
AS3647/47B
Datasheet, Confidential - D e t a i l e d D e s c r i p t i o n
1. R/sC = Read, self clear; after readout the register is automatically cleared
Table 15. PWM and Indicator Register
PWM and Indicator Register
Addr: 9
This register defines the PWM mode (e.g. for indicator) and 4/1MHz mode
switching
Bit
Bit Name
Default Access
Description
Define the AS3647/47B PWM with 31.25kHz operation for
indicator or low current mode ( mode_setting =01)
00
1/16 duty cycle
1:0
inct_pwm
00
R/W
01
2/16 duty cycle
10
11
3/16 duty cycle
4/16 duty cycle
Exact frequency switching between 4MHz/1MHz for assist
and flash modes for operation close to maximum
pulsewidth
2
freq_switch_on
0
R/W
0
Pulseskip operation is allowed for all modes -
results in better efficiency
1
In flash and assist light mode (indicator mode or low
current mode using PWM always will use pulseskip) if
led_current >=40h , the DCDC is running at 4MHz or
1MHz (pulseskip is disabled) - results in improved
noise performance;
Table 17. Minimum LED Current Register
Minimum LED Current Register
Addr: Eh
This register reports the minimum LED current from the last operation
cycle
Bit
Bit Name
Default Access
Description
led_current_min
7:0
12
00h
R
Minimum current through the current sink (only including all
current reductions as described in Current Reduction by
VIN measurements in Flash Mode excluding current
reductions caused by TXMASK )
1. As the internal change of this register is asynchronous to the readout, it is recommended to readout the register
after the flash pulse. The register will store the minimum current through the LED after e.g. a previous flash.
This current can be used for a subsequent flash pulse for a safe operating range.
2. This register is only set if an actual current reduction happens ( fault_uvlo (see page 27) =1) otherwise
led_current_min =0.
Table 18. Actual LED Current Register
Addr: Fh
Actual LED Current Register
This register reports the actual set LED current
Bit
Bit Name
Default Access
Description
7:0
led_current_actual
1
00h
R
Actual set current through the current sink (including all
current reductions as described in Flash Current
Reductions including LED current ramp up/down)
1. As the internal change of this register is asynchronous to the readout, it is recommended to readout the register
twice and compare the results.
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