cost N-channel FETs for high side switching applications.
An internal charge pump boosts the gate above the posi-
tive rail, fully enhancing an N-channel MOSFET with no
external components. Micropower operation, with 8µA
standby current and 85µA operating current, allows use
in virtually all systems with maximum efficiency.
Included on-chip is overcurrent sensing to provide au-
tomatic shutdown in case of short circuits. A time delay
can be added in series with the current sense to prevent
false triggering on high in-rush loads such as capacitors
and incandescent lamps.
The LTC1155 operates off of a 4.5V to 18V supply input and
safely drives the gates of virtually all FETs. The LTC1155
is well suited for low voltage (battery-powered) applica-
tions, particularly where micropower “sleep” operation
is required.
The LTC1155 is available in both 8-pin PDIP and 8-pin
SO packages.
All registered trademarks and trademarks are the property of their respective owners.
Fully Enhances N-Channel Power MOSFETs
8µA Standby Current
85µA ON Current
Short-Circuit Protection
Wide Power Supply Range: 4.5V to 18V
Controlled Switching ON and OFF Times
No External Charge Pump Components
Replaces P-Channel High Side MOSFETs
Compatible with Standard Logic Families
Available in 8-Pin SO Package
APPLICATIONS
n
n
n
n
n
n
n
Laptop Power Bus Switching
SCSI Termination Power Switching
Cellular Phone Power Management
P-Channel Switch Replacement
Relay and Solenoid Drivers
Low Frequency Half H-Bridge
Motor Speed and Torque Control
TYPICAL APPLICATION
Laptop Computer Power Bus Switch with Short-Circuit Protection
V
S
= 4.5V TO 5.5V
R
SEN
0.02
R
DLY
100k
C
DLY
0.1µF
DS1
G1
IN1
+
10µF
V
S
LTC1155
GND
DS2
G2
C
DLY
0.1µF
R
DLY
100k
R
SEN
0.02
Switch Voltage Drop
0.25
0.20
*IRLR034
5A
MAX
TTL, CMOS INPUT
POWER BUS
*IRLR034
5A
MAX
TTL, CMOS INPUT
VOLTAGE DROP (V)
0.15
IN2
0.10
0.05
µP
SYSTEM
GND
*SURFACE MOUNT
1155 TA01
DISK
DRIVE
DISPLAY
PRINTER,
ETC.
0.00
0
1
2
OUTPUT CURRENT (A)
3
1155 TA02
Rev. C
Document Feedback
For more information
www.analog.com
1
LTC1155
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage ..........................................................22V
Input Voltage........................(V
S
+0.3V) to (GND – 0.3V)
Gate Voltage ..........................(V
S
+24V) to (GND – 0.3V)
Current (Any Pin) ...................................................50mA
Storage Temperature Range.................. – 65°C to 150°C
Operating Temperature Range
LTC1155C ................................................ 0°C to 70°C
LTC1155I ............................................ – 40°C to 85°C
LTC1155M
(OBSOLETE)
................... – 55°C to 125°C
Lead Temperature Range (Soldering, 10 sec.) ...... 300°C
PIN CONFIGURATION
TOP VIEW
DS1 1
G1 2
GND 3
IN1 4
J8 PACKAGE
8-LEAD CERDIP
T
JMAX
= 150°C,
θ
JA
= 100°C/W (J8)
8 DS2
7 G2
6 V
S
5 IN2
DS1 1
G1 2
GND 3
IN1 4
N8 PACKAGE
8-LEAD PDIP
T
JMAX
= 100°C,
θ
JA
= 130°C/W (N8)
TOP VIEW
8 DS2
7 G2
6 V
S
5 IN2
DS1 1
G1 2
GND 3
IN1 4
TOP VIEW
8
7
6
5
DS2
G2
V
S
IN2
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 100°C,
θ
JA
= 150°C/W
OBSOLETE PACKAGE
ORDER INFORMATION
LEAD FREE FINISH
LTC1155CN8#PBF
LTC1155IN8#PBF
LTC1155CJ8#PBF
LTC1155MJ8#PBF
LTC1155CS8#PBF
LTC1155IS8#PBF
TAPE AND REEL
LTC1155CN8#TRPBF
LTC1155IN8#TRPBF
LTC1155CJ8#TRPBF
LTC1155MJ8#TRPBF
LTC1155CS8#TRPBF
LTC1155IS8#TRPBF
1155
1155I
PART MARKING*
PACKAGE DESCRIPTION
8-Lead PDIP
8-Lead PDIP
OBSOLETE PACKAGE
8-Lead CERDIP
8-Lead CERDIP
8-Lead Plastic SO
8-Lead Plastic SO
0°C to 70°C
–55°C to 125°C
0°C to 70°C
–40°C to 85°C
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
Rev. C
2
For more information
www.analog.com
LTC1155
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
= 4.5V to 18V, unless otherwise noted.
