LTC1727ES8-5#TR [Linear]
LTC1727 - Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C;型号: | LTC1727ES8-5#TR |
厂家: | Linear |
描述: | LTC1727 - Micropower Precision Triple Supply Monitors in 8-Lead MSOP and 5-Lead SOT-23 Packages; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C 光电二极管 |
文件: | 总16页 (文件大小:162K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC1727/LTC1728
Micropower Precision
Triple Supply Monitors
in 8-Lead MSOP and
5-Lead SOT-23 Packages
U
FEATURES
DESCRIPTIO
The LTC®1727 is a triple supply monitor intended for
systemswithmultiplesupplyvoltages. Eachsupplymoni-
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.
■
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 VCC3 ≥ 1V
or VCC5/VCC25/VCC18 ≥ 1V
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
CC5/VCC25/VCC18 or VCC3 down to 1V. The LTC1727/
LTC1728 may also be configured to monitor any one or
two VCC inputs instead of three, depending on system
requirements.
V
■
■
■
LTC1727 Includes Monitor Output for Each Supply
LTC1727: 8-Lead MSOP and SO Packages
LTC1728: 5-Lead SOT-23 Package
U
Verylow(10µAtypical)supplycurrentmakestheLTC1727/
LTC1728 ideal for power conscious systems.
APPLICATIO S
The LTC1727 is available in an 8-lead MSOP or SO
package and the LTC1728 is available in a 5-lead SOT-23
package.
■
Desktop Computers
■
Notebook Computers
■
Intelligent Instruments
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Portable Battery-Powered Equipment
■
Network Servers
U
TYPICAL APPLICATIO
3.3V
Triple Supply Monitor with Power Good Output
(3.3V, 2.5V and Adjustable)
5V
1.8V
DC/DC
CONVERTER
SYSTEM
LOGIC
R3
R4
5
4
3
1
LTC1727-2.5
V
V
V
RST
10k 10k
CC3
1
2
3
4
8
7
6
5
POWER
GOOD
3.3V
2.5V
V
V
V
COMP3
COMP25
RST
CC3
LTC1728-5
CC5
CC25
CCA
R1
61.9k
1%
0.1µF
R1
ADJUSTABLE
SUPPLY
SYSTEM
RESET
2
0.1µF
GND
CCA
R2
R2
GND COMPA
1727/28 TA01
100k
1%
1727/28 TA08
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1
LTC1727/LTC1728
W W W
U
ABSOLUTE AXI U RATI GS (Notes 1, 2)
Operating Temperature Range
VCC3, VCC5/VCC25/VCC18, VCCA ................... –0.3V to 7V
RST ........................................................... –0.3V to 7V
COMPA, COMP3, COMP25/COMP5
(Note 3) ............................................. – 40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................ 300°C
(MS8 and SO-8 Only) ............................ –0.3V to 7V
W
U
/O
PACKAGE RDER I FOR ATIO
TOP VIEW
TOP VIEW
TOP VIEW
V
1
2
3
4
8
7
6
5
COMP3
COMP25/
COMP5
CC3
/
V
1
2
3
4
8 COMP3
7 COMP25/COMP5
6 RST
V
CC25
RST 1
GND 2
5 V
CC3
CC5
CC3
V
/V
V
CC5 CC25
V
GND
V
4 V
V
/
CCA
V
RST
CC5
CC25
CC18
CCA
5 COMPA
V
CCA
3
/
GND
COMPA
MS8 PACKAGE
8-LEAD PLASTIC MSOP
S5 PACKAGE
5-LEAD PLASTIC SOT-23
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX = 125°C, θJA = 200°C/W
TJMAX = 125°C, θJA = 250°C/W
TJMAX = 125°C, θJA = 150°C/W
ORDER
MS8
ORDER
PART NUMBER
S8
ORDER
S5
PART NUMBER PART MARKING
PART MARKING PART NUMBER PART MARKING
LTC1727EMS8-2.5
LTC1727EMS8-5
LTHY
LTHX
LTC1727ES8-2.5
LTC1727IS8-2.5
LTC1727ES8-5
LTC1727IS8-5
172725
727I25
17275
LTC1728ES5-1.8
LTC1728ES5-2.5
LTC1728ES5-3.3
LTC1728ES5-5
LTPH
LTIA
LTYP
LTHZ
1727I5
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
