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參數(shù)資料
| 型號： | MAX807MCUE |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Full-Featured uP Supervisory Circuit with +/-1.5% Reset Accuracy |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| 封裝： | TSSOP-16 |
| 文件頁數(shù)： | 15/16頁 |
| 文件大?。?/td> | 196K |
| 代理商： | MAX807MCUE |
Backup-Battery Replacement
The backup battery may be disconnected while V
CC
is
above the reset threshold, provided BATT is bypassed
with a 0.1μF capacitor to ground. No precautions are
necessary to avoid spurious reset pulses.
Negative-Going V
CC
Transients
While issuing resets to the μP during power-up, power-
down, and brownout conditions, these supervisors are
relatively immune to short-duration negative-going V
CC
transients (glitches). It is usually undesirable to reset
the μP when V
CC
experiences only small glitches.
The
Typical Operating Characteristics
show Maximum
Transient Duration vs. Reset Comparator Overdrive, for
which reset pulses are not generated. The graph was
produced using negative-going V
CC
pulses, starting at
5V and ending below the reset threshold by the magni-
tude indicated (reset comparator overdrive). The graph
shows the maximum pulse width that a negative-going
V
CC
transient may typically have without causing a
reset pulse to be issued. As the amplitude of the tran-
sient increases (i.e., goes farther below the reset
threshold), the maximum allowable pulse width
decreases.
Typically, a V
CC
transient that goes 40mV below the
reset threshold and lasts for 3μs or less will not cause a
reset pulse to be issued.
A 0.1μF bypass capacitor mounted close to the V
CC
pin provides additional transient immunity.
Watchdog Software Considerations
To help the watchdog timer keep a closer watch on soft-
ware execution, you can use the method of setting and
resetting 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 where the watchdog timer continues to be reset
within the loop, keeping the watchdog from timing out.
Figure 16 shows an example 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 I/O is continually set low
and the watchdog timer is allowed to time out, causing
a reset or interrupt to be issued.
Maximum V
CC
Fall Time
The V
CC
fall time is limited by the propagation delay of
the battery switchover comparator and should not
exceed 0.03V/μs. A standard rule for filter capacitance
on most regulators is on the order of 100μF per amp of
current. When the power supply is shut off or the main
battery is disconnected, the associated initial V
CC
fall
rate is just the inverse or 1A / 100μF = 0.01V/μs. The
V
CC
fall rate decreases with time as V
CC
falls exponen-
tially, which more than satisfies the maximum fall-time
requirement.
M
Full-Featured μP Supervisory Circuit with
±1.5% Reset Accuracy
______________________________________________________________________________________
15
Figure 15. Adding Hysteresis to the Power-Fail Comparator
MAX807
V
CC
GND
PFI
*OPTIONAL
R2
R3
R1
VIN
+5V
C1*
TO
μ
P
PFO
TRIP
= 2.265 R1 + R2
V
H
= 2.265 / R2
||
R3 V
L
V
||
R3 - 2.265 + 5 - 2.265 = 2.265
PFO
+5V
0V
0V
V
H
V
TRIP
V
IN
V
L
Figure 16. Watchdog Flow Diagram
START
SET
WDI
LOW
SUBROUTINE
OR PROGRAM LOOP,
SET WDI
HIGH
RETURN
END
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX807MCUE+ | 功能描述:監(jiān)控電路 Full-Featured 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 |
| MAX807MCUE+T | 功能描述:監(jiān)控電路 Full-Featured 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 |
| MAX807MCUE-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 |
| MAX807MCWE | 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 |
| MAX807MCWE+ | 功能描述:監(jiān)控電路 Full-Featured 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 |
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