LINER LTC1154 High side micropower mosfet driver Datasheet

LTC1154
High Side Micropower
MOSFET Driver
FEATURES
DESCRIPTION
n
The LTC®1154 single high side gate driver allows using low
cost N-channel FETs for high side switching applications. An
internal charge pump boosts the gate drive voltage above
the positive rail, fully enhancing an N-channel MOS switch
with no external components. Micropower operation, with
8μA standby current and 85μA operating current, allows
use in virtually all systems with maximum efficiency.
n
n
n
n
n
n
n
n
Fully Enhances N-Channel Power MOSFETs
8μA IQ Standby Current
85μA IQ ON Current
No External Charge Pump Capacitors
4.5V to 18V Supply Range
Short-Circuit Protection
Thermal Shutdown via PTC Thermistor
Status Output Indicates Shutdown
Available in 8-Pin SOIC and PDIP Packages
Included on chip is programmable overcurrent sensing.
A time delay can be added to prevent false triggering on
high inrush current loads. An active high shutdown input
is also provided and interfaces directly to a standard PTC
thermistor for thermal shutdown. An open-drain output
is provided to report switch status to the μP. An active
low enable input is provided to control multiple switches
in banks.
APPLICATIONS
n
n
n
n
n
n
Laptop Computer Power Switching
SCSI Termination Power Switching
Cellular Telephone Power Management
Battery Charging and Management
High Side Industrial and Automotive Switching
Stepper Motor and DC Motor Control
The LTC1154 is available in both 8-pin DIP and 8-pin SOIC
packages.
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.
TYPICAL APPLICATION
Ultralow Voltage Drop High Side Switch with
Short-Circuit Protection
Standby Supply Current
50
5V
VIN = 0V
TJ = 25°C
45
0.036Ω*
IN
0.1μF**
μP
200k**
EN
DS
LTC1154
STATUS
GND
IRLR024
G
SD
40
2.7A MAX
VS
SUPPLY CURRENT (μA)
51k
35
30
25
20
15
10
5V
LOAD
5
0
ALL COMPONENTS SHOWN ARE SURFACE MOUNT.
* IMS026 INTERNATIONAL MANUFACTURING SERVICE, INC. (401) 683-9700
** NOT REQUIRED IF LOAD IS RESISTIVE OR INDUCTIVE.
LTC1154 • TA01
0
5
10
15
SUPPLY VOLTAGE (V)
20
LTC1153 • TA02
1154fb
1
LTC1154
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage ..........................................................22V
Input Voltage.......................(VS + 0.3V) to (GND – 0.3V)
Enable Input Voltage ...........(VS + 0.3V) to (GND – 0.3V)
Gate Voltage .........................(VS + 24V) to (GND – 0.3V)
Status Output Voltage ...............................................15V
Current (Any Pin) ...................................................50mA
Operating Temperature
LTC1154C ................................................ 0°C to 70°C
LTC1154H .......................................... –40°C to 150°C
Storage Temperature Range....................–65°c to 150°C
Lead Temperature (Soldering, 10 sec.) ................. 300°C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
IN 1
8
VS
IN 1
8
VS
ENABLE 2
7
DRAIN SENSE
ENABLE 2
7
DRAIN SENSE
STATUS 3
6
GATE
STATUS 3
6
GATE
GND 4
5
SHUTDOWN
GND 4
5
SHUTDOWN
S8 PACKAGE
8-LEAD PLASTIC SOIC
TJMAX = 100°C, θJA = 150°C/W
N8 PACKAGE
8-LEAD PLASTIC DIP
TJMAX = 100°C, θJA = 130°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1154CN8#PBF
LTC1154CN8#TRPBF
8-Lead Plastic DIP
0°C to 70°C
LTC1154CS8#PBF
LTC1154CS8#TRPBF
