参数资料
型号: MAX792MESE+
厂商: Maxim Integrated Products
文件页数: 12/16页
文件大小: 0K
描述: IC SUPERVISOR MPU 16-SOIC
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
标准包装: 50
类型: 简单复位/加电复位
监视电压数目: 1
输出: 推挽式,推挽式
复位: 高有效/低有效
复位超时: 最小为 140 ms
电压 - 阀值: 4.37V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 16-SOIC(0.154",3.90mm 宽)
供应商设备封装: 16-SOIC
包装: 管件
Microprocessor and Nonvolatile
Memory Supervisory Circuits
MIN 100ns (V CC = 5V)
1.6s
MIN 300ns (V CC = 3V)
V CC
WDI
3
V CC
0.1 μ F
V CC
WDPO
MAX792
μ P POWER
WDO
70ns
MAX820
RESET
WDI
1
11
RESET
I/O
CLOCK CC Q
V CC = 5V
Figure 7. WDI, WDO, and WDPO Timing Diagram
9
MR
GND
WDPO
WDO
16
15
D
V
CLEAR Q
default is 1.6s. Select alternative timeout periods by
connecting an external capacitor from SWT to GND
(see Selecting an Alternative Watchdog Timeout sec-
tion). When V CC is below the reset threshold, the watch-
+5V
REACTIVATE
0.1 μ F
12
*
TWO
CONSECUTIVE
WATCHDOG
FAULT
INDICATION
dog function is disabled.
Watchdog Output
4.7k
* FOR SYSTEM RESET ON EVERY
WATCHDOG FAULT, OMIT THE
FLIP-FLOP, AND DIODE–OR
WDO remains high if there is a transition or pulse at WDI
during the watchdog timeout period. The watchdog
function is disabled and WDO is a logic high when V CC
is below the reset threshold. If a system reset is desired
on every watchdog fault, simply diode-OR connect WDO
to MR (Figure 8). When a watchdog fault occurs in this
mode, WDO goes low, pulling MR low and causing a
reset pulse to be issued. As soon as reset is asserted,
the watchdog timer clears and WDO goes high. With
WDO connected to MR , a continuous high or low on WDI
will cause 200ms reset pulses to be issued every
1.6sec (SWT connected to V CC ). When reset is not
asserted, if no transition occurs at WDI during the
watchdog timeout period, WDO goes low 70ns after the
falling edge of WDPO and remains low until the next tran-
sition at WDI (Figure 7). A single additional flip-flop can
force the system into a hardware shutdown if there are
two successive watchdog faults (Figure 8). When the
MAX792/MAX820 are operated from a 5V supply, WDO
has a 2 x TTL output characteristic.
Watchdog-Pulse Output
As described in the preceding section, WDPO can be
used as the clock input to an external D flip-flop. Upon
the absence of a watchdog edge or pulse at WDI at the
end of a watchdog timeout period, WDPO will pulse low
for 1.7ms. The falling edge of WDPO precedes WDO by
70ns. Since WDO is high when WDPO goes low, the flip-
flop’s Q output remains high after WDO goes low (Figure
8). If the watchdog timer is not reset by a transition at
CONNECT WDO TO MR.
Figure 8. Two consecutive watchdog faults latch the system in
reset.
WDI, WDO remains low and the next WDPO following a
second watchdog timeout period clocks a logic low to
the Q output, pulling MR low and causing the
MAX792/MAX820 latch in reset. If the watchdog timer is
reset by a transition at WDI, WDO will go high and the
flip-flop ’s Q output will remain high. Thus a system
shutdown is only caused by two successive watchdog
faults.
Selecting an Alternative Watchdog Timeout Period
The SWT input controls the watchdog timeout period.
Connecting SWT to V CC selects the internal 1.6sec
watchdog timeout period. Select an alternative watch-
dog timeout period by connecting a capacitor between
SWT and GND. Do not leave SWT floating and do not
connect it to ground. The following formula determines
the watchdog timeout period:
Watchdog Timeout Period =
k x (capacitor value in nF)ms
where k = 27 for V CC = 3V, and k = 16.2 for V CC = 5V.
This applies for capacitor values in excess of 4.7nF. If
the watchdog function is unused, connect SWT to V CC .
12
______________________________________________________________________________________
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MAX792MESE+ 功能描述:监控电路 MPU & NV Memory Supervisor 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
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MAX792MESE-T 功能描述:监控电路 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
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