LTC1326/LTC1326-2.5
Micropower Precision
Triple Supply Monitors
FEATURES
■
DESCRIPTIO
■
■
■
■
■
■
■
■
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Simultaneously Monitors Three Supplies
LTC1326: 5V, 3.3V and ADJ
LTC1326-2.5: 2.5V, 3.3V and ADJ
Guaranteed Threshold Accuracy:
±0.75%
Low Supply Current: 20µA
Internal Reset Time Delay: 200ms
Manual Push-Button Reset Input
Active Low and Active High Reset Outputs
Active Low “Soft” Reset Output
Power Supply Glitch Immunity
Guaranteed RESET for V
CC3
≥
1V or V
CC5
≥
1V
or V
CC25
≥
1V
8-Pin SO and MSOP Packages
The LTC
®
1326/LTC1326-2.5 are triple supply monitors
intended for systems with multiple supply voltages. They
provide micropower operation, small size and high accu-
racy supply monitoring.
Tight 0.75% threshold accuracy and glitch immunity
ensure reliable reset operation without false triggering.
The 20µA typical supply current makes the LTC1326/
LTC1326-2.5 ideal for power-conscious systems.
The RST output is guaranteed to be in the correct state for
V
CC3
, V
CC5
or V
CC25
down to 1V. The LTC1326/LTC1326-2.5
can be configured to monitor one, two or three inputs,
depending on system requirements.
A manual push-button 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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 4843302.
APPLICATIO S
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Desktop Computers
Notebook Computers
Intelligent Instruments
Portable Battery-Powered Equipment
TYPICAL APPLICATIO
DC/DC
CONVERTER
2.5V
3.3V
V
CORE
RST Output Voltage vs Supply Voltage (LTC1326-2.5)
3.5
SYSTEM
LOGIC
RST OUTPUT VOLTAGE (V)
3.0
2.5
2.0
1.5
1.0
0.5
V
CC25
= V
CCA
= V
CC3
4.7k PULL-UP FROM RST TO V
CC3
T
A
= 25°C
0.1µF
V
CC25
V
CC3
V
CCA
LTC1326-2.5
RST
PBR
PUSH-BUTTON
RESET
GND
SRST
0
0
0.5
1.0
1.5 2.0
V
CC3
(V)
2.5
3.0
3.5
1326/2.5 TA01
U
1326/2.5 TA02
U
U
132625fc
1
LTC1326/LTC1326-2.5
ABSOLUTE
AXI U
RATI GS
Terminal Voltage
V
CC3
, V
CC5
, V
CC25
, V
CCA
......................... – 0.5V to 7V
RST, SRST ............................................ – 0.5V to 7V
RST ...................................... – 0.5V to (V
CC3
+ 0.3V)
PBR .......................................................... – 7V to 7V
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
CC3
V
CC5
V
CCA
GND
1
2
3
4
8
7
6
5
PBR
SRST
RST
RST
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 250°C/W
ORDER PART NUMBER
LTC1326CMS8
LTC1326IMS8
TOP VIEW
V
CC3
V
CC25
V
CCA
GND
1
2
3
4
MS8 PART NUMBER
LTBA
LTUH
8
7
6
5
PBR
SRST
RST
RST
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 250°C/W
ORDER PART NUMBER
LTC1326CMS8-2.5
LTC1326IMS8-2.5
MS8 PART NUMBER
LTEK
LTUJ
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult factory for parts specified with wider operating temperature ranges.
2
U
U
W
W W
U
W
(Notes 1, 2)
Operating Temperature Range
LTC1326C/LTC1326C-2.5 ....................... 0°C to 70°C
LTC1326I/LTC1326I-2.5 ..................... – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
V
CC3
1
V
CC5
2
V
CCA
3
GND 4
8 PBR
7 SRST
6 RST
5 RST
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER PART NUMBER
LTC1326CS8
LTC1326IS8
TOP VIEW
V
CC3
1
V
CC25
2
V
CCA
3
GND 4
S8 PART NUMBER
1326
1326I
8 PBR
7 SRST
6 RST
5 RST
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER PART NUMBER
LTC1326CS8-2.5
LTC1326IS8-2.5
S8 PART NUMBER
132625
326I25
132625fc
LTC1326/LTC1326-2.5
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC3
= 3.3V, V
CC5
= 5V (for LTC1326),V
CC25
= 2.5V (for LTC1326-2.5),
V
CCA
= V
CC3
, T
A
= 25°C unless otherwise noted.
