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LTC1536
1536fa
Precision Triple Supply Monitor
for PCI Applications
1
2
3
4
8
7
6
5
V
CC3
V
CC5
V
CCA
GND
PBR
SRST
RST
RST
LTC1536
PUSHBUTTON
RESET
PCI
LOCAL
BUS
R
PU
SELECTED TO MEET RISE TIME
SLEW RATE REQUIREMENTS (1k MIN)
5V ± 5%
3.3V ± 0.3V
0.1µF
R
PU
RST
1536 TA01
PWR GOOD
0.1µF
Motherboard PCI RST Generation
TIME (20ns/DIV)
VOLTAGE (1V/DIV)
5
4
3
2
1
0
1536 TA02
V
CC5
= 5V TO 3V STEP
V
CC3
= V
CCA
= 3.3V
4.7k PULL-UP FROM
RST TO V
CC3
RST
V
CC5
Power Fail Waveform
5V Dropping Below 3.3V by 300mV
■
Simultaneously Monitors 5V, 3.3V and
Adjustable Inputs
■
Guaranteed Threshold Accuracy: ±0.75%
■
Low Supply Current: 100µA
■
Internal Reset Time Delay: 200ms
■
Manual Pushbutton Reset Input
■
Active Low and Active High Reset Outputs
■
Active Low “Soft” Reset Output
■
Power Supply Glitch Immunity
■
Guaranteed Reset for Either V
CC3
≥ 1V or V
CC5
≥ 1V
■
Meets PCI t
FAIL
Timing Specifications Rev 2.1
■
8-Pin SO and MSOP Packages
The LTC
®
1536 is designed for PCI local bus applications
with multiple supply voltages that require low power,
small size, high speed and high accuracy supply
monitoring.
For 3.3V and 5V supplies that are >500mV below spec or
for the condition when the 5V supply falls below the 3.3V
supply, the LTC1536 has a very fast response time capable
of meeting the PCI t
FAIL
timing specification. Tight 0.75%
threshold accuracy and glitch immunity ensure reliable
reset operation without false triggering.
The RST output is guaranteed to be in the correct state for
V
CC5
or V
CC3
down to 1V. The 100µA typical supply current
makes the LTC1536 ideal for power-conscious systems.
A manual pushbutton reset input provides the ability to
generate a very narrow “soft” reset pulse (100µs typ) or a
200ms reset pulse equivalent to a power-on reset. Both
SRST and RST outputs are open-drain and can be OR-tied
with other reset sources.
■
PCI-Based Systems
■
Desktop Computers
■
Notebook Computers
■
Intelligent Instruments
■
Portable Battery-Powered Equipment
■
Network Servers
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
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