All except LTC1728-1.8/LTC1728-3.3. The ● denotes specifications which
apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V,
VCC25 = 2.5V, VCCA = VCC3 unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
3.036
4.600
2.300
0.985
1
TYP
MAX
3.135
4.750
2.375
1.015
7
UNITS
V
V
V
V
V
V
Reset Threshold V
Reset Threshold V
Reset Threshold V
Reset Threshold V
V
V
V
V
Input Threshold
●
●
●
●
●
●
3.086
4.675
2.338
1.000
V
V
V
V
V
V
RT3
CC3
CC3
Input Threshold (5V Version)
RT5
CC5
CC5
Input Threshold (2.5V Version)
RT25
RTA
CC25
CC25
Input Threshold
CCA
CCA
V
V
, V /V Operating Voltage
CC3 CC5 CC25
RST, COMP3, COMP5, COMP25 in Correct Logic State
CCOP
CCOPA
, V /V
CC3 CC5 CC25
Operating Voltage
Minimum Supply Voltage to Guarantee COMPA
in Correct Logic State
2
2.3
I
V
Supply Current
V
V
/V
> V
CC3
●
●
1
10
2
20
µA
µA
VCC3
CC3
CC5 CC25
/V
< V , V
= 3.3V (Note 4)
CC5 CC25
CC3 CC3
I
I
I
t
t
V
V
V
Supply Current
V
V
V
< V , V = 2.5V (Note 4)
CC3 CC25
●
●
●
●
1
10
2
µA
µA
nA
ms
µs
VCC25
VCC5
VCCA
RST
CC25
CC25
Supply Current
Input Current
= 5V, V
< V
CC5
20
CC5
CCA
CC5
CCA
CC3
= 1V
–15
140
0
15
Reset Pulse Width
Undervoltage Detect to RST
RST Low with 10k Pull-Up to V (Note 5)
200
110
280
CC3
V
V
, V
, V
or V
Less Than Reset
CCA
UV
CC
CC5 CC25 CC3
or COMPX
Threshold V by More Than 1% (Note 5)
RT
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2
LTC1727/LTC1728
All except LTC1728-1.8/LTC1728-3.3. The ● denotes specifications which
ELECTRICAL CHARACTERISTICS
VCC25 = 2.5V, VCCA = VCC3 unless otherwise noted.
apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC3 = 3.3V, VCC5 = 5V,
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
Output Voltage Low, RST, COMPX
I
I
I
I
= 2.5mA, V
= 100µA, V
= 100µA, V
= 100µA, V
= 3V, V /V
CC5 CC25
= 0V
= 0V
= 1V
= 1V
●
●
●
●
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
OL
SINK
SINK
SINK
SINK
CC3
CC3
CC3
CC3
= 1V, V /V
CC5 CC25
= 0V, V /V
CC5 CC25
= 1V, V /V
CC5 CC25
V
Output Voltage High, RST, COMPX (Note 6)
I
= 1µA
●
V
CC3
– 1
V
OH
SOURCE
LTC1727-5/LTC1728-5 Only
Reset Override Voltage (Note 7)
V
V
Override V
Ability to Assert RST
V
±0.025
CC3
V
OVR
CC5
CC5
LTC1728-1.8 The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at
TA = 25°C. VCC3 = 3V, VCC18 = 1.8V, VCCA = VCC3 unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
2.760
1.656
0.985
1
TYP
MAX
2.850
1.710
1.015
7
UNITS
V
V
V
V
Reset Threshold V
Reset Threshold V
Reset Threshold V
V
V
V
Input Threshold
●
●
●
●
2.805
1.683
1.000
V
V
V
V
RT3
RT18
RTA
CC3
CC3
Input Threshold
CC18
CCA
CC18
Input Threshold
CCA
V
V
, V Operating Voltage
CC3 CC18
RST in Correct Logic State
CCOP
VCC3
I
Supply Current
V
V
> V
CC3
●
●
1
10
2
20
µA
µA
CC3
CC18
CC18
< V , V
= 3V (Note 4)
CC3 CC3
I
I
t
t
V
V
Supply Current
V
V
< V , V = 1.8V (Note 4)
CC3 CC18
●
●
●
1
2
µA
nA
ms
µs
VCC18
VCCA
RST
CC18
CC18
Input Current
= 1V
CCA
–15
140
0
15
CCA
Reset Pulse Width
Undervoltage Detect to RST
RST Low (Note 5)
, V or V Less Than Reset (Note 5)
CCA
200
110
280
V
V
UV
CC
CC18 CC3
Threshold V by More Than 1%
RT
V
Output Voltage Low, RST
I
I
I
I
= 2.5mA, V
= 100µA, V
= 100µA, V
= 100µA, V
= 3V, V
= 1V, V
= 0V, V
= 1V, V
= 0V
= 0V
