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參數資料
| 型號： | ADM690 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Microprocessor Supervisory Circuits(微處理器監控電路) |
| 中文描述： | 微處理器監控電路（微處理器監控電路） |
| 文件頁數： | 8/16頁 |
| 文件大小： | 207K |
| 代理商： | ADM690 |
ADM690–ADM695
REV. A
–8–
CE
Gating and RAM Write Protection (ADM691/ADM693/
ADM695)
T he ADM691/ADM693/ADM695 products include memory
protection circuitry which ensures the integrity of data in mem-
ory by preventing write operations when V
CC
is at an invalid
level. T here are two additional pins,
CE
IN
and
CE
OUT
, which
may be used to control the Chip Enable or Write inputs of
CMOS RAM. When V
CC
is present,
CE
OUT
is a buffered replica
of
CE
IN
, with a 5 ns propagation delay. When V
CC
falls below
the reset voltage threshold or V
BAT T
, an internal gate forces
CE
OUT
high, independent of
CE
IN
.
CE
OUT
typically drives the
CE
,
CS
, or write input of battery
backed up CMOS RAM. T his ensures the integrity of the data
in memory by preventing write operations when V
CC
is at an in-
valid level. Similar protection of EEPROMs can be achieved by
using the
CE
OUT
to drive the store or write inputs.
If the 5 ns typical propagation delay of
CE
OUT
is excessive, con-
nect
CE
IN
to GND and use the resulting
CE
OUT
to control a
high speed external logic gate.
ADM69x
CE
OUT
CE
IN
V
CC
LOW = 0
V
CC
OK = 1
Figure 5. Chip Enable Gating
Power Fail Warning Comparator
An additional comparator is provided for early warning of failure
in the microprocessor’s power supply. T he Power Fail Input
(PFI) is compared to an internal +1.3 V reference. T he Power
Fail Output (
PFO
) goes low when the voltage at PFI is less than
1.3 V. T ypically PFI is driven by an external voltage divider
which senses either the unregulated dc input to the system’s 5 V
regulator or the regulated 5 V output. T he voltage divider ratio
can be chosen such that the voltage at PFI falls below 1.3 V sev-
eral milliseconds before the +5 V power supply falls below the
reset threshold.
PFO
is normally used to interrupt the micropro-
cessor so that data can be stored in RAM and the shut down
procedure executed before power is lost
ADM69x
POWER
FAIL
INPUT
R
2
INPUT
POWER
1.3V
PFO
POWER
FAIL
OUTPUT
R
1
Figure 7. Power Fail Comparator
T able II. Input and Output Status In Battery Backup Mode
Signal
Status
V
OUT
V
OUT
is connected to V
BAT T
via an internal
PMOS switch.
Logic low.
Logic high. T he open circuit output voltage is
equal to V
OUT
.
Logic low.
Logic high. T he open circuit voltage is equal to
V
OUT .
WDI is ignored. It is internally disconnected
from the internal pull-up resistor and does not
source or sink current as long as its input voltage
is between GND and V
OUT
. T he input voltage
does not affect supply current.
Logic high. T he open circuit voltage is equal
to V
OUT
.
T he Power Fail Comparator is turned off and
has no effect on the Power Fail Output.
Logic low.
CE
IN
is ignored. It is internally disconnected
from its internal pull-up and does not source or
sink current as long as its input voltage is
between GND and V
OUT
. T he input voltage
does not affect supply current.
Logic high. T he open circuit voltage is equal to
V
OUT
.
OSC IN is ignored.
OSC SEL is ignored.
RESET
RESET
LOW LINE
BAT T ON
WDI
WDO
PFI
PFO
CE
IN
CE
OUT
OSC IN
OSC SEL
t
1
t
1
= RESET TIME.
V1 = RESET VOLTAGE THRESHOLD LOW
V2 = RESET VOLTAGE THRESHOLD HIGH
HYSTERESIS = V2–V1
V2
V2
V1
V1
t
1
V
CC
LOW LINE
RESET
CE
IN
CE
OUT
Figure 6. Chip Enable Timing
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADM690A | 制造商:AD 制造商全稱:Analog Devices 功能描述:Microprocessor Supervisory Circuits |
| ADM690AAN | 功能描述:IC SUPERVISOR MPU 4.65V 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 |
| ADM690AANZ | 功能描述:IC SUPERVISOR MPU 4.65V WD 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 監控器 系列:- 其它有關文件:STM6717 View All Specifications 標準包裝:1 系列:- 類型:多壓監控器 監視電壓數目:2 輸出:開路漏極或開路集電極 復位:低有效 復位超時:最小為 600 ms 電壓 - 閥值:1.11V，3.075V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應商設備封裝:SOT-23-5 包裝:Digi-Reel® 產品目錄頁面:1194 (CN2011-ZH PDF) 其它名稱:497-7019-6 |
| ADM690AARM | 功能描述:IC SUPERVISOR MPU 4.65V WD 8MSOP 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 |
| ADM690AARM-REEL | 制造商:Analog Devices 功能描述:Processor Supervisor 4.65V 4.65V 8-Pin MSOP T/R |
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