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參數(shù)資料
| 型號： | MAX6746KA29 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay |
| 中文描述： | 復(fù)位電路的電容可調(diào)的復(fù)位/看門狗超時周期 |
| 文件頁數(shù)： | 7/14頁 |
| 文件大小： | 187K |
| 代理商： | MAX6746KA29 |
Detailed Description
The MAX6746
–
MAX6753 assert a reset signal whenever
the V
CC
supply voltage or RESET IN falls below its reset
threshold. The reset output remains asserted for the
reset timeout period after V
CC
and RESET IN rise above
its respective reset threshold. A watchdog timer triggers
a reset pulse whenever a watchdog fault occurs.
The reset and watchdog delays are adjustable with
external capacitors. The MAX6746
–
MAX6751 contain a
watchdog select input that extends the watchdog time-
out period to 128x.
The MAX6752 and MAX6753 have a sophisticated
watchdog timer that detects when the processor is run-
ning outside an expected window of operation. The
watchdog signals a fault when the input pulses arrive too
early (faster that the selected t
WD1
timeout period) or too
late (slower than the selected t
WD2
timeout period) (see
Figure 1).
Reset Output
The reset output is typically connected to the reset input
of a μP. A μP
’
s reset input starts or restarts the μP in a
known state. The MAX6746
–
MAX6753 μP supervisory
circuits provide the reset logic to prevent code-execu-
tion errors during power-up, power-down, and
brownout conditions (see the
Typical Operating Circuit
).
RESET
changes from high to low whenever the moni-
tored voltage, RESET IN and/or V
CC
drop below the
reset threshold voltages. Once V
RESET IN
and/or V
CC
exceeds its respective reset threshold voltage(s),
RESET
remains low for the reset timeout period, then
goes high.
RESET
is guaranteed to be in the correct logic state for
V
CC
greater than 1V. For applications requiring valid
reset logic when V
CC
is less than 1V, see the section
Ensuring a Valid RESET Output Down to V
CC
= 0V.
RESET IN Threshold
The MAX6748
–
MAX6751 monitor the voltage on RESET IN
using an adjustable reset threshold (V
RESET IN
) set with
an external resistor voltage-divider (
Figure
2). Use the
following formula to calculate the externally monitored
voltage (V
MON_TH
):
V
MON_TH
= V
RESET IN
x (R1 + R2) / R2
M
μP Reset Circuits with Capacitor-Adjustable
Reset/Watchdog Timeout Delay
_______________________________________________________________________________________
7
WDI CONDITION 1
WDI CONDITION 2
WDI CONDITION 3
GUARANTEED TO
NOT ASSERT
RESET
GUARANTEED TO
ASSERT
RESET
t
WD1
(MIN)
t
WD1
(MAX)
*UNDETERMINED
*UNDETERMINED
FAST FAULT
NORMAL OPERATION
SLOW FAULT
*UNDETERMINED STATES MAY OR MAY NOT GENERATE A FAULT CONDITION
GUARANTEED
TO ASSERT
RESET
t
WD2
(MIN)
t
WD2
(MAX)
Figure 1. MAX6752/MAX6753 Detailed Watchdog Input Timing Relationship
MAX6748
MAX6749
MAX6750
MAX6751
RESET IN
GND
V
CC
V
CC
V
MON_TH
V
MON_TH
= 1.235 x (R1 + R2) / R2
R1
R2
Figure 2. Calculating the Monitored Threshold Voltage
(V
MON_TH
)
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6746KA29/V+T | 功能描述:監(jiān)控電路 Microprocessor Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout delay RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 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 |
| MAX6746KA29+T | 功能描述:監(jiān)控電路 Single uPower Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 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 |
| MAX6746KA29+TG48 | 制造商:Maxim Integrated Products 功能描述:?P RESET CIRCUITS WITH CAPACITOR-ADJUSTABLE RESET/WATCHDOG T - Tape and Reel |
| MAX6746KA29-T | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 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 |
| MAX6746KA29-TG48 | 制造商:Maxim Integrated Products 功能描述:?P RESET CIRCUITS WITH CAPACITOR-ADJUSTABLE RESET/WATCHDOG T - Tape and Reel |
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