= 1V
= 1V
●
●
●
●
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
OL
OH
SINK
SINK
SINK
SINK
CC3
CC3
CC3
CC3
CC18
CC18
CC18
CC18
V
Output Voltage High, RST
I
= 1µA (Note 6)
●
V
CC3
– 1
V
SOURCE
LTC1728-3.3 The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at
TA = 25°C. VCC3 = 3.3V, VCC18 = 1.8V, VCCA = VCC3 unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
3.036
1.656
0.985
1
TYP
MAX
3.135
1.710
1.015
7
UNITS
V
V
V
V
Reset Threshold V
Reset Threshold V
Reset Threshold V
V
V
V
Input Threshold
●
●
●
●
3.086
1.683
1.000
V
V
V
V
RT3
RT18
RTA
CC3
CC3
Input Threshold
CC18
CCA
CC18
Input Threshold
CCA
V
V
, V Operating Voltage
CC3 CC18
RST in Correct Logic State
CCOP
VCC3
I
Supply Current
V
V
> V
CC3
●
●
1
10
2
20
µA
µA
CC3
CC18
CC18
< V , V
= 3.3V (Note 4)
< V , V = 1.8V (Note 4)
CC3 CC18
CC3 CC3
I
I
t
t
V
V
Supply Current
V
V
●
●
●
1
2
µA
nA
ms
µs
VCC18
VCCA
RST
CC18
CC18
Input Current
= 1V
CCA
–15
140
0
15
CCA
Reset Pulse Width
Undervoltage Detect to RST
RST Low (Note 5)
, V or V Less Than Reset (Note 5)
CCA
200
110
280
V
V
UV
CC
CC18 CC3
Threshold V by More Than 1%
RT
V
V
Output Voltage Low, RST
I
I
I
I
= 2.5mA, V
= 100µA, V
= 100µA, V
= 100µA, V
= 3.3V, V = 0V
CC18
●
●
●
●
0.15
0.05
0.05
0.05
0.4
0.3
0.3
0.3
V
V
V
V
OL
OH
SINK
SINK
SINK
SINK
CC3
CC3
CC3
CC3
= 1V, V
= 0V, V
= 1V, V
= 0V
CC18
CC18
CC18
= 1V
= 1V
Output Voltage High, RST
I
= 1µA (Note 6)
●
V
CC3
– 1
V
SOURCE
17278fa
3
LTC1727/LTC1728
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
Note 5: Measured from when input passes through the input threshold
of the device may be impaired.
(V ) until RST or COMPX passes through 1.5V.
RTX
Note 2: All voltage values are with respect to GND.
Note 6: The output pins RST and COMPX have internal pull-ups to V
of
CC3
typically 6µA. However, external pull-up resistors may be used when faster
rise times are required or for V voltages greater than V
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.
.
CC3
OH
Note 7: The V
reset override voltage is valid for an operating range less
CC5
than approximately 4.15V. Above this point the override is turned off and
the V pin functions normally.
Note 4: Both V
and V /V
/V can act as the supply depending
CC5
CC3
CC5 CC25 CC18
on which pin has the greatest potential.
U W
TYPICAL PERFOR A CE CHARACTERISTICS
VCCA Threshold Voltage
vs Temperature
Typical Transient Duration
vs Comparator Overdrive
VCCA Input Current
vs Input Voltage
450
400
350
300
250
200
150
100
50
2.0
1.5
1.015
1.010
1.005
1.000
0.995
0.990
0.985
T = 25°C
A
T
A
= 25°C
RESET OCCURS
ABOVE CURVE
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
0
0.1
1
10
100
1
–60 –40 –20
0
20 40 60 80 100
0.80 0.85 0.90 0.95
1.05 1.10 1.15 1.20
TEMPERATURE (°C)
RESET COMPARATOR OVERDRIVE VOLTAGE (% OF V
)
INPUT VOLTAGE (V)
CC
1727/28 G03
1727/28 G01
1727/28 G02
Reset Pulse Width
vs Temperature
RST, COMPX ISINK
vs Supply Voltage
IVCC25 vs Temperature
(LTC1727-2.5/LT1728-2.5)
1.5
10
9
8
7
6
5
4
3
2
1
0
280
260
T
= 25°C
V
V
V
= 3.3V
A
CC3
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
= 2.5V
CC25
CCA
= 3.3V
V
= 0.4V
OL
240
220
200
180
160
V
= 0.2V
OL
140
–20
0
20 40
80 100
0
1
2
3
4
5
6
–60
60 80
–60 –40
60
