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参数资料
| 型号： | MAX6318 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | CLAMP |
| 中文描述： | 5引脚、微处理器监控电路，带有看门狗及手动复位 |
| 文件页数： | 14/16页 |
| 文件大小： | 176K |
| 代理商： | MAX6318 |
MAX6316–MAX6322
5-Pin P Supervisory Circuits with
Watchdog and Manual Reset
_______________________________________________________________________________________
7
Bidirectional
R
RE
ES
SE
ETT Output
The MAX6316M/MAX6318MH/MAX6319MH are designed
to interface with Ps that have bidirectional reset pins,
such as the Motorola 68HC11. Like an open-drain output,
these devices allow the P or other devices to pull the
bidirectional reset (RESET) low and assert a reset condi-
tion. However, unlike a standard open-drain output, it
includes the commonly specified 4.7k
pull-up resistor
with a P-channel active pull-up in parallel.
This configuration allows the MAX6316M/MAX6318MH/
MAX6319MH to solve a problem associated with Ps
that have bidirectional reset pins in systems where sev-
eral devices connect to RESET (Figure 3). These Ps
can often determine if a reset was asserted by an exter-
nal device (i.e., the supervisor IC) or by the P itself
(due to a watchdog fault, clock error, or other source),
and then jump to a vector appropriate for the source of
the reset. However, if the P does assert reset, it does
not retain the information, but must determine the
cause after the reset has occurred.
The following procedure describes how this is done in
the Motorola 68HC11. In all cases of reset, the P pulls
RESET low for about four external-clock cycles. It then
releases RESET, waits for two external-clock cycles,
then checks RESET’s state. If RESET is still low, the P
concludes that the source of the reset was external
and, when RESET eventually reaches the high state, it
jumps to the normal reset vector. In this case, stored-
state information is erased and processing begins from
scratch. If, on the other hand, RESET is high after a
delay of two external-clock cycles, the processor
knows that it caused the reset itself and can jump to a
different vector and use stored-state information to
determine what caused the reset.
A problem occurs with faster Ps; two external-clock
cycles are only 500ns at 4MHz. When there are several
devices on the reset line, and only a passive pull-up resis-
tor is used, the input capacitance and stray capacitance
can prevent RESET from reaching the logic high state (0.8
x VCC) in the time allowed. If this happens, all resets will
be interpreted as external. The P output stage is guaran-
teed to sink 1.6mA, so the rise time can not be reduced
considerably by decreasing the 4.7k
internal pull-up
resistance. See Bidirectional Pull-Up Characteristics in the
Typical Operating Characteristics.
The MAX6316M/MAX6318MH/MAX6319MH overcome
this problem with an active pull-up FET in parallel with the
4.7k
resistor (Figures 4 and 5). The pull-up transistor
holds RESET high until the P reset I/O or the supervisory
circuit itself forces the line low. Once RESET goes below
VPTH, a comparator sets the transition edge flip-flop, indi-
cating that the next transition for RESET will be low to
high. When RESET is released, the 4.7k
resistor pulls
RESET up toward VCC. Once RESET rises above VPTH
but is below (0.85 x VCC), the active P-channel pull-up
turns on. Once RESET rises above (0.85 x VCC) or the
2s one-shot times out, the active pull-up turns off. The
parallel combination of the 4.7k
pull-up and the
4.7k
MR**
CIN
RESET
CIRCUITRY
RESET***
WDI*
VCC
MAX6316M
MAX6318MH
MAX6319MH
CSTRAY
68HC11
RESET
CIRCUITRY
CIN
RESET
VCC
OTHER DEVICES
CIN
RESET
MAX6316M/MAX6318MH
MAX6316M/MAX6319MH
ACTIVE-HIGH PUSH/PULL MAX6318MH/MAX6319MH
*
**
***
Figure 3. MAX6316M/MAX6318MH/MAX6319MH Supports Additional Devices on the Reset Bus
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX6318LH | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:5-Pin uP Supervisory Circuits with Watchdog and Manual Reset |
| MAX6318LHUK25AW | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX6318LHUK25AW+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 |
| MAX6318LHUK25AW-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 |
| MAX6318LHUK25AX | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
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