SYMBOL
V
RT3
V
RT5
V
RT25
V
RTA
V
CC
I
VCC3
I
VCC5
I
VCC25
I
VCCA
t
RST
PARAMETER
Reset Threshold V
CC3
Reset Threshold V
CC5
(LTC1326)
Reset Threshold V
CC25
(LTC1326-2.5)
Reset Threshold V
CCA
V
CC3
Operating Voltage
V
CC3
Supply Current
V
CC5
Input Current (LTC1326)
V
CC25
Input Current (LTC1326-2.5)
V
CCA
Input Current
Reset Pulse Width
CONDITIONS
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
RST in Correct Logic State
PBR = V
CC3
V
CC5
= 5V
V
CC25
= 2.5V
V
CCA
= 1V
RST Low with 10kΩ Pull-Up to V
CC3
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
SRST Low with 10kΩ Pull-Up to V
CC3
V
CC25
, V
CC3
or V
CCA
Less Than Reset
Threshold V
RT
by More Than 1%
PBR = 0V
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
3.094
3.052
4.687
4.625
2.344
2.312
0.992
0.980
1
TYP
3.118
3.118
4.725
4.725
2.363
2.363
1.000
1.000
20
4
2.8
MAX
3.135
3.143
4.750
4.762
2.375
2.381
1.007
1.007
7
40
10
7
15
280
300
200
UNITS
V
V
V
V
V
V
V
V
V
µA
µA
µA
nA
ms
ms
µs
µs
–15
140
140
50
0
200
200
100
13
t
SRST
t
UV
I
PBR
Soft Reset Pulse Width
V
CC
Undervoltage Detect to RST
PBR Pull-Up Current
3
3
2
40
7
7
10
15
0.8
µA
µA
V
V
ns
V
IL
V
IH
t
PW
t
DB
t
PB
PBR, RST Input Low Voltage
PBR, RST Input High Voltage
PBR Min Pulse Width
PBR Debounce
PBR Assertion Time for Transition
from Soft to Hard Reset Mode
RST Output Voltage Low
Deassertion of PBR Input to SRST
Output (PBR Pulse Width = 1µs)
PBR Held Less Than V
IL
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
I
SINK
= 5mA
I
SINK
= 100µA,
0°C
≤
T
A
≤
70°C
I
SINK
= 100µA,
–40°C
≤
T
A
≤
85°C
I
SINK
= 100µA,
0°C
≤
T
A
≤
70°C
I
SINK
= 100µA,
–40°C
≤
T
A
≤
85°C
SRST Output Voltage Low
RST Output Voltage Low
I
SINK
= 2.5mA
I
SINK
= 2.5mA
V
CC3
= 1V, V
CC5
= 0V
V
CC3
= 0V, V
CC5
= 1V
V
CC3
= 1V, V
CC5
= 1V
V
CC3
= 1.1V, V
CC5
= 0V
V
CC3
= 0V, V
CC5
= 1.1V
V
CC3
= 1.1V, V
CC5
= 1.1V
V
CC3
= 1V, V
CC25
= 0V
V
CC3
= 0V, V
CC25
= 1V
V
CC3
= 1V, V
CC25
= 1V
V
CC3
= 1.1V, V
CC25
= 0V
V
CC3
= 0V, V
CC25
= 1.1V
V
CC3
= 1.1V, V
CC25
= 1.1V
●
20
35
ms
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
1.4
1.4
2.0
2.0
0.15
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.15
0.15
2.8
3.0
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
s
s
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
132625fc
V
OL
3
LTC1326/LTC1326-2.5
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. LTC1326 Only V
CC3
= 3.3V, V
CC5
= 5V, V
CCA
= V
CC3
, T
A
= 25°C unless
otherwise noted.
