LP3972 datasheet(45/59 Pages) NSC

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2C Compatible Interface (Continued)

BACKUP BATTERY CHARGER CONTROL REGISTER (BCCR)

This register specifies the status of the main battery supply. NBUB bit

Backup Battery Charger Control Register (BCCR) 8h’89

Bit

7**

5**

4**

3**

Designation

NBUB

CNBFL

nBFLT

BUCEN

IBUC

Reset Value

Note: ** denotes one time factory programmable EPROM registers for default values

Backup Battery Charger Control Register (BCCR) 8h’89 Definitions

Bit

Access

Name

Description

R/W

NBUB

No back-up battery default setting. Logic will not allow switch over to

back-up battery.

0 = Back up Battery Enabled, Default

1 = Back up Battery Disabled

R/W

CNBFL

Control for nBATT_FLT output signal

0 = nBATT_FLT Enabled

1 = nBATT_FLT Disabled

5:3

R/W

BFLT

nBATT_FLT monitors the battery voltage and can be set to the Assert

voltages listed below.

Data Code

3h’01

3h’02

3h’03

3h’04

3h’05

Asserted

2.6

2.8

3.0

3.2

3.4

De-Asserted

2.8

3.0

3.2

3.4

3.6

Note:

Default

R/W

BUCEN

Enables backup battery charger

0 = Back up Battery Charger Disabled

1 = Back up Battery Charger Enabled

1:0

R/W

IBUC

Charger current setting for back-up battery

Data Code

2h’00

2h’01

2h’02

2h’03

BU Charger I (µA)

260

190

325

390

Note:

Default

LP3972 数据表(PDF) 45 Page - National Semiconductor (TI)

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