1154
8-Lead Plastic SIOC
0°C to 70°C
LTC1154HS8#PBF
LTC1154HS8#TRPBF
1154H
8-Lead Plastic SIOC
–40°C to 150°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1154CN8
LTC1154CN8#TR
8-Lead Plastic DIP
0°C to 70°C
LTC1154CS8
LTC1154CS8#TR
1154
8-Lead Plastic SIOC
0°C to 70°C
LTC1154HS8
LTC1154HS8#TR
1154H
8-Lead Plastic SIOC
–40°C to 150°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
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 4.5V to 18V, TA = 25°C, VEN = 0V, VSD = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
l
TYP
MAX
VS
Supply Voltage
18
V
IQ
Quiescent Current OFF
VS = 5V, VIN = 0V
8
20
μA
Quiescent Current ON
VS = 5V, VIN = 5V
85
120
μA
Quiescent Current ON
VS = 12V, VIN = 5V
180
400
μA
VINH
Input High Voltage
l
4.5
UNITS
2
V
1154fb
2
LTC1154
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 4.5V to 18V, TA = 25°C, VEN = 0V, VSD = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
MAX
UNITS
0.8
V
l
±1
μA
VINL
Input Low Voltage
IIN
Input Current
CIN
Input Capacitance
VENH
ENABLE Input High Voltage
l
VENL
ENABLE Input Low Voltage
l
l
0V < VIN < VS
TYP
l
3.5
5
pF
2.6
V
1
0.6
V
±1
μA
IEN
ENABLE Input Current
VSDH
Shutdown Input High Voltage
l
VSDL
Shutdown Input Low Voltage
l
0.8
V
ISD
Shutdown Input Current
l
±1
μA
VSEN
Drain Sense Threshold Voltage
120
125
mV
mV
ISEN
Drain Sense Input Current
0V < VSEN < VS
l
±0.1
μA
VGATE – VS
Gate Voltage Above Supply
VS = 5V
VS = 6V
VS = 12V
l
l
l
7
8.3
18
9
15
25
V
V
V
VSTAT
Status Output Low Voltage
ISTAT = 400μA
l
0.05
0.4
V
ISTAT
Status Output Leakage Current
VSTAT = 12V
l
1
μA
tON
Turn-ON Time
VS = 5V, CGATE = 1000pF
Time for VGATE > VS + 2V
Time for VGATE > VS + 5V
30
100
110
450
300
1000
μs
μs
VS = 12V, CGATE = 1000pF
Time for VGATE > VS + 5V
Time for VGATE > VS + 10V
20
50
80
160
200
500
μs
μs
VS = 5V, CGATE = 1000pF, Time for VGATE < 1V
10
36
60
μs
VS = 12V, CGATE = 1000pF, Time for VGATE < 1V
10
28
60
μs
VS = 5V, CGATE = 1000pF, Time for VGATE < 1V
5
25
40
μs
VS = 12V, CGATE = 1000pF, Time for VGATE < 1V
5
23
40
μs
VS = 5V, CGATE = 1000pF, Time for VGATE < 1V
17
40
μs
VS = 12V, CGATE = 1000pF, Time for VGATE < 1V
13
35
μs
tOFF
tSC
tSD
Turn-OFF Time
Short-Circuit Turn-OFF Time
Shutdown Turn-OFF Time
0V < VIN < VS
0V < VIN < VS
l
2
80
75
6
7.5
15
V
100
100
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.
1154fb
3
LTC1154
TYPICAL PERFORMANCE CHARACTERISTICS
Standby Supply Current
Supply Current ON
50
VIN = 0V
TA = 25°C
45
TA = 25°C
900
22
20
800
35
30
25
20
18
700
VGATE – VS (V)
SUPPLY CURRENT (μA)
40
SUPPLY CURRENT (μA)
High Side Gate Voltage
24
1000
600
500
400
16
14
12
300
10
10
200
8
5
100
6
15
0
0
0
0
5
10
15
SUPPLY VOLTAGE (V)
20
0
5
LTC1154 • TPC01
5
0
20
10
15
SUPPLY VOLTAGE (V)
20
10
15
SUPPLY VOLTAGE (V)
LTC1154 • TPC02
LTC1154 • TPC03
Input Threshold Voltage
Drain Sense Threshold Voltage
INPUT THRESHOLD VOLTAGE (V)
2.2
2.0
1.8
VON
1.6
VOFF
1.4
1.2
1.0
0.8
0.6
0.4
0
5
15
10
SUPPLY VOLTAGE (V)
30
140
27
130
24
120
21
110
18
100
90
70
6
60
3
0
0
5
15
10
SUPPLY VOLTAGE (V)
20
1000
VGS = 5V
300
200
VGS = 2V
100
0
0
5
10
15
SUPPLY VOLTAGE (V)
20
LTC1153 • TPC07
40
TURN-OFF TIME (μs)
400
10
CGATE = 1000pF
TIME FOR VGATE < 1V
VSEN = VS – 1V
NO EXTERNAL DELAY
45
40
TURN-OFF TIME (μs)
800
8
50
CGATE = 1000pF
TIME FOR VGATE < 1V
45
