LT1910
Protected High Side
MOSFET Driver
FEATURES
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DESCRIPTION
The LT
®
1910 is a high side gate driver that allows the use of
low cost N-channel power MOSFETs for high side switching
applications. It contains a completely self-contained charge
pump to fully enhance an N-channel MOSFET switch with
no external components.
When the internal drain comparator senses that the switch
current has exceeded the preset level, the switch is turned
off and a fault flag is asserted. The switch remains off for
a period of time set by an external timing capacitor and
then automatically attempts to restart. If the fault still
exists, this cycle repeats until the fault is removed, thus
protecting the MOSFET. The fault flag becomes inactive
once the switch restarts successfully.
The LT1910 has been specifically designed for harsh
operating environments such as industrial, avionics and
automotive applications where poor supply regulation and/
or transients may be present. The device will not sustain
damage from supply transients of –15V to 60V.
The LT1910 is available in the SO-8 package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
8V to 48V Power Supply Range
Protected from –15V to 60V Supply Transients
Short-Circuit Protected
Automatic Restart Timer
Open-Collector Fault Flag
Fully Enhances N-Channel MOSFET Switches
Programmable Current Limit, Delay Time and
Autorestart Period
Voltage Limited Gate Drive
Defaults to Off State with Open Input
Available in SO-8 Package
APPLICATIONS
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Industrial Control
Avionics Systems
Automotive Switches
Stepper Motor and DC Motor Control
Electronic Circuit Breaker
TYPICAL APPLICATION
Fault Protected High Side Switch
5V
5.1k
FAULT
OUTPUT
OFF ON
LT1910
V
+
FAULT
IN
TIMER
SENSE
GATE
IRFZ34
GND
0.1μF
24V
0.50
0.45
0.01Ω
TOTAL DROP (V)
0.40
0.35
0.30
0.25
0.20
0.15
0.10
1910 TA01
Switch Drop vs Load Current
+
10μF
50V
LOAD
0.05
0
0
1
3
2
LOAD CURRENT (A)
4
5
1910 TA02
1910fa
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LT1910
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
GND 1
TIMER 2
FAULT
3
IN 4
8
7
6
5
V
+
NC
SENSE
GATE
Supply Voltage (Pin 8) ............................... –15V to 60V
Input Voltage (Pin 4) ..................... (GND – 0.3V) to 15V
GATE Voltage (Pin 5)................................................ 75V
SENSE Voltage (Pin 6) ........................................ V
+
±5V
FAULT
Voltage (Pin 3) .............................................. 36V
Current (Pins 1, 2, 4, 5, 6, 8) ................................ 40mA
Operating Temperature Range (Note 2)
LT1910E ............................................... –40°C to 85°C
LT1910I .............................................. –40°C to 125°C
Junction Temperature Range ................ –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER INFORMATION
LEAD FREE FINISH
LT1910ES8#PBF
LT1910IS8#PBF
LEAD BASED FINISH
LT1910ES8
LT1910IS8
TAPE AND REEL
LT1910ES8#TRPBF
LT1910IS8#TRPBF
TAPE AND REEL
LT1910ES8#TR
LT1910IS8#TR
PART MARKING
1910E
1910I
PART MARKING
1910E
1910I
PACKAGE DESCRIPTION
8-Lead Plastic SO
8-Lead Plastic SO
PACKAGE DESCRIPTION
8-Lead Plastic SO
8-Lead Plastic SO
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
ELECTRICAL CHARACTERISTICS
SYMBOL
I
S
ΔI
S(ON)
V
INH
V
INL
I
IN
C
IN
V
T(TH)
V
T(CL)
I
T
V
SENSE
PARAMETER
Supply Current (Off State)
Delta Supply Current (On State)
Input High Voltage
Input Low Voltage
Input Current
Input Capacitance (Note 3)
Timer Threshold Voltage
Timer Clamp Voltage
Timer Charge Current
Drain-Sense Threshold Voltage Temperature
Coefficient (Note 3)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 12V to 48V unless otherwise noted.
CONDITIONS
V
+
= 48V, V
IN
= 0.8V
V
IN
= 2V, Measure Increase in I
S
E-Grade
I-Grade
E-Grade
I-Grade
V
IN
= 2V
V
IN
= 5V
V
IN
= 2V, Adjust V
T
V
IN
= 0.8V
V
IN
= V
T
= 2V
l
l
l
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MIN
1.2
2
3.5
TYP
1.9
0.8
MAX
2.5
1.2
UNITS
mA
mA
V
V
0.8
0.7
15
55
2.6
3.2
9
50
30
110
5
2.9
3.5
14
65
0.33
3.2
3.8
20
80
50
185
V
V
μA
μA
pF
V
V
μA
mV
%/°C
1910fa
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LT1910
ELECTRICAL CHARACTERISTICS
SYMBOL
I
SENSE
PARAMETER
Drain Sense Input Current
V
GATE
– V
+
Gate Voltage Above Supply
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 12V to 48V unless otherwise noted.
