AS3682 datasheet(24/43 Pages) AMSCO

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AS3682

austriamicrosystems

Data Sheet

Timing Control of CURR11, CURR12, CURR13 in Normal Mode and Soft Flash Mode

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Revision 2.21

24 - 43

11.3 Timing Control of CURR11, CURR12, CURR13 in Normal Mode and Soft Flash

Mode

Connecting the Current Sinks

The load of current sinks CURR11, CURR12, and CURR13 must be connected to the charge pump output (CP_OUT).

Setting the Current Values

Current sinks CURR11, CURR12, and CURR13 are all programmed by the same register settings (registers

current1_preview

(page 20) and Current1_strobe (page 20)). They should be connected in parallel (pins CURR11,

CURR12, and CURR13 must be connected externally) to increase the driving capability, e.g., for a photo camera flash

LED.

The current defined in these registers (current1_preview and Current1_strobe) is the total current, which means each

current sink contributes one-third of the preset current value.

Turning the Current Sinks On/Off in Preview Mode

The current sinks in preview mode are controlled programmatically by bit preview_on (page 25) or by pin GPIO0/P0. Bit

preview_on

defines which sink is selected.

Turning the Current Sinks On/Off in Strobe Mode

The current sinks in strobe mode are controlled by pin STROBE/F2. This signal is called STROBE_SIGNAL. The duration

of the strobe current is dependent on the following parameters:

In Mode 1 (selected by bit Strobe_mode (page 25)) the strobe current is started by the rising edge of the

STROBE_SIGNAL

. The duration of the strobe current is defined by the value in register Strobe_mode1 (page 25) only.

The minimum duration of the strobe current is 100ms, the maximum is 800ms.

In Mode 2 (selected by bit Strobe_mode (page 25)) the strobe current is started by the rising edge of the

STROBE_SIGNAL

. The duration of the strobe current is dependent on the length of the STROBE_SIGNAL and the value in

If register Strobe_mode2 setting = 000 to 111, strobe current stops with the falling edge of STROBE_SIGNAL but is lim-

ited to the value defined in the register (100ms to 800ms).

In Mode 3 (selected by bit Strobe_mode (page 25)) the strobe current is started by the rising edge of the

STROBE_SIGNAL

and it stops with the falling edge of the STROBE_SIGNAL. In Mode 3 there is no limitation of the strobe

time.

Table 27. Current Sink_1x Control Register

Addr: 00

Powerdown_control

This register switches the charge pump and current sinks 1x on and off.

Bit

Bit Name

Default

Access

Description

cp_led_on

See cp_led_on (page 30).

curr11_on

R/W

CURR11 enable/disable signal.

0 = Switch CURR11 off.

1 = Switch CURR11 on.

curr12_on

R/W

CURR12 enable/disable signal.

0 = Switch CURR12 off.

1 = Switch CURR12 on.

curr13_on

R/W

CURR13 enable/disable signal.

0 = Switch CURR13 off.

1 = Switch CURR13 on.

7:4

N/A

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