LP3971 Datasheet, PDF (26/57 Pages) National Semiconductor (TI) – POWER MANAGEMENT UNIT FOR ADVANCED APPLICATION PROCESSORS

LP3971
SNVS432U – JANUARY 2006 – REVISED OCTOBER 2008
SYSTEM CONTROL REGISTER (SCR2) 8H'0E
Bit
Designation
Reset Value
7
BBCS
1
6
SEB2
0
5
BPTR**
0**
4
WUP3_
sense
1
3
2
GPIO2
0
0
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1
0
GPIO1
0
0
SYSTEM CONTROL REGISTER (SCR2) 8H'0E DEFINITIONS
Bit
Access
Name
Description
7
R/W
BBCS
Sets GPIO1 as control input for Back Up battery charger
0 = Back Up battery Charger GPIO Disabled
1 = Back Up battery Charger GPIO Pin Enabled
6
R/W
SEB2
PWR_EN soft Low voltage Supply Enabled OR'ed with PWR_EN Pin
0 = Low voltage Supply Output Enabled
1 = Low voltage Supply Output Disabled
5
R/W
BPTR
Bypass RTC_LDO Output Voltage to LDO1 Output Voltage Tracking
0 = RTC_LDO1 Tracking enabled
1 = RTC-LDO1 Tracking disabled
4
R/W
WUP3_ Spare Wakeup control input
sense
0 = Active High
1 = Active Low
3:2
R/W
GPIO2
Configure direction and output sense of GPIO2 Pin
Data Code
GPIO2
2h'00
Hi-Z
2h'01
Output Low
2h'02
Input
2h'03
Output high
1:0
R/W
GPIO1
Configure direction and output sense of GPIO1 Pin
Data Code
GPIO1
2h'00
Hi-Z
2h'01
Output Low
2h'02
Input
2h'03
Output high
BUCKS OUTPUT VOLTAGE ENABLE REGISTER (BOVEN) 8H'10
Bit
Designation
Reset Value
7
Reserved
0
6
B2ENC**
1**
5
Reserved
0
4
B3EN
1
3
Reserved
0
2
B2EN
1
1
Reserved
0
0
B1EN
1
BUCKS ENABLE REGISTER (BOVEN) 8H'10 DEFINITIONS
Bit
Access
7
—
6
R/W
5
—
4
R/W
3
—
2
R/W
Name
—
B2ENC
—
B3EN
—
B2EN
Description
Reserved
Connects Buck 2 enable to SYS_EN or PWR_EN Logic Control pin
0 = Buck 2 enable connected to PWR_EN
1 = Buck 2 enable connected to SYS_EN
Reserved
V_CC_Buck3 Supply Output Enabled
0 = V_CC_Buck3 Supply Output Disabled
1 = V_CC_Buck3 Supply Output Enabled
Reserved
V_CC_Buck2 Supply Output Enabled
0 = V_CC_Buck2 Supply Output Disabled
1 = V_CC_Buck2 Supply Output Enabled
26
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