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參數資料
| 型號： | MAX691ACSE-T |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Microprocessor Supervisory Circuits |
| 中文描述： | 1-CHANNEL POWER SUPPLY MANAGEMENT CKT, PDSO16 |
| 封裝： | 0.150 INCH, MS-012AC, SOIC-16 |
| 文件頁數： | 6/17頁 |
| 文件大小： | 204K |
| 代理商： | MAX691ACSE-T |
MAX691A/MAX693A/MAX800L/MAX800M
Microprocessor Supervisory Circuits
14
______________________________________________________________________________________
parator. Select the ratio of R1 and R2 such that PFI sees
1.25V when VIN falls to the desired trip point (VTRIP).
Resistor R3 adds hysteresis. It will typically be an order
of magnitude greater than R1 or R2. The current
through R1 and R2 should be at least 1A to ensure that
the 25nA (max) PFI input current does not shift the trip
point. R3 should be larger than 10k
Ω to prevent it from
loading down the PFO pin. Capacitor C1 adds noise
rejection.
Monitoring a Negative Voltage
The power-fail comparator can be used to monitor a
negative supply voltage using Figure 12’s circuit. When
the negative supply is valid, PFO is low. When the neg-
ative supply voltage drops, PFO goes high. This cir-
cuit’s accuracy is affected by the PFI threshold
tolerance, the VCC voltage, and resistors R1 and R2.
Backup-Battery Replacement
The backup battery may be disconnected while VCC is
above the reset threshold. No precautions are neces-
sary to avoid spurious reset pulses.
Negative-Going VCC Transients
While issuing resets to the P during power-up, power-
down, and brownout conditions, these supervisors are
relatively immune to short-duration, negative-going VCC
transients (glitches). It is usually undesirable to reset
the P when VCC experiences only small glitches.
Figure 13 shows maximum transient duration vs. reset-
comparator overdrive, for which reset pulses are not
generated. The graph was produced using negative-
going VCC pulses, starting at 5V and ending below the
reset threshold by the magnitude indicated (reset com-
parator overdrive). The graph shows the maximum
pulse width a negative-going VCC transient may typical-
ly have without causing a reset pulse to be issued. As
the amplitude of the transient increases (i.e., goes far-
ther below the reset threshold), the maximum allowable
pulse width decreases. Typically, a VCC transient that
goes 100mV below the reset threshold and lasts for
40s or less will not cause a reset pulse to be issued.
A 100nF bypass capacitor mounted close to the VCC
pin provides additional transient immunity.
Connecting a Timing Capacitor at OSC IN
When OSC SEL is connected to ground, OSC IN dis-
connects from its internal 10A (typ) pullup and is inter-
nally connected to a ±100nA current source. When a
capacitor is connected from OSC IN to ground (to
select alternative reset and watchdog timeout periods),
the current source charges and discharges the timing
capacitor to create the oscillator that controls the reset
and watchdog timeout period. To prevent timing errors
or oscillator startup problems, minimize external current
leakage sources at this pin, and locate the capacitor as
close to OSC IN as possible. The sum of PC-board
leakage plus OSC capacitor leakage must be small
compared to ±100nA.
100
0
10
1000
10000
40
20
80
60
MAX791-16
RESET COMPARATOR OVERDRIVE,
(Reset Threshold Voltage - VCC) (mV)
MAXIMUM
TRANSIENT
DURATION
(μ
s)
100
VCC = 5V
TA = +25
°C
0.1
μF CAPACITOR
FROM VOUT TO GND
Figure 13. Maximum Transient Duration without Causing a
Reset Pulse vs. Reset Comparator Overdrive
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX691ACUE | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數: 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 |
| MAX691ACUE+ | 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數: 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 |
| MAX691ACUE+T | 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數: 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 |
| MAX691ACUE-T | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數: 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 |
| MAX691ACWE | 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數: 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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