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參數(shù)資料
| 型號： | LTC1235 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Microprocessor Supervisory Circuit |
| 中文描述： | 微處理器監(jiān)控電路 |
| 文件頁數(shù)： | 13/16頁 |
| 文件大小： | 295K |
| 代理商： | LTC1235 |
13
LTC1235
U
S
A
O
PPLICATI
U
U
The 10.7ms allows enough time to execute shut-down
procedure for microprocessor and 831mV of hysteresis
would prevent PFO from going low due to the noise of V
IN
.
Example 2:
The circuit in Figure 9 can be used to measure
the regulated 5V supply to provide early warning of power
failure. Because of variations in the PFI threshold, this
circuit requires adjustment to ensure that the PFI com-
parator trips before the reset threshold is reached. Adjust
R5 such that the PFO output goes low when the V
CC
supply
reaches the desired level (e.g., 4.85V).
Monitoring the Status of the Battery
C3 can also monitor the status of the memory backup
battery (Figure 10). If desired, the CE OUT can be used to
apply a test load to the battery. Since CE OUT is forced high
in battery backup mode, the test load will not be applied to
the battery while it is in use, even if the microprocessor is
not powered.
Figure 11. Watchdog Time-out Period and Reset Active Time
Watchdog Timer
The LTC1235 provides a watchdog timer function to
monitor the activity of the microprocessor. If the micro-
processor does not toggle the Watchdog Input (WDI)
within the time-out period, the reset outputs are forced to
active states for a minimum of 140ms. The watchdog
time-out period is fixed at 1.0 second minimum on the
LTC1235. This time-out period provides adequate time for
many systems to service the watchdog timer immediately
after a reset. Figure 11 shows the timing diagram of
watchdog time-out period and reset active time. The
watchdog time-out period is restarted as soon as the reset
outputs are inactive. When either a high-to-low or low-to-
high transition occurs at the WDI pin prior to time-out, the
watchdog time is reset and begins to time out again. To
ensure the watchdog time does not time out, either a high-
to-low or low-to-high transition on the WDI pin must
occur at or less than the minimum time-out period. If the
input to the WDI pin remains either high or low, reset
pulses will be issued every 1.6 seconds typically. The
watchdog timer can be deactivated by floating the WDI pin.
The timer is also disabled when V
CC
falls below the reset
voltage threshold or V
BATT
.
The Watchdog Output, WDO, goes low if the watchdog
timer is allowed to time out and remains low until set high
by the next transition on the WDI pin. WDO is also set high
when V
CC
falls below the reset voltage threshold or V
BATT
.
+3V
OPTIONAL TEST LOAD
V
CC
+5V
LTC1235 F09
V
BATT
GND
PFI
LTC1235
R1
1M
RL 20K
R2
1M
CE IN
LOW BATTERY SIGNAL
TO μP I/O PIN
TO
μ
P I/O PIN
}
PFO
CE OUT
BACKUP
Figure 10. Backup Battery Monitor with Optional Test Load
t1 = RESET ACTIVE TIME
t2 = WATCHDOG TIME-OUT PERIOD
V
CC
= 5V
WDI
t1
WDO
RESET
t2
t1
LTC1235 F11
t1
t2
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1235C | Microprocessor Supervisory Circuit |
| LTC1235CN | Microprocessor Supervisory Circuit |
| LTC1235CS | Microprocessor Supervisory Circuit |
| LTC1261 | Switched Capacitor Regulated Voltage Inverter(開關(guān)電容穩(wěn)壓電壓反相器) |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1235CN | 功能描述:IC MPU SUPERVISORY CIRCUIT 16DIP RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| LTC1235CN#PBF | 功能描述:IC MPU SUPERVISORY CIRCUIT 16DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 其它有關(guān)文件:STM6905 View All Specifications 標(biāo)準(zhǔn)包裝:1 系列:- 類型:多壓監(jiān)控器 監(jiān)視電壓數(shù)目:5 輸出:開路漏極或開路集電極 復(fù)位:低有效 復(fù)位超時:最小為 140 ms 電壓 - 閥值:2.188V，2.955V，可調(diào)，可調(diào)，可調(diào) 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1197 (CN2011-ZH PDF) 其它名稱:497-8728-6 |
| LTC1235CSW | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
| LTC1235CSW#PBF | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 其它有關(guān)文件:STM6905 View All Specifications 標(biāo)準(zhǔn)包裝:1 系列:- 類型:多壓監(jiān)控器 監(jiān)視電壓數(shù)目:5 輸出:開路漏極或開路集電極 復(fù)位:低有效 復(fù)位超時:最小為 140 ms 電壓 - 閥值:2.188V，2.955V，可調(diào)，可調(diào)，可調(diào) 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1197 (CN2011-ZH PDF) 其它名稱:497-8728-6 |
| LTC1235CSW#TR | 功能描述:IC MPU SUPERVISRY CIRCUIT 16SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 監(jiān)控器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 類型:簡單復(fù)位/加電復(fù)位 監(jiān)視電壓數(shù)目:1 輸出:開路漏極或開路集電極 復(fù)位:高有效 復(fù)位超時:- 電壓 - 閥值:1.8V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:6-TSOP（0.059"，1.50mm 寬）5 引線 供應(yīng)商設(shè)備封裝:5-TSOP 包裝:剪切帶 (CT) 其它名稱:NCP301HSN18T1GOSCT |
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