参数资料
型号: TC1271ASBVCT
元件分类: 电源管理
英文描述: 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5
封装: LEAD FREE, PLASTIC, SOT-23, 5 PIN
文件页数: 18/40页
文件大小: 551K
代理商: TC1271ASBVCT
2007 Microchip Technology Inc.
DS22035B-page 25
TC1270A/70AN/71A
5.6
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
TC127XA (Figure 5-7). If there are other components
in the system that 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 5-7:
Interfacing the TC1270A or
TC1271A Push-Pull Output to a Bidirectional
Reset I/O pin.
5.7
Migration Paths
Figure 5-8 shows the 5-pin SOT-23 footprint of the
TC1270A, TC1270AN and TC1271A devices. Devices
that are in the 3-pin SOT-23 package could be used in
that circuit with the loss of the Manual Reset
functionality. Examples of compatible footprint devices
in the SOT-23-3 package are the MCP111, MCP112,
TC54, and TC51 devices. This allows the system to be
designed to offer a “base” functionality and a higher
end system with the “enhanced” functionality, which
includes a manual reset.
FIGURE 5-8:
SOT-23 5-pin to 3-pin
Comparison.
5.8
Reset Signal Integrity During
Power-Down
The TC1270A and TC1271A reset output is valid down
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 shut down well above this voltage.
However, in situations where the Reset signal must be
maintained valid to VDD = 0V, external circuitry is
required.
For devices where the Reset signal is active-low, a
pull-down resistor must be connected from the
TC1270A RST pin to ground to discharge stray
capacitances and hold the output low (Figure 5-9).
Similarly for devices where the Reset signal is
active-high, a pull-up resistor to VDD is required to
ensure a valid high RST signal for VDD below 1.0V
This resistor value, though not critical, should be
chosen such that it does not appreciably load the Reset
pin under normal operation (100 k
Ω will be suitable for
most applications).
FIGURE 5-9:
Ensuring a valid active-low
Reset pin output state as VDD approaches 0V.
FIGURE 5-10:
Ensuring a valid active-high
Reset pin output state as VDD approaches 0V.
MR
VSS
VDD
RST
Reset I/O
TC1270A/71A
VDD
or
RST
Buffered
Reset to
system
4.7 k
Ω
3
2
1
SOT-23-3
1
2
3
5
4
SOT-23-5
NC
VDD
MR
RST
VSS
VDD
or
RST
or
RST
MR
VSS
VDD
RST
TC1270A
VDD
R1
100 k
Ω
MR
VSS
VDD
RST
TC1271A
VDD
R1
100 k
Ω
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TC1271ASBVCTTR 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Voltage Supervisor with Manual Reset Input
TC1271ASBVRCTR 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Voltage Supervisor with Manual Reset Input
TC1271ASCVCTTR 功能描述:监控电路 Vltg Detector 2.93V Reset Threshold 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
TC1271ASCVRCTR 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Voltage Supervisor with Manual Reset Input
TC1271ASVCTTR 功能描述:监控电路 5Pin uP Reset Mon 2.93V Reset Thresh 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