systems with multiple supply voltages. Each supply moni-
tor has its own open-drain output for individual supply
monitoring. A common open-drain reset output remains
low until all three supplies have been in compliance for
200ms. Tight 1.5% accuracy specifications and glitch
immunity ensure reliable reset operation without false
triggering.
The LTC1728 is functionally identical to the LTC1727
without the individual monitor outputs.
The
RST
output is guaranteed to be in the correct state
for V
CC5
/V
CC25
/V
CC18
or V
CC3
down to 1V. The LTC1727/
LTC1728 may also be configured to monitor any one or
two V
CC
inputs instead of three, depending on system
requirements.
Very low (10µA typical) supply current makes the LTC1727/
LTC1728 ideal for power conscious systems.
The LTC1727 is available in an 8-lead MSOP or SO pack-
age and the LTC1728 is available in a 5-lead SOT-23
package.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
n
n
n
n
n
n
n
n
n
Monitors Three Inputs Simultaneously
LTC1727-5: 5V, 3.3V and ADJ
LTC1727-2.5: 2.5V, 3.3V and ADJ
LTC1728-5: 5V, 3.3V and ADJ
LTC1728-2.5: 2.5V, 3.3V and ADJ
LTC1728-1.8: 3V, 1.8V and ADJ
LTC1728-3.3: 3.3V, 1.8V and ADJ
±1.5% Threshold Accuracy Over Temperature
Very Low Supply Current: 10µA Typ
200ms Reset Time Delay
Active Low RESET Output
Power Supply Glitch Immunity
Guaranteed
RESET
for V
CC3
≥ 1V
or V
CC5
/V
CC25
/V
CC18
≥ 1V
LTC1727 Includes Monitor Output for Each Supply
LTC1727: 8-Lead MSOP and SO Packages
LTC1728: 5-Lead SOT-23 Package
APPLICATIONS
n
n
n
n
n
Desktop Computers
Notebook Computers
Intelligent Instruments
Portable Battery-Powered Equipment
Network Servers
TYPICAL APPLICATION
DC/DC
CONVERTER
3.3V
5V
1.8V
SYSTEM
LOGIC
Triple Supply Monitor with Power Good Output
(3.3V, 2.5V and Adjustable)
LTC1727-2.5
3.3V
2.5V
ADJUSTABLE
SUPPLY
R1
R2
V
CC3
COMP3
10k
10k
POWER
GOOD
SYSTEM
RESET
1727/28 TA08
V
CC3
V
CC5
V
CCA
RST
LTC1728-5
0.1µF
0.1µF
61.9k
1%
100k
1%
V
CC25
COMP25
V
CCA
GND
RST
COMPA
GND
1727/28 TA01
17278fd
For more information
www.linear.com/LTC1727
1
LTC1727/LTC1728
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
V
CC3
, V
CC5
/V
CC25
/V
CC18
, V
CCA ........................
– 0.3V to 7V
RST
............................................................. – 0.3V to 7V
COMPA, COMP3, COMP25/COMP5
(MS8 and SO-8 Only) ............................. – 0.3V to 7V
Operating Temperature Range
LTC1727/LTC1728E (Note 3) ............... – 40°C to 85°C
LTC1728H ..........................................– 40°C to 125°C
LTC1727I..............................................– 40°C to 85°C
Storage Temperature Range.................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
V
CC3
V
CC5
/V
CC25
V
CCA
GND
1
2
3
4
8
7
6
5
COMP3
COMP25/COMP5
RST
COMPA
V
CC3
1
V
CC5
/
2
V
CC25
V
CCA
3
GND 4
8
7
6
5
COMP3
COMP25/
COMP5
RST
COMPA
TOP VIEW
RST
1
GND 2
V
CCA
3
5 V
CC3
V
CC5
/
4 V
CC25
/
V
CC18
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 200°C/W
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 125°C,
θ
JA
= 250°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
LTHY
LTHX
172725
727I25
17275
172715
LTPH
LTIA
LTYP
LTHZ
LTHZ
PACKAGE DESCRIPTION
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SO
8-Lead Plastic SOT-23
8-Lead Plastic SOT-23
8-Lead Plastic SOT-23
8-Lead Plastic SOT-23
8-Lead Plastic SOT-23
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 125°C
LTC1727EMS8-2.5#PBF LTC1727EMS8-2.5#TRPBF
LTC1727EMS8-2.5#PBF LTC1727EMS8-2.5#TRPBF
LTC1727ES8-2.5#PBF
LTC1727IS8-2.5#PBF
LTC1727ES8-5#PBF
LTC1727IS8-5#PBF
LTC1728ES5-1.8#PBF
LTC1728ES5-2.5#PBF
LTC1728ES5-3.3#PBF
LTC1728ES5-5#PBF
LTC1728HS5-5#PBF
LTC1727ES8-2.5#TRPBF
LTC1727IS8-2.5#TRPBF
LTC1727ES8-5#TRPBF
LTC1727IS8-5#TRPBF
LTC1728ES5-1.8#TRPBF
LTC1728ES5-2.5#TRPBF
LTC1728ES5-3.3#TRPBF
LTC1728ES5-5#TRPBF
LTC1728HS5-5#TRPBF
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
17278fd
2
For more information
www.linear.com/LTC1727
LTC1727/LTC1728
All except LTC1728-1.8/LTC1728-3.3. The
l
denotes specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC3
= 3.3V, V
CC5
= 5V,
V
CC25
= 2.5V, V
CCA
= V
CC3
unless otherwise noted.