–40 –20
20
TEMPERATURE (°C)
0
40
100
V
OR V
(V)
CC5
TEMPERATURE (°C)
CC3
1727/28 G05
1727/28 G06
1727/28 G04
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4
LTC1727/LTC1728
U W
TYPICAL PERFOR A CE CHARACTERISTICS
I
VCC3 vs Temperature (LTC1727-2.5/
IVCC3 vs Temperature
(LTC1727-5/LTC1728-5)
IVCC5 vs Temperature
(LTC1727-5/LTC1728-5)
LTC1728-2.5/LTC1728-3.3)
15
14
13
12
11
10
9
15
14
13
12
11
10
9
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
V
CC5
V
CC3
V
CCA
= 5V
= 3.3V
= 3.3V
V
V
V
= 5V
= 3.3V
= 3.3V
V
V
V
= 3.3V
= 2.5V
CC5
CC3
CCA
CC3
CC25
CCA
= 3.3V
8
8
7
7
6
6
5
5
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–60
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
20
TEMPERATURE (°C)
0
40
100
–40 –20
0
40
100
1727/28 G09
1727/28 G07
1727/28 G08
VCC3 Threshold Voltage
vs Temperature
(All But LTC1728-1.8)
VCC5 Threshold Voltage
vs Temperature
(LTC1727-5/LTC1728-5)
VCC25 Threshold Voltage
vs Temperature
(LTC1727-2.5/LTC1728-2.5)
2.3750
2.3675
2.3600
2.3525
2.3450
2.3375
2.3300
2.3225
2.3150
2.3075
2.3000
3.135
3.125
3.115
3.105
3.095
3.085
3.075
3.065
3.055
3.045
3.035
4.750
4.725
4.700
4.675
4.650
4.625
4.600
–60
20
TEMPERATURE (°C)
60 80
–60
20
TEMPERATURE (°C)
60 80
–40 –20
0
40
100
–40 –20
0
40
100
–60
0
20 40
–40 –20
60 80
100
TEMPERATURE (°C)
1727/28 G10
1727/28 G11
1727/28 G12
IVCC18 vs Temperature
(LTC1728-1.8/LTC1728-3.3)
IVCC3 vs Temperature
(LTC1728-1.8)
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
15
V
V
V
= 3V
V
V
V
= 3V
CC18
= 3V
CCA
CC3
CC3
14
13
12
11
10
9
= 1.8V
= 1.8V
CC18
= 3V
CCA
8
7
6
5
–60 –40 –20
TEMPERATURE (°C)
20 40 60
80
–60
20
TEMPERATURE (°C)
60 80
0
100
–40 –20
0
40
100
1727/28 G13
1727/28 G14
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5
LTC1727/LTC1728
U W
TYPICAL PERFOR A CE CHARACTERISTICS
V
CC18 Threshold Voltage
vs Temperature
VCC3 Threshold Voltage
vs Temperature (LTC1728-1.8)
(LTC1728-1.8/LTC1728-3.3)
2.845
2.835
2.825
2.815
2.805
2.795
2.785
2.775
2.765
1.710
1.700
1.690
1.680
1.670
1.660
1.650
40 60
TEMPERATURE (°C)
80
–60 –40 –20
0
20
80 100
–60
20
TEMPERATURE (°C)
60
–40 –20
0
40
100
1727/28 G15
1727/28 G16
U
U
U
PI FU CTIO S
(LTC1727/LTC1728)
VCC3 (Pin 1/Pin 5): 3.3V Sense Input and Power
Supply Pin. (3V Sense Input and Power Supply Pin for
LTC1728-1.8.) This pin provides power to the part
when the voltage on VCC3 is greater than the voltage on
VCC5/VCC25/VCC18. Bypass to ground with a ≥0.1µF
ceramic capacitor.
VCCA (Pin 3/Pin 3): 1V Sense, High Impedance Input. If
unused, it can be tied to either VCC3 or VCC5/VCC25/VCC18
.
GND (Pin 4/Pin 2): Ground.
COMPA(Pin5):VCCAComparatorOutputfortheLTC1727.
Active high, open-drain logic output with weak pull-up to
VCC3. Asserted when VCCA is above VRTA. Deasserted
when VCCA is below VRTA or if both the VCC3 and VCC5
supply pins are too low to power the internal bandgap
reference (typically <2.0V). Can be pulled greater than
VCC3 using an external pull-up.
VCC5 (Pin 2/Pin 4): 5V Sense Input and Power Supply
Pin. This pin is used on the LTC1727-5/LTC1728-5 to
provide power to the part when the voltage on VCC5 is
greater than the voltage on VCC3. Bypass to ground with
a ≥0.1µF ceramic capacitor.
