AS3687 datasheet(17/55 Pages) AMSCO

17 / 55 page

AS3687/87XM

Datasheet

www.austriamicrosystems.com/AS3687

1v3-4

16 - 54

Figure

14 – Automatic Mode Switching

Charge Pump

1:1, 1:1.5, 1:2

CPOUT

1.0µF

CURR30

CURR31

CURR32

CURR33

CURR1

CURR2

200mV

(curr3x_switch)

450mV

(currhv_switch)

curr30_on_cp

curr31_on_cp

curr32_on_cp

curr33_on_cp

curr1_on_cp

curr2_on_cp

Debounce

Mode Switching

1:1 -> 1:1.5

1:1.5 -> 1:2

cp_mode<1:0>

CURR6

curr6_on_cp

Battery

VBAT

C2_P

500nF

C2_N

C1_P

500nF

C1_N

1µF

7.2.2 Soft Start

An implemented soft start mechanism reduces the inrush current. Battery current is smoothed when switching the

charge pump on and also at each switching condition. This precaution reduces electromagnetic radiation

significantly.

7.2.3 Charge Pump Registers

Reg. Control

Addr: 00h

This register enables/disables the Charge Pump and the Step Up DC/DC Converter.

Bit

Bit Name

Default

Access

Description

cp_on

R/W

0 = Set Charge Pump into 1:1 mode (off state) unless

cp_auto_on is set

1 = Enable manual or automatic mode switching – see

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