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| 型号： | MAX6867UK36D4L+T |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | Nanopower µP Supervisory Circuits with Manual Reset and Watchdog Timer |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO5 |
| 封装： | LEAD FREE, MO-178AA, SOT-23, 5 PIN |
| 文件页数： | 3/17页 |
| 文件大小： | 489K |
| 代理商： | MAX6867UK36D4L+T |
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–MAX6869
Nanopower P Supervisory Circuits with
Manual Reset and Watchdog Timer
______________________________________________________________________________________
11
Detailed Description
RESET/RESET Output
A P’s reset input starts the P in a known state. The
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–
MAX6869 P supervisory circuits assert a reset to prevent
code-execution errors during power-up, power-down, and
brownout conditions. The MAX6854/MAX6855/MAX6856/
MAX6858/MAX6860–MAX6869 reset output is guaranteed
to be valid for VCC down to 1.1V.
Whenever VCC falls below the reset threshold, the reset
output asserts low for RESET and high for RESET.
Once VCC exceeds the reset threshold, an internal
timer keeps the reset output asserted for the specified
reset timeout period, then after this interval the reset
output deasserts (see Figure 2).
Manual Reset Input
Many P-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. The MAX6854/
MAX6855/MAX6856/MAX6861–MAX6869 feature an
MR input. A logic low on MR asserts a reset. Reset
remains asserted while MR is low and for the timeout
period, tRP, after MR returns high. The devices provide
an internal 10k
pullup from MR to VCC. Leave MR
unconnected or connect to VCC if unused. MR can be
driven with CMOS logic levels or with open-drain/col-
lector outputs. Connect a normally open momentary
switch from MR to GND to implement a manual reset
function; external debounce circuitry is not required. If
MR is driven by long cables or the device is used in a
noisy environment, connect a 0.1F capacitor from MR
to GND to provide additional noise immunity.
Watchdog Input
The MAX6864–MAX6869’s watchdog timer circuitry
monitors the P’s activity. If the P does not toggle
(low-to-high or high-to-low) the watchdog input (WDI)
within the watchdog timeout period (tWDI), reset asserts
for the reset timeout period (tRP). The internal timer is
cleared when reset asserts, when manual reset is
asserted, or by a rising or falling edge on WDI. The
watchdog input detects pulses as short as 150ns.
While reset is asserted the watchdog timer does not
count. As soon as reset deasserts, the watchdog timer
resumes counting (Figure 3).
Applications Information
Selecting the Reset Timeout Period
The reset timeout period for the MAX6854/MAX6855/
MAX6856/MAX6858/MAX6860/MAX6864–MAX6869 is
fixed (see Table 4). The MAX6861/MAX6862/MAX6863
feature a reset timeout select input, CT. Connect CT
according to Table 1 to select between the available
10ms and 150ms (min) reset timeout periods. The time-
out period can be changed while a reset timeout period
is in progress, but will not update until the reset timeout
period has expired.
VCC
WDI
tWD
tWDI
tRP
RESET*
VCC
OV
*RESET IS THE INVERSE OF RESET.
Figure 3. Detailed Watchdog Input Timing Relationship
Table 1. MAX6861/MAX6862/MAX6863
Reset Timeout Period Selection
CT CONNECTION
MIN
TYP
MAX
UNITS
LOW
10
15
25
HIGH
150
225
300
ms
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| MAX6867UK36D4S+T | 功能描述:监控电路 Single nPower 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 |
| MAX6867UK36D4S-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 |
| MAX6867UK36D5L+T | 功能描述:监控电路 Single nPower 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 |
| MAX6867UK36D5L-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 |
| MAX6867UK36D5S+T | 功能描述:监控电路 Single nPower 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 |
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