CONDITIONS
V
+
= 48V, V
SENSE
= 65mV
V
+
= 8V
V
+
= 12V
V
+
= 24V
E-Grade
I-Grade
V
+
= 48V
E-Grade
I-Grade
V
F(TH)
FAULT
Output High Threshold Voltage
FAULT
Output Low Threshold Voltage
FAULT
Output Low Voltage
Turn-On Time
Turn-Off Time
Current Limit Turn-Off Time
V
IN
= 2V, I
F
= 1mA, Adjust V
T
I
F
= 1mA
V
+
= 24V, V
GATE
= 32V, C
GATE
= 1nF
V
+
= 24V, V
GATE
= 2V, C
GATE
= 1nF
V
+
= 24V, (V
+
– V
SENSE
)→0.1V, C
GATE
= 1nF
l
l
l
l
l
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MIN
4
7
10
10
10
10
3.1
3.0
100
TYP
0.5
4.5
8.5
12
12
12
12
3.4
3.3
0.07
220
25
20
MAX
1.5
6
10
14
15
14
15
3.7
3.6
0.4
400
100
50
UNITS
μA
V
V
V
V
V
V
V
V
V
μs
μs
μs
V
FOL
t
ON
t
OFF
t
OFF(CL)
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:
The LT1910E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LT1910I is guaranteed to meet
performance specifications over the full –40°C to 125°C operating
temperature range.
Note 3:
Guaranteed but not tested.
TYPICAL PERFORMANCE CHARACTERISTICS
Input Voltage vs Temperature
Supply Current vs Supply Voltage
3.6
3.4
3.2
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
0
10
30
40
20
SUPPLY VOLTAGE (V)
50
1910 G01
Supply Current vs Temperature
5.0
4.5
4.0
1.8
INPUT VOLTAGE (V)
1.6
1.4
V
INL
1.2
1.0
0.8
–50
V
+
= 48V
2.0
T
A
= 25°C
ON STATE
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
–50
–25
25
50
75
0
TEMPERATURE (°C)
100
125
OFF STATE
ON STATE
V
INH
OFF STATE
–25
75
0
25
50
TEMPERATURE (°C)
100
125
1910 G02
1910 G03
1910fa
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LT1910
TYPICAL PERFORMANCE CHARACTERISTICS
Input Current vs Temperature
200
180
TIMER THRESHOLD VOLTAGE (V)
160
INPUT CURRENT (μA)
140
120
100
80
60
40
20
0
–50
–25
25
50
75
0
TEMPERATURE (°C)
100
125
2.6
–50
–25
75
0
25
50
TEMPERATURE (°C)
100
125
3.2
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
V
IN
= 2V
V
IN
= 5V
3.1
3.0
2.9
2.8
2.7
3.2
Timer Threshold Voltage
vs Temperature
V
IN
= 2V
TIMER CLAMP VOLTAGE (V)
3.8
3.7
3.6
3.5
3.4
3.3
Timer Clamp Voltage
vs Temperature
V
IN
≤ 0.8V
1910 G04
1910 G05
1910 G06
MOSFET GATE VOLTAGE ABOVE V
+
(V
GATE
– V
+
) (V)
Timer Charge Current
vs Tempeature
20
TIMER CHARGE CURRENT (μA)
18
16
14
12
10
8
–50
DRAIN SENSE THRESHOLD VOLTAGE (mV)
V
IN
= V
T
= 2V
90
85
80
75
70
65
60
55
50
45
Drain Sense Threshold Voltage
vs Temperature
V
+
= 24V
MOSFET Gate Voltage Above V
+
(V
GATE
– V
+
) vs Supply Voltage
16
14
12
10
8
6
4
2
0
0
5
10 15 20 25 30 35 40 45 50
SUPPLY VOLTAGE (V)
LTC1266 • F04
T
A
= 25°C
T
A
= 125°C
T
A
= –40°C
–25
75
0
25
50
TEMPERATURE (°C)
100
125
40
–50
–25
25
50
75
0
TEMPERATURE (°C)
100
125
1910 G07
1910 G08
MOSFET Gate Drive Current
vs V
GATE
– V
+
100
MOSFET GATE DRIVE CURRENT (μA)
T
A
= 25°C
FAULT THRESHOLD VOLTAGE (V)
3.7
3.6
3.5
3.4
3.3
3.2
3.1
Fault Threshold Voltage
vs Temperature
FAULT OUTPUT LOW VOLTAGE (V)
V
IN
= 2V
I
F
= 1mA
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
–25
0
25
50
75
TEMPERATURE (°C)
100
125
Fault Output Low Voltage
vs Temperature
I
F
= 1mA
10
FAULT HIGH THRESHOLD
1
V
+
= 8V
V
+
= 12V V
+
≥ 24V
FAULT LOW THRESHOLD
0.1
0
2
4
6
8
10
+
(V)
V
GATE
– V
12
14
16
3.0
–50
0
–50
–25
25
50
75
0
TEMPERATURE ( C)
100
125
1910 G10
1910 G11
1910 G012
1910fa
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LT1910