RST (Pin 6/Pin 1): Reset Logic Output. Active low, open-
drain logic output with weak pull-up to VCC3. Can be pulled
up greater than VCC3 when interfacing to 5V logic. As-
sertedwhenoneorallofthesuppliesarebelowtripthresh-
olds and held for 200ms after all supplies become valid.
VCC25 (Pin 2/Pin 4): 2.5V Sense Input and Power Supply
Pin. ThispinisusedontheLTC1727-2.5/LTC1728-2.5to
provide power to the part when the voltage on VCC25 is
greater than the voltage on VCC3. Bypass to ground with
a ≥0.1µF ceramic capacitor.
COMP5 (Pin 7): VCC5 Comparator Output for the
LTC1727-5. Active high, open-drain logic output with
VCC18 (Pin 2/Pin 4): 1.8V Sense Input and Power Supply
Pin. ThispinisusedontheLTC1728-1.8/LTC1728-3.3to
provide power to the part when the voltage on VCC18 is
greater than the voltage on VCC3. Bypass to ground with
a ≥0.1µF ceramic capacitor.
weak pull-up to VCC3. Asserted when VCC5 is above VRT5
.
CanbepulledgreaterthanVCC3 usinganexternalpull-up.
17278fa
6
LTC1727/LTC1728
U
U
U
PI FU CTIO S
(LTC1727/LTC1728)
COMP25 (Pin 7): VCC25 Comparator Output for the COMP3(Pin8):VCC3 ComparatorOutputfortheLTC1727.
LTC1727-2.5. Active high, open-drain logic output with Active high, open-drain logic output with weak pull-up to
weak pull-up to VCC3. Asserted when VCC25 is above
VCC3. Asserted when VCC3 is above VRT3. Can be pulled
VRT25. Can be pulled greater than VCC3 using an external greater than VCC3 using an external pull-up.
pull-up.
W
BLOCK DIAGRA S
LTC1727-5/LTC1727-2.5
V
CC3
6µA
–
+
COMP3
8
7
6
5
V
1
CC3
V
CC3
POWER
DETECT
6µA
V
CC
INTERNAL
COMP25/
COMP5
V
CC25
/
CC5
2
V
–
+
V
CC3
6µA
200ms PULSE GENERATOR
–
+
RST
V
CCA
3
4
200ms
DELAY
GND
V
CC3
6µA
COMPA
BANDGAP
REFERENCE
1727 BD1
17278fa
7
LTC1727/LTC1728
W
BLOCK DIAGRA S
LTC1728-5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3
–
+
V
5
CC3
POWER
DETECT
V
INTERNAL
CC
V
CC3
V
/
/
CC5
6µA
V
4
CC25
V
CC18
–
+
200ms PULSE GENERATOR
1
RST
200ms
DELAY
–
+
V
3
2
CCA
GND
BANDGAP
REFERENCE
1727 BD2
W U
W
TI I G DIAGRA
VCC Monitor Timing
V
RTX
V
CCX
t
RST
t
UV
1.5V
RST
COMPX
1727 TD01
17278fa
8
LTC1727/LTC1728
U
W U U
APPLICATIO S I FOR ATIO
Supply Monitoring
Power-Down
The LTC1727 is a low power, high accuracy triple supply
monitoring circuit with three monitor outputs and a
200ms microprocessor reset output.
On power-down, once any of the VCC inputs drop below
itsthreshold,RSTisheldatalogiclow.Alogiclowof0.3V
is guaranteed until both VCC3 and VCC5/VCC25/VCC18 drop
below 1V.
The LTC1728 is a low power, high accuracy triple supply
monitoring circuit with a single 200ms microprocessor
reset output.
Glitch Immunity
The RST output of the LTC1727/LTC1728 have two forms
ofglitchimmunitybuiltin.First,theinputmonitorsrequire
the input voltage to transition at least 10% of the input
threshold (0.1 • VRTH) below the input threshold for
approximately 50µs in order to force the monitor output
low. The duration of the transition must be longer for
voltage transitions of lesser magnitude (see Figure 1).
Secondly, the reset pulse width of approximately 200ms
acts to debounce the RST output ensuring that the RST
output will always be in the correct state.
All three VCC inputs must be above predetermined thresh-
olds for reset not to be invoked. The LTC1727/LTC1728
willassertresetduringpower-up,power-downandbrown-
out conditions on any one or all of the VCC inputs.
Power Detect
The LTC1727/LTC1728 are powered from the 3.3V/3V
input pin (VCC3), the 1.8V input pin (VCC18), the 2.5V
input pin (VCC25) or the 5V input pin (VCC5), whichever
pin has the highest potential. This ensures the part pulls
the RST pin low as soon as either input pin is ≥1V.
