參數(shù)資料
型號： MAX819LCSA
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 電源管理
英文描述： +5V Microprocessor Supervisory Circuits
中文描述： 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8
封裝： 0.150 INCH, SOIC-8
文件頁數(shù)： 12/16頁
文件大?。?/td> 114K
代理商： MAX819LCSA
M
+5V Mic roproc essor S upervisory Circ uits
12
______________________________________________________________________________________
Bac kup-Battery S witc hover
In a brownout or power failure, it may be necessary to
preserve the contents of RAM. With a backup battery
installed at BATT, the MAX817/MAX818/MAX819 auto-
matically switch RAM to backup power when V
CC
falls.
These devices require two conditions before switching
to battery-backup mode: 1) V
CC
must be below the
reset threshold, and 2) V
CC
must be below V
BATT
.
Table 1 lists the status of the inputs and outputs in bat-
tery-backup mode.
As long as V
CC
exceeds the reset threshold, OUT con-
nects to V
CC
through a 5
PMOS power switch. Once
V
CC
falls below the reset threshold, V
CC
or V
BATT
(whichever is higher) switches to OUT. When V
CC
falls
below V
RST
and V
BATT
, BATT switches to OUT through
an 80
switch.
When V
CC
exceeds the reset threshold, it is connected to
the substrate, regardless of the voltage applied to BATT
(Figure 10). During this time, the diode (D1) between
BATT and the substrate will conduct current from BATT
to V
CC
if V
BATT
is 0.6V greater than V
CC
. When BATT
connects to OUT, backup mode is activated and the
internal circuitry is powered from the battery (Table 1).
When V
CC
is just below V
BATT
, the current draw from
BATT is typically 6μA. When V
CC
drops to more than 1V
below V
BATT
, the internal switchover comparator shuts
off and the supply current falls to less than 1μA.
__________Applic ations Information
The MAX817/MAX818/MAX819 are protected for typical
short-circuit conditions of 10sec or less. Shorting OUT
to ground for longer than 10sec destroys the device.
Decouple V
CC
, OUT, and BATT to ground by placing
0.1μF capacitors as close to the device as possible.
Connected to V
OUT
. Current drawn from
the battery is less than 1μA, as long as
V
CC
< V
BATT
- 0.2V.
Logic low
Watchdog timer is disabled.
V
BATT
Disconnected from V
OUT
.
Connected to V
BATT
through an internal 80
PMOS switch.
V
CC
V
RESET
V
WDI
Logic high. The open-circuit voltage is equal
to V
OUT
.
High impedance
V
CE
OUT
V
CE
IN
V
OUT
STATUS
SIGNAL
Table 1. Input and Output Status in
Battery-Backup Mode
Figure 9. Monitoring an Additional Supply by Connecting
PFO to MR.
MAX819
V2
(RESET)
= 1.25
ADDITIONAL SUPPLY RESET VOLTAGE
R1 + R2
( )
R1
R2
μ
P
V
CC
V1
V2
RESET
PFI
RESET
MR
PFO
Figure 10. Backup-Battery-Switchover Block Diagram
SW1/SW2
SW3/SW4
CONDITION
V
CC
> Reset Threshold
Open
Closed
Closed
Open
Open
Closed
V
CC
< Reset Threshold and
V
CC
> V
BATT
V
CC
< Reset Threshold and
V
CC
< V
BATT
RESET THRESHOLD = 4.65V IN MAX81_L
RESET THRESHOLD = 4.4V IN MAX81_M
OUT
D3
SUBSTRATE
D1
D2
SW2
SW1
SW4
SW3
BATT
V
CC
MAX817
MAX818
MAX819
相關(guān)PDF資料
PDF描述
MAX819LCUA +5V Microprocessor Supervisory Circuits
MAX819LEPA +5V Microprocessor Supervisory Circuits
MAX819LESA Circular Connector; MIL SPEC:MIL-C-26482, Series I, Solder; Body Material:Aluminum; Series:PT06; No. of Contacts:3; Connector Shell Size:12; Connecting Termination:Solder; Circular Shell Style:Straight Plug
MAX819M +5V Microprocessor Supervisory Circuits
MAX819MCPA PT 4C 4#16 PIN PLUG
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX819LCSA+ 功能描述:監(jiān)控電路 5V 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
MAX819LCSA+T 功能描述:監(jiān)控電路 5V 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
MAX819LCSA-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(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
MAX819LCUA 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
MAX819LCUA+ 功能描述:監(jiān)控電路 5V 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
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