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參數(shù)資料
| 型號： | MAX691A |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Microprocessor Supervisory Circuits(帶看門狗復(fù)位、片選和支持備用電池的復(fù)位器) |
| 中文描述： | 微處理器監(jiān)控電路 |
| 文件頁數(shù)： | 9/16頁 |
| 文件大?。?/td> | 164K |
| 代理商： | MAX691A |
M
Mic roproc essor S upervisory Circ uits
_______________________________________________________________________________________
9
Chip-Enable S ignal Gating
The MAX691A/MAX693A/MAX800L/MAX800M provide
internal gating of chip-enable (CE) signals to prevent
erroneous data from being written to CMOS RAM in the
event of a power failure. During normal operation, the
CE gate is enabled and passes all CE transitions. When
reset is asserted, this path becomes disabled, prevent-
ing erroneous data from corrupting the CMOS RAM. All
–—OUT (Figure 4).
The 10ns max CE propagation delay from –—IN to –—
OUT enables the parts to be used with most μPs.
Chip-Enable Input
The Chip-Enable Input (–—IN) is high impedance (dis-
abled mode) while RESET and –————are asserted.
CC
falls below
During a power-down sequence where V
a high-impedance state when the voltage at –—–IN
goes high or 15μs after reset is asserted, whichever
occurs first (Figure 5).
During a power-up sequence, –—–IN remains high
impedance, regardless of –—IN activity, until reset is
deasserted following the reset timeout period.
In the high-impedance mode, the leakage currents into
this terminal are ±1μA max over temperature. In the
as a 75
resistor in series with the load at –—OUT.
The propagation delay through the CE transmission
gate depends on both the source impedance of the
Enable Output (–—OUT) (see Chip-Enable Propagation
Delay vs. –—–OUT Load Capacitance in the Typical
is production tested from the 50% point of –—IN to the
50% point of –—OUT using a 50
driver and 50pF of
load capacitance (Figure 6). For minimum propagation
use a low output-impedance driver.
Chip-Enable Output
In the enabled mode, the impedance of –—–OUT is
equivalent to 75
in series with the source driving –—
transmission gate is
IN. In the disabled mode, the 75
. This source
turns off when the transmission gate is enabled.
–——W—L———–Output
–—O—W———N—is the buffered output of the reset threshold
comparator. –—O—W———N—typically sinks 3.2mA at 0.1V.
CC
above the –—O—W———N—thresh-
For normal operation (V
OUT
.
Power-Fail Comparator
The power-fail comparator is an uncommitted comparator
that has no effect on the other functions of the IC.
Common uses include low-battery indication (Figure 7),
and early power-fail warning (see Typical Operating
Circuit.
Power-Fail Input
PFI is the input to the power-fail comparator. PFI has a
guaranteed input leakage of ±25nA max over tempera-
ture. The typical comparator delay is 25μs from V
IL
to
V
(power failing), and 60μs from V
to V
(power
being restored). If unused, connect this input to ground.
OSC SEL
OSC IN
7
8
EXTERNAL
OSCILLATOR
OSC SEL
OSC IN
7
8
EXTERNAL
CLOCK
OSC SEL
OSC IN
7
8
INTERNAL OSCILLATOR
100ms WATCHDOG
OSC SEL
OSC IN
7
8
INTERNAL OSCILLATOR
1.6sec WATCHDOG
MAX691A
MAX693A
MAX800L
MAX800M
N.C.
N.C.
N.C.
50kHz
Figure 3. Oscillator Circuits
Watchdog Timeout Period
Normal
1024 clks
(600/47pF x C)ms
100ms
1.6sec
OSC SEL
OSC IN
Immediately After Reset
4096 clks
(2.4/47pF x C)sec
1.6sec
1.6sec
Reset Timeout Period
Low
Low
Floating
Floating
External Clock Input
External Capacitor
Low
Floating
2048 clks
(1200/47pF x C)ms
200ms
200ms
Table 1. Reset Pulse Width and Watchdog Timeout Selections
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX691AC/D | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX691ACPE | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX691ACPE+ | 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX691ACSE | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX691ACSE+ | 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
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