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参数资料
| 型号： | MAX817LEPA+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR MPU 5V 8-DIP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 备用电池电路 |
| 监视电压数目： | 1 |
| 复位： | 低有效 |
| 复位超时： | 最小为 140 ms |
| 电压 - 阀值： | 4.65V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 8-DIP（0.300"，7.62mm） |
| 供应商设备封装： | 8-PDIP |
| 包装： | 管件 |
+5V Microprocessor Supervisory Circuits
On the MAX819, MR must be high or open to enable
the battery freshness seal. Once the battery freshness
seal is enabled its operation is unaffected by MR .
Watchdog Input (MAX817/MAX818)
V CC
In the MAX817/MAX818, the watchdog circuit monitors
the μP’s activity. If the μP does not toggle the watchdog
input (WDI) within t WD (1.6sec), reset asserts. The inter-
RESET
t RP
t WD
nal 1.6sec timer is cleared by either a reset pulse or by
toggling WDI, which can detect pulses as short as
50ns. The timer remains cleared and does not count for
as long as reset is asserted. As soon as reset is
released, the timer starts counting (Figure 4).
To disable the watchdog function, leave WDI uncon-
nected or three-state the driver connected to WDI. The
watchdog input is internally driven low during the first
WDI
Figure 4. Watchdog Timing
7/8 of the watchdog timeout period, then momentarily
pulses high, resetting the watchdog counter. When
WDI is left open-circuited, this internal driver clears the
1.6sec timer every 1.4sec. When WDI is three-stated or
left unconnected, the maximum allowable leakage cur-
rent is 10μA and the maximum allowable load capaci-
tance is 200pF.
Chip-Enable Gating (MAX818)
Internal gating of the chip-enable (CE) signal prevents
erroneous data from corrupting CMOS RAM in the
event of an undervoltage condition. The MAX818 uses
a series transmission gate from CE IN to CE OUT
(Figure 5). During normal operation (reset not assert-
ed), the CE transmission gate is enabled and passes
all CE transitions. When reset is asserted, this path
becomes disabled, preventing erroneous data from
corrupting the CMOS RAM. The short CE propagation
delay from CE IN to CE OUT enables the MAX818 to be
used with most μPs. If CE IN is low when reset asserts,
CE IN
MAX817
MAX818
RESET
GENERATOR
CHIP-ENABLE
OUTPUT
CONTROL
BATTERY
SWITCHOVER
CIRCUITRY
BATTERY
FRESHNESS
SEAL CIRCUITRY
OUT
P
N
CE OUT
CE OUT remains low for typically 15μs to permit the
current write cycle to complete.
Chip-Enable Input (MAX818)
Figure 5. Chip-Enable Transmission Gate
The CE transmission gate is disabled and CE IN is high
impedance (disabled mode) while reset is asserted.
During a power-down sequence when V CC passes the
V CC
V RST
V RST
V RST
V RST
reset threshold, the CE transmission gate disables and
CE IN immediately becomes high impedance if the volt-
age at CE IN is high. If CE IN is low when reset asserts,
V CE OUT
V BATT
V BATT
the CE transmission gate will disable 15μs after reset
asserts (Figure 6). This permits the current write cycle
to complete during power-down.
V RESET
t RP
15 μ s
t RP
V CE IN
Figure 6. Chip-Enable Timing
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX817LEPA+ | 功能描述:监控电路 5V MPU 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 |
| MAX817LESA | 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 |
| MAX817LESA+ | 功能描述:监控电路 5V MPU 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 |
| MAX817LESA+T | 功能描述:监控电路 5V MPU 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 |
| MAX817LESA-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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