參數(shù)資料
型號： LP3972SQXE514
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 電源管理
英文描述： 1-CHANNEL POWER SUPPLY SUPPORT CKT, QCC40
封裝： 5 X 5 MM, LLP-40
文件頁數(shù)： 46/60頁
文件大?。?/td> 1171K
代理商： LP3972SQXE514
GENERAL PURPOSE I/O FUNCTIONALITY (GPIO1 AND
GPIO2)
LP3972 has 2 general purpose I/Os for system control. I2C
compatible interface will be used for setting any of the pins to
input, output or hi-Z mode. Inputs value can be read via serial
interface (GPIO1,2 bits). The pin 29 functionality needs to be
set to GPIO by serial interface register bit nEXTCHGEN.
(GPIO/CHG)
Controls
Port Function
Reg
batmonchg
GPIO<1>
Nextchgen_sel
bucen
GPIO1
Gpin 1
Function
X
1
0
Input = 0
0
Enabled
X
1
0
Input = 1
0
Not Enabled
1
0
1
X
0
X
1
X
Enabled
0
X
HiZ
1
0
X
Input (dig)->
Input
0
1
0
X
Output = 0
0
1
0
X
Output = 1
0
GPIO<1>
Factory fm disabled
GPIO_tstiob
GPIO2
gpin2
0
1
HiZ
0
1
0
1
Input (dig)->
input
0
1
Output = 0
0
1
Output = 1
0
The LP3972 has provision for two battery connections, the
main battery V
BAT and Backup Battery (See Applications
Schematic Diagrams 1 & 2 of the LP3972 Data Sheet).
The function of the battery switch is to connect power to the
LDO_RTC from the appropriate battery, depending on con-
ditions described below:
If only the backup battery is applied, the switch will
automatically connect the LDO_RTC power to this battery.
If only the main battery is applied, the switch will
automatically connect the LDO_RTC power to this battery.
If both batteries are applied, and the main battery is
sufficiently charged (V
BAT > 3.1V), the switch will
automatically connect the RTC LDO power to the main
battery.
As the main battery is discharged by use, the user will be
warned by a separate circuit called nBATT_FLT. Then if
no action is taken to restore the charge on the main
battery, and discharging is continued the battery switch will
protect the LDO_RTC by disconnecting from the main
battery and connecting to the backup battery.
— The main battery voltage at which the LDO_RTC is
switched from main to backup battery is 2.9V typically.
— There is a hysteresis voltage in this switch operation
so, the LDO_RTC will not be reconnected to main
battery until main battery voltage is greater than 3.1V
typically.
Additionally, the user may wish to disable the battery
switch, such as, in the case when only a main battery is
used. This is accomplished by setting the “no back up
battery bit” in the control register 8h’89 bit 7 NBUB. With
this bit set to “1”, the above described switching will not
occur, that is the LDO_RTC will remain connected to the
main battery even as it is discharged below the 2.9 Volt
threshold.
REGULATED VOLTAGES OK
All the power domains have own register bit (X_OK) that pro-
cessor can read via serial interface to be sure that enabled
powers are OK (regulating). Note that these read only bits are
only valid when regulators are settled (avoid reading these
bits during voltage change or power up).
www.national.com
50
LP3972
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LP3972SQX-E514 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
LP3972SQX-E514/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
LP3972SQX-I414/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
LP3972SQX-I514 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
LP3972SQX-I514/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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