AS3649 datasheet(29/39 Pages) AMSCO

29 / 39 page

AS3649

Datasheet - Detailed Descr i p ti on

www.ams.com/AS3649

1.0-2

29 - 39

fault_overtemp

R/sC

see Overtemperature Protection on page 13

0No fault

Junction temperature limit has been exceeded

fault_led_short

R/sC

see Short Circuit Protection on page 13

0No fault

A shorted LED is detected (pin LED_OUT1/2)

fault_ovp

R/sC

see Overvoltage Protection on page 13

0No fault

An overvoltage condition is detected (pin VOUT)

1. R/sC = Read, self clear; after readout the register is automatically cleared

Table 16. 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

2:0

inct_pwm

R/W

Define the AS3649 PWM with 31.5kHz or 7.9kHz operation for indicator

or low current mode (mode_setting=01)

000

1/16 duty cycle / 31.5kHz

001

2/16 duty cycle / 31.5kHz

010

3/16 duty cycle / 31.5kHz

011

4/16 duty cycle / 31.5kHz

100

1/64 duty cycle / 7.9kHz; needs const_v_mode=1 (additional

quiescent current)

101

2/64 duty cycle / 7.9kHz; needs const_v_mode=1

(additional quiescent current)

110

3/64 duty cycle / 7.9kHz; needs const_v_mode=1

(additional quiescent current)

111

(4/64 duty cycle / 7.9kHz) -

don’t use; use 000 setting instead

freq_switch_on

0R/W

Exact frequency switching between 4MHz/1MHz for operation close to

maximum

pulsewidth - see Table 4 on page 12

Pulseskip operation is allowed depending on dcdc_skip_enable

(see page 28)

if led_current1>=40h or led_current2>=40h and current_boost=0,

the DCDC is running at 4MHz or 1MHz and pulseskip is disabled -

results in improved noise performance

Table 15. Fault Register (Continued)

Addr: 8

Fault Register

This register identifies all the different fault conditions and provide information about the

LED detection

Bit

Bit Name

Default

Access

Description

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