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參數(shù)資料
| 型號： | MAX6829 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Dual Ultra-Low-Voltage SOT23 レP Supervisors with Manual Reset and Watchdog Timer |
| 中文描述： | 雙路、超低電壓、SOT23封裝、微處理器監(jiān)控電路，帶有手動復位及看門狗定時器 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大小： | 205K |
| 代理商： | MAX6829 |
outputs. Connect a normally open momentary switch
from
MR
to GND to create a manual-reset function;
external debounce circuitry is not required. If
MR
is dri-
ven from long cables or the device is used in a noisy
environment, connect a 0.1μF capacitor from
MR
to
GND to provide additional noise immunity.
Watchdog Input
The watchdog circuit monitors the μP
’
s activity. If the
μP does not toggle (low to high or high to low) the
watchdog input (WDI) within the watchdog timeout peri-
od (1.6s nominal), reset asserts for the reset timeout
period. The internal 1.6s timer can be cleared by either
a reset pulse or by toggling WDI. The WDI can detect
pulses as short as 50ns. While reset is asserted, the
timer remains cleared and does not count. As soon as
reset is released, the timer starts counting (Figure 4).
Disable the watchdog function by leaving WDI uncon-
nected or by three-stating the driver connected to WDI.
The watchdog input is internally driven low during the
first 7/8 of the watchdog timeout period and high for the
last 1/8 of the watchdog timeout period. When WDI is left
unconnected, this internal driver clears the 1.6s timer
every 1.4s. When WDI is three-stated or unconnected,
the maximum allowable leakage current is 10μA and the
maximum allowable load capacitance is 200pF.
Adjustable Reset Thresholds
The MAX6826/MAX6827/MAX6828 provide a user
adjustable input to monitor a second voltage. The
threshold voltage at RSTIN is typically 0.63V. To moni-
tor a voltage higher than 0.63V, connect a resistor-
divider to the circuit as shown in Figure 5. The
threshold at V
MONITOR
is:
Note that RSTIN is powered by V
CC
, and its voltage
must therefore remain lower than V
CC
.
Applications Information
Watchdog Input Current
The WDI inputs are internally driven through a buffer
and series resistor from the watchdog timer (Figure 1).
When WDI is left unconnected, the watchdog timer is
serviced within the watchdog timeout period by a low-
high-low pulse from the counter chain. For minimum
watchdog input current (minimum overall power con-
sumption), leave WDI low for the majority of the watch-
dog timeout period, pulsing it low-high-low once within
the first 7/8 of the watchdog timeout period to reset the
watchdog timer. If WDI is externally driven high for the
majority of the timeout period, up to 160μA can flow into
WDI.
Interfacing to μPs
with Bidirectional Reset Pins
Since the
RESET
output on the MAX6828/MAX6831
is open drain, these devices interface easily with μPs
that have bidirectional reset pins, such as the Motorola
68HC11. Connecting the μP supervisor
’
s
RESET
output
V
V
R
R
R
MONITOR TRIP
_
.
=
+
0 63
1
2
2
M
Dual Ultra-Low-Voltage SOT23 μP Supervisors
with Manual Reset and Watchdog Timer
_______________________________________________________________________________________
9
Figure 5. Monitoring a Voltage
V
MONITOR
R1
R2
V
CC
≥
V
RSTIN
RSTIN
MAX6826
MAX6827
MAX6828
V
CC
t
WD
t
RP
t
RP
t
RST
WDI
RESET*
*RESET IS THE INVERSE OF RESET.
Figure 4. Watchdog Timing Relationship
Figure 6. Interfacing Open-Drain
RESET
to μPs with
Bidirectional Reset I/O
MAX6828
MAX6831
RESET
GENERATOR
GND
GND
V
CC
V
CC
RESET
RESET
μ
P
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6829RDUT | 制造商:Maxim Integrated Products 功能描述:DUAL ULTRA LOW VOLTAGE SOT23 MICROP - Cut Tape Product |
| MAX6829RDUT+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX6829RDUT+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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX6829RDUT-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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| MAX6829REUT | 制造商:Maxim Integrated Products 功能描述:DUAL ULTRA LOW VOLTAGE SOT23 MICROP - Cut Tape Product |
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