The individual monitor outputs of the LTC1727 do not
have hysteresis and will track the monitor inputs relative
to the monitor’s input threshold (VRTA, VRT25, VRT3 and
VRT5). A very slow moving input voltage with ripple riding
on it may cause the individual monitor outputs (COMPA,
COMP25, COMP3 and COMP5) to toggle on the ripple as
the input voltage passes the input threshold. The slow
response time of the LTC1727’s input monitors has a
tendencytointegratesignalsontheinputsimprovingtheir
immunity to noise and ripple.
Power-Up
Upon power-up, either the VCC5/VCC25/VCC18 or VCC3 pin,
canpowerthepart. ThisensuresthatRSTwillbelowwhen
either VCC5/VCC25/VCC18 or VCC3 reaches 1V. As long as
any one of the VCC inputs is below its predetermined
threshold, RST will stay a logic low. Once all of the VCC
inputs rise above their thresholds, an internal timer is
started and RST is released after 200ms.
RST is reasserted whenever any one of the VCC inputs
drops below its predetermined threshold and remains
asserted until 200ms after all of the VCC inputs are above
their thresholds.
450
400
350
300
250
200
150
100
50
On the LTC1727, each of the comparator outputs will be
lowuntiltheVCC inputthatismonitoredbythatcompara-
tor rises above the appropriate predetermined threshold.
The COMP3, and COMP5/COMP25 outputs are guaran-
teed to be in the correct logic state for either VCC3 or
VCC5/VCC25 greater than 1V. The COMPA output requires
the internal bandgap reference to be valid before the
correct logic state can be output. Therefore, the COMPA
output will be held low until VCCA is above 1V and VCC3 or
VCC5/VCC25 is greater than 2V (typ).
0
0.1
1
10
100
RESET MONITOR OVERDRIVE VOLTAGE (% OF V
)
CC
1727/28 F01
Figure 1. Transient Duration vs Comparator Overdrive
17278fa
9
LTC1727/LTC1728
U
W U U
APPLICATIO S I FOR ATIO
When monitoring either 3.3V or 5V with VCC3 strapped to
VCC5 (see Figure 2), the part determines which is the
appropriate range. The part handles this situation as
shown in Figure 3. Above 1V and below VRT3, RST is held
low. From VRT3 to approximately 4.15V the part assumes
3.3V supply monitoring and RST is deasserted. Above
approximately 4.15V the part operates as a 5V monitor.
Inmostsystemsthe5Vsupplywillpassthroughthe3.1V
to 4.15V region in <200ms during power-up, and the
RST output will behave as desired. Table 1 summarizes
the state of RST at various operating voltages with
Override Functions (5V Versions Only)
The VCCA pin, if unused, can be tied to either VCC3 or VCC5
.
This is an obvious solution since the trip points for VCC3
andVCC5 willalwaysbegreaterthanthetrippointforVCCA
.
The VCC5 input trip point is disabled if its voltage is equal
to the voltage on VCC3 ±25mV and the voltage on VCC5 is
less than 4.15V. In this manner, the LTC1727-5/
LTC1728-5 will behave as a 3.3V monitor and VCC5 reset
capability will be disabled.
V
CC3 = VCC5.
The VCC5 trip point is reenabled when the voltage on VCC5
is equal to the voltage on VCC3 ±25mV and the two inputs
aregreaterthanapproximately4.15V. Inthismanner, the
part can function as a 5V monitor with the 3.3V monitor
disabled.
Table 1. Override Truth Table (VCC3 = VCC5
)
INPUTS (V = V = V
)
CC
RST
—
0
CC3
CC5
0V ≤ V ≤ 1V
CC
1V ≤ V ≤ V
CC
RT3
V
≤ V ≤ 4.15V
1
RT3
CC
4.15V ≤ V ≤ V
0
CC
RT5
V
≤ V
1
RT5
CC
V
CC
3.3V OR 5V
LTC1728-5
5
4
3
2
R1
10k
V
V
V
CC3
CC5
CCA
1
TO SYSTEM
RESET
RST
GND
1727/28 F02
Figure 2. Single Supply Monitor with Others Disabled
5
V
= V
= V
= 0V TO 5V
CCA
CC3
CC5
10k PULL-UP FROM RST TO V
CC3
4
3
2
1
0
0
1
2
3
4
5
SUPPLY VOLTAGE (V)
1727/28 F03
Figure 3. RST Voltage vs Supply Voltage
17278fa
10
LTC1727/LTC1728
U
W U U
APPLICATIO S I FOR ATIO
Figure 4 contains a simple circuit for 5V systems that can’t
risk the RST output going high in the 3.1V to 4.15V range
(possibly due to very slow rise time on the 5V supply).
