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參數(shù)資料
| 型號： | MAX690A |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Microprocessor Supervisory Circuits(帶看門狗和電池開關(guān)的復位器,復位門限4.65V) |
| 中文描述： | 微處理器監(jiān)控電路 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大小： | 122K |
| 代理商： | MAX690A |
M
V
BATT
is 0.6V or greater than V
CC
.
When V
connects to V
, backup mode is activat-
ed and the internal circuitry is powered from the battery
(Table 1). When V
is just below V
, the current
drawn from V
is typically 30μA. When V
drops to
more than 1V below V
, the internal switchover com-
parator shuts off and the supply current falls to less
than 1μA.
__________Applic ations Information
Using a S uperCap as a Bac kup
Power S ourc e
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 V
.
However, after a long time, the diode leakage current will
pull the SuperCap voltage up to V
. When using a
SuperCap with the MAX690A/MAX802L/MAX805L, V
CC
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 V
-
0.5V. At the maximum V
of 5.5V, the SuperCap
charges up to 5.0V, only 0.5V above the maximum
reset threshold—well within the requisite 0.6V.
Mic roproc essor S upervisory Circ uits
8
_______________________________________________________________________________________
V
BATT
V
CC
V
OUT
RESET
GND
TOSTATIC RAM
TO
μ
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
V
CC
GND
TO
μ
P
MAX690
MAX692A
MAX802L
MAX802M
MAX805L
+5V
R
2
R
1
R
3
PFI
*OPTIONAL
+5V
0V
PFO
V
L
V
H
V
TRIP
V
IN
0V
V
IN
C1*
Figure 6. Adding Hysteresis to the Power-Fail Comparator
Allowable Bac kup Power-S ourc e
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
Table 2. Allowable Backup-Battery Voltages
(see Using a SuperCap as a Backup Power Source
section for use with a SuperCap)
MAXIMUM BACKUP-BATTERY
PART NO.
VOLTAGE (V)
MAX690A/
MAX802L/MAX805L
MAX692A/
MAX802M
4.80
4.55
VTRIP
1.25/
R2
+
R2
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.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX692A | Microprocessor Supervisory Circuits(帶看門狗和電池開關(guān)復位器,復位閾值4.40V) |
| MAX8069 | Low-Voltage Reference |
| MAX8069ESA | Low-Voltage Reference |
| MAX8069CCZQ | Low-Voltage Reference |
| MAX807MCUE | Full-Featured uP Supervisory Circuit with +/-1.5% Reset Accuracy |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX690AC/D | 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(guān):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 |
| MAX690ACPA | 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(guān):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 |
| MAX690ACPA+ | 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):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 |
| MAX690ACSA | 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(guān):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 |
| MAX690ACSA+ | 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 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):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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