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| 型号： | MAX807NCWE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/16页 |
| 文件大小： | 0K |
| 描述： | IC SUPERVISOR MPU 16-SOIC |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 46 |
| 类型： | 备用电池电路 |
| 监视电压数目： | 1 |
| 复位： | 高有效/低有效 |
| 复位超时： | 最小为 140 ms |
| 电压 - 阀值： | 4.425V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 16-SOIC W |
| 包装： | 管件 |
Full-Featured μP Supervisory Circuit with
±1.5% Reset Accuracy
BATT OK Output
The BATT OK comparator monitors the backup battery
voltage, comparing it with a 2.265V reference (V CC ≥
4V). BATT OK remains high as long as the backup bat-
tery voltage remains above 2.265V, signaling that the
backup battery has sufficient voltage to maintain the
memory of static RAM. When the battery voltage drops
below 2.265V, the BATT OK output drops low, signaling
that the backup battery needs to be changed.
Applications Information
The MAX807 is not short-circuit protected. Shorting
OUT to ground, other than power-up transients such as
charging a decoupling capacitor, may destroy the
device. If long leads connect to the IC’s inputs, ensure
that these lines are free from ringing and other condi-
tions that would forward bias the IC’s protection diodes.
There are two distinct modes of operation:
1) Normal Operating Mode, with all circuitry powered
up. Typical supply current from V CC is 70μA, while
only leakage currents flow from the battery.
2) Battery-Backup Mode, where V CC is below V BATT
and V RST . The supply current from the battery is typ-
ically less than 1μA.
Using SuperCaps or
MaxCaps with the MAX807
BATT has the same operating voltage range as V CC , and
the battery-switchover threshold voltage is typically
V BATT when V CC is decreasing or V BATT + 0.06V when
SuperCap (e.g., order of 0.47F) and a simple charging
circuit as a backup source (Figure 13). Since V BATT can
exceed V CC while V CC is above the reset threshold,
there are no special precautions when using these μP
supervisors with a SuperCap.
Alternative Chip-Enable Gating
Using memory devices with CE and CE inputs allows
the MAX807 CE loop to be bypassed. To do this, con-
nect CE IN to ground, pull up CE OUT to OUT, and
connect CE OUT to the CE input of each memory
device (Figure 14). The CE input of each part then con-
nects directly to the chip-select logic, which does not
have to be gated by the MAX807.
Adding Hysteresis to the
Power-Fail Comparator
The power-fail comparator has a typical input hystere-
sis of 20mV. This is sufficient for most applications
where a power-supply line is being monitored through
an external voltage-divider (Figure 10).
Figure 15 shows how to add hysteresis to the power-fail
comparator. Select the ratio of R1 and R2 such that PFI
sees 2.265V when V IN falls to the desired trip point
(V TRIP ). Resistor R3 adds hysteresis. It will typically be
an order of magnitude greater than R1 or R2. The cur-
rent through R1 and R2 should be at least 1μA to
ensure that the 25nA (max) PFI input current does not
shift the trip point. R3 should be larger than 10k ? to
prevent it from loading down the PFO pin. Capacitor C1
adds additional noise rejection.
V CC is increasing. This hysteresis allows use of a
Rp*
CE
+5V
OUT
CE
RAM 1
1N4148
V CC
CE IN
CE OUT
CE
RAM 2
CE
BATT
OUT
0.47F
MAX807
CE
RAM 3
CE
MAX807
GND
GND
*MAXIMUM Rp VALUE DEPENDS ON
THE NUMBER OF RAMs.
MINIMUM Rp VALUE IS 1k ?.
CE
CE
ACTIVE-HIGH CE
LINES FROM LOGIC
RAM 4
Figure 13. SuperCap or MaxCap on BATT
Figure 14. Alternate CE Gating
14
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX807NCWE+ | 功能描述:监控电路 Full-Featured 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 |
| MAX807NCWE+T | 功能描述:监控电路 Full-Featured 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 |
| MAX807NCWE-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 |
| MAX807NEPE | 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 |
| MAX807NEPE+ | 功能描述:监控电路 Full-Featured 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 |
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