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參數資料
| 型號： | MAX795 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Hex Inverters 20-LCCC -55 to 125 |
| 中文描述： | 3.0V/3.3V可調、微處理器監(jiān)控電路 |
| 文件頁數： | 15/20頁 |
| 文件大?。?/td> | 150K |
| 代理商： | MAX795 |
__________Applic ations Information
These μP supervisory circuits are not short-circuit pro-
tected. Shorting V
OUT
to ground, excluding power-up
transients such as charging a decoupling capacitor,
destroys the device. Decouple both V
CC
and BATT
pins to ground by placing 0.1μF ceramic capacitors as
close to the device as possible.
Driving an External S witc h with BAT T ON
BATT ON can be directly connected to the base of a
PNP transistor or the gate of a PMOS transistor. The
PNP connection is straightforward: connect the emitter
to V
CC
, the collector to OUT, and the base to BATT ON
(Figure 14a). No current-limiting resistor is required,
but a resistor connecting the base of the PNP to BATT
ON can be used to limit the current drawn from V
CC
,
prolonging battery life in portable equipment.
If you are using a PMOS transistor, however, it must be
connected backwards from the traditional method.
Connect the gate to BATT ON, the drain to V
CC
, and
the source to OUT (Figure 14b). This method orients
the body diode from V
CC
to OUT and prevents the
backup battery from discharging through the FET when
its gate is high. Two PMOS transistors in the Siliconix
LITTLE FOOT series are specified with V
GS
down to
-2.7V. The Si9433DY has a maximum 100m
drain-
source on-resistance with 2.7V of gate drive and a 2A
drain-source current. The Si9434DY specifies a 60m
drain-source on-resistance with 2.7V of gate drive and
a 5.1A drain-source current.
Using a S uperCap as a Bac kup
Power S ourc e
SuperCaps are capacitors with extremely high
capacitance values (e.g., order of 0.47F) for their size.
Figure 15 shows two ways to use a SuperCap as a
backup power source. The SuperCap can be connect-
ed through a diode to the 3V input (Figure 15a); or, if a
5V supply is also available, the SuperCap can be
charged up to the 5V supply (Figure 15b), allowing a
longer backup period. Since V
BATT
can exceed V
CC
while V
CC
is above the reset threshold, there are no
special precautions when using these μP supervisors
with a SuperCap.
Operation without a
Bac kup Power S ourc e
These μP supervisors were designed for battery-
backed applications. If a backup battery is not used,
connect BATT, OUT, and V
CC
together, or use a differ-
ent μP supervisor. See the μP Supervisory Circuits
table at the end of this data sheet.
Replac ing the Bac kup Battery
The backup power source can be removed while V
CC
remains valid, without danger of triggering a reset
pulse, provided that BATT is decoupled with a 0.1μF
capacitor to ground. As long as V
CC
stays above the
reset threshold, battery-backup mode cannot be
entered.
M
3.0V /3.3V Adjustable Mic roproc essor
S upervisory Circ uits
______________________________________________________________________________________
15
CE IN
CE OUT
High impedance
Pulled to BATT
RESET
RESET
Logic low
Pulled up to V
CC
BATT
LOWLINE
Connected to OUT
Logic low
WDO
WDI
Logic low
Disabled
BATT OK
PFI
Logic low
Disabled
PFO
MR
Logic low
Disabled, but still pulled up to V
CC
V
CC
Disconnected from OUT
Pulled up to BATT
BATT ON
OUT
Connected to BATT through an internal
140
switch
PIN NAME
STATUS
Table 1. Input and Output Status in
Battery-Backup Mode
V
CC
3.3V
3.6V
3.3V
3.6V
V
OUT
V
BATT
= 3.6V
V
RST
V
SW
Figure 13. Battery Switchover Timing
LITTLE FOOT is a trademark of Siliconix Inc.
SuperCap is a trademark of Baknor Industries.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX795RCPA | 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 |
| MAX795RCPA+ | 功能描述:監(jiān)控電路 3/3.3/AdjV 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 |
| MAX795RCSA | 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 |
| MAX795RCSA+ | 功能描述:監(jiān)控電路 3/3.3/AdjV 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 |
| MAX795RCSA+T | 功能描述:監(jiān)控電路 3/3.3/AdjV 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 |
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