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參數(shù)資料
| 型號(hào)： | MAX690ACSA-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, PDSO8 |
| 封裝： | SOP-8 |
| 文件頁數(shù)： | 13/14頁 |
| 文件大小： | 661K |
| 代理商： | MAX690ACSA-T |
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L
When VBATT connects to VOUT, backup mode is activat-
ed and the internal circuitry is powered from the battery
(Table 1). When VCC is just below VBATT, the current
drawn from VBATT is typically 30A. When VCC drops to
more than 1V below VBATT, the internal switchover com-
parator shuts off and the supply current falls to less
than 1A.
__________Applications Information
Using a SuperCap as a Backup
Power Source
SuperCaps are capacitors with extremely high capaci-
tance values, on the order of 0.1F. Figure 4 shows a
SuperCap used as a backup power source. Do not allow
the SuperCap’s voltage to exceed the maximum reset
threshold by more than 0.6V. In Figure 4’s circuit, the
SuperCap rapidly charges to within a diode drop of VCC.
However, after a long time, the diode leakage current will
pull the SuperCap voltage up to VCC. When using a
SuperCap with the MAX690A/MAX802L/MAX805L, VCC
may not exceed 4.75V + 0.6V = 5.35V.
Use the SuperCap circuit of Figure 5 with a MAX692A
or MAX802M and a ±10% supply.
This circuit
ensures that the SuperCap only charges to VCC -
0.5V. At the maximum VCC of 5.5V, the SuperCap
charges up to 5.0V, only 0.5V above the maximum
reset threshold—well within the requisite 0.6V.
Microprocessor Supervisory Circuits
8
_______________________________________________________________________________________
VBATT
VCC
VOUT
RESET
GND
TO STATIC RAM
TO
P
0.1F
MAX692A
MAX802M
+5V
+
100k
Figure 5. Using a SuperCap as a Backup Power Source with
the MAX692A/MAX802M and a +5V ±10% Supply
PFO
VCC
GND
TO
P
MAX690
MAX692A
MAX802L
MAX802M
MAX805L
+5V
R2
R1
R3
PFI
*OPTIONAL
+5V
0V
PFO
VL
VH
VTRIP
VIN
0V
VIN
C1*
Figure 6. Adding Hysteresis to the Power-Fail Comparator
Allowable Backup Power-Source
Batteries
Lithium batteries work very well as backup batteries due to
very low self-discharge rates and high energy density.
Single lithium batteries with open-circuit voltages of 3.0V to
3.6V are ideal. Any battery with an open-circuit voltage
less than the minimum reset threshold plus 0.3V can be
connected directly to the VBATT input of the
MAX690A/MAX692A/MAX802L/MAX802M/MAX805L with
Table 2. Allowable Backup-Battery Voltages
(see Using a SuperCap as a Backup Power Source
section for use with a SuperCap)
PART NO.
MAXIMUM BACKUP-BATTERY
VOLTAGE (V)
MAX690A/
MAX802L/MAX805L
4.80
MAX692A/
MAX802M
4.55
VTRIP
1.25/
R2
VIH
1.25/
R2 || R3
R1 R2 || R3
VL 1.25
R1
5
1.25
R3
1.25
R2
=
+
=
+
+
=
SuperCap is a trademark of Baknor Industries.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX690AEJA | 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 |
| MAX690AEPA | 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 |
| MAX690AEPA+ | 功能描述:監(jiān)控電路 MPU 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 |
| MAX690AESA | 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 |
| MAX690AESA/GG8 | 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 |
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