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1.5-4

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AS3647/47B

Datasheet, Confidential - D e ta 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

Addr: 9

PWM and Indicator Register

This register defines the PWM mode (e.g. for indicator) and 4/1MHz mode

switching

Bit

Bit Name

Default Access

Description

1:0

inct_pwm

00

R/W

Define the AS3647/47B PWM with 31.25kHz operation for

indicator or low current mode (mode_setting=01)

00

1/16 duty cycle

01

2/16 duty cycle

10

3/16 duty cycle

11

4/16 duty cycle

2

freq_switch_on

0R/W

Exact frequency switching between 4MHz/1MHz for assist

and flash modes for operation close to maximum

pulsewidth

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

Addr: Eh

Minimum LED Current Register

This register reports the minimum LED current from the last operation

cycle

Bit

Bit Name

Default Access

Description

7:0

led_current_min

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.