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参数资料
型号： TCM811SERCTRG
元件分类： 电源管理
英文描述： 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO4
封装： SOT-143, 4 PIN
文件页数： 14/16页
文件大小： 479K
代理商： TCM811SERCTRG
2007 Microchip Technology Inc.
DS21615C-page 7
TCM811/TCM812
4.0
APPLICATIONS INFORMATION
The
TCM811/TCM812
provides
accurate
VDD
monitoring and reset timing during power-up, power-
down, and brownout/sag conditions. These devices
also reject negative-going transients (glitches) on the
power supply line. Figure 4-1 shows the maximum
transient duration vs. maximum negative excursion
(overdrive) for glitch rejection. Any combination of
duration and overdrive that is under the curve will not
generate a reset signal. Combinations above the curve
are detected as a brownout or power-down. Transient
immunity can be improved by adding a 0.1 F capacitor
in close proximity to the VDD pin of the TCM811/
TCM812.
FIGURE 4-1:
Maximum Transient Duration
vs. Overdrive for Glitch Rejection at +25°C.
4.1
RESET Signal Integrity During
Power-Down
The TCM811 RESET push-pull output is valid to
VDD = 1.0V. Below this voltage the output becomes an
"open circuit" and does not sink current. This means
CMOS logic inputs to the microcontroller will be floating
at an undetermined voltage. Most digital systems are
completely shutdown well above this voltage. How-
ever, in situations where RESET must be maintained
valid to VDD = 0V, a pull-down resistor must be con-
nected from RESET to ground to discharge stray
capacitances and hold the output low (Figure 4-2). This
resistor value, though not critical, should be chosen
such that it does not appreciably load RESET under
normal operation (100 k
Ω will be suitable for most
applications). Similarly, a pull-up resistor to VDD is
required for the TCM812 to ensure a valid high RESET
for VDD below 1.1V.
FIGURE 4-2:
The addition of R1 at the
RESET output of the TCM811 ensures that the
RESET output is valid to V
DD = 0V.
4.2
Controllers and Processors With
Bidirectional I/O Pins
Some microcontrollers have bidirectional reset pins.
Depending on the current drive capability of the
controller pin, an indeterminate logic level may result if
there is a logic conflict. This can be avoided by adding
a 4.7 k
Ω resistor in series with the output of the
TCM811/TCM812 (Figure 4-3). If there are other
components in the system which require a reset signal,
they should be buffered so as not to load the reset line.
If the other components are required to follow the reset
I/O of the microcontroller, the buffer should be
connected as shown with the solid line.
FIGURE 4-3:
Interfacing the TCM811 to a
Bidirectional Reset I/O.
RESET COMPARATOR OVERDRIVE,
VTH - VDD (mV)
400
240
160
320
80
0
1
10
100
1000
MAXIMUM
TRANSIENT
DURATION
(sec)
TA = +25C
VTH
Duration
Overdrive =
VD D
VDD
TCM81xL/M
TCM81xR/S/T
TCM811
V
DD
V
DD
R1
100 k
Ω
RESET
GND
4
2
0.1F
1
TCM811
V
DD
RESET
GND
RESET
GND
Buffered RESET
To Other System
Components
BUFFER
Micro
4.7 k
Ω
controller
0.1F
4
2
1
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相关代理商/技术参数
参数描述
TCM811TERC 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-Pin Microcontroller Reset Monitors
TCM811TERCTR 功能描述:监控电路 4-Pin uP 38V Reset 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
TCM811TERCTR 制造商:Microchip Technology Inc 功能描述:RESET MONITOR 3.08V SOT-143-4 811
TCM812 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-Pin Microcontroller Reset Monitors
TCM812AFVRCTR 制造商:Microchip Technology Inc 功能描述:
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