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參數資料
| 型號： | LMC6953 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | PCI Local Bus Power Supervisor |
| 中文描述： | PCI本地總線電源監 |
| 文件頁數： | 8/12頁 |
| 文件大小： | 218K |
| 代理商： | LMC6953 |
Truth Table
Power
Failure
Fail
X
X
X
X
X
OK
5V
Over-Voltage
X
Fail
X
X
X
X
OK
5V
Under-Voltage
X
X
Fail
X
X
X
OK
3.3V
Over-Voltage
X
X
X
Fail
X
X
OK
3.3V
Under-Voltage
X
X
X
X
Fail
X
OK
MR
RESET
High
High
High
High
High
Low
High
Low
Low
Low
Low
Low
Low
High
X = Don’t Care
Pin Description
Pin
Name
V
DD
Function
1
5V input supply voltage. This pin supplies power to the internal comparators. It can be
connected to a capacitor acting as a back-up battery. Otherwise, it should be shorted
to the 5V pin.
5V input supply voltage. This pin is not connected to the positive power supply of the
internal comparators. It provides input signal to the 5V window comparators as well as
the power failure comparator.
3.3V input supply voltage. This pin provides input signal to the 3.3V window
comparators and the power failure comparator.
Manual reset input pin. It takes 5V CMOS logic low and triggers RESET . If not used,
this pin should be connected to V
DD
.
Ground.
This pin should be grounded at all times.
Active low reset output. RESET holds low for 100 ms after both 5V and 3.3V powers
recover, or after manual reset signal returns to high state.
External capacitor pin. The value of C
EXT
sets the reset delay.
2
5V
3
3.3V
4
MR
5
6
7
PWR__GND
GND
RESET
8
C
EXT
Application Note
HOW THE LMC6953 FUNCTIONS
The LMC6953 is a power supply supervisor with its perfor-
mance specifications compliant to PCI Specifications Revi-
sion
2.1.
The
chip
monitors
brown-out, power failure and manual reset interrupt situa-
tions.
During power-up, the LMC6953 holds RESET low for 100
ms after both 5V and 3.3V are within specified windows. It
asserts reset in 490 ns when a brown-out is detected.
Brown-out
occurs
when
5V
over-voltage or below 4.25V under-voltage or when 3.3V
supply is above 4.1V over-voltage or 2.5V under-voltage. In
case of power failure where the 5V supply falls under 3.3V
supply by 300 mV maximum, reset is asserted in 90 ns. RE-
SET also can be asserted by sending a 5V CMOS logic low
to the manual reset pin.
Each time RESET is asserted, it holds low for 100 ms after a
fault condition is recovered. The 100 ms reset delay is gen-
erated by the 0.01 μF C
capacitor, and can be adjusted
by changing the value of C
EXT
.
It is highly recommended to place lands on printed circuit
boards for 120 pF capacitors between pin 2 and ground and
power-up,
power-down,
supply
is
above
5.75V
also between pin 3 and ground. As power supplies may
change abruptly, there can be very high frequency noise
present and the capacitors can minimize the noise,
MINIMUM SUPPLY VOLTAGE FOR RESET ASSERTION
The LMC6953 guarantees V
= 1.55V as the minimum
supply voltage to achieve consistent RESET assertion. This
ensures system stability in initialization state.
DS012846-12
FIGURE 1. Output Voltage vs Supply Voltage
www.national.com
8
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| LMC6953CM | 功能描述:監控電路 RoHS:否 制造商:STMicroelectronics 監測電壓數: 監測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| LMC6953CM/NOPB | 功能描述:監控電路 RoHS:否 制造商:STMicroelectronics 監測電壓數: 監測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| LMC6953CMX | 功能描述:監控電路 RoHS:否 制造商:STMicroelectronics 監測電壓數: 監測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| LMC6953CMX/NOPB | 功能描述:監控電路 RoHS:否 制造商:STMicroelectronics 監測電壓數: 監測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| LMC7001A | 制造商:BLACK BOX 功能描述:CONVERTER |
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