500
4
6
SUPPLY VOLTAGE (V)
Short-Circuit Turn-OFF Delay
Time
50
CGATE = 1000pF
600
2
LTC1154 • TPC06
Turn-OFF Time
700
0
-5$t51$
Turn-ON Time
900
12
9
50
20
15
80
LTC1154 • TPC04
TURN-ON TIME (μs)
Low Side Gate Voltage
150
VGATE (V)
DRAIN SENSE THRESHOLD VOLTAGE (mV)
2.4
35
30
25
20
15
35
30
25
20
15
10
10
5
5
0
0
0
5
10
15
SUPPLY VOLTAGE (V)
20
LTC1154 • TPC08
0
5
10
15
SUPPLY VOLTAGE (V)
20
LTC1154 • TPC09
1154fb
4
LTC1154
TYPICAL PERFORMANCE CHARACTERISTICS
Standby Supply Current
Supply Current ON
50
900
VIN = 5V
VEN = 0V
2.2
800
SUPPLY CURRENT (μA)
35
30
25
20
15
VS = 18V
10
700
600
500
400
VS = 12V
300
200
5
100
VS = 5V
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
VS = 5V
100
0
–50
125
–25
2.2
4.5
ENABLE THRESHOLD VOLTAGE (V)
5.0
2.0
1.8
1.6
VS = 5V
VS = 18V
0.8
0.6
0.4
–50
25
0
50
75
TEMPERATURE (°C)
25
0
50
75
TEMPERATURE (°C)
100
125
VS = 5V
1.2
VS = 18V
1.0
0.8
100
125
–25
25
0
50
75
TEMPERATURE (°C)
125
LTC1154 • TPC12
Gate Drive Current
VS = 12V
TA = 25°C
4.0
3.5
DISABLE
3.0
2.5
2.0
1.5
1.0
0
–50
100
1000
0.5
–25
1.4
ENABLE Threshold Voltage
Shutdown Threshold Voltage
1.0
1.6
LTC1154 • TPC11
2.4
1.2
1.8
0.6
LTC1154 • TPC10
1.4
2.0
0.4
–50
GATE DRIVE CURRENT (μA)
SUPPLY CURRENT (μA)
40
2.4
INPUT THRESHOLD VOLTAGE (V)
VIN = 0V
VEN = 0V
45
SHUTDOWN THRESHOLD VOLTAGE (V)
Input ON Threshold Voltage
1000
100
VS = 18V
VS = 12V
10
VS = 5V
1
ENABLE
–25
25
0
50
75
TEMPERATURE (°C)
LTC1154 • TPC13
100
125
0.1
0
4
8
12
16
GATE VOLTAGE ABOVE SUPPLY (V)
20
LTC1154 • TPC14
LTC1154 • TPC15
PIN FUNCTIONS
Input and Shutdown Pins
ENABLE Input Pin
The LTC1154 input pin is active high and activates all of the
protection and charge pump circuitry when switched ON.
The shutdown pin is designed to immediately disable the
switch if a secondary fault condition (over temperature,
etc.) is detected. The LTC1154 logic and shutdown inputs
are high impedance CMOS gates with ESD protection
diodes to ground and supply and therefore should not be
forced beyond the power supply rails. The shutdown pin
should be connected to ground when not in use.
The ENABLE input can be used to enable a number of
LTC1154 high side switches in banks or to provide a secondary means of control. It can also act as an inverting
input. The ENABLE input is a high impedance CMOS gate
with ESD clamp diodes to ground and supply and therefore
should not be forced beyond the power supply rails. This
pin should be grounded when not in use.
1154fb
5
LTC1154
PIN FUNCTIONS
Gate Drive Pin
Drain Sense 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 impedance 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.
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,
or ENABLE input, to reset the short-circuit latch and turn
the MOSFET back on.
Supply Pin
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 overcurrent protection,
short the drain sense to supply.
The supply pin of the LTC1154 serves two vital purposes.
The first is obvious: it powers the input, gate drive, regulation and protection circuitry. The second purpose is less
obvious: it provides a Kelvin connection to the top of the
drain sense resistor for the internal 100mV reference.
The LTC1154 is designed to be continuously powered so
that the gate of the MOSFET is actively driven at all times.
