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參數(shù)資料
| 型號(hào)： | TPS3813I50MDBVREP |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO6 |
| 封裝： | 3 X 3 MM, PLASTIC, SOT-23, 6 PIN |
| 文件頁(yè)數(shù)： | 12/16頁(yè) |
| 文件大小： | 446K |
| 代理商： | TPS3813I50MDBVREP |
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TIMING RULES OF WINDOW-WATCHDOG
PROGRAMMABLE WINDOW-WATCHDOG BY USING AN EXTERNAL CAPACITOR
t
window,typ +
C
(ext)
15.55 pF )
1
6.25 ms
(1)
LOWER BOUNDARY CALCULATION
WATCHDOG SOFTWARE CONSIDERATIONS
APPLICATION EXAMPLE
SGLS343A – MAY 2006 – REVISED MAY 2006
After the reset of the supervisor is released, the lower boundary of the first WDI window is disabled. However,
after the first WDI pulse low-to-high transition is detected, the lower boundary function of the window is enabled.
All further WDI pulses will need to fit into the configured window frame.
The upper boundary of the watchdog timer can be set by an external capacitor connected between the WDT pin
and GND. Common consumer electronic capacitors can be used to implement this feature. They should have
low ESR and low tolerances since the tolerances have to be considered if the calculations are performed. The
first formula is used to calculate the upper window frame. After calculating the upper window frame, the lower
boundary can be calculated. As in the last example, the most important values are the tboundary,max and twindow,min.
The trigger pulse has to fit into this window frame.
The external capacitor should have a value between a minimum of 47 pF and a maximum of 63 nF.
SELECTED OPERATION MODE
WINDOW FRAME
twindow,max = 1.25 x twindow,typ
WDT = external capacitor C(ext)
WDR = 0 V and WDR = VDD
twindow,min = 0.75 x twindow,typ
The lower boundary can be calculated based on the values given in the switching characteristics. Additionally,
facts have to be taken into account to verify that the lower boundary is where it is expected. Since the internal
oscillator of the window watchdog is running free, any rising edge at the WDI pin will be taken into account at
the next internal clock cycle. This happens regardless of the external source. Since the shift between internal
and external clock is not known, it is best to consider the worst case condition for calculating this value.
SELECTED OPERATION MODE
LOWER BOUNDARY OF FRAME
tboundary,max = twindow,max / 23.5
WDR = 0 V
tboundary,typ = twindow,typ / 25.8
tboundary,min = twindow,min / 28.7
WDT = external capacitor C(ext)
tboundary,max = twindow,max / 51.6
WDR = VDD
tboundary,typ = twindow,typ / 64.5
tboundary,min = twindow,min / 92.7
To benefit from the window watchdog feature and help the watchdog timer monitor the software execution more
closely, it is recommended that the watchdog be set and reset at different points in the program rather than
pulsing the watchdog input periodically by using the prescaler of a microcontroller or DSP. Furthermore, the
watchdog trigger pulses should be set to different timings inside the window frame to release a defined reset, if
the program should hang in any subroutine. This allows the window watchdog to detect timeouts of the trigger
pulse as well as pulses that distort the lower boundary.
A typical application example (see Figure 3) is used to describe the function of the watchdog in more detail.
To configure the window watchdog function, two pins are provided by the TPS3813. These pins set the window
timeout and ratio.
The window watchdog ratio is a fixed ratio, which determines the lower boundary of the window frame. It can be
configured in two different frame sizes.
5
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS3813I50QDBVRQ1 | 功能描述:監(jiān)控電路 Proc Sup Circuit W/ Window Watchdog RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| TPS3813I50QDBVRSV | 制造商:Texas Instruments 功能描述: |
| TPS3813J25DBVR | 功能描述:監(jiān)控電路 w/Prog Watchdog Window RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| TPS3813J25DBVRG4 | 功能描述:監(jiān)控電路 w/Prog Watchdog Window RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| TPS3813J25DBVT | 功能描述:監(jiān)控電路 w/Prog Watchdog Window RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
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