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| 型号： | AS1917Z-T |
| 厂商： | ams |
| 文件页数： | 10/15页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR ACT HIGH SOT23-5 |
| 标准包装： | 1 |
| 类型： | 简单复位/加电复位 |
| 监视电压数目： | 1 |
| 输出： | 推挽式，图腾柱 |
| 复位： | 高有效 |
| 复位超时： | 最小为 100 ms |
| 电压 - 阀值： | 2.32V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SC-74A，SOT-753 |
| 供应商设备封装： | SOT-23-5 |
| 包装： | 标准包装 |
| 其它名称： | AS1917Z-TDKR |
AS1916 - AS1918
Datasheet - A p p l i c a t i o n I n f o r m a t i o n
9 Application Information
9.1 Watchdog Input Current
The watchdog input is driven through an internal buffer and an internal series resistor from the watchdog timer (see Figure 11 on page 8) . When
pin WDI is left unconnected (watchdog disabled), the watchdog timer is serviced within the watchdog timeout period (see t WD on page 5 ) by a
low-high-low pulse from the counter chain.
For minimum watchdog input current (minimum overall power consumption), pull WDI low for most of the watchdog timeout period, pulsing it low-
high-low once within the first 7/8 (87.5%) of the watchdog timeout period to reset the watchdog timer.
Note: If WDI is externally driven high for the majority of the timeout period, up to 160μA can flow into pin WDI.
9.2 Interfacing to Bi-Directional CPU Reset Pins
Since the reset output of the AS1918 is open drain, this device interfaces easily with processors that have bi-directional reset pins. Connecting
the processor reset output directly to the AS1918 RESETN pin with a single pullup resistor (see Figure 12) allows the AS1918 to assert a reset.
Figure 12. AS1918 RESETN-to-CPU Bi-Directional Reset Pin
V CC
VCC 5
VCC
AS1918
CPU
1
RESETN
RESETN
Reset
Generator
G N D
GND 2
9.3 Fast Negative-Going Transients
Fast, negative-going V CC transients normally do not require the CPU to be shutdown. The AS1916 - AS1918 are virtually immune to such
transients. Resets are issued to the CPU during power-up, powerdown, and brownout conditions.
Note: V CC transients that go 100mV below the reset threshold and last ≤ 55μs typically will not assert a reset pulse.
9.4 Valid Reset to V CC = 0
The AS1916 - AS1918 are guaranteed to operate properly down to V CC = 1V.
For AS1916 and AS1917 applications requiring valid reset levels down to V CC = 0, a pulldown resistor to active-low outputs and a pullup resistor
to active-high outputs will ensure that the reset line is valid during the interval where the reset output can no longer sink or source current.
9.5 Watchdog Tips
Careful consideration should be taken when implementing the AS1916 - AS1918 watchdog feature.
One method of supervising software code execution is to set/reset the watchdog input at different places in the code, rather than pulsing the
watchdog input high-low-high or low-high-low. This method avoids a loop condition in which the watchdog timer would continue to be reset inside
the loop, preventing the watchdog from ever timing out.
Figure 13 shows a flowchart where the input/output driving the watchdog is set high at the beginning of the routine, set low at the beginning of
every subroutine, then set high again when the routine returns to the beginning. If the routine should hang in a subroutine, the problem would
quickly be corrected, since the I/O is continually set low and the watchdog timer is allowed to time out, causing a reset or interrupt to be issued
(see Watchdog Input Current on page 9) . This method results in higher averaged WDI input current over time than a case where WDI is held low
for the majority (87.5%) of the timeout period and periodically pulsing it low-high-low.
www.austriamicrosystems.com/Supervisors/AS1916
Revision 1.04
9 - 14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AS1918 | 制造商:AMSCO 制造商全称:austriamicrosystems AG 功能描述:Microprocessor Supervisory Circuits with Manual Reset and Watchdog |
| AS1918R-T | 功能描述:IC SUPERVISOR ACT LOW SOT23-5 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:1 系列:- 类型:简单复位/加电复位 监视电压数目:1 输出:开路漏极或开路集电极 复位:高有效 复位超时:- 电压 - 阀值:1.8V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:6-TSOP（0.059"，1.50mm 宽）5 引线 供应商设备封装:5-TSOP 包装:剪切带 (CT) 其它名称:NCP301HSN18T1GOSCT |
| AS1918S-T | 功能描述:IC SUPERVISOR ACT LOW SOT23-5 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 其它有关文件:STM6905 View All Specifications 标准包装:1 系列:- 类型:多压监控器 监视电压数目:5 输出:开路漏极或开路集电极 复位:低有效 复位超时:最小为 140 ms 电压 - 阀值:2.188V，2.955V，可调，可调，可调 工作温度:-40°C ~ 85°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-TSSOP 包装:Digi-Reel® 产品目录页面:1197 (CN2011-ZH PDF) 其它名称:497-8728-6 |
| AS1918V-T | 功能描述:IC SUPERVISOR ACT LOW SOT23-5 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 标准包装:1 系列:- 类型:简单复位/加电复位 监视电压数目:1 输出:开路漏极或开路集电极 复位:高有效 复位超时:- 电压 - 阀值:1.8V 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:6-TSOP（0.059"，1.50mm 宽）5 引线 供应商设备封装:5-TSOP 包装:剪切带 (CT) 其它名称:NCP301HSN18T1GOSCT |
| AS1918Z-T | 功能描述:IC SUPERVISOR ACT LOW SOT23-5 RoHS:是 类别:集成电路 (IC) >> PMIC - 监控器 系列:- 其它有关文件:STM6905 View All Specifications 标准包装:1 系列:- 类型:多压监控器 监视电压数目:5 输出:开路漏极或开路集电极 复位:低有效 复位超时:最小为 140 ms 电压 - 阀值:2.188V，2.955V，可调，可调，可调 工作温度:-40°C ~ 85°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-TSSOP 包装:Digi-Reel® 产品目录页面:1197 (CN2011-ZH PDF) 其它名称:497-8728-6 |
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