Diode D1 powers the LTC1728-5 while dropping ≈0.6V
from the VCC5 pin to the VCC3 pin. This prevents the part’s
internal override circuit from being activated. Without the
override circuit active, the RST pin stays low until VCC5
reaches VRT5 4.675V. (See Figure 5.)
LTC1727-2.5/LTC1728-2.5/LTC1728-1.8/LTC1728-3.3
Override Functions
TheVCCA pin, ifunused, canbetiedtoeitherVCC3 orVCC25
VCC18. This is an obvious solution since the trip points for
CC3 and VCC25/VCC18 will always be greater than the trip
/
V
point for VCCA. Likewise, the VCC25/VCC18, if unused, can
be tied to VCC3. VCC3 must always be used. Tying VCC3 to
V
CC25/VCC18 and operating off of a 2.5V/1.8V supply will
result in the continuous assertion of RST.
5V
LTC1728-5
D1
5
4
3
2
R1
10k
V
V
V
CC3
CC5
CCA
1
TO SYSTEM
RESET
RST
GND
D1: MMBD914 OR EQUIVALENT
0.1µF
1727/28 F04
Figure 4. LTC1728-5 Monitoring a Single 5V
Supply. D1 Used to Avoid RST High Near 3.1V
to 4V (See Figure 3).
5
V
CC5
= V
CCA
= 0V TO 5V
10k PULL-UP FROM RST TO V
CC5
T
A
= 25°C
4
3
2
1
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
(V)
V
CC5
1727/28 F05
Figure 5. RST Output Voltage
Characteristics of the Circuit in Figure 4
17278fa
11
LTC1727/LTC1728
U
TYPICAL APPLICATIO S
Triple Supply Monitor (3.3V, 5V and Adjustable)
LTC1728-5
5
4
3
2
1
SYSTEM RESET
3.3V
5V
V
V
V
RST
CC3
CC5
CCA
ADJUSTABLE SUPPLY
OR DC/DC FEEDBACK
DIVIDER
R1*
R2*
GND
1727/28 TA03
*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL
COMBINATION OF R1 AND R2 ≤ 66.5k
Dual Supply Monitor (3.3V and 5V, Defeat VCCA Input)
LTC1728-5
5
4
3
2
1
3.3V
5V
V
V
V
RST
SYSTEM RESET
CC3
CC5
CCA
GND
1727/28 TA04
Dual Supply Monitor (3.3V or 5V Plus Adjustable)
3.3V OR
5V
LTC1728-5
10k
5
4
3
2
1
SYSTEM RESET
V
V
V
RST
CC3
CC5
CCA
R1*
ADJUSTABLE
SUPPLY
R2*
GND
1727/28 TA05
*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL
COMBINATION OF R1 AND R2 ≤ 66.5k
REFER TO LTC1728-5 OVERRIDE FUNCTIONS IN
THE APPLICATIONS INFORMATION SECTION
17278fa
12
LTC1727/LTC1728
U
TYPICAL APPLICATIO S
Dual Supply Monitor (3.3V Plus Adjustable)
3.3V
LTC1728-2.5
10k
5
4
3
2
1
V
V
V
RST
SYSTEM RESET
CC3
CC25
CCA
R1*
ADJUSTABLE
SUPPLY
R2*
GND
1727/28 TA06
*TO PRESERVE THRESHOLD ACCURACY, SET PARALLEL
COMBINATION OF R1 AND R2 ≤ 66.5k
Using VCCA Tied to DC/DC Feedback Divider
2.9V
35.7k
1%
LTC1728-5
LTC1435
V
5
4
3
2
1
6
SYSTEM RESET
3.3V
V
V
V
RST
CC3
CC5
CCA
OSENSE
2.8k
1%
5V
22.1k
1%
GND
ADJUSTABLE
RESET TRIP
THRESHOLD 2.74V
1727/28 TA07
17278fa
13
LTC1727/LTC1728
U
PACKAGE DESCRIPTIO
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
0.52
(.206)
REF
8
7 6
5
3.00 ± 0.102
(.118 ± .004)
NOTE 4
4.88 ± 0.1
(.192 ± .004)
0.889 ± 0.127
(.035 ± .005)
DETAIL “A”
0.254
(.010)
0° – 6° TYP
GAUGE PLANE
5.23
(.206)
MIN
3.2 – 3.45
(.126 – .136)
1
2
3
4
0.53 ± 0.015
(.021 ± .006)
1.10
(.043)
MAX
0.86
(.34)
REF
DETAIL “A”
0.18
(.077)
0.65
(.0256)
BSC
0.42 ± 0.04
(.0165 ± .0015)
TYP
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
0.13 ± 0.05
RECOMMENDED SOLDER PAD LAYOUT