SYMBOL
V
OH
PARAMETER
RST Output Voltage High (Note 3)
SRST Output Voltage High (Note 3)
RST Output Voltage High
t
PHL
t
PLH
V
OVR
Prop Delay RST to RST
High Input to Low Output
Prop Delay RST to RST
Low Input to High Output
V
CC5
Reset Override Voltage
CONDITIONS
I
SOURCE
= 1µA
I
SOURCE
= 1µA
I
SOURCE
= 600µA
C
RST
= 20pF
C
RST
= 20pF
Override V
CC5
Ability to Assert RST (Note 4)
●
●
●
ELECTRICAL CHARACTERISTICS
MIN
V
CC3
– 1
V
CC3
– 1
V
CC3
– 1
TYP
MAX
UNITS
V
V
V
25
45
V
CC3
±0.025
ns
ns
V
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
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 6µA typ. However, external pull-up resistors may be used when
faster rise times are required.
Note 4:
The V
CC5
reset override voltage is valid for an operating range less
than approximately 4.15V. Above this point the override is turned off and
the V
CC5
pin functions normally.
TYPICAL PERFOR A CE CHARACTERISTICS
I
VCC3
vs Temperature
25
24
23
22
5.0
4.8
4.6
4.4
I
VCC25
(µA)
I
VCC5
(µA)
4.2
4.0
3.8
3.6
3.4
3.2
80
100
3.0
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
I
VCC3
(µA)
21
20
19
18
17
16
15
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
4
U W
1326/2.5 G01
I
VCC5
vs Temperature
(LTC1326)
3.00
2.95
2.90
2.85
2.80
2.75
2.70
2.65
2.60
2.55
I
VCC25
vs Temperature
(LTC1326-2.5)
2.50
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1326/2.5 G02
1326/2.5 G03
132625fc
LTC1326/LTC1326-2.5
TYPICAL PERFOR A CE CHARACTERISTICS
V
CCA
Input Current vs Input Voltage
3
2
INPUT CURRENT (nA)
T
A
= 25°C
TRANSIENT DURATION (µs)
TRANSIENT DURATION (µs)
1
0
–1
–2
–3
0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15 1.2
INPUT VOLTAGE (V)
1326/2.5 G04
V
CCA
Transient Immunity
40
35
TRANSIENT DURATION (µs)
35
V
CC5
THRESHOLD VOLTAGE, V
RT5
(V)
30
25
20
15
10
5
0
0.01
0.1
1
0.001
V
CCA
RESET COMPARATOR OVERDRIVE (V)
1326/2.5 G07
TRANSIENT DURATION (µs)
RESET OCCURS
ABOVE CURVE
T
A
= 25°C
V
CC25
Threshold Voltage
vs Temperature (LTC1326-2.5)
2.375
V
CC25
THRESHOLD VOLTAGE, V
RT25
(V)
2.370
3.130
3.125
3.120
3.115
3.110
3.105
3.100
– 60 – 40 – 20
V
CCA
THRESHOLD VOLTAGE, V
RTA
(V)
V
CC3
THRESHOLD VOLTAGE, V
RT3
(V)
2.365
2.360
2.355
2.350
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
U W
80
1326/2.5 G10
V
CC5
Transient Immunity
(LTC1326)
50
45
40
35
30
25
20
15
10
5
0
0.001
0.01
0.1
1
V
CC5
RESET COMPARATOR OVERDRIVE (V)
1326/2.5 G05
V
CC25
Transient Immunity
(LTC1326-2.5)
45
40
35
30
25
20
15
10
5
0
0.01
0.1
1
0.001
V
CC25
RESET COMPARATOR OVERDRIVE (V)
1326/2.5 G06
RESET OCCURS
ABOVE CURVE
T
A
= 25°C
RESET OCCURS
ABOVE CURVE
T
A
= 25°C
V
CC3
Transient Immunity
40
RESET OCCURS
ABOVE CURVE
T
A
= 25°C
4.750
4.745
4.740
4.735
4.730
4.725
4.720
4.715
4.710
4.705
V
CC5
Threshold Voltage
vs Temperature (LTC1326)
30
25
20
15
10
5
0
0.01
0.1
1
0.001
V
CC3
RESET COMPARATOR OVERDRIVE (V)
1326/2.5 G08
4.700
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1326/2.5 G09
V
CC3
Threshold Voltage
vs Temperature
3.135
1.005
1.004
1.003
1.002
1.001
1.000
0.999
0.998
0.997
0.996
V
CCA
Threshold Voltage
vs Temperature
100
0
20
40
60
80
100
TEMPERATURE (°C)
1326/2.5 G11
0.995
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1326/2.5 G12
132625fc
5
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