. Figure

10 shows the fade out time at 10-bit resolution.

Figure 9. LED Current (Dimming Up) vs. Fade In Time

Fade In Time (Dimming Up)

49.95

50.00

50.05

50.10

50.15

50.20

50.25

0.0

0.5

1.0

1.5

2.0

2.5

Time (μs)