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| 型号： | SP690ACN-L |
| 厂商： | Exar Corporation |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR MPU LP 8NSOIC |
| 产品变化通告： | SP690A,S,T |
| 标准包装： | 98 |
| 类型： | 简单复位/加电复位 |
| 监视电压数目： | 1 |
| 复位： | 低有效 |
| 复位超时： | 最小为 140 ms |
| 电压 - 阀值： | 4.65V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 管件 |
| 其它名称： | 1016-1529-5 SP690ACN-L-ND |
+5V
V CC
PFI
V IN
R 1
Operation Without a Backup Power
Source
If a backup power source is not used, ground
V BATT and connect V OUT to V CC . Since there is
no need to switch over to any backup power
PFO
R 3
*C 1
R 2
*optional
source, V OUT does not need to be switched. A
direct connection to V CC eliminates any voltage
drops across the switch which may push V OUT
below V CC .
GND
V TRIP =
connect to μ P
1.25
R 2
R 1 + R 2
Replacing the Backup Battery
The backup battery can be removed while V CC
remains valid, without danger of triggering
1.25
R 2
=
V L - 1.25
R 1
+ 5.0 - 1.25
R 3
RESET/RESET. As long as V CC stays above the
reset threshold, battery-backup mode cannot be
entered.
PFO
V H =
1.25
R 2 || R 3
R 1 + R 2 || R 3
Adding Hysteresis to the Power-Fail
Comparator
+5V
0V
0V
V L V TRIP V H
V IN
Hysteresis adds a noise margin to the power-fail
comparator and prevents repeated triggering of
PFO when V IN is close to its trip point. Figure 18
shows how to add hysteresis to the power-fail
Figure 18. Adding Hysteresis to the POWER-FAIL
Comparator
Allowable Backup Power-Source
Batteries
Lithium batteries work very well as backup
batteries due to very low self-discharge rate and
high energy density. Single lithium batteries
with open-circuit voltages of 3.0V to 3.6V are
ideal. Any battery with an open-circuit voltage
less than the minimum reset threshold plus 0.3V
can be connected directly to the V BATT input of
this series with no additional circuitry; see
FIGURE 12. However, batteries with open-
circuit voltages that are greater than this value
cannot be used for backup, as current is sourced
into V OUT through the diode (D1 in Figure 13)
when V CC is close to the reset threshold.
comparator. Select the ratio of R 1 and R 2 such
that PFI sees 1.25V when V IN falls to its trip
point (V TRIP ). R 3 adds the hysteresis. It will
typically be an order of magnitude greater (about
10 times) than R 1 or R 2 . The current through R 1
and R 2 should be at least 1 μ A to ensure that the
25nA (max) PFI input current does not shift the
trip point. R 3 should be larger than 10K ? so it
does not load down the PFO pin. Capacitor C1
adds additional noise rejection.
Monitoring a Negative Voltage
The power-fail comparator can be used to monitor
a negative supply rail using the circuit of Figure
19. When the negative rail is valid, PFO is low.
When the negative supply voltage drops, PFO
goes high. This circuit's accuracy is
affected by the PFI threshold tolerance, the V CC
voltage, and the resistors, R1 and R2.
Date: 11/29/04
SP690A/692A Low Power Microprocessor Supervisory with Battery Switch-Over
12
? Copyright 2004 Sipex Corporation
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相关代理商/技术参数 |
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|---|---|
| SP690ACN-L/TR | 功能描述:监控电路 LW PWR MICRO 4.65V TEMP 0C to 70C RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| SP690ACP | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP690ACP-L | 功能描述:监控电路 LW PWR MICRO 4.65V TEMP 0C to 70C RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| SP690AEN | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP690AEN/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Power Microprocessor Supervisory with Battery Switch-Over |
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