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参数资料
| 型号： | TC1270SERCTRG |
| 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： | 11/14页 |
| 文件大小： | 662K |
| 代理商： | TC1270SERCTRG |
TC1270/TC1271
DS21381D-page 6
2007 Microchip Technology Inc.
4.0
APPLICATIONS INFORMATION
4.1
VCC Transient Rejection
The
TC1270/TC1271
provides
accurate
VCC
monitoring and Reset timing during power-up,
power-down, and brownout/sag conditions, and rejects
negative-going transients (glitches) on the power
supply line. Figure 4-3 shows the maximum transient
duration vs. maximum negative excursion (overdrive)
for glitch rejection. Any combination of duration and
overdrive that lays under the curve will not generate a
Reset signal. Combinations above the curve are
detected as a brown-out or power-down. Transient
immunity can be improved by adding a capacitor in
close proximity to the VCC pin of the TC1270/TC1271.
FIGURE 4-1:
Maximum Transient
Duration vs. Overdrive for Glitch Rejection at
+25°C.
4.2
Reset Signal Integrity During
Power-Down
The TC1270 RESET output is valid to VCC =1.0V.
Below this voltage the output becomes an “open circuit”
and does not sink current. This means CMOS logic
inputs to the microprocessor will be floating at an
undetermined voltage. Most digital systems are
completely shut down well above this voltage.
However, in situations where RESET must be
maintained valid to VCC = 0V, a pull-down resistor must
be connected 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 VCC is
required for the TC1271 to ensure a valid high RESET
for VCC below 1.1V.
FIGURE 4-2:
Ensuring RESET Valid to
VCC = 0V.
4.3
Processors With Bidirectional
I/O Pins
Some microprocessor’s (such as Motorola 68HC11)
have bidirectional Reset pins. Depending on the
current drive capability of the processor pin, an indeter-
minate 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 TC1270/TC1271
(Figure 4-3). If there are other components in the sys-
tem which require a Reset signal, they should be buff-
ered so as not to load the Reset line. If the other
components are required to follow the Reset I/O of the
microprocessor, the buffer should be connected as
shown with the solid line.
FIGURE 4-3:
Interfacing to Bidirectional
Reset I/O.
RESET COMPARATOR OVERDRIVE,
VTH - VCC (mV)
400
240
160
320
80
0
1
10
100
1000
MAXIMUM
TRANSIENT
DURA
TION
(msec)
TA = +25°C
VTH
Duration
Overdrive
VCC
TC127LMJ
TC127xR/S/T
TC1270
VCC
R1
100k
RESET
GND
TC1270
VCC
RESET
GND
RESET
GND
Buffered RESET
To Other System
Components
Buffer
μP
4.7k
VCC
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC1270TERC | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-Pin レP Reset Monitors |
| TC1270TERCTR | 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 |
| TC1271 | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-Pin Reset Monitors |
| TC1271A | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Voltage Supervisor with Manual Reset Input |
| TC1271AFVRCTR | 制造商:Microchip Technology Inc 功能描述: |
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