AS3689 datasheet(41/72 Pages) AMSOSRAM

41 / 72 page

AS3689

austriami crosyst ems

Datasheet, Confidential

www.austriamicrosystems.com (mlg, ptr)

Revision 1.0.2 / 20070115

39 - 70

7.4.6.1 Overtemp comparator Registers

Addr: 12h

Curr3 control1

This register select the modes of the current sinks30..33 current.

Bit

Bit Name

Default

Access Description

preview_off_after

strobe

R/W

Select the switch off mode after strobe pulse

0=normal preview/strobe mode,

1=switch off preview after strobe duration has expired

2:1

preview_ctrl

00b

R/W

Preview is triggered by

00b = off

01b = software trigger

10b = GPIO active high

11b = GPIO active low

R/W

reserved

curr3x_ext_ovtemp

R/W

Selects overtemperature switch off of flash LED

0b = normal operation of CURR3x

1b = if the voltage on GPIO drops below 1.25V (above 1.25V if

ext_ov_temp_inv=1), CURR3x is switched from strobe to preview

current levels

(can be used to monitor the temperature of the flash led or as

general input to reduce the current through the flash LED e.g. to

temporarily reduce the current from the battery)

curr3x_strobe_high

R/W

Doubles curr3x current during strobe

0b = normal operation of CURR3x (0..160 mA)

1b = Doubles current during strobe (0..320mA)

R/W

reserved

Addr: 2Bh

Curr low voltage status2

This register controls the curr42 current sink current.

Bit

Bit Name

Default

Access

Description

ovtemp_ext

Overtemp comparator status bit

0b = no overtemperature, GPIO>1.25V

1b = overtemperature, GPIO<1.25V

Addr: 2Ch

gpio current

Bit

Bit Name

Default

Access

Description

ext_ov_temp_inv

R/w

Polarity of external overtemp comparator

0b = active high (Overtemperature when Vgpio>1.25V)

1b = active low (Overtemperature when Vgpio< 1.25V)

7.4.7 External chargepump

This external charge pump uses external schottky diodes and capacitors to generate low current outputs in the

range of –15V to +15V. The device delivers a square wave signals and an inverted square wave signals at

250kHz or 500kHz with full Battery voltage swing. Depending on the external configuration the battery voltage is

multiplied and / or inverted. A feedback loop with a dedicated regulation pin controls the output voltage by

modulating the duty circle.

E.g.: There are 3 Schottky Diodes, 2 Resistors and 3 Capacitors externally required for –6V output voltage.

For the Schottky Diodes the BAS40 (2 diodes in a SOT666 package) is recommended.

AS3689 Datasheet(PDF) 41 Page - ams-OSRAM AG

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