If it is necessary to remove power from the supply pin
and then re-apply it, the input pin (or enable pin) should
be cycled a few milliseconds after the power is re-applied
to reset the input latch and protection circuitry. Also, the
input and enable pins should be isolated with 10k resistors
to limit the current flowing through the ESD protection
diodes to the supply pin.
The supply pin of the LTC1154 should never 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 voltage transients
are anticipated.
Some loads, such as large supply capacitors, lamps, or
motors require high inrush currents. An RC time delay
can 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
Information Section).
Status Pin
The status pin is an open-drain output which is driven
low whenever a fault condition is detected. A 51k pull-up
resistor should be connected between this output and a
logic supply. The status pins of multiple LTC1154s can be
OR’d together if independent fault sensing is not required.
No connection is required to this pin when not in use.
BLOCK DIAGRAM
DRAIN
SENSE
ANALOG SECTION
VS
LOW STANDBY
CURRENT
REGULATOR
SHUTDOWN
TTL-TO-CMOS
CONVERTER
10μs
DELAY
COMP
100mV
REFERENCE
SHUTDOWN
GATE CHARGE
AND DISCHARGE
CONTROL LOGIC
ANALOG
GATE
DIGITAL
R
INPUT
ENABLE
STATUS
TTL-TO-CMOS
CONVERTER
VOLTAGE
REGULATORS
INPUT
LATCH
ONE
SHOT
S
OSCILLATOR
AND CHARGE
PUMP
FAST/SLOW
GATE CHARGE
LOGIC
GND
FAULT DETECTION
AND STATUS
OUTPUT DRIVER
LTC1154 • BD01
1154fb
6
LTC1154
TRUTH TABLE
INPUTS
OUTPUTS
SWITCH
CONDITION
IN
EN
SD
X
H
X
L
H
SWITCH OFF
L
X
X
L
H
SWITCH OFF
H
L
L
H
H
SWITCH ON
H
L
L
L
L
SWITCH LATCHED OFF
(OVER CURRENT)
H
L
L
L
SWITCH LATCHED OFF
(SHUTDOWN)
L = LOGIC LOW
H = LOGIC HIGH
X = IRRELEVANT
GATE STATUS
= EDGE TRIGGERED
The Truth Table demonstrates how the LTC1154 receives
inputs and returns status information to the μP. The
ENABLE and input signal from the μP controls the switch
in its normal operating mode, where the rise and fall
time of the gate drive are controlled to limit EMI and RFI
emissions. The shutdown and overcurrent detection circuitry however, switch the gate off at a much higher rate
to limit the exposure of the MOSFET switch and the load
to dangerous conditions. The status pin remains high as
long as the switch is operating normally, and is driven
low only when a fault condition is detected. Note that the
shutdown pin is edge-sensitive and latches the output off
even if the shutdown pin returns to a low state.
OPERATION
The LTC1154 is a single micropower MOSFET driver
with built-in protection, status feedback and gate charge
pump. The LTC1154 consists of the following functional
blocks:
from each other so that the noise generated by the charge
pump logic is not coupled into the 100mV reference or
the analog comparator.
Gate Charge Pump
TTL and CMOS Compatible Inputs
The LTC1154 input and shutdown input have been designed
to accommodate a wide range of logic families. Both input thresholds are set at about 1.3V with approximately
100mV of hysteresis.
A low standby current voltage regulator provides continuous bias for the TTL-to-CMOS converter. The TTL-to-CMOS
converter output enables the rest of the circuitry. In this
way the power consumption is kept to a minimum in the
standby mode.
ENABLE Input
The ENABLE input is CMOS compatible and inhibits the
input signal whenever it is held logic high. This input
should be grounded when not in use.
Internal Voltage Regulation
The output of the TTL-to-CMOS converter drives two
regulated supplies which power the low voltage CMOS
logic and analog blocks. The regulator outputs are isolated
Gate drive for the MOSFET switch is produced by an adaptive charge pump circuit which generates a gate voltage
substantially higher than the power supply voltage. The
charge pump capacitors are included on chip and therefore no external components are required to generate the
gate drive.
Drain Current Sense
The LTC1154 is configured to sense the current flowing
into the drain of the power MOSFET in a high side application. An internal 100mV reference is compared to
the drop across a sense resistor (typically 0.002Ω to
0.10Ω) in series with the drain lead. If the drop across
this resistor exceeds the internal 100mV threshold, the
input latch is reset and the gate is quickly discharged via
a large N-channel transistor.
