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LTC1235CSW 参数 Datasheet PDF下载

LTC1235CSW图片预览
型号: LTC1235CSW
PDF下载: 下载PDF文件 查看货源
内容描述: 微处理器监控电路 [Microprocessor Supervisory Circuit]
分类和应用: 电源电路电源管理电路微处理器光电二极管监控
文件页数/大小: 16 页 / 224 K
品牌: LINER [ LINEAR TECHNOLOGY ]
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LTC1235
Microprocessor
Supervisory Circuit
FEATURES
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DESCRIPTION
The LTC
®
1235 provides complete power supply monitoring
and battery control functions for microprocessor reset,
battery backup, RAM write protection, power failure warn-
ing and watchdog timing. The LTC1235 has all the LTC695
features plus conditional battery backup and external reset
control. When an out-of-tolerance power supply condition
occurs, the reset outputs are forced to active states and
the Chip Enable output write-protects external memory.
The
RESET
output is guaranteed to remain logic low with
V
CC
as low as 1V. External reset control is provided by a
debounced pushbutton reset input.
The LTC1235 powers the active CMOS RAMs with a charge
pumped NMOS power switch to achieve low dropout and
low supply current. When primary power is lost, auxiliary
power, connected to the battery input pin, provides backup
power to the RAMs. The LTC1235 can be programmed by
a P signal to either back up the RAMs or not. This extends
the battery life in situations where RAM data need not
always be saved when power goes down.
For an early warning of impending power failure, the
LTC1235 provides an internal comparator with a user-
defined threshold. An internal watchdog timer is also
available, which forces the reset pins to active states when
the watchdog input is not toggled prior to the time-out
period.
Guaranteed Reset Assertion at V
CC
= 1V
1.5mA Maximum Supply Current
Fast (35ns Max.) Onboard Gating of RAM Chip
Enable Signals
Conditional Battery Backup Extends Battery Life
4.65V Precision Voltage Monitor
Power OK/Reset Time Delay: 200ms
External Reset Control
Minimum External Component Count
1μA Maximum Standby Current
Voltage Monitor for Power Fail or Low Battery
Warning
Thermal Limiting
Performance Specified Over Temperature
All the LTC695 Features Plus Conditional Battery
Backup and External Reset Control
APPLICATIONS
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Critical μP Power Monitoring
Intelligent Instruments
Battery-Powered Computers and Controllers
Automotive Systems
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATION
V
IN
≥ 7.5V
LT1086-5
BATTERY LIFE (NORMALIZED)
V
IN
ADJ
V
OUT
+5V
10
Battery Life vs
Backup Duty Cycle
V
CC
V
OUT
LTC1235
V
BATT
BACKUP
RESET
PFI
PB RST
PFO
WDI
0.1μF
POWER TO
μP
CMOS RAM POWER
I/O LINE
μP
RESET
μP NMI
I/O LINE
μP
SYSTEM
9
8
7
6
5
4
3
2
1
0
0
20
60
80
40
BACKUP DUTY CYCLE (%)
100
1235 TA02
+
10μF
+
100μF
LTC1235
0.1μF
51k
+3V
10k
1235 TA1
LTC695
(WITHOUT
CONDITIONAL
BATTERY
BACKUP)
THE LTC1235 EXTENDS BATTERY LIFE BY PROVIDING BATTERY POWER ONLY WHEN REQUIRED TO BACK UP RAM DATA.
IT SAVES THE BATTERY WHEN NO DATA BACKUP IS NEEDED. THE μP REQUESTS BACKUP WITH THE BACKUP PIN.
1235fa
1