1
LTC1536
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
0.1
µ
F
R
PU
RST
1536 TA01
PWR GOOD
0.1
µ
F
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
s
Simultaneously Monitors 5V, 3.3V and
Adjustable Inputs
s
Guaranteed Threshold Accuracy:
±
0.75%
s
Low Supply Current: 100
µ
A
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 V
CC3
≥
1V or V
CC5
≥
1V
s
Meets PCI t
FAIL
Timing Specifications Rev 2.1
s
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 100
µ
A 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 (100
µ
s 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.
s
PCI-Based Systems
s
Desktop Computers
s
Notebook Computers
s
Intelligent Instruments
s
Portable Battery-Powered Equipment
s
Network Servers
, LTC and LT are registered trademarks of Linear Technology Corporation.
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LTC1536
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
(Notes 1, 2)
Terminal Voltage
V
CC3
, V
CC5
, V
CCA
.................................... – 0.3V to 7V
RST, SRST ............................................ – 0.3V to 7V
RST ......................................... – 0.3V to V
CC3
+ 0.3V
PBR .......................................................... – 7V to 7V
Operating Temperature Range
LTC1536C .............................................. 0
°
C to 70
°
C
LTC1536I ............................................ – 40
°
C to 85
°
C
Storage Temperature Range ................ – 65
°
C to 150
°
C
Lead Temperature (Soldering, 10 sec)................. 300
°
C
W
U
U
PACKAGE/ORDER I FOR ATIO
ORDER
PART NUMBER
ORDER
PART NUMBER
LTC1536CMS8
1
2
3
4
8
7
6
5
TOP VIEW
S8 PACKAGE
8-LEAD PLASTIC SO
V
CC3
V
CC5
V
CCA
GND
PBR
SRST
RST
RST
T
JMAX
= 125
°
C,
θ
JA
= 150
°
C/ W
1
2
3
4
V
CC3
V
CC5
V
CCA
GND
8
7
6
5
PBR
SRST
RST
RST
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125
°
C,
θ
JA
= 160
°
C/ W
MS8 PART MARKING
LTBV
Consult factory for Military grade parts.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
RT3
Reset Threshold V
CC3
0
°
C
≤
T
A
≤
70
°
C
q
2.962
2.985
3.000
V
– 40
°
C
≤
T
A
≤
85
°
C
q
2.925
2.985
3.008
V
V
RT5
Reset Threshold V
CC5
0
°
C
≤
T
A
≤
70
°
C
q
4.687
4.725
4.750
V
– 40
°
C
≤
T
A
≤
85
°
C
q
4.625
4.725
4.762
V
V
RTA
Reset Threshold V
CCA
0
°
C
≤
T
A
≤
70
°
C
q
0.992
1.000
1.007
V
– 40
°
C
≤
T
A
≤
85
°
C
q
0.980
1.000
1.007
V
V
CC
V
CC3
or V
CC5
Operating Voltage
RST in Correct Logic State
q
1
7
V
I
VCC3
V
CC3
Supply Current
PBR = V
CC3
q
100
200
µ
A
I
VCC5
V
CC5
Input Current
V
CC5
= 5V
q
10
20
µ
A
I
VCCA
V
CCA
Input Current
V
CCA
= 1V, 0
°
C
≤
T
A
≤
70
°
C
q
– 5
0
5
nA
V
CCA
= 1V, – 40
°
C
≤
T
A
≤
85
°
C
q
– 15
0
15
nA
t
RST
Reset Pulse Width
RST Low with 10k
Ω
Pull-Up to V
CC3
0
°
C to 70
°
C
q
140
200
280
ms
– 40
°
C to 85
°
C
q
140
200
300
ms
t
SRST
Soft Reset Pulse Width
SRST Low with 10k
Ω
Pull-Up to V
CC3
q
50
100
200
µ
s
t
UV
V
CC
Undervoltage Detect to RST
V
CC5
, V
CC3
or V
CCA
Less Than Reset
13
µ
s
Threshold V
RT
by 1%
ELECTRICAL CHARACTERISTICS
V
CC3
= 3.3V, V
CC5
= 5V, V
CCA
= V
CC3
, T
A
= 25
°
C unless otherwise noted.