SYMBOL PARAMETER
V
RT3
V
RT5
V
RT25
V
RTA
V
CCOP
V
CCOPA
I
VCC3
I
VCC25
I
VCC5
I
VCCA
t
RST
t
UV
V
OL
Reset Threshold V
CC3
Reset Threshold V
CC5
Reset Threshold V
CC25
Reset Threshold V
CCA
V
CC3
, V
CC5
/V
CC25
Operating Voltage
V
CC3
, V
CC5
/V
CC25
Operating Voltage
V
CC3
Supply Current
V
CC25
Supply Current
V
CC5
Supply Current
V
CCA
Input Current
Reset Pulse Width
V
CC
Undervoltage Detect to
RST
or COMPX
Output Voltage Low,
RST,
COMPX
CONDITIONS
V
CC3
Input Threshold
V
CC5
Input Threshold (5V Version)
V
CC25
Input Threshold (2.5V Version)
V
CCA
Input Threshold
RST,
COMP3, COMP5, COMP25 in Correct Logic State
Minimum Supply Voltage to Guarantee COMPA
in Correct Logic State
V
CC5
/V
CC25
> V
CC3
V
CC5
/V
CC25
< V
CC3
, V
CC3
= 3.3V (Note 4)
V
CC25
< V
CC3
, V
CC25
= 2.5V (Note 4)
V
CC5
= 5V, V
CC3
< V
CC5
V
CCA
= 1V
–40°C < T
A
< 125°C
RST
Low with 10k Pull-Up to V
CC3
(Note 5)
–40°C < T
A
< 125°C
V
CC5
, V
CC25
, V
CC3
or V
CCA
Less Than Reset
Threshold V
RT
by More Than 1% (Note 5)
I
SINK
= 2.5mA, V
CC3
= 3V, V
CC5
/V
CC25
= 0V
I
SINK
= 100µA, V
CC3
= 1V, V
CC5
/V
CC25
= 0V
I
SINK
= 100µA, V
CC3
= 0V, V
CC5
/V
CC25
= 1V
I
SINK
= 100µA, V
CC3
= 1V, V
CC5
/V
CC25
= 1V
l
l
l
l
l
V
CC3
– 1
l
l
l
l
l
l
l
l
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
MIN
3.036
4.600
2.300
0.985
1
TYP
3.086
4.675
2.338
1.000
2
1
10
1
10
MAX UNITS
3.135
4.750
2.375
1.015
7
2.3
2
20
2
20
15
50
280
350
V
V
V
V
V
V
µA
µA
µA
µA
nA
nA
ms
ms
µs
0.4
0.3
0.3
0.3
V
V
V
V
V
–15
–20
140
140
0
0
200
110
0.15
0.05
0.05
0.05
V
OH
Output Voltage High,
RST,
COMPX (Note 6) I
SOURCE
= 1µA
LTC1727-5/LTC1728-5 Only
V
OVR
V
CC5
Reset Override Voltage (Note 7)
Override V
CC5
Ability to Assert
RST
V
CC3
±0.025
V
LTC1728-1.8 The
l
denotes specifications which apply over the full operating temperature range, otherwise specifications are at
T
A
= 25°C. V
CC3
= 3V, V
CC18
= 1.8V, V
CCA
= V
CC3
unless otherwise noted.