Controlled Gate Rise and Fall Times
When the input is switched ON and OFF, the gate is charged
by the internal charge pump and discharged in a controlled
1154fb
7
LTC1154
OPERATION
manner. The charge and discharge rates have been set to
minimize RFI and EMI emissions in normal operation. If
a short-circuit or current overload condition is encountered, the gate is discharged very quickly (typically a few
microseconds) by a large N-channel transistor.
Status Output Driver
The status circuitry continuously monitors the fault detection logic. This open-drain output is driven low when
the gate of the MOSFET is driven low by the protection
circuitry. The status circuitry is reset along with the input
latch when the input, or ENABLE input, is cycled.
APPLICATIONS INFORMATION
MOSFET and Load Protection
The LTC1154 protects the power MOSFET switch by removing drive from the gate as soon as an overcurrent condition
is detected. Resistive and inductive loads can be protected
with no external time delay in series with the drain sense
pin. Lamp loads, however, require that the overcurrent
protection be delayed long enough to start the lamp but
short enough to ensure the safety of the MOSFET.
Resistive Loads
Loads that are primarily resistive should be protected with
as short a delay as possible to minimize the amount of time
that the MOSFET is subjected to an overload condition. The
drain sense circuitry has a built-in delay of approximately
10μs to eliminate false triggering by power supply or load
transient conditions. This delay is sufficient to “mask”
short load current transients and the starting of a small
capacitor (<1μF) in parallel with the load. The drain sense
pin can therefore be connected directly to the drain current
sense resistor as shown in Figure 1.
Inductive Loads
Loads that are primarily inductive, such as relays, solenoids
and stepper motor windings should be protected with as
short a delay as possible to minimize the amount of time
that the MOSFET is subjected to an overload condition.
The built-in 10μs delay will ensure that the overcurrent
protection is not false-triggered by a supply or load
transient. No external delay components are required as
shown in Figure 2.
Large inductive loads (>0.1mH) may require diodes connected directly across the inductor to safely divert the
stored energy to ground. Many inductive loads have these
diodes included. If not, a diode of the proper current rating
should be connected across the load, as shown in Figure
2, to safely divert the stored energy.
12V
IN
+
100μF
VS
EN
0.036Ω
DS
LTC1154
STATUS
G
IRFZ24
15V
SD
GND
RLOAD
12Ω
CLOAD ≤ 1μF
LTC1154 • F01
Figure 1. Protecting Resistive Loads
12V
IN
VS
EN
+
100μF
0.036Ω
DS
LTC1154
STATUS
G
IRFZ24
15V
GND
SD
1N5400
12V, 1A
SOLENOID
LTC1154 • F02
Figure 2. Protecting Inductive Loads
1154fb
8
LTC1154
APPLICATIONS INFORMATION
Capacitive Loads
Lamp Loads
Large capacitive loads, such as complex electrical systems
with large bypass capacitors, should be powered using
the circuit shown in Figure 3. The gate drive to the power
MOSFET is passed through an RC delay network, R1 and
C1, which greatly reduces the turn-on ramp rate of the
switch. And since the MOSFET source voltage follows the
gate voltage, the load is powered smoothly and slowly from
ground. This dramatically reduces the start-up current
flowing into the supply capacitor(s) which, in turn, reduces
supply transients and allows for slower activation of sensitive electrical loads. (Diode, D1, provides a direct path for
the LTC1154 protection circuitry to quickly discharge the
gate in the event of an overcurrent condition).
The inrush current created by a lamp during turn-on can be
10 to 20 times greater than the rated operating current. The
circuit shown in Figure 4 shifts the current limit threshold
up by a factor of 11:1 (to 30A) for 100ms when the bulb
is first turned on. The current limit then drops down to
2.7A after the inrush current has subsided.
