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| 型号： | MAX703CSA-T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 6/9页 |
| 文件大小： | 0K |
| 描述： | IC MPU SUPERVISORY CIRCUIT 8SOIC |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 备用电池电路 |
| 监视电压数目： | 1 |
| 输出： | 推挽式，图腾柱 |
| 复位： | 低有效 |
| 复位超时： | 最小为 140 ms |
| 电压 - 阀值： | 4.65V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOIC |
| 包装： | 带卷 (TR) |
Low-Cost Microprocessor Supervisory
Circuits with Battery Backup
drops to more than 1V below V BATT , the internal
switchover comparator shuts off and the supply current
+5V
falls to less than 1μA.
V CC
V OUT
TO STATIC RAM
Manual Reset
The manual reset input ( MR ) allows RESET to be acti-
MAX704
vated by a pushbutton switch. The switch is effectively
V BATT
RESET
TO μ P
debounced by the 140ms minimum reset pulse width.
Because it is TTL/CMOS compatible, MR can be driven
100k ?
0.1F
GND
by an external logic line.
Applications Information
Using a SuperCap ? as a
Backup Power Source
SuperCaps are capacitors with extremely high capaci-
tance values (on the order of 0.1 Farad). When using
SuperCaps, if V CC exceeds the MAX703/MAX704 reset
thresholds (4.65V and 4.40V, respectively), V BATT may
not exceed V CC by more than 0.6V. Thus, with a 5% tol-
erance on V CC , V BATT should not exceed V CC (min)
+ 0.6V = 5.35V. Similarly, with a 10% tolerance on V CC ,
V BATT should not exceed 5.1V.
Figure 4’s SuperCap circuit uses the MAX703 with a
±5% tolerance voltage supply. In this circuit, the
SuperCap rapidly charges to within a diode drop of
V CC . However, the diode leakage current with trickle-
charge the SuperCap voltage to V CC . If V BATT = 5.25V
and the power is suddenly removed and then reapplied
with V CC = 4.75V, V BATT - V CC does not exceed the
allowable 0.6V difference voltage.
Figure 5’s circuit uses the MAX704 with a ±10% tole-
rance voltage supply. Note that if V CC = 5.5V and
Figure 5. Using a SuperCap as a Backup Power Source with
the MAX704 and a +5V ±10% Supply
Batteries and Power Supplies
as Backup Power Sources
Lithium batteries work well as backup batteries
because they have very low self-discharge rates and
high-energy density. Single lithium batteries with open-
circuit voltages of 3.0V to 3.6V are ideal for use with the
MAX703/MAX704. Batteries with an open-circuit volt-
age less than the minimum reset threshold plus 0.3V
can be directly connected to the MAX703/MAX704
V BATT input with no additional circuitry (see the Typical
Operating Circuit).
However, batteries with open-circuit voltages greater
than the reset threshold plus 0.3V CANNOT be used as
backup batteries, since they source current into the
substrate through diode D1 (Figure 3) when V CC is
close to the reset threshold.
Table 2. Allowable Backup-Battery Voltages
V BATT ≤ 5.1V, the power can be suddenly removed
and reapplied with V CC = 4.5V, and V BATT - V CC will
not exceed the allowable 0.6V voltage difference.
PART
MAX703
MAX704
MAXIMUM BACKUP-BATTERY VOLTAGE (V)
4.80
4.55
+5V
Using the MAX703/MAX704 without a
V CC
V OUT
TO STATIC RAM
Backup Power Source
If a backup power source is not used, ground V BATT
MAX703
and connect V CC to V OUT . A direct connection to V CC
0.1F
V BATT
GND
RESET
TO μ P
eliminates any voltage drop across the internal switch,
which would otherwise appear at V OUT . Alternatively,
use the MAX705–MAX708, which do not have battery-
backup capabilities.
Figure 4. Using a SuperCap as a Backup Power Source with a
MAX703 and a +5V ±5% Supply
SuperCap is a registered trademark of Bankor Industries.
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX703EPA | 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 |
| MAX703EPA+ | 功能描述:监控电路 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 |
| MAX703ESA | 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 |
| MAX703ESA+ | 功能描述:监控电路 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 |
| MAX703ESA+T | 功能描述:监控电路 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 |
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