SYMBOL
V
S
I
Q
PARAMETER
Supply Voltage
Quiescent Current OFF
Quiescent Current ON
Quiescent Current ON
V
INH
V
INL
I
IN
C
IN
V
SEN
I
SEN
V
GATE
-V
S
t
ON
Input High Voltage
Input Low Voltage
Input Current
Input Capacitance
Drain Sense Threshold Voltage
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
l
LTC1155M (OBSOLETE)
MIN
TYP
MAX
4.5
8
85
180
l
l
LTC1155C/LTC1155I
MIN
TYP
MAX
4.5
8
85
180
2.0
18
20
120
400
0.8
±1.0
5
80
75
6.0
7.5
15
50
200
50
120
10
10
5
5
100
100
6.8
8.5
18
250
1100
180
450
36
26
16
16
120
125
±0.1
9.0
15
25
750
2000
500
1200
60
60
30
30
UNITS
V
µA
µA
µA
V
V
µA
pF
mV
mV
µA
V
V
V
µs
µs
µs
µs
µs
µs
µs
µs
18
20
120
400
0.8
±1.0
5
V
IN
= 0V, V
S
= 5V (Note 2)
V
S
= 5V, V
IN
= 5V (Note 3)
V
S
= 12V, V
IN
= 5V (Note 3)
2.0
0V < V
IN
< V
S
l
80
75
6.0
7.5
15
50
200
50
120
10
10
5
5
100
100
6.8
8.5
18
250
1100
180
450
36
26
16
16
120
125
±0.1
9.0
15
25
750
2000
500
1200
60
60
30
30
Drain Sense Input Current
Gate Voltage Above Supply
0V < V
SEN
< V
S
V
S
= 5V
V
S
= 6V
V
S
= 12V
V
S
= 5V, C
GATE
= 1000pF
Time for V
GATE
> V
S
+ 2V
Time for V
GATE
> V
S
+ 5V
V
S
= 12V, C
GATE
= 1000pF
Time for V
GATE
> V
S
+ 5V
Time for V
GATE
> V
S
+ 10V
l
l
l
Turn ON Time
t
OFF
Turn OFF Time
V
S
= 5V, C
GATE
= 1000pF
Time for V
GATE
< 1V
V
S
= 12V, C
GATE
= 1000pF
Time for V
GATE
< 1V
t
SC
Short-Circuit Turn OFF Time
V
S
= 5V, C
GATE
= 1000pF
Time for V
GATE
< 1V
V
S
= 12V, C
GATE
= 1000pF
Time for V
GATE
< 1V
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Quiescent current OFF is for both channels in OFF condition.
Note 3:
Quiescent current ON is per driver and is measured independently.
