LTC1326/LTC1326-2.5
Micropower Precision
Triple Supply Monitors
FEATURES
s
DESCRIPTIO
s
s
s
s
s
s
s
s
s
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
s
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
3.0
RST OUTPUT VOLTAGE (V)
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
1
LTC1326/LTC1326-2.5
ABSOLUTE
(Notes 1, 2)
AXI U
RATI GS
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
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
ORDER
PART NUMBER
LTC1326CMS8
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 250°C/W
MS8 PART NUMBER
LTBA
ORDER
PART NUMBER
TOP VIEW
V
CC3
V
CC25
V
CCA
GND
1
2
3
4
8
7
6
5
PBR
SRST
RST
RST
LTC1326CMS8-2.5
MS8 PART MARKING
LTEK
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 250°C/W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
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
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
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
q
q
q
q
q
q
q
q
q
q
2
U
U
W
W W
U
W
TOP VIEW
V
CC3
1
V
CC5
2
V
CCA
3
GND 4
8 PBR
7 SRST
6 RST
5 RST
ORDER
PART NUMBER
LTC1326CS8
LTC1326IS8
S8 PART NUMBER
1326
1326I
ORDER
PART NUMBER
LTC1326CS8-2.5
LTC1326IS8-2.5
S8 PART MARKING
132625
326I25
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
TOP VIEW
V
CC3
1
V
CC25
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
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
MAX
3.143
3.143
4.762
4.762
2.381
2.381
1.007
1.007
7
40
UNITS
V
V
V
V
V
V
V
V
V
µA
LTC1326/LTC1326-2.5
ELECTRICAL CHARACTERISTICS
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
I
VCC5
I
VCC25
I
VCCA
PARAMETER
V
CC5
Input Current (LTC1326)
V
CC25
Input Current (LTC1326-2.5)
V
CCA
Input Current
CONDITIONS
V
CC5
= 5V
V
CC25
= 2.5V
V
CCA
= 1V
0°C
≤
T
A
≤
70°C
–40°C
≤
T
A
≤
85°C
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
q
q
q
q
q
q
q
q
q
q
q
q
MIN
TYP
4
2.8
MAX
7
7
5
15
280
300
200
UNITS
µA
µA
nA
nA
ms
ms
µs
µs
–5
–15
140
140
50
0
0
200
200
100
13
t
RST
Reset Pulse Width
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
I
SOURCE
= 1µA
I
SOURCE
= 1µA
I
SOURCE
= 600µA
C
RST
= 20pF
C
RST
= 20pF
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
q
20
35
ms
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
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
V
V
V
V
OL
V
OH
RST Output Voltage High (Note 3)
SRST Output Voltage High (Note 3)
RST Output Voltage High
V
CC3
– 1
V
CC3
– 1
V
CC3
– 1
25
45
t
PHL
t
PLH
Prop Delay RST to RST
High Input to Low Output
Prop Delay RST to RST
Low Input to High Output
ns
ns
3
LTC1326/LTC1326-2.5
ELECTRICAL CHARACTERISTICS
LTC1326 Only V
CC3
= 3.3V, V
CC5
= 5V, V
CCA
= V
CC3
, T
A
= 25°C unless otherwise noted.
SYMBOL
V
OVR
PARAMETER
V
CC5
Reset Override Voltage
CONDITIONS
Override V
CC5
Ability to Assert RST (Note 4)
MIN
TYP
V
CC3
±0.025
MAX
UNITS
V
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 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)
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
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
V
CC5
Transient Immunity
(LTC1326)
50
45
40
35
30
25
20
15
10
5
0
0.01
0.1
1
0.001
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
LTC1326/LTC1326-2.5
TYPICAL PERFOR A CE CHARACTERISTICS
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)
Reset Pulse Width
vs Temperature
225
SOFT RESET PULSE WIDTH, t
SRST
(µs)
RESET PULSE WIDTH, t
RST
(ms)
220
215
210
205
200
195
190
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
112.5
110.0
107.5
105.0
102.5
100.0
97.5
PBR ASSERTION TIME TO RESET, t
PB
(SEC)
U W
80
1326/2.5 G10
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
“Soft” Reset Pulse Width
vs Temperature
2.25
2.20
2.15
2.10
2.05
2.00
1.95
PBR Assertion Time to Reset
vs Temperature
80
100
95.0
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1.90
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1326/2.5 G13
1326/2.5 G14
1326/2.5 G15
5
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