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APE1601

CTRL1

GND

CTRL0

EN

GPIO

PWM

LED

OFF

LED

ON

Figure 6. The PWM dimming application circuit for 2WLEDs

Besides, A

PE1601/A has 100us delay time between mode transfer. This delay time makes

different dimming frequency corresponds to different maximum duty of CTRLX pin. When

the duty cycle of dimming frequency excess maximum duty, the A

PE1601/As can't transfer

the mode normally. Equation (4) shows the relation between maximum duty of CTRLX pin

and PWM dimming frequency. Table 5 is shown the common dimming frequency and its

corresponding maximum duty. For better performance consideration, the maximum PWM

dimming frequency is recommended below 1 kHz.

(4)

Table 5. The common dimming frequency and

its corresponding maximum duty.

Dimming

Frequency (Hz)

CTRLX

Maximum Duty

ILED

Minimum Duty

1K

0.90

0.10

900

0.91

0.09

800

0.92

0.08

700

0.93

0.07

600

0.94

0.06

500

0.95

0.05

400

0.96

0.04

300

0.97

0.03

200

0.98

0.02

APE1601/A

Advanced Power

Electronics Corp.

White LED Driver (120mA Charge Pump with Current Source)