DS
0.036Ω
100k
DS
VN2222LL
LTC1154
G
STATUS
0.1μF
1M
SD
MTP3055EL
9.1V
RD
100k
12V/1A
BULB
D1
1N4148
R1
100k
LTC1154 • F04
R2
100k
Figure 4. Lamp Driver with Delayed Protection
MTP3055E
SD
C1
0.33μF
OUT
15V
+
CLOAD
100μF
LTC1154 • F03
Figure 3. Powering Large Capacitive Loads
The RC network, RD and CD, in series with the drain sense
input should be set to trip based on the expected characteristics of the load after start-up. With this circuit, it is possible
to power a large capacitive load and still react quickly to
an overcurrent condition. The ramp rate at the output of
the switch as it lifts off ground is approximately:
dV/dt = (VGATE – VTH)/(R1 • C1)
And therefore the current flowing into the capacitor during
start-up is approximately:
ISTART-UP = CLOAD • dV/dt
Using the values shown in Figure 3, the start-up current
is less than 100mA and does not false-trigger the drain
sense circuitry which is set at 2.7A with a 1ms delay.
Selecting RD and CD
Figure 5 is a graph of normalized overcurrent shutdown
time versus normalized MOSFET current. This graph is
used to select the two delay components, RD and CD,
which make up a simple RC delay between the drain sense
resistor and the drain sense input.
10
OVERCURRENT SHUTDOWN TIME (1 = RC)
GND
EN
10k
0.036Ω
LTC1154
G
VS
470μF
CD
0.01μF
STATUS
470μF
IN
+
VS
EN
+
GND
12V
IN
12V
1
0.1
0.01
1
10
100
MOSFET CURRENT (1 = SET CURRENT)
LTC1154 • F05
Figure 5. Overcurrent Shutdown Time vs MOSFET Current
1154fb
9
LTC1154
APPLICATIONS INFORMATION
The Y axis of the graph is normalized to one RC time
constant. The X axis is normalized to the current. (The
set current is defined as the current required to develop
100mV across the drain sense resistor).
Note that the shutdown time is shorter for increasing levels
of MOSFET current. This ensures that the total energy
dissipated by the MOSFET is always within the bounds
established by the manufacturer for safe operation. (See
MOSFET data sheet for further information).
12V
5V
+
120k 10k
10μF
IN
5V
μP OR
CONTROL
LOGIC
VS
0.05Ω
10k
DS
EN
LTC1154
10k
MTP12N06
G
STATUS
15V
SD
GND
10k LOAD
300Ω
Using a Speed-Up Diode
LTC1154 • F07
To reduce the amount of time that the power MOSFET is
in a short-circuit condition, “bypass” the delay resistor
with a small signal diode as shown in Figure 6. The diode
will engage when the drop across the drain sense resistor
exceeds about 0.7V, providing a direct path to the sense pin
and dramatically reducing the amount of time the MOSFET
is in an overload condition. The drain sense resistor value
12V
+
100μF
IN
VS
0.01μF
EN
1N4148
0.036Ω
100k
DS
LTC1154
STATUS
IRF530
G
15V
GND
SD
LOAD
Figure 7. Reverse Battery Protection
Since the LTC1154 draws very little current while in normal
operation, the drop across the ground resistor is minimal.
The 5V μP (or control logic) is protected by the 10k resistors in series with the input and status pins.
Current Limited Power Supplies
The LTC1154 requires at least 3.5V at the supply pin to
ensure proper operation. It is therefore necessary that the
supply to the LTC1154 be held higher than 3.5V at all times,
even when the output of the switch is short circuited to
ground. The output voltage of a current limited regulator
may drop very quickly during short-circuit and pull the
supply pin of the LTC1154 below 3.5V before the shutdown
circuitry has had time to respond and remove drive from
the gate of the power MOSFET. A supply filter should be
LTC1154 • F06
Figure 6. Using a Speed-Up Diode
is selected to limit the maximum DC current to 2.8A. The
diode conducts when the drain current exceeds 20A and
reduces the turn-off time to 15μs.
Reverse Battery Protection
The LTC1154 can be protected against reverse battery
conditions by connecting a resistor in series with the
ground lead as shown in Figure 7. The resistor limits the
supply current to less than 50mA with –12V applied.
>7V
5V/2A
REGULATOR
+
+
*20Ω
100μF
+
IN
47μF*
VS
0.1μF
EN
0.1Ω
10μF
1N4148
100k
DS
LTC1154
STATUS
GND
IRLR024
G
SHORTCIRCUIT
SD
*SUPPLY FILTER COMPONENTS
LTC1154 • F08
Figure 8. Supply Filter for Current Limited Supplies
1154fb
10
LTC1154
APPLICATIONS INFORMATION
added as shown in Figure 8 which holds the supply pin of
the LTC1154 high long enough for the overcurrent shutdown
circuitry to respond and fully discharge the gate.
