SH3100 Datasheet, PDF (36/80 Pages) Semtech Corporation – Supervisory IC with I2C Interface and PWM

SH3100
POWER MANAGEMENT
Register Descriptions (continued)
Address(hex): 33
Register Name CauseOfReset
Bit 7
Bit 6
Bit No.
[3]
Description
VBO
[2]
WDTCode
Violation
[1]
WDTExpired
[0]
PORB
Bit 5
Bit Value
0
1
0
1
0
1
0
1
Description
(R/W) Shows what caused the Default Value: 0000 1001
last reset
Reset Event: (see description)
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
VBO
Value Description
WDTCode
Violation
WDT expired
PORB
VDD has not dropped below the programmed VBO level since this bit was last
cleared
VDD dropped below the VBO level at some point since this bit was last cleared.
Writing 1 to this bit clears it
Either the watchdog is disabled, or else only the correct code sequence has been
written in good time, to the WDTCode register
The watchdog was enabled, and an incorrect code was written to the WDTCode
register
Writing 1 to this bit clears it
Either the watchdog is disabled, or else WDTCode register has been refreshed in a
timely fashion
The watchdog is enabled, but the WDTCode register has not been refreshed in
time to prevent the watchdog expiring
Writing 1 to this bit clears it
VDD has not dropped below 1 V since this bit was last cleared
VDD dropped below 1 V at some time since this bit was last cleared
Writing 1 to this bit clears it
Address(hex): 34
Register Name WDTCode
Bit 7
Bit 6
Bit 5
Bit No.
[7:0]
Description
WDT refresh code
Description
Bit 4
(R/W) Watchdog refresh code
Bit 3
Bit 2
Default Value: 0000 0000
Reset Event: P, W, B
Bit 1
Bit 0
WDTCode
Bit Value Value Description
Once the watchdog is enabled by writing to the WDTPeriod
register, alternate writes of 5A and C3 are expected within the
time set by WDTPeriod and WDTPrescaler registers to prevent
NRESET activation. Once enabled, the watchdog can not be
disabled by software
© 2006 Semtech Corp.
36
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