Datasheet
LP3972
www.ti.com
SNVS468K –SEPTEMBER 2006–REVISED MAY 2013
TI DEFINED CONTROL AND STATUS REGISTERS
SYSTEM CONTROL REGISTER 1 (SCR1)
System Control Register 1 (SCR1) 8h’80
Bit 7
(1)
6
(1)
5
(1)
4 3 2 1 0
Designation BPSEN SENDL FPWM3 FPWM2 FPWM1 BK_SLOMOD BK_SSEN
Reset Value 0 1 0 0 0 0 0 0
(1) One-time factory programmable EPROM registers for default values
System Control Register 1 (SCR1) 8h’80 Definitions
Bit Access Name Description
7 R/W BPSEN Bypass System enable safety Lock. Prevents activation of PWR_EN
when SYS_EN is low.
0 = PWR_EN "AND" with SYS_EN signal, Default
1 = PWR_EN independent of SYS_EN
Delay time for High Voltage Power Domains LDO2, LDO3, LDO4,
Buck2, and Buck3 after activation of SYS_EN. V
CC
_LDO1 has no
delay.
Data Code Delay (ms)
6:5 R/W SENDL
2h’0 0.0
2h’1 0.5
2h’2 1.0 (Default)
2h’3 1.4
4 R/W FPWM3 Buck3 PWM/PFM Mode select
0 - Auto Switch between PFM and PWM operation
1 - PWM Mode Only will not switch to PFM
3 R/W FPWM2 Buck2 PWM/PFM Mode select
0 - Auto Switch between PFM and PWM operation
1 - PWM Mode Only will not switch to PFM
2 R/W FPWM1 Buck1 PWM/PFM Mode select
0 - Auto Switch between PFM and PWM operation
1 - PWM Mode Only will not switch to PFM
1 R BK_SLOMOD Buck Spread Spectrum Modulation Bucks 1-3
0 = 10 kHz triangular wave spread spectrum modulation
1 = 2 kHz triangular wave spread spectrum modulation
0 R BK_SSEN Spread spectrum function Bucks 1-3
0 = SS Output Disabled
1 = SS Output Enabled
SYSTEM CONTROL REGISTER 2 (SCR2)
System Control Register 2 (SCR2) 8h’81
Bit 7 6 5
(1)
4 3 2 1 0
Designation BBCS SHBU BPTR WUP3 GPIO2 GPIO1
1 0 1 1 0 0 1 0
(1) One time factory programmable EPROM registers for default values
System Control Register 2 (SCR2) 8h’81 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
Shut down Back up battery to prevent battery drain during shipping
6 R/W SHBU 0 = Back up Battery Enabled
1 = Back up battery Disabled
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