Rev. C
For more information
www.analog.com
3
LTC1155
TYPICAL PERFORMANCE CHARACTERISTICS
Standby Supply Current
50
45
40
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
35
30
25
20
15
10
5
0
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G01
Supply Current/Side (ON)
1000
900
800
700
V
GATE
– V
S
(V)
600
500
400
300
200
100
0
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G02
High Side Gate Voltage
24
22
20
18
16
14
12
10
8
6
4
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 TPC03
V
IN1
= V
IN2
= 0V
T
J
= 25°C
V
IN1
OR V
IN2
= 2V
T
J
= 25°C
Input Threshold Voltage
2.4
2.2
INPUT THRESHOLD VOLTAGE (V)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G04
Drain Sense Threshold Voltage
150
DRAIN SENSE THRESHOLD VOLTAGE (V)
140
130
120
V
GATE
(V)
110
100
90
80
70
60
50
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G05
Low Side Gate Voltage
30
27
24
21
18
15
12
9
6
3
0
0
2
8
6
4
SUPPLY VOLTAGE (V)
10
1155 G06
V
ON
V
OFF
Turn ON Time
1000
900
800
600
500
400
300
200
100
0
0
V
GS
= 2V
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G07
Turn OFF Time
50
45
40
30
25
20
15
10
5
0
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G08
Short-Circuit Turn OFF Delay Time
50
45
40
TURN-OFF TIME (µs)
35
30
25
20
15
10
5
0
0
15
5
10
SUPPLY VOLTAGE (V)
20
1155 G09
C
GATE
= 1000pF
C
GATE
= 100pF
TIME FOR V
GATE
< 1V
C
GATE
= 1000pF
TIME FOR V
GATE
< 1V
TURN OFF TIME (µs)
TURN-ON TIME (µs)
700
35
V
GS
= 5V
V
SEN
= V
S
–1V
NO EXTERNAL DELAY
Rev. C
4
For more information
www.analog.com
LTC1155
TYPICAL PERFORMANCE CHARACTERISTICS
Standby Supply Current
50
45
40
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
35
30
25
20
15
10
5
V
S
= 5V
0
25
50
75
TEMPERATURE (°C)
100
125
0
–50 – 25
V
S
= 18V
1000
900
800
INPUT THRESHOLD (V)
700
600
500
400
300
200
100
V
S
= 5V
V
S
= 12V
Supply Current Per Side (ON)
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0
25
50
75
TEMPERATURE (°C)
100
125
Input ON Threshold
V
S
= 5V
V
S
= 18V
0
– 50 –25
0.4
–50 – 25
0
25
50
75
TEMPERATURE (°C)
100
125
1155 G10
1155 G11
1155 G12
PIN FUNCTIONS
Input Pin
The LTC1155 logic input is a high impedance CMOS gate
and should be grounded when not in use. These input
pins have ESD protection diodes to ground and supply
and, therefore, should not be forced beyond the power
supply rails.
Gate Drive Pin
The gate drive pin is either driven to ground when the
switch is turned OFF or driven above the supply rail when
the switch is turned ON. This pin is a relatively high imped-
ance when driven above the rail (the equivalent of a few
hundred kΩ). Care should be taken to minimize any loading
of this pin by parasitic resistance to ground or supply.
Supply Pin
The supply pin of the LTC1155 serves two vital purposes.
The first is obvious: it powers the input, gate drive, regula-
tion and protection circuitry. The second purpose is less
obvious: it provides a Kelvin connection to the top of the
two drain sense resistors for the internal 100mV reference.
The supply pin should be connected directly to the power
supply source as close as possible to the top of the two
sense resistors.
The supply pin of the LTC1155 should not be forced below
ground as this may result in permanent damage to the
device. A 300Ω resistor should be inserted in series with
the ground pin if negative supply voltages are anticipated.
Drain Sense Pin
As noted previously, the drain sense pin is compared
against the supply pin voltage. If the voltage at this pin is
more than 100mV below the supply pin, the input latch will
be reset and the MOSFET gate will be quickly discharged.
Cycle the input to reset the short-circuit latch and turn the
MOSFET back on.
This pin is also a high impedance CMOS gate with ESD
protection and, therefore, should not be forced beyond the
power supply rails. To defeat the over current protection,
short the drain sense to supply.
Some loads, such as large supply capacitors, lamps or
motors require high inrush currents. An RC time delay
must be added between the sense resistor and the drain
sense pin to ensure that the drain sense circuitry does not
false trigger during start-up. This time constant can be
set from a few microseconds to many seconds. However,
very long delays may put the MOSFET in risk of being
destroyed by a short-circuit condition (see Applications
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Test/Measurement
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