S8 PART MARKING
1536
1536I
LTC1536CS8
LTC1536IS8
3
LTC1536
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
PBR
PBR Pull-Up Current
PBR = 0V, 0
°
C
≤
T
A
≤
70
°
C
q
3
7
10
µ
A
PBR = 0V, – 40
°
C
≤
T
A
≤
85
°
C
q
3
7
15
µ
A
V
IL
PBR, RST Input Low Voltage
q
0.8
V
V
IH
PBR, RST Input High Voltage
q
2
V
t
PW
PBR Min Pulse Width
q
40
ns
t
DB
PBR Debounce
Deassertion of PBR Input to SRST
q
20
35
ms
Output (PBR Pulse Width = 1
µ
s)
t
PB
PBR Assertion Time for Transition
PBR Held Less Than V
IL
, 0
°
C to 70
°
C
q
1.4
2.0
2.8
s
from Soft to Hard Reset Mode
PBR Held Less Than V
IL
, – 40
°
C to 85
°
C
q
1.4
2.0
3.0
s
V
OL
RST Output Voltage Low
I
SINK
= 5mA
q
0.15
0.4
V
I
SINK
= 100
µ
A
V
CC3
= 1V, V
CC5
= 0V
q
0.05
0.4
V
0
°
C
≤
T
A
≤
70
°
C
V
CC3
= 0V, V
CC5
= 1V
q
0.05
0.4
V
V
CC3
= 1V, V
CC5
= 1V
q
0.05
0.4
V
I
SINK
= 100
µ
A
V
CC3
= 1.1V, V
CC5
= 0V
q
0.05
0.4
V
– 40
°
C
≤
T
A
≤
85
°
C
V
CC3
= 0V, V
CC5
= 1.1V
q
0.05
0.4
V
V
CC3
= 1.1V, V
CC5
= 1.1V
q
0.05
0.4
V
SRST Output Voltage Low
I
SINK
= 2.5mA
q
0.15
0.4
V
RST Output Voltage Low
I
SINK
= 2.5mA
q
0.15
0.4
V
V
OH
RST Output Voltage High (Note 3)
I
SOURCE
= 1
µ
A
q
V
CC3
– 1
V
SRST Output Voltage High (Note 3)
I
SOURCE
= 1
µ
A
q
V
CC3
– 1
V
RST Output Voltage High
I
SOURCE
= 600
µ
A
q
V
CC3
– 1
V
t
PHL
Propagation Delay RST to RST
C
RST
= 20pF
25
ns
High Input to Low Output
t
PLH
Propagation Delay RST to RST
C
RST
= 20pF
45
ns
Low Input to High Output
t
FAIL
V
CC5
or V
CC3
0.5V Undervoltage
V
CC5
Drops Below 4.25V or V
CC3
Drops
q
150
450
ns
to RST (Note 4)
Below 2.5V (Note 5)
t
PF
V
CC5
< (V
CC3
– 300mV) RST (Note 4)
V
CC5
Drops Below V
CC3
By 300mV
q
50
90
ns
(Note 6)
ELECTRICAL CHARACTERISTICS
V
CC3
= 3.3V, V
CC5
= 5V, V
CCA
= V
CC3
, T
A
= 25
°
C unless otherwise noted.
Note 4: Conforms to PCI Local Bus Specification Rev 2.1,
Sect. 4.3.2 for t
FAIL
.
Note 5: V
CC3
or V
CC5
falling at – 0.1V/
µ
s, time measured from
V
RTX
– 500mV to RST at 1.5V.
Note 6: V
CC5
falling from 5V to 3V in
≤
10ns, time measured from
V
CC5
= (V
CC3
– 300mV) to RST at 1.5V.
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: All voltage values are with respect to GND.
