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參數(shù)資料
| 型號： | MAX791MJE |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Dual D-type Positive-Edge-Triggered Flip-Flops With Clear And Preset 20-LCCC -55 to 125 |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, CDIP16 |
| 封裝： | 0.300 INCH, CERAMIC, DIP-16 |
| 文件頁數(shù)： | 9/20頁 |
| 文件大小： | 146K |
| 代理商： | MAX791MJE |
RES ET Output
The MAX791’s RESET output ensures that the μP pow-
ers up in a known state, and prevents code-execution
errors during power-down or brownout conditions.
The RESET output is active low, and typically sinks
3.2mA at 0.1V saturation voltage in its active state.
When deasserted, RESET sources 1.6mA at typically
V
OUT
- 0.5V. When no backup battery is used, RESET
output is guaranteed to be valid down to V
CC
= 1V, and
an external 10k
pull-down resistor on RESET ensures
that RESET will be valid with V
CC
down to GND (Figure
4). As V
CC
goes below 1V, the gate drive to the RESET
output switch reduces accordingly, increasing the
r
DS(ON)
and the saturation voltage. The 10k
pull-down
resistor ensures the parallel combination of switch plus
resistor is around 10k
and the output saturation volt-
age is below 0.4V while sinking 40μA. When using a
10k
external pull-down resistor, the high state for the
RESET output with V
CC
= 4.75V is 4.5V typical. For bat-
tery voltages
≥
2V connected to VBATT, RESET
remains valid for V
CC
from 0V to 5.5V.
RESET will be asserted during the following conditions:
1)
V
CC
< 4.65V (typ)
2)
MR < 1.25V (typ)
3)
RESET remains asserted for 200ms (typ) after V
CC
rises above 4.65V or after MR has exceeded
1.25V.
The MAX791 battery-switchover comparator does not
affect RESET assertion. However, RESET is asserted in
battery-backup mode since V
CC
must be below the
reset threshold to enter this mode.
Watc hdog Func tion
The watchdog monitors μP activity via the Watchdog
Input (WDI). If the μP becomes inactive, WDO and
WDPO are asserted. To use the watchdog function,
connect WDI to a bus line or μP I/O line. If WDI remains
high or low for longer than the watchdog timeout period
(1.6sec nominal), WDPO and WDO are asserted, indi-
cating a software fault condition (see Watchdog Output
and Watchdog-Pulse Outputsections).
Watc hdog Input
A change of state (high to low, low to high, or a mini-
mum 100ns pulse) at WDI during the watchdog period
resets the watchdog timer. The watchdog default time-
out is 1.6sec. Select alternative timeout periods by con-
necting an external capacitor from SWT to GND (see
Selecting an Alternative Watchdog Timeoutsection).
To disable the watchdog function, leave WDI floating.
An internal resistor network (100k
equivalent imped-
ance at WDI) biases WDI to approximately 1.6V.
Internal comparators detect this level and disable the
watchdog timer. When V
CC
is below the reset thresh-
old, the watchdog function is disabled and WDI is dis-
connected from its internal resistor network, thus
becoming high impedance.
Watc hdog Output
WDO remains high if there is a transition or pulse at
WDI during the watchdog-timeout period. The watch-
dog function is disabled and WDO is a logic high when
V
CC
is below the reset threshold, battery-backup mode
is enabled, or WDI is an open circuit. In watchdog
mode, if no transition occurs at WDI during the watch-
M
Mic roproc essor S upervisory Circ uit
_______________________________________________________________________________________
9
WDPO
WDI
70ns
1.6sec
100ns MIN
WDO
Figure 5. WDI, –W——–and –W———–Timing Diagram (V
CC
mode)
MAX791
RESET
10k
TO
μ
P RESET
15
Figure 4. Adding an external pull-down resistor ensures
CC
down to GND.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX791MSE/PR | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX792CSE | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX792LC/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 |
| MAX792LCPE | 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 |
| MAX792LCPE+ | 功能描述:監(jiān)控電路 MPU & NV Memory 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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