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參數(shù)資料
| 型號： | MAX6826 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 4-By-4 Register Files With 3-State Outputs 16-CDIP -55 to 125 |
| 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(fù)位及看門狗定時器 |
| 文件頁數(shù)： | 10/12頁 |
| 文件大?。?/td> | 205K |
| 代理商： | MAX6826 |
M
directly to the microcontroller
’
s
RESET
pin with a single
pullup resistor allows the device to assert a reset
(Figure 6).
Negative-Going V
CC
Transients
These supervisors are relatively immune to short-dura-
tion, negative-going V
CC
transients (glitches), which
usually do not require the entire system to shut down.
Resets are issued to the μP during power-up, power-
down, and brownout conditions. The
Typical Operating
Characteristics
show a graph of the Maximum V
CC
Transient Duration vs. Reset Threshold Overdrive, for
which reset pulses are
not
generated. The graph was
produced using negative-going V
CC
pulses, starting at
the standard monitored voltage and ending below the
reset threshold by the magnitude indicated (reset
threshold overdrive). The graph shows the maximum
pulse width that a negative-going V
CC
transient can
typically have without triggering a reset pulse. As the
amplitude of the transient increases (i.e., goes farther
below the reset threshold), the maximum allowable
pulse width decreases. Typically, a V
CC
transient that
goes 100mV below the reset threshold and lasts for
20μs or less will not trigger a reset pulse.
Ensuring a Valid RESET
Output Down to V
CC
= 0
The MAX6826
–
MAX6831 are guaranteed to operate
properly down to V
CC
= 1V. In applications that require
valid reset levels down to V
CC
= 0, a pulldown resistor
to active-low outputs (push/pull only, Figure 7) and a
pullup resistor to active-high outputs (push/pull only) will
ensure that the reset line is valid while the reset output
can no longer sink or source current. This scheme does
not work with the open-drain outputs of the
MAX6828/MAX6831. The resistor value used is not criti-
cal, but it must be small enough not to load the reset
output when V
CC
is above the reset threshold. For falling
slew rates greater than 1V/s, a 100k
is adequate.
Watchdog Software Considerations
One way to help the watchdog timer monitor software
execution more closely is to set and reset the watchdog
input at different points in the program, rather than
pulsing the watchdog input high-low-high or low-high-
low. This technique avoids a stuck loop, in which the
watchdog timer would continue to be reset inside the
loop, keeping the watchdog from timing out.
Figure 8 shows an example of a flow diagram where the
I/O driving the watchdog input is set high at the begin-
ning of the program, set low at the beginning of every
subroutine or loop, then set high again when the pro-
gram returns to the beginning. If the program should
hang in any subroutine, the problem would quickly be
corrected, since the I/O is continually set low and the
watchdog timer is allowed to time out, causing a reset
or interrupt to be issued. As described in the
Watchdog
Input Current
section, this scheme results in higher time
average WDI input current than does leaving WDI low
for the majority of the timeout period and periodically
pulsing it low-high-low.
Dual Ultra-Low-Voltage SOT23 μP Supervisors
with Manual Reset and Watchdog Timer
10
______________________________________________________________________________________
Figure 8. Watchdog Flow Diagram
START
SET WDI
HIGH
PROGRAM
CODE
SUBROUTINE OR
PROGRAM LOOP
SET WDI LOW
RETURN
MAX6826
MAX6829
V
CC
R1
100k
RESET
GND
Figure 7. RESET Valid to V
CC
= Ground Circuit
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX6827 | Dual Ultra-Low-Voltage SOT23 レP Supervisors with Manual Reset and Watchdog Timer |
| MAX6828 | Dual Ultra-Low-Voltage SOT23 レP Supervisors with Manual Reset and Watchdog Timer |
| MAX6829 | Dual Ultra-Low-Voltage SOT23 レP Supervisors with Manual Reset and Watchdog Timer |
| MAX6830 | 16-Bit Shift Registers 28-LCCC -55 to 125 |
| MAX6831 | 16-Bit Shift Registers 24-CDIP -55 to 125 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6826LUT | 制造商:Maxim Integrated Products 功能描述:DUAL ULTRA_LOW_VOLTAGE SOT23 MICROPROCESSOR S - Rail/Tube |
| MAX6826LUT+ | 制造商:Maxim Integrated Products 功能描述:PROCESSOR SUPERVISOR 4.63V/ADJV 10UA 6PIN SOT-23 - Rail/Tube |
| MAX6826LUT+T | 功能描述:監(jiān)控電路 Dual 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 |
| MAX6826LUT-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 |
| MAX6826MUT | 制造商:Maxim Integrated Products 功能描述:DUAL ULTRA_LOW_VOLTAGE SOT23 MICROP - Rail/Tube |
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