參數(shù)資料
型號(hào)： 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(yè)數(shù)： 49/60頁(yè)
文件大?。?/td> 1171K
代理商： LP3972SQXE514
POWER-ON TIMING
Symbol
Description
Min
Typ
Max
Units
t1
Delay from V
CC_RTC assertion to nRSTO de-assertion
50
mS
t2
Delay from nBATT_FLT de-assertion to nRSTI assertion
100
S
t3
Delay from nRST de-assertion to SYS_EN assertion
10
mS
t4
Delay from SYS_EN assertion to PWR_EN assertion
125
mS
t5
Delay from PWR_EN assertion to nRSTO de-assertion
125
mS
HARDWARE RESET SEQUENCE
Hardware reset initiates when the nRSTI signal is asserted
(low). Upon assertion of nRST the processor enters hardware
reset state. The LP3972 holds the nRST low long enough (50
ms typ.) to allow the processor time to initiate the reset state.
RESET SEQUENCE
1.
nRSTI is asserted.
2.
nRSTO is asserted and will de-asserts after a minimum
of 50 mS
3.
The Applications processor waits for the de-assertion of
nBATT_FLT to indicate system power (V
IN) is available.
4.
After system power (V
IN) is turned on, the LP3972 de-
asserts nBATT_FLT.
5.
The Applications processor asserts SYS_EN, the
LP3972 enables the system high-voltage power
supplies. The Applications processor starts its
countdown timer.
6.
The LP3972 enables the high-voltage power supplies.
7.
Countdown timer expires; the Applications processor
asserts PWR_EN to enable the low-voltage power
supplies. The processor starts the countdown timer.
8.
The Applications processor asserts PWR_EN, the
LP3972 enables the low-voltage regulators.
9.
Countdown timer expires; If enabled power domains are
OK (I2C read) the power up sequence continues by
enabling the processors 13 MHz oscillator and PLL’s.
10. The Applications processor begins the execution of
code.
53
www.national.com
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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