(.005 ± .002)
0.65
(.0256)
BCS
MSOP (MS8) 1001
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
7
5
8
6
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 1298
17278fa
14
LTC1727/LTC1728
U
PACKAGE DESCRIPTIO
S5 Package
5-Lead Plastic SOT-23
(Reference LTC DWG # 05-08-1633)
(Reference LTC DWG # 05-08-1635)
2.80 – 3.10
(.110 – .118)
(NOTE 3)
SOT-23
(Original)
SOT-23
(ThinSOT)
.90 – 1.45
1.00 MAX
A
A1
A2
L
(.035 – .057)
(.039 MAX)
.00 – .15
(.00 – .006)
.01 – .10
(.0004 – .004)
2.60 – 3.00
1.50 – 1.75
(.102 – .118) (.059 – .069)
(NOTE 3)
.90 – 1.30
(.035 – .051)
.80 – .90
(.031 – .035)
.35 – .55
(.014 – .021)
.30 – .50 REF
(.012 – .019 REF)
PIN ONE
.95
(.037)
REF
.25 – .50
(.010 – .020)
(5PLCS, NOTE 2)
.20
(.008)
A2
A
DATUM ‘A’
1.90
(.074)
REF
L
.09 – .20
(.004 – .008)
(NOTE 2)
A1
S5 SOT-23 0401
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
MILLIMETERS
2. DIMENSIONS ARE IN
(INCHES)
3. DRAWING NOT TO SCALE
4. DIMENSIONS ARE INCLUSIVE OF PLATING
5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
6. MOLD FLASH SHALL NOT EXCEED .254mm
7. PACKAGE EIAJ REFERENCE IS:
SC-74A (EIAJ) FOR ORIGINAL
JEDEC MO-193 FOR THIN
17278fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC1727/LTC1728
U
TYPICAL APPLICATIO
Triple Supply Monitor with Manual Reset Button
12V (±5%)
V
TRIP
= 11.2V
(±0.17V)
5V 3.3V
5
4
3
1
2
V
V
V
RST
CC3
100nF
LTC1728-5
R1
CC5
R3*
10k
5%
1.07M
100nF
0.1%
GND
CCA
R2
105k
0.1%
MANUAL
1727/28 TA02
RESET BUTTON
(NORMALLY OPEN)
V
CCA
V
=
(R1 + R2)
TRIP
R2
V
V
TRIP
– 1
*OPTIONAL RESISTOR RECOMMENDED
TO EXTEND ESD TOLERANCE
R1 = R2
(
)
CCA
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC690
5V Supply Monitor, Watchdog Timer and Battery Backup
3.3V Supply Monitor, Watchdog Timer and Battery Backup
5V Supply Monitor and Watchdog Timer
4.65V Threshold
LTC694-3.3
LTC699
2.9V Threshold
4.65V Threshold
LTC1232
5V Supply Monitor, Watchdog Timer and Push-Button Reset
Micropower Precision Triple Supply Monitor for 5V, 3.3V and ADJ
Micropower Precision Triple Supply Monitor for 2.5V, 3.3V and ADJ
Micropower Quad Comparators with 1% Reference
4.37V/4.62V Threshold
LTC1326
4.725V, 3.118V, 1V Thresholds (±0.75%)
2.363V, 3.118V, 1V Thresholds (±0.75%)
LTC1326-2.5
LTC1443/LTC1444
LTC1445
LTC1443 Has 1.182V Reference, LTC1444/LTC1445
Have 1.221V Reference and Adjustable Hysteresis
LTC1536
Precision Triple Supply Monitor for PCI Applications
Nanopower Comparator with 2% Reference
Meets PCI t
Timing Specifications
FAIL
LTC1540
1.182V Reference, 300nA Supply Current, 8-Pin MSOP
Adjustable RESET and Watchdog Time Outs
Adjustable RESET and Watchdog Time Outs
Push-Pull RESET Output, SOT-23
LTC1726-2.5
LTC1726-5
LTC1985-1.8
Micropower Triple Supply Monitor for 2.5V, 3.3V and ADJ
Micropower Triple Supply Monitor for 5V, 3.3V and ADJ
Micropower Triple Supply Monitor for 3.3V, 1.8V and ADJ
17278fa
LT/TP 1101 1.5K REV A • PRINTED IN THE USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 1999
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