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AS3643

Datasheet, Confidential - D e ta i l e d D e s c r i p t i o n

Operating Mode and Currents

The output currents and operating mode are selected according to the following table:

Table 5. Operating Mode and current settings

AS3643 configuration

operating mode and currents

mode_

setting

(see

page

24)

out_on

(see

page

24)

Condition

Mode

LED_OUT1/2

output current

Always write same

content to register Cur-

rent Set1 (led_current)

and Current Set2

SCL

low

for

OUT

1

XX

X

X

if previous operating

mode was indicator,

assist light or flash mode

shutdown

all registers are reset to

their default values

0

XX

10, 01

or 11

0

standby

0

XX

00

X

ext_torch_on (see page

22) not 10

0X

ext_torch_on =10

1X

ext_torch_on =10

external torch mode

LED current is defined

by the 7LSB

led_current and

led_current2

2. The MSB bit of this register not used to protect the LED; therefore the maximum assist / torch light current = half

the maximum flash current

XX

01

1

indicator mode or

low current pwm mode

3

3. The low current mode is a general purpose PWM mode to drive less current through the LED in average, but

keep the actual pulsed current in a range where the light output from the LED is still specified. As only the 6

LSBs of led_current are used the maximum current is limited to 1/4 of the maximum flash current.

LED current is defined

by the 6LSB bits (bits

5...0) of led_current and

modulated with

31.25kHz defined by

register inct_pwm (1/

16...4/16)

X

X

10

1

assist light mode

LED current is defined

by the 7LSB

of led_current and

led_current2

XX

11

1

strobe_on (see page 25)

= 0

flash mode;

flash duration defined by

flash_timeout (see page

24)

LED current is defined

by led_current and

current can be reduced

during flash, see Flash

Current Reductions

below

X0->1

strobe_on = 1 and

strobe_type (see page

25) = 0

X1

strobe_on = 1 and

strobe_type = 1

flash mode;

flash duration defined by

STROBE input; timeout

defined by flash_timeout