Five volt linear regulators with small output capacitors are
the most difficult to protect as they can “switch” from a
voltage mode to a current limited mode very quickly. The
large output capacitors on many switching regulators may
be able to hold the supply pin of the LTC1154 above 3.5V
sufficiently long that this extra filtering is not required.
Because the LTC1154 is micropower in both the standby
and ON state, the voltage drop across the supply filter is
less than 2mV, and does not significantly alter the accuracy
of the 100mV drain sense threshold voltage.
TYPICAL APPLICATIONS
High Side Driver with Thermal Shutdown
6V
5V
High Side Driver with Overvoltage Shutdown
4.75V TO 5.25V
5V
+
+
100μF
μP OR
CONTROL
LOGIC
IN
VS
EN
DS
10μF
EN
DS
5.6V
LTC1154
STATUS†
IRLZ24
G
VS
100Ω
μP OR
CONTROL
LOGIC
LTC1154
STATUS†
IN
IRLD024
G
30k
GND
GND
SD
PTC
THERMISTOR
(100°C)*
*RL3006-50-100-25-PT0 KEYSTONE
SD
6V
LOAD
5V
LOAD
SWITCH IS SHUTDOWN WHEN VS > 5.7V
LTC1154 • TA03
LTC1154 • TA05
†A 51k pullup resistor should be connected between Status Output and 5V Logic Supply.
High Side Driver with Undervoltage Shutdown
5V
24V to 28V High Side Switch with Thermal Shutdown
24V TO 28V
+
100μF
1N4148*
+
10k
100μF
3k
+
1μF**
5V
μP OR
CONTROL
LOGIC
IN
VS
EN
DS
2N2907
μP OR
CONTROL
LOGIC
IRLZ24
G
18V
10μF
VS
IN
LTC1154
STATUS†
+
5V
EN
DS
LTC1154
STATUS†
MTP12N06
G
200k
GND
GND
SD
*OPTIONAL IF SUPPLY VOLTAGE LESS THAN 6V.
**CAPACITOR CHARGED TO SUPPLY VOLTAGE.
SHUTDOWN OCCURS WHEN SUPPLY VOLTAGE
DROPS BY 0.6V.
10k
SD
6V
LOAD
* KEYSTONE RL2006-100-100-30-PT.
MOUNT ON MOSFET OR LOAD HEAT SINK
PTC
THERMISTOR
(100°C)*
24V TO 28V
LOAD
LTC1154 • TA06
LTC1154 • TA04
1154fb
11
LTC1154
TYPICAL APPLICATIONS
24V to 28V Switch with Bootstrapped Supply
24V TO 28V
High Side Relay Driver with Overcurrent
Protection and Status Feedback
12V
+
100μF
+
100k
100μF
2Ω
+
5V
μP OR
CONTROL
LOGIC
18V
IN
VS
EN
DS
10μF
6.2k
μP OR
CONTROL
LOGIC
1N4148
LTC1154
STATUS
†
VS
EN
DS
10k
0.01μF
MTD3055E
G
STATUS
15V
GND
SD
* KEYSTONE RL2006-100-100-30-PT.
MOUNT ON MOSFET OR LOAD HEAT SINK.
IQ(OFF) = 60MA, IQ(ON) = 1mA.
1N4148
LTC1154
†
MTP15N06E
G
IN
200k
GND
PTC
THERMISTOR
(100°C)*
0.02Ω
5V
TO 12V
LOAD
SD
1N4001
24V TO 28V
LOAD
COIL CURRENT LIMITED TO 350mA.
CONTACT CURRENT LIMITED TO 5A.
LTC1154 • TA07
LTC1154 • TA08
†A 51k pullup resistor should be connected between Status Output and 5V Logic Supply.
“4-Cell-to-5V” Extremely Low Voltage Drop Regulator with
Overcurrent Shutdown, Status Feedback, Ramped Turn-ON
and 8μA Standby Current
4-CELL
BATTERY
PACK
+
100μF
0.036Ω
5V
μP OR
CONTROL
LOGIC
IN
VS
EN
DS
LTC1154
STATUS†
200pF
100k
100k
G
0.22μF
GND
SD
IRLR024
1N4148
10k
8
7
1
3
LT1431
6
5
4
5V/2A
+
470μF
ESR < 0.5Ω
LTC1154 • TA09
1154fb
12
LTC1154
TYPICAL APPLICATIONS
Bank Controlled High Side Switches with “Global” Thermal
and Overvoltage Shutdown
12V
IN
VS
100Ω
EN
+
470μF
DS
LTC1154
STATUS
G
IRLR024
15V
GND
SD
IN
VS
OUTPUT 1
5V
EN
DS
LTC1154
51k
STATUS
G
IRLR024
15V
μP OR
CONTROL
LOGIC
GND
SD
IN
VS
EN
OUTPUT 2
DS
LTC1154
STATUS
G
IRLR024
15V
GND
SD
IN
VS
EN
DS
OUTPUT 3
120k
LTC1154
STATUS
G
IRLR024
15V
GND
SD
OUTPUT 4
15V
*KEYSTONE RL2006-100-100-30-PT.
