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参数资料
| 型号： | DS1707EUA+T&R |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 电源管理 |
| 英文描述： | 3.3 and 5.0 Volt MicroMonitor |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封装： | 0.118 INCH, ROHS COMPLIANT, MICRO, SOP-8 |
| 文件页数： | 5/12页 |
| 文件大小： | 251K |
| 代理商： | DS1707EUA+T&R |
DS1707/DS1708
2 of 10
The third function the DS1707/DS1708 performs is pushbutton reset control. The DS1707/DS1708
debounces the pushbutton input and guarantees an active reset pulse width of 130 ms minimum.
OPERATION
Power Monitor
The DS1707/DS1708 detects out-of-tolerance power supply conditions and warns a processor-based
system of impending power failure. When VCC falls below the minimum VCC tolerance, a comparator
outputs the RST and RST signals. RST and RST are excellent control signals for a microprocessor, as
processing is stopped at the last possible moment of valid VCC. On power-up, RST and RST are kept
active for a minimum of 130 ms to allow the power supply and processor to stabilize.
Pushbutton Reset
The DS1707/DS1708 provides an input pin for direct connection to a pushbutton reset (see Figure 2). The
pushbutton reset input requires an active low signal. Internally, this input is debounced and timed such
that RST and RST signals of at least 130 ms minimum will be generated. The 130 ms delay commences
as the pushbutton reset input is released from the low level. The pushbutton can be initiated by connecting
the NMI output to the PBRST input as shown in Figure 3.
Non-Maskable Interrupt
The DS1707/DS1708 generates a non-maskable interrupt ( NMI ) for early warning of a power failure. A
precision comparator monitors the voltage level at the IN pin relative to an on-chip reference generated
by an internal band gap. The IN pin is a high impedance input allowing for a user-defined sense point. An
external resistor voltage divider network (Figure 5) is used to interface with high voltage signals. This
sense point may be derived from a regulated supply or from a higher DC voltage level closer to the main
system power input. Since the IN trip point VTP is 1.25 volts, the proper values for R1 and R2 can be
determined by the equation as shown in Figure 5. Proper operation of the DS1707/DS1708 requires that
the voltage at the IN pin be limited to VCC. Therefore, the maximum allowable voltage at the supply being
monitored (VMAX) can also be derived as shown in Figure 5. A simple approach to solving the equation is
to select a value for R2 high enough to keep power consumption low, and solve for R1. The flexibility of
the IN input pin allows for detection of power loss at the earliest point in a power supply system,
maximizing the amount of time for system shut-down between NMI and RST/ RST .
When the supply being monitored decays to the voltage sense point, the DS1707/DS1708 pulses the NMI
output to the active state for a minimum 200
ms. The NMI power-fail detection circuitry also has built-in
hysteresis of 100
mV. The supply must be below the voltage sense point for approximately 5 ms before a
low NMI will be generated. In this way, power supply noise is removed from the monitoring function,
preventing false interrupts. During a power-up, any detected IN pin levels below VTP by the comparator
are disabled from generating an interrupt until VCC rises to VCCTP. As a result, any potential NMI pulse
will not be initiated until VCC reaches VCCTP.
Connecting NMI to PBRST would allow the non-maskable interrupt to generate an automatic reset when
an out-of-tolerance condition occurred in a monitored supply. An example is shown in Figure 3.
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PDF描述 |
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| DS1708EPA+ | 3.3 and 5.0 Volt MicroMonitor |
| DS1708ESA+ | 3.3 and 5.0 Volt MicroMonitor |
| DS1708EUA+ | 3.3 and 5.0 Volt MicroMonitor |
| DS1708EUA+T&R | 3.3 and 5.0 Volt MicroMonitor |
| DS1708REPA+ | 3.3 and 5.0 Volt MicroMonitor |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1708 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:3.3 and 5.0 Volt MicroMonitor |
| DS17-08A | 功能描述:整流器 17 Amps 800V RoHS:否 制造商:Vishay Semiconductors 产品:Standard Recovery Rectifiers 配置: 反向电压:100 V 正向电压下降: 恢复时间:1.2 us 正向连续电流:2 A 最大浪涌电流:35 A 反向电流 IR:5 uA 安装风格:SMD/SMT 封装 / 箱体:DO-221AC 封装:Reel |
| DS1708EPA | 功能描述:监控电路 3.3/5V MicroMonitor 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 |
| DS1708EPA+ | 功能描述:监控电路 3.3/5V MicroMonitor 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 |
| DS1708ESA | 功能描述:监控电路 3.3/5V MicroMonitor 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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