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參數(shù)資料
| 型號： | MAX16998AAUA+ |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 時鐘/數(shù)據(jù)恢復及定時提取 |
| 英文描述： | 1 TIMER(S), PROGRAMMABLE TIMER, PDSO8 |
| 封裝： | 3 X 3 MM, ROHS COMPLIANT, MO-187-AA, MICRO MAX PACKAGE-8 |
| 文件頁數(shù)： | 4/16頁 |
| 文件大?。?/td> | 146K |
| 代理商： | MAX16998AAUA+ |
MAX16997/MAX16998
WDI falling edge occurs within the watchdog timeout
period (tWP) and is considered a late fault that asserts
RESET. In case 3, the WDI falling edge occurs within the
open window period and is considered a
good WDI sig-
nal falling edge. In this case, RESET stays high. In case
4, the WDI falling edge occurs within the indeterminate
region. In this case, the RESET state is indeterminate.
These devices assert ENABLE after three consecutive
bad WDI falling edges. ENABLE returns high after three
consecutive good WDI signal falling edges (see Figure 3).
Either a rising edge at RESET or a falling edge at WDI
clears the internal watchdog timer. The watchdog timer
remains cleared while RESET is asserted. The watch-
dog timer begins counting when RESET goes high.
WDI falling edges are ignored when RESET is low.
Applications Information
Selecting the Reset Timeout Capacitor
The reset timeout period is adjustable to accommodate a
variety of P applications. Adjust the reset timeout period
(tRESET) by connecting a capacitor (CSRT) between SRT
and ground. See the Reset Timeout Period vs. CSRT
graph in the
Typical Operating Characteristics. Calculate
the reset timeout capacitance using the equation below:
where VRAMP is in volts, tRESET is in seconds, IRAMP is
in nA, and CSRT is in nF.
Leakage currents and stray capacitance (e.g., a scope
probe, which induces both) at SRT may cause errors in
the reset timeout period. If precise time control is
required, use capacitors with low leakage current and
high stability.
Selecting the Watchdog
Timeout Capacitor
The watchdog timeout period is adjustable to accom-
modate a variety of P applications. With this feature,
the watchdog timeout can be optimized for software
execution. The programmer determines how often the
watchdog timer should be serviced. Adjust the watch-
dog timeout period (tWP) by connecting a capacitor
(CSWT) between SWT and GND. For normal mode
operation, calculate the watchdog timeout capacitance
using the following equation:
where VRAMP is in volts, tWP is in seconds, IRAMP is in nA,
and CSWT is in nF. See the Watchdog Timeout Period vs.
CSWT graph in the Typical Operating Characteristics.
For the MAX16998B/MAX16998D, the open window size
is factory-set to 50% (MAX16998B) or 75% (MAX16998D)
of the watchdog period. Leakage currents and stray
capacitance (e.g., a scope probe, which induces both) at
SWT may cause errors in the watchdog timeout period. If
precise time control is required, use capacitors with low
leakage current and high stability. To disable the watch-
dog timer function, connect SWT to ground and connect
WDI to either the high- or low-logic state.
Ct
I
V
SWT
WP
RAMP
=×
×
4
Ct
I
V
SRT
RESET
RAMP
=×
High-Voltage Watchdog Timers with
Adjustable Timeout Delay
12
______________________________________________________________________________________
tWDImin
RESET RISING EDGE
tWDImax
tWP
(50% or 75%) x tWP
CASE 1 (FAST FAULT)
CASE 2 (SLOW FAULT)
CASE 3 (GOOD WDI)
CASE 4 (INDETERMINATE)
CLOSED WINDOW
OPEN WINDOW
INDETERMINATE
Figure 8. The MAX16998B/D Window Watchdog Diagram
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX16998AAUA/V+ | 功能描述:監(jiān)控電路 Watchdog Timer w/Adj Timeout Delay 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX16998AAUA/V+T | 功能描述:監(jiān)控電路 Watchdog Timer w/Adj Timeout Delay 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX16998AAUA+ | 功能描述:監(jiān)控電路 Watchdog Timer w/Adj Timeout Delay 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX16998AAUA+T | 功能描述:監(jiān)控電路 Watchdog Timer w/Adj Timeout Delay 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX16998BAUA/V+ | 功能描述:監(jiān)控電路 Watchdog Timer w/Adj Timeout Delay 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
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