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| 型号： | SP708CN-L/TR |
| 厂商： | Exar Corporation |
| 文件页数： | 9/17页 |
| 文件大小： | 0K |
| 描述： | IC MPU SUPERVISORY CIRCUIT 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 简单复位/加电复位 |
| 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： | 4.4V |
| 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-SOICN |
| 包装： | 带卷 (TR) |
S P 7 0 5 - S P 7 0 8 - S P 8 1 3 L
L o w P o w e r M i c r o p r o c e s s o r S u p e r v i s o r y C i r c u i t s
FEATURES
The SP705-708/813L series provides four key
functions:
1. A reset output during power-up, power-
down and brownout conditions.
2. An independent watchdog output that goes
LOW if the watchdog input has not been
toggled within 1.6 seconds.
3. A 1.25V threshold detector for power-fail
warning, low battery detection, or monitoring
a power supply other than +5V.
4. An active-LOW manual-reset that allows
RESET to be triggered by a pushbutton switch.
The SP707/708 devices are the same as the
SP705/706 devices except for the active-HIGH
RESET substitution of the watchdog timer. The
SP813L is the same as the SP705 except an
active-HIGH RESET is provided rather than an
active-LOW RESET . The SP705/707/813L
devices generate a reset when the supply
voltage drops below 4.65V. The SP706/708
devices generate a reset below 4.40V.
The SP705-708/813L series is ideally suited
for applications in automotive systems,
intelligent instruments, and battery-powered
computers and controllers. The SP705-
708/813L series is ideally applied in
environments where monitoring of power
supply to a μP and its related components is
critical.
THEORY OF OPERATION
The SP705-708/813L series is a
microprocessor (μP) supervisory circuit that
monitors the power supplied to digital circuits
such as microprocessors, microcontrollers, or
memory. The series is an ideal solution for
portable, battery-powered equipment that
requires power supply monitoring.
Implementing this series will reduce the
number of components and overall complexity.
The watchdog functions of this product family
will continuously oversee the operational
status of a system. The operational features
and benefits of the SP705-708/813L series are
described in more detail below.
RESET O UTPUT
A microprocessor's reset input starts the μP in
a known state. The SP705-708/813L series
asserts reset during power-up and prevents
code execution errors during power down or
brownout conditions.
On power-up, once V CC reaches 1.1V, RESET is
a guaranteed logic LOW of 0.4V or less. As V CC
rises, RESET stays LOW. When V CC rises above
the reset threshold, an internal timer releases
RESET after 200ms. RESET pulses LOW
whenever V CC dips below the reset threshold,
such as in a brownout condition. When a
brownout condition occurs in the middle of a
previously initiated reset pulse, the pulse
continues for at least another 140ms. On
power down, once V CC falls below the reset
threshold, RESET stays LOW and is
guaranteed to be 0.4V or less until V CC drops
below 1.1V.
The SP707/708/813L active-HIGH RESET
output is simply the complement of the RESET
output and is guaranteed to be valid with V CC
down to 1.1V. Some μ Ps, such as Intel's
80C51, require an active-HIGH reset pulse.
W ATCHDOG T IMER
The SP705/706/813L watchdog circuit
monitors the μP's activity. If the μP does not
toggle the watchdog input (WDI) within 1.6
seconds and WDI is not tri-stated, WDO goes
LOW. As long as RESET is asserted or the WDI
input is tri-stated, the watchdog timer will stay
cleared and will not count. As soon as RESET
is released and WDI is driven HIGH or LOW,
the timer will start counting. Pulses as short as
50ns can be detected.
Typically, WDO will be connected to the non-
maskable interrupt input (NMI) of a μP. When
V CC drops below the reset threshold, WDO will
go LOW whether or not the watchdog timer
had timed out. Normally this would trigger an
NMI but RESET goes LOW simultaneously and
thus overrides the NMI.
If WDI is left unconnected, WDO can be used
as a low-line output. Since floating WDI
disables the internal timer, WDO goes LOW
only when V CC falls below the reset threshold,
thus functioning as a low-line output.
? 2010 Exar Corporation
9/17
Rev. 2.0.0
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP708CP | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Power Microprocessor Supervisory Circuits |
| SP708CP-L/TR | 制造商:EXAR 制造商全称:EXAR 功能描述:Low Power Microprocessor Supervisory Circuits |
| SP708CU | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Power Microprocessor Supervisory Circuits |
| SP708CU-L/TR | 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 |
| SP708EN | 制造商:Exar Corporation 功能描述: |
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