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參數(shù)資料
| 型號(hào)： | LP3972 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Power Management Unit for Advanced Application Processors |
| 中文描述： | 電源管理單元的高級(jí)應(yīng)用處理器 |
| 文件頁數(shù)： | 15/59頁 |
| 文件大?。?/td> | 1072K |
| 代理商： | LP3972 |
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Back-Up Charger Electrical Characteristics
Unless otherwise noted, V
IN
= V
BATT
= 3.6V. Typical values and limits appearing in normal type apply for T
J
= 25C. Limits ap-
pearing in
boldface
type apply over the entire junction temperature range for operation, 40C to +125C. (Notes 2, 6) and
(Note 8).
Symbol
V
IN
I
OUT
Parameter
Conditions
Min
3.3
Typ
Max
5.5
Units
V
μA
Operational Voltage Range
Backup Battery Charging Current
Voltage at V
IN
V
IN
= 3.6V, Backup_Bat = 2.5V,
Backup Battery Charger Enabled
(Note 8)
V
IN
= 5.0V Backup Battery Charger
Enabled. Programmable
Backup_Bat = 0V, Backup Battery
Charger Enabled
I
OUT
≤
50 μA, V
OUT
= 3.15V
V
OUT
+ 0.4
≤
V
BATT
= V
IN
≤
5.0V
f
<
10 kHz
I
OUT
<
50 μA
0 μA
≤
I
OUT
≤
100 μA
190
V
OUT
Charger Termination Voltage
2.91
3.1
V
Backup Battery Charger Short
Circuit Current
Power Supply Ripple Rejection
Ratio
9
mA
PSRR
15
dB
I
Q
C
OUT
Quiescent Current
Output Capacitance
Output Capacitor ESR
25
0.1
μA
μF
m
5
500
LP3972 BATTERY SWITCH OPERATION
The LP3972 has provisions for two battery connections, the main battery Vbat and Backup Battery
The function of the battery switch is to connect power to the RTC LDO from the appropriate battery, depending on conditions
described below:
If only the backup battery is applied, the switch will automatically connect the RTC LDO power to this battery.
If only the main battery is applied, the switch will automatically connect the RTC LDO power to this battery
If both batteries are applied, and the main battery is sufficiently charged (Vbat
>
3.1V), the switch will automatically connect
the RTC LDO power to the main battery.
As the main battery is discharged a separate circuit called nBATT_FLT will warn the system. Then if no action is taken to
restore the charge on the main battery, and discharging is continued the battery switch will disconnect the input of the RTC_LDO
from the main battery and connect to the backup battery.
The main battery voltage at which the RTC LDO is switched over from main to backup battery is 2.8V typically.
There is a hysteric voltage in this switch operation so; the RTC LDO will not be reconnected to main battery until main battery
voltage is greater than 3.1V typically.
The system designer may wish to disable the battery switch when only a main battery is used. This is accomplished by setting
the “no back up battery bit” in the control register 8h’0B bit 7 NBUB. With this bit set to “1”, the above described switching will not
occur, that is the RTC LDO will remain connected to the main battery even as it is discharged below the 2.9V threshold. The
Backup battery input should also be connected to main battery.
L
www.national.com
15
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP3972_08 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Power Management Unit for Advanced Application Processors |
| LP3972SQ-0514/NOPB | 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel |
| LP3972SQ-5810/NOPB | 功能描述:監(jiān)控電路 Pwr Mgmt Unit RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| LP3972SQ-A413 | 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel |
| LP3972SQ-A413/NOPB | 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel |
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