TYPICAL PERFORMANCE CHARACTERISTICS
Turn-On Time vs Temperature
400
V
+
= 24V
V
GATE
= 32V
350 C
GATE
= 1nF
TURN-OFF TIME ( s)
TURN-ON TIME ( s)
300
250
200
150
100
–50
100
Turn-Off Time vs Temperature
AUTOMATIC RESTART PERIOD (ms)
V
+
= 24V
90 V
GATE
= 2V
C
GATE
= 1nF
80
70
60
50
40
30
20
10
CURRENT LIMIT
NORMAL
1000
Automatic Restart Period
vs Temperature
V
+
= 24V
C
T
= 3.3μF
C
T
= 1μF
100
C
T
= 0.33μF
C
T
= 0.1μF
10
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
1910 G15
–25
75
0
25
50
TEMPERATURE ( C)
100
125
0
–50
–25
25
50
75
0
TEMPERATURE ( C)
100
125
1910 G13
1910 G014
PIN FUNCTIONS
GND (Pin 1):
Common Ground.
TIMER (Pin 2):
A timing capacitor, C
T
, from the TIMER
pin to ground sets the restart time following overcurrent
detection. Upon detection of an overcurrent condition, C
T
is rapidly discharged to less than 1V and then recharged
by a 14μA nominal current source back to the 2.9V timer
threshold, whereupon the restart is attempted. When-
ever TIMER pulls below 2.9V, the GATE pin pulls low to
turn off the external switch. This cycle repeats until the
overcurrent condition goes away and the switch restarts
successfully. During normal operation the pin clamps at
3.5V nominal.
FAULT
(Pin 3):
The
FAULT
pin monitors the TIMER pin
voltage and indicates the overcurrent condition. Whenever
the TIMER pin is pulled below 3.3V at the onset of a cur-
rent limit condition, the
FAULT
pin pulls active LOW. The
FAULT
pin resets HIGH immediately when the TIMER pin
ramps above 3.4V during autorestart. The
FAULT
pin is an
open-collector output, thus requiring an external pull-up
resistor and is intended for logic interface. The resistor
should be selected with a typical 1mA pull-up at low status
and less than 2mA under worst-case conditions.
IN (Pin 4):
The IN pin threshold is TTL/CMOS compatible
and has approximately 200mV of hysteresis. When the
IN pin is pulled active HIGH above 2V, an internal charge
pump is activated to pull up the GATE pin. The IN pin can
be pulled as high as 15V regardless of whether the sup-
ply is on or off. If the IN pin is left open, an internal 75k
pull-down resistor pulls the pin below 0.8V to ensure that
the GATE pin is inactive LOW.
GATE (Pin 5):
The GATE pin drives the power MOSFET
gate. When the IN pin is greater than 2V, the GATE pin is
pumped approximately 12V above the supply. It has rela-
tively high impedance (the equivalence of a few hundred
kΩ) when pumped above the rail. Care should be taken
to minimize any loading by parasitic resistance to ground
or supply. The GATE pin pulls LOW when the TIMER pin
falls below 2.9V.
SENSE (Pin 6):
The SENSE pin connects to the input of
a supply-referenced comparator with a 65mV nominal
offset. When the SENSE pin is taken more than 65mV
below supply, the MOSFET gate is driven LOW and the
timing capacitor is discharged. The SENSE pin threshold
has a 0.33%/°C temperature coefficient (TC), which closely
matches the TC of the drain-sense resistor formed from
the copper trace of the PCB.
For loads requiring high inrush current, an RC timing delay
can be added between the drain-sense resistor and the
SENSE pin to ensure that the current-sense comparator
does not false trigger during start-up (see Applications
1910fa
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