參數(shù)資料
型號(hào)： ADM694
廠商： Analog Devices, Inc.
英文描述： Microprocessor Supervisory Circuits(微處理器監(jiān)控電路)
中文描述： 微處理器監(jiān)控電路（微處理器監(jiān)控電路）
文件頁數(shù)： 8/16頁
文件大?。?/td> 207K
代理商： ADM694
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
相關(guān)PDF資料
PDF描述
ADM695 Microprocessor Supervisory Circuits(微處理器監(jiān)控電路)
ADM690 Microprocessor Supervisory Circuits(微處理器監(jiān)控電路)
ADM696 Microprocessor Supervisory Circuits(微處理器監(jiān)控電路)
ADM697 Microprocessor Supervisory Circuits(微處理器監(jiān)控電路)
ADM697AN Microprocessor Supervisory Circuits
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADM694AN 功能描述:IC SUPER MPU 4.65 100MA 8DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時(shí):- 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(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT
ADM694ANZ 功能描述:IC SUPER MPU 4.65 100MA 8DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:100 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極，開路漏極 復(fù)位:高有效/低有效 復(fù)位超時(shí):最小為 250 ms 電壓 - 閥值:4.37V，4.62V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:管件 產(chǎn)品目錄頁面:1337 (CN2011-ZH PDF)
ADM694ANZ 制造商:Analog Devices 功能描述:IC SUPERVISORY CIRCUIT
ADM694AQ 制造商:AD 制造商全稱:Analog Devices 功能描述:Microprocessor Supervisory Circuits
ADM694SQ 功能描述:IC SUPERVISOR MPU 4.65V 8CDIP RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時(shí):- 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(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT
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