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参数资料
| 型号： | LP3972SQXA413 |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, QCC40 |
| 封装： | 5 X 5 MM, LLP-40 |
| 文件页数： | 48/60页 |
| 文件大小： | 1171K |
| 代理商： | LP3972SQXA413 |
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Application Note - LP3972 Reset Sequence
INITIAL COLD START POWER ON SEQUENCE
1.
The Back up battery is connected to the PMU, power is
applied to the back-up battery pin, the LDO_RTC turns
on and supplies a stable output voltage to the
V
CC_BATT pin of the Applications processor (initiating
the power-on reset event) with nRSTO asserted from the
LP3972 to the processor.
2.
nRSTO 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 applied, the LP3972 de-
asserts nBATT_FLT. Note that BOTH nRSTO and
nBATT_FLT need to be de-asserted before SYS_EN is
enabled. The sequence of the two signals is independent
of each other.
5.
The Applications processor asserts SYS_EN, the
LP3972 enables the system high-voltage power
supplies. The Applications processor starts its
countdown timer set to 125 mS.
6.
The LP3972 enables the high-voltage power supplies.
— LDO1 power for V
CC_MVT (Power for internal logic
and I/O Blocks), BG (Bandgap reference voltage),
OSC13M (13 MHz oscillator voltage) and PLL
enabled first, followed by others if delay is on.
7.
Countdown timer expires; the Applications processor
asserts PWR_EN to enable the low-voltage power
supplies. The processor starts the countdown timer set
to 125 mS period.
8.
The Applications processor asserts PWR_EN (ext. pin or
I2C), 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.
20207622
* Note that BOTH nRSTO and nBATT_FLT need to be de-asserted before SYS_EN is enabled. The sequence of the two signals is independent of each other
and can occur is either order.
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LP3972
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LP3972SQX-A413 | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| LP3972SQX-A413/NOPB | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| LP3972SQXA514 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Power Management Unit for Advanced Application Processors |
| LP3972SQX-A514 | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| LP3972SQX-A514/NOPB | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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