參數(shù)資料
型號(hào)： MAX6750KA26
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(shí)周期
文件頁(yè)數(shù)： 8/14頁(yè)
文件大小： 187K
代理商： MAX6750KA26
M
where V
MON_TH
is the desired reset threshold voltage
and V
TH
is the reset input threshold (1.235V). Resistors
R1 and R2 can have very high values to minimize cur-
rent consumption due to low leakage currents. Set R2
to some conveniently high value (500k
, for example)
and calculate R1 based on the desired reset threshold
voltage, using the following formula:
R1 = R2 x (V
MON_TH
/V
RESET IN
- 1) (
)
The MAX6748 and MAX6749 do not monitor V
CC
sup-
ply voltage, therefore, V
CC
must be greater than 1.5V to
guarantee RESET IN threshold accuracy and timing
performance. The MAX6748 and MAX6749 can be con-
figured to monitor V
CC
voltage by connecting V
CC
to
V
MON_TH.
Dual-Voltage Monitoring
(MAX6750/MAX6751)
The MAX6750 and MAX6751 contain both factory-
trimmed threshold voltages and an adjustable reset
threshold input, allowing the monitoring of two voltages,
V
CC
and V
MON_TH
(see
Figure
2).
RESET
is asserted
when either of the voltages falls below it respective
threshold voltages.
Manual Reset (MAX6746/MAX6747)
Many μP-based products require manual reset capabil-
ity, to allow an operator or external logic circuitry to initi-
ate a reset. The manual reset input (
MR
) can connect
directly to a switch without an external pullup resistor or
debouncing network.
MR
is internally pulled up to V
CC
and, therefore, can be left unconnected if unused.
MR
is designed to reject fast, falling transients (typically
100ns pulses) and it must be held low for a minimum of
1μs to assert the reset output. A 0.1μF capacitor from
MR
to ground provides additional noise immunity. After
MR
transitions from low to high, reset remains asserted
for the duration of the reset timeout period.
A manual reset option can easily be implemented
with the MAX6748
–
MAX6751 by connecting a normally
open momentary switch in parallel with R2 (
Figure
3).
When the switch is closed, the voltage on RESET IN
goes to zero, initiating a reset. Similar to the MAX6746/
MAX6747 manual reset, reset remains asserted while
the voltage at RESET IN is zero and for the reset time-
out period after the switch is opened.
μP Reset Circuits with Capacitor-Adjustable
Reset/Watchdog Timeout Delay
8
_______________________________________________________________________________________
V
CC
WDI
t
WD
t
RP
RESET
NORMAL MODE (WDS = GND)
V
CC
OV
OV
Figure 4a. Watchdog Timing Diagram, WDS = GND
MAX6748
MAX6749
MAX6750
MAX6751
RESET IN
GND
V
CC
V
CC
V
MON_TH
R1
R2
Figure 3. Adding an External Manual Reset Function to the
MAX6748
–
MAX6751
相關(guān)PDF資料
PDF描述
MAX6750KA29 UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay
MAX6750KA46 UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay
MAX6751KA16 UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay
MAX6751KA23 UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay
MAX6751KA26 UP Reset Circuits with Capacitor-Adjustable Reset/Watchdog Timeout Delay
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX6750KA26+ 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX6750KA26+T 功能描述:監(jiān)控電路 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
MAX6750KA26-T 功能描述:監(jiān)控電路 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
MAX6750KA27 制造商:Maxim Integrated Products 功能描述:SINGLE/DUAL-VOLT MICROPROC. RESET C - Rail/Tube
MAX6750KA27+T 功能描述:監(jiān)控電路 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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