LTC1536 Datasheet, PDF (1/12 Pages) Linear Technology – Precision Triple Supply Monitor for PCI Applications

LTC1536
Precision Triple Supply Monitor
for PCI Applications
FEATURES
s _{Simultaneously Monitors 5V, 3.3V and}
Adjustable Inputs
s _{Guaranteed Threshold Accuracy: ±0.75%}
s _{Low Supply Current: 100µA}
s _{Internal Reset Time Delay: 200ms}
s _{Manual Pushbutton Reset Input}
s _{Active Low and Active High Reset Outputs}
s _{Active Low “Soft” Reset Output}
s _{Power Supply Glitch Immunity}
s _{Guaranteed Reset for Either VCC3 ≥ 1V or VCC5 ≥ 1V}
s _{Meets PCI tFAIL Timing Specifications Rev 2.1}
s _{8-Pin SO and MSOP Packages}
U
APPLICATIO S
s _{PCI-Based Systems}
s _{Desktop Computers}
s _{Notebook Computers}
s _{Intelligent Instruments}
s _{Portable Battery-Powered Equipment}
s _{Network Servers}
DESCRIPTIO
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Motherboard PCI RST Generation
3.3V ± 0.3V
5V ± 5%
PWR GOOD
0.1µF
0.1µF
LTC1536
PUSHBUTTON
RESET
R_PU
1
8
V_CC3 PBR
2
7
V_CC5 SRST
3
6
RST
V_CCA RST
4
5
GND RST
R_PU SELECTED TO MEET RISE TIME
SLEW RATE REQUIREMENTS (1k MIN)
PCI
LOCAL
BUS
1536 TA01
Power Fail Waveform
5V Dropping Below 3.3V by 300mV
V_CC5 = 5V TO 3V STEP
V_CC3 = V_CCA = 3.3V
4.7k PULL-UP FROM
5
RST TO V_CC3
4
V_CC5
3
2
RST
1
0
TIME (20ns/DIV)
1536 TA02
1