Note 3: The output pins SRST and RST have weak internal pull-ups to
V
CC3
of 6
µ
A. However, external pull-up resistors may be used when faster
rise times are required.
4
LTC1536
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
V
CCA
Input Current
vs Input Voltage
TEMPERATURE (
°
C)
– 45
0
I
VCC3
(
µ
A)
20
40
60
80
140
120
– 5
35
55
1536 G01
100
– 25
15
75
I
VCC3
vs Temperature
INPUT VOLTAGE (V)
0.8
– 3
INPUT CURRENT (nA)
– 2
– 1
0
1
0.9
1.0
1.1
1.2
1536 G03
2
3
0.85
0.95
1.05
1.15
T
A
= 25
°
C
TEMPERATURE (
°
C)
– 45
0
I
VCC5
(
µ
A)
2.5
5.0
7.5
10.0
20.0
15.0
– 5
35
55
1536 G02
17.5
12.5
– 25
15
75
I
VCC5
vs Temperature
TEMPERATURE (
°
C)
– 60
V
CC5
THRESHOLD VOLTAGE, V
RT5
(V)
4.750
4.745
4.740
4.735
4.730
4.725
4.720
4.715
4.710
4.705
4.700
– 20
20
40
1536 G04
– 40
0
60
80
100
V
CC5
Threshold Voltage
vs Temperature
V
CCA
Threshold Voltage
vs Temperature
TEMPERATURE (
°
C)
– 60
V
CCA
THRESHOLD VOLTAGE, V
RTA
(V)
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
0.997
0.996
0.995
– 20
20
40
1536 G06
– 40
0
60
80
100
V
CC3
Threshold Voltage
vs Temperature
TEMPERATURE (
°
C)
– 60
V
CC3
THRESHOLD VOLTAGE, V
RT3
(V)
60
1536 G05
– 20
20
– 40
80
0
40
100
3.010
3.005
3.000
2.995
2.990
2.985
2.980
2.975
2.970
2.965
2.960
PBR Assertion Time to Reset
vs Temperature
Reset Pulse Width
vs Temperature
TEMPERATURE (
°
C)
– 50
210
215
220
25
75
1536 G07
205
200
– 25
0
50
100
195
190
RESET PULSE WIDTH, t
RST
(ms)
225
“Soft” Reset Pulse Width
vs Temperature
TEMPERATURE (
°
C)
– 50
105.0
107.5
110.0
25
75
1536 G08
102.5
100.0
– 25
0
50
100
97.5
95.0
SOFT RESET PULSE WIDTH, t
SRST
(
µ
s)
112.5
TEMPERATURE (
°
C)
– 50
2.10
2.15
2.20
25
75
1536 G09
2.05
2.00
– 25
0
50
100
1.95
1.90
PBR ASSERTION TIME TO RESET, t
PB
(SEC)
2.25
5
LTC1536
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
V
CC3
Typical Transient Duration
vs Reset Comparator Overdrive
V
CCA
Typical Transient Duration
vs Reset Comparator Overdrive
V
CC3
RESET COMPARATOR OVERDRIVE, V
RT3
– V
CC3
(V)
0.001
20
TYPICAL TRANSIENT DURATION (
µ
s)
30
40
45
50
0.01
0.1
1
1536 G10
10
0
25
35
15
5
RESET OCCURS
ABOVE CURVE
V
CCA
RESET COMPARATOR OVERDRIVE, V
RTA
– V
CCA
(V)
0.001
20
TYPICAL TRANSIENT DURATION (
µ
s)
30
40
0.01
0.1
1
1536 G12
10
0
25
35
15
5
RESET OCCURS
ABOVE CURVE
V
CC5
Typical Transient Duration
vs Reset Comparator Overdrive
V
CC5
RESET COMPARATOR OVERDRIVE, V
RT5
– V
CC5
(V)
0.001
20
TYPICAL TRANSIENT DURATION (
µ
s)
30
40
45
0.01
0.1
1