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AS3542 3v2
Data Sheet, Strictly Confidential - D e ta i l e d D e s c r i p t i o n - S Y S T E M F u n c t i o n s
10 Detailed Description - SYSTEM Functions
10.1 SYSTEM
10.1.1 General
The system block handles the power up, power down and regulator voltage settings of the AFE.
The PWGD and XRES outputs can be configured to operate in push/pull (2 different driver strengths) open-drain mode
or to be tri-state. For a more detailed description of the GPIO functionality of these pins please refer to chapter
.
10.1.2 Power Up/Down Conditions
The chip powers up when one of the following condition is true:
The chip automatically shuts off if one of the following conditions arises:
Table 27. Power UP Conditions
#
Source
Description
1
PWRUP PwUp
ON_KEY High Level at PRWUP pin of >= 1/3 BVDD
2
CHGIN PwUp
Charger Plug-In … High level at CHGIN pin of >= 4.0V
3
VBUS PwUp
USB Plug-In …. High level at VBUS pin of >= 4.5V
4
WAKEUP PwUp
Wake-Up Timer power-up on RTC clock
4
MCLK PwUp
ON_KEY High Level at MCLK pin of >= 1/3 BVDD
Table 28. Power DOWN Conditions
#
Source
Description
1
SERIF MAJOR PwDn
Power-Down
by SERIF writing 0h to register 20h
This Power-Down clears wake-up as well.
2
Emergency PwDn
Power-Down
if PWRUP pin is HIGH for 10sec.
This time can be reduced to 5sec with bit 7 in register 21h.
3
Wake-Up PwDn
write 4h to reg. 1Ch and 0h to reg. 1Ah … disable heartbeat source
Write 3 times to reg.22h to define wake-up time;
Power-Down
by heartbeat without source by writing 9h to reg. 20h
4
Heartbeat PwDn
write 4h to reg. 1Ch and 4h/8h or Ch to reg. 1Ah … select HBT source
write 9h to reg. 20h … enable heartbeat with source
Power-Down
if no edge on the selected HBT source is seen for 500ms.
5
SERIF Watch-Dog
PwDn
write 3h to reg. 20h … enable SERIF watch-dog
Power-Down
if no SERIF read is seen for 500ms.
6
Junction-Temp PwDn
Power-Down
if junction temperature rises up to 140degC.
This threshold can be lowered with bits <4:0> in reg 21h.
This supervisor can be disabled with bit 2 in reg. 20h.
7
BVDD LOW PwDn
Power-Down
if AVDD27 LDO has 10% under-voltage for more than 680us.
This supervisor can get disabled with bit 6 in reg. 21h.
8
PVDD1 LOW PwDn
Power-Down
if enabled with bit 1 in reg. 23h and
PVDD1 LDO has 10% under-voltage for more than 680us.
9
PVDD2 LOW PwDn
Power-Down
if enabled with bit 3 in reg. 23h and
PVDD2 LDO has 10% under-voltage for more than 680us.
10
CVDD1 LOW PwDn
Power-Down
if enabled with bit 7 in reg. 23h and
CVDD1 DCDC has 10% under-voltage for more than 680us.
11
CVDD2 LOW PwDn
Power-Down
if enabled with bit 1 in reg. 24h and
CVDD2 DCDC has 10% under-voltage for more than 680us.