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| 型号： | MAX6727AKAWED6+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 12/18页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR MPU SOT23-8 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 多压监控器 |
| 监视电压数目： | 3 |
| 输出： | 开路漏极或开路集电极 |
| 复位： | 低有效 |
| 复位超时： | 最小为 560 ms |
| 电压 - 阀值： | 0.833V，1.665V，可调 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-8 |
| 供应商设备封装： | SOT-23-8 |
| 包装： | 带卷 (TR) |
Dual/Triple, Ultra-Low-Voltage, SOT23 μP
Supervisory Circuits
Applications Information
Interfacing to μPs with Bidirectional
Reset Pins
Most μPs with bidirectional reset pins can interface
directly to open-drain RST output options. Systems
simultaneously requiring a push-pull RST output and a
bidirectional reset interface can be in logic contention.
To prevent contention, connect a 4.7k ? resistor
between RST and the μP’s reset I/O port as shown in
Figure 4.
Adding Hysteresis to the Power-Fail
Comparator
The power-fail comparator has a typical input hysteresis
of 3mV. This is sufficient for most applications where a
power-supply line is being monitored through an external
voltage-divider (see the Power-Fail Comparator section).
If additional noise margin is desired, connect a resistor
between PFO and PFI as shown in Figure 5. Select the
values of R1, R2, and R3 so PFI sees V PFI (626mV) when
V EXT falls to its power-fail trip point (V FAIL ) and when V IN
rises to its power-good trip point (V GOOD ). The hysteresis
window extends between the specified V FAIL and V GOOD
thresholds. R3 adds the additional hysteresis by sinking
current from the R1/R2 divider network when PFO is
logic-low and sourcing current into the network when PFO
is logic-high. R3 is typically an order of magnitude greater
than R1 or R2.
The current through R2 should be at least 2.5μA to ensure
that the 100nA (max) PFI input current does not signifi-
cantly shift the trip points. Therefore, R2 < V PFI /10μA <
62k ? for most applications. R3 will provide additional hys-
teresis for PFO push-pull (V OH = V CC 1) or open-drain
(V OH = V PULLUP ) applications.
Monitoring an Additional Power Supply
These μP supervisors can monitor either positive or
negative supplies using a resistor voltage-divider to
PFI. PFO can be used to generate an interrupt to the μP
or cause reset to assert (Figure 3).
Monitoring a Negative Voltage
The power-fail comparator can be used to monitor a
negative supply voltage using the circuit shown in
Figure 3. When the negative supply is valid, PFO is low.
When the negative supply voltage drops, PFO goes
high. The circuit ’s accuracy is affected by the PFI
threshold tolerance, V CC , R1, and R2.
Negative-Going V CC Transients
The MAX6715A–MAX6729A/MAX6797A supervisors are
relatively immune to short-duration negative-going V CC
transients (glitches). It is usually undesirable to reset
the μP when V CC experiences only small glitches. The
Typical Operating Characteristics show Maximum
Transient Duration vs. Reset Threshold Overdrive, for
which reset pulses are not generated. The graph was
produced using negative-going V CC pulses, starting
above V TH and ending below the reset threshold by the
V CC 1 V CC 2
RESET TO OTHER SYSTEM COMPONENTS
A
R3
V IN
V GOOD
V FAIL
MAX6715A–
MAX6729A/
V EXT
MAX6729A
PFO
V CC 2
V CC 1
MAX6797A
RST
4.7k ?
RESET
μ P
R1
R2
PFI
PFO
V GOOD = DESIRED V EXT GOOD VOLTAGE THRESHOLD
V FAIL = DESIRED V EXT FAIL VOLTAGE THRESHOLD
V OH = V CC 1 (FOR PUSH-PULL PFO)
R2 = 50k ? (FOR > 10 μ A R2 CURRENT)
GND
GND
GND
R1 = R2 ((V GOOD - V PFI ) - (V PFI )(V GOOD - V FAIL )/V OH )/V PFI
R3 = (R1 x V OH )/(V GOOD - V FAIL )
Figure 4. Interfacing to μPs with Bidirectional Reset I/O
Figure 5. Adding Hysteresis to Power-Fail for Push-Pull PFO
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX6727AKAWGD1+T | 功能描述:监控电路 Triple uPower Supervisor 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 |
| MAX6727AKAWGD2+T | 功能描述:监控电路 Triple uPower Supervisor 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 |
| MAX6727AKAWGD3+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX6727AKAWGD3+T | 功能描述:监控电路 Triple uPower Supervisor 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 |
| MAX6727AKAWGD4+T | 功能描述:监控电路 Dual/Triple Ultra-Low-Voltage SOT23 N
|
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