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參數資料
| 型號： | ADM708 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Low Cost uP Supervisory Circuits |
| 中文描述： | 低成本的監控電路 |
| 文件頁數： | 7/8頁 |
| 文件大小： | 143K |
| 代理商： | ADM708 |
ADM705–ADM708
REV. B
–7–
If, in the event of inactivity on the WDI line, a system reset is
required, then the
WDO
output should be connected to the
MR
input as shown in Figure 16.
ADM705/
ADM706
RESET
GND
I/O LINE
P
MR
WDI
WDO
RESET
Figure 16.
RESET
from
WDO
Monitoring Additional Supply Levels
It is possible to use the power-fail comparator to monitor a
second supply as shown in Figure 17. The two sensing resistors,
R1 and R2, are selected so that the voltage on PFI drops below
1.25 V at the minimum acceptable input supply. The
PFO
output may be connected to the
MR
input so that a RESET is
generated when the supply drops out of tolerance. In this case, if
either supply drops out of tolerance, a
RESET
will be generated.
ADM705/
ADM706
PFI
RESET
GND
P
MR
PFO
RESET
V
CC
R1
R2
V
X
5V
Figure 17. Monitoring 5 V and an Additional Supply, V
X
Ps With Bidirectional
RESET
In order to prevent contention for microprocessors with a bidi-
rectional reset line, a current limiting resistor should be inserted
between the ADM70x
RESET
output pin and the
μ
P reset pin.
This will limit the current to a safe level if there are conflicting
output reset levels. A suitable resistor value is 4.7 k
. If the
reset output is required for other uses, it should be buffered as
shown in Figure 18.
ADM70x
RESET
GND
P
RESET
GND
BUFFERED
RESET
5V
V
CC
Figure 18. Bidirectional I-O
RESET
APPLICATIONS
A Typical Operating Circuit is shown in Figure 15. The unregu-
lated dc input supply is monitored using the PFI input via the
resistive divider network. Resistors R1 and R2 should be selected
so that when the supply voltage drops below the desired level
(e.g., 8 V), the voltage on PFI drops below the 1.25 V threshold
thereby generating an interrupt to the
μ
P. Monitoring the pre-
regulator input gives additional time to execute an orderly
shutdown procedure before power is lost.
ADM705/
ADM706
PFI
RESET
I/O LINE
GND
P
MR
WDI
PFO
RESET
V
CC
5V
WDO
V
CC
UNREGULATED
DC
INTERRUPT
NMI
MANUAL
RESET
GND
IN
OUT
ADM666
R1
R2
Figure 15. Typical Application Circuit
Microprocessor activity is monitored using the WDI input. This
is driven using an output line from the processor. The software
routines should toggle this line at least once every 1.6 seconds.
If a problem occurs and this line is not toggled,
WDO
goes low
and a nonmaskable interrupt is generated. This interrupt rou-
tine may be used to clear the problem.
4V
V
CC
5V
2 s/DIV
0V
5V
RESET
T
A
= 25 C
Figure 14. ADM705/ADM707
RESET
Response Time
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADM7088ARZREEL | 制造商:Analog Devices 功能描述: |
| ADM708AN | 功能描述:IC SUPERVISOR MPU 4.4V WD 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 監控器 系列:- 標準包裝:1 系列:- 類型:簡單復位/加電復位 監視電壓數目:1 輸出:開路漏極或開路集電極 復位:高有效 復位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應商設備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| ADM708ANZ | 功能描述:IC SUPERVISOR MPU 4.4V WD 8-DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 監控器 系列:- 標準包裝:1 系列:- 類型:簡單復位/加電復位 監視電壓數目:1 輸出:開路漏極或開路集電極 復位:高有效 復位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應商設備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| ADM708AR | 功能描述:IC SUPERVISOR MPU 4.4 WD 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 監控器 系列:- 標準包裝:400 系列:- 類型:備用電池電路 監視電壓數目:1 輸出:開路漏極，推挽式 復位:高有效/低有效 復位超時:最小為 35 ms 電壓 - 閥值:4.65V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:16-SOIC W 包裝:帶卷 (TR) 其它名稱:ADM691ARZ-REEL7TR |
| ADM708ARM | 功能描述:IC SUPERVISOR MPU 4.4V WD 8-MSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 監控器 系列:- 標準包裝:400 系列:- 類型:備用電池電路 監視電壓數目:1 輸出:開路漏極，推挽式 復位:高有效/低有效 復位超時:最小為 35 ms 電壓 - 閥值:4.65V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:16-SOIC W 包裝:帶卷 (TR) 其它名稱:ADM691ARZ-REEL7TR |
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