AS3687 datasheet(18/55 Pages) AMSCO

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AS3687/87XM

Datasheet

www.austriamicrosystems.com/AS3687

1v3-4

17 - 54

Addr: 23h

CP Control

This register controls the Charge Pump.

Bit

Bit Name

Default

Access

Description

cp_clk

R/W

Clock frequency selection.

0 = 1 MHz

1 = 500 kHz

2:1

cp_mode

00b

R/W

Charge Pump mode (in manual mode sets this mode, in

automatic mode reports the actual mode used)

00 = 1:1 mode

01 = 1:1.5 mode

10 = 1:2 mode

11 = NA

Note:

Direct switching from 1:1.5 mode into 1:2 in manual

mode and vice versa is not allowed. Always switch over 1:1

mode.

4:3 cp_mode_switching

00b

R/W

Set the mode switching algorithm:

00 = Automatic Mode switching; 1:1, 1:1.5 and 1:2 allowed

01 = Automatic Mode switching; only 1:1 and 1:1.5 allowed

10 = Manual Mode switching; register cp_mode defines the

actual charge pump mode used

11 = reserved

cp_start_debounce

R/W

0 = Mode switching debounce timer is always 240us

1 = Upon startup (cp_on set to 1) the mode switching

debounce time is first started with 2ms then reduced to

240us

cp_auto_on

R/W

0 = Charge Pump is switched on/off with cp_on

1 = Charge Pump is automatically switched on if a current

sink, which is connected to the charge pump (defined by

registers CP Mode Switch 1 & 2) is switched on

Note :

Don’t use automatic mode switching together with external PWM for the current sources connceted

to the charge pump with less than 500us high time.

CP Mode Switch 1

Addr: 24h

Setup which current sinks are connected (via leds) to the charge pump; if set to ‘1’ the

correspond current source (sink) is used for automatic mode selection of the charge

pump

Bit

Bit Name

Default

Access

Description

curr30_on_cp

R/W

0 = current Sink CURR30 is not connected to charge pump

1 = current sink CURR30 is connected to charge pump

curr31_on_cp

R/W

0 = current Sink CURR31 is not connected to charge pump

1 = current sink CURR31 is connected to charge pump

curr32_on_cp

R/W

0 = current Sink CURR32 is not connected to charge pump

1 = current sink CURR32 is connected to charge pump

curr33_on_cp

R/W

0 = current Sink CURR33 is not connected to charge pump

1 = current sink CURR33 is connected to charge pump

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