SYMBOL
V
RT3
V
RT18
V
RTA
V
CCOP
I
VCC3
I
VCC18
I
VCCA
t
RST
t
UV
V
OL
PARAMETER
Reset Threshold V
CC3
Reset Threshold V
CC18
Reset Threshold V
CCA
V
CC3
, V
CC18
Operating Voltage
V
CC3
Supply Current
V
CC18
Supply Current
V
CCA
Input Current
Reset Pulse Width
V
CC
Undervoltage Detect to
RST
Output Voltage Low,
RST
CONDITIONS
V
CC3
Input Threshold
V
CC18
Input Threshold
V
CCA
Input Threshold
RST
in Correct Logic State
V
CC18
> V
CC3
V
CC18
< V
CC3
, V
CC3
= 3V (Note 4)
V
CC18
< V
CC3
, V
CC18
= 1.8V (Note 4)
V
CCA
= 1V
RST
Low (Note 5)
V
CC18
, V
CC3
or V
CCA
Less Than Reset (Note 5)
Threshold V
RT
by More Than 1%
I
SINK
= 2.5mA, V
CC3
= 3V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 0V, V
CC18
= 1V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 1V
I
SOURCE
= 1µA (Note 6)
l
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
2.760
1.656
0.985
1
TYP
2.805
1.683
1.000
1
10
1
MAX
2.850
1.710
1.015
7
2
20
2
15
280
UNITS
V
V
V
V
µA
µA
µA
nA
ms
µs
–15
140
0
200
110
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
V
17278fd
V
OH
Output Voltage High,
RST
V
CC3
– 1
For more information
www.linear.com/LTC1727
3
LTC1727/LTC1728
ELECTRICAL CHARACTERISTICS
LTC1728-3.3 The
l
denotes specifications which apply over the full operating temperature range, otherwise specifications are at
T
A
= 25°C. V
CC3
= 3.3V, V
CC18
= 1.8V, V
CCA
= V
CC3
unless otherwise noted.
SYMBOL
V
RT3
V
RT18
V
RTA
V
CCOP
I
VCC3
I
VCC18
I
VCCA
t
RST
t
UV
V
OL
PARAMETER
Reset Threshold V
CC3
Reset Threshold V
CC18
Reset Threshold V
CCA
V
CC3
, V
CC18
Operating Voltage
V
CC3
Supply Current
V
CC18
Supply Current
V
CCA
Input Current
Reset Pulse Width
V
CC
Undervoltage Detect to
RST
Output Voltage Low,
RST
CONDITIONS
V
CC3
Input Threshold
V
CC18
Input Threshold
V
CCA
Input Threshold
RST
in Correct Logic State
V
CC18
> V
CC3
V
CC18
< V
CC3
, V
CC3
= 3.3V (Note 4)
V
CC18
< V
CC3
, V
CC18
= 1.8V (Note 4)
V
CCA
= 1V
RST
Low (Note 5)
V
CC18
, V
CC3
or V
CCA
Less Than Reset (Note 5)
Threshold V
RT
by More Than 1%
I
SINK
= 2.5mA, V
CC3
= 3.3V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 0V
I
SINK
= 100µA, V
CC3
= 0V, V
CC18
= 1V
I
SINK
= 100µA, V
CC3
= 1V, V
CC18
= 1V
I
SOURCE
= 1µA (Note 6)
l
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
3.036
1.656
0.985
1
TYP
3.086
1.683
1.000
1
10
1
MAX
3.135
1.710
1.015
7
2
20
2
15
280
UNITS
V
V
V
V
µA
µA
µA
nA
ms
µs
–15
140
0
200
110
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
V
V
OH
Output Voltage High,
RST
V
CC3
– 1
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 LTC1727E/LTC1728E are guaranteed to meet specified
performance from 0°C to 70°C and are designed, characterized and
assured to meet the extended temperature limits of –40°C to 85°C
but are not tested at these temperatures.
Note 4:
Both V
CC3
and V
CC5
/V
CC25
/V
CC18
can act as the supply depending
on which pin has the greatest potential.
Note 5:
Measured from when input passes through the input threshold
(V
RTX
) until
RST
or COMPX passes through 1.5V.
Note 6:
The output pins
RST
and COMPX have internal pull-ups to V
CC3
of
typically 6µA. However, external pull-up resistors may be used when faster
rise times are required or for V
OH
voltages greater than V
CC3
.
Note 7:
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
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Programming Basics
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