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| 型号： | MAX16998BAUA/V+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 12/16页 |
| 文件大小： | 0K |
| 描述： | IC TIMER WATCHDOG 8UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 监视器电路 |
| 监视电压数目： | 1 |
| 输出： | 开路漏极或开路集电极 |
| 复位： | 低有效 |
| 复位超时： | 可调节/可选择 |
| 电压 - 阀值： | 可调节/可选择 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 8-uMAX |
| 包装： | 管件 |
High-Voltage Watchdog Timers with
Adjustable Timeout Delay
WDI falling edge occurs within the watchdog timeout
period (t WP ) 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
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 μP 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 (t WP ) by connecting a capacitor
(C SWT ) between SWT and GND. For normal mode
operation, calculate the watchdog timeout capacitance
using the following equation:
Selecting the Reset Timeout Capacitor
The reset timeout period is adjustable to accommodate a
C SWT = t WP ×
I RAMP
4 × V RAMP
C SRT RESET × RAMP
= t
variety of μP applications. Adjust the reset timeout period
(t RESET ) by connecting a capacitor (C SRT ) between SRT
and ground. See the Reset Timeout Period vs. C SRT
graph in the Typical Operating Characteristics. Calculate
the reset timeout capacitance using the equation below:
I
V RAMP
where V RAMP is in volts, t RESET is in seconds, I RAMP is
in nA, and C SRT is in nF.
where V RAMP is in volts, t WP is in seconds, I RAMP is in nA,
and C SWT is in nF. See the Watchdog Timeout Period vs.
C SWT 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.
RESET RISING EDGE
CLOSED WINDOW
(50% or 75%) x t WP
t WDImin t WDImax
INDETERMINATE
OPEN WINDOW
t WP
CASE 1 (FAST FAULT)
CASE 2 (SLOW FAULT)
CASE 3 (GOOD WDI)
CASE 4 (INDETERMINATE)
Figure 8. The MAX16998B/D Window Watchdog Diagram
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX16998DAUA/V+ | 功能描述:监控电路 Watchdog Timer w/Adj Timeout Delay RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX16998DAUA/V+T | 功能描述:监控电路 Watchdog Timer w/Adj Timeout Delay RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX16998DAUA+ | 功能描述:监控电路 Watchdog Timer w/Adj Timeout Delay RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX16998DAUA+T | 功能描述:监控电路 Watchdog Timer w/Adj Timeout Delay RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| MAX16999AUA05+ | 功能描述:线性稳压器 - 标准 Low Out V Low-Q for High-Temp Aps RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L |
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