参数资料
型号: MAX821MUS+T
厂商: Maxim Integrated Products
文件页数: 6/7页
文件大小: 0K
描述: IC MONITOR VOLT MPU SOT143-4
产品培训模块: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
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: 低有效
复位超时: 可调节/可选择
电压 - 阀值: 4.38V
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: TO-253-4,TO-253AA
供应商设备封装: SOT-143-4
包装: 标准包装
产品目录页面: 1413 (CN2011-ZH PDF)
其它名称: MAX821MUS+TDKR
4-Pin μP Voltage Monitors with Pin-Selectable
Power-On Reset Timeout Delay
Ensuring a Valid RESET Output
Down to V CC = 0V
When V CC falls below 1V, the MAX821 RESET output
no longer sinks current—it becomes an open circuit.
V CC
V CC
Therefore, high-impedance CMOS logic inputs con-
nected to the RESET output can drift to undetermined
V CC
V CC
R1
voltages. This presents no problem in most applica-
tions, since most μ P and other circuitry is inoperative
with V CC below 1V. However, in applications where the
RESET output must be valid down to 0V, adding a pull-
down resistor to the RESET pin will cause any stray
MAX821
RESET
R1
MAX822
RESET
leakage currents to flow to ground, holding RESET low
(Figure 2a). R1’s value is not critical; 100k ? is large
enough not to load RESET , and small enough to pull
a)
GND
b)
GND
RESET to ground.
A 100k ? pull-up resistor to V CC is also recommended
for the MAX822 if RESET is required to remain valid for
V CC < 1V (Figure 2b).
Figure 2. RESET/ RESET Valid to V CC = Ground Circuit
Interfacing to μPs with
Bidirectional Reset Pins
μPs with bidirectional reset pins (such as the Motorola
BUFFER
BUFFERED RESET
TO OTHER SYSTEM
COMPONENTS
68HC11 series) can contend with the MAX821 reset
output. For example, if the MAX821 RESET output is
asserted high and the μP wants to pull it low, indetermi-
V CC
V CC
nate logic levels may result. To correct such cases,
connect a 4.7k ? resistor between the MAX821 RESET
output and the μP reset I/O (Figure 3). Buffer the reset
MAX821
RESET
4.7k
μ P
RESET
output to other system components.
___________________Chip Information
GND
GND
TRANSISTOR COUNT: 492
Figure 3. Interfacing to μPs with Bidirectional Reset I/O
6
_______________________________________________________________________________________
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MAX821PUS-T 功能描述:监控电路 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
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