MOUNT ON COMMON HEAT SINK.
PTC
THERMISTOR
(100°C)*
LTC1154 • TA10
1154fb
13
LTC1154
TYPICAL APPLICATIONS
12V Step-Up Regulator with Ultralow Standby Current,
Overcurrent Protection and Status Feedback
0.02Ω
5V
+
+
20Ω
470μF
47μF
IN
VS
EN
DS
10k
5
+
1N4148
VIN
150μF
1N4148
3
LTC1154
STATUS
STATUS
100k
1
1.24k
1%
100k
G
1k
0.1μF
SD
GND
10.72k
1%
4
VSW
LT1070
2
FB
V
GND
C
0.22μF
51k
12V/1A
330μF
+
ON/OFF
1N5820
50μH
IRLZ24
1μF
LTC1154 • TA11
12V Step-Up Regulator with 1A Overcurrent Protection,
Switch Status Feedback and Ramped Output
50μH
1N5820
5V
+
+
150μF
330μF
0.1Ω
5
1N4148
VIN
VSW 4
LT1070
2
FB
VC
GND
3
1
1k
10.72k
1%
ON/OFF
IN
VS
10k
0.1μF
51k
1.24k
1%
EN
DS
LTC1154
STATUS
STATUS
1N4148
100k
100k
G
IRF530
12V
1μF
GND
SD
+
0.22μF
12V/1A
47μF
LTC1154 • TA12
1154fb
14
LTC1154
PACKAGE DESCRIPTION
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
.255 ± .015*
(6.477 ± 0.381)
.300 – .325
(7.620 – 8.255)
.008 – .015
(0.203 – 0.381)
(
+.035
.325 –.015
8.255
+0.889
–0.381
)
.045 – .065
(1.143 – 1.651)
.130 ± .005
(3.302 ± 0.127)
.065
(1.651)
TYP
.100
(2.54)
BSC
.120
(3.048) .020
MIN (0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
N8 1002
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
1154fb
15
LTC1154
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
8
.245
MIN
7
6
5
.160 ±.005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
× 45°
(0.254 – 0.508)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
NOTE:
1. DIMENSIONS IN
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
2
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 0303
1154fb
16
LTC1154
REVISION HISTORY
(Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
4/11
Updated Graph TPC05
4
Updated SCSI Termination Typical Application
18
Updated Related Parts
18
1154fb
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
17
LTC1154
TYPICAL APPLICATIONS
Auto-Reset High Side Switch with Overcurrent and Overcurrent Temperature Shutdown
12V
+
RT
1M**
100μF
1M
0.036Ω
ON/OFF
IN
VS
EN
+
DS
LTC1154
CT
100μF**
MTP12N06
G
STATUS
VN2222LL
18V
200k
SD
GND
PTC
THERMISTOR
(100°C)*
*KEYSTONE RL2006-100-100-30-PT.
**AUTO-RESET PERIOD ≈ 800ms WITH COMPONENTS SHOWN
12V
LOAD
LTC1154 • TA13
SCSI Termination Power Switch with 1A Overcurrent Shutdown, Auto-Reset and Load Soft-Start
0.1Ω
MTD3055EL
1N5817
7"
5V
+
1M
100μF
1M
ON/OFF
+
IN
0.1μF
DS
LTC1154
+
45"564
1μF
10k
1N4148
+
VS
EN
10μF
20Ω
47μF
1N4148
100k
VN2222LL
0.22μF
SD
GND
100k
G
-5$t5"
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC4440/LTC4440-5
High Speed, High Voltage High Side Gate Driver
Up to 80V Supply Voltage, 8V ≤ VCC ≤ 15V, 2.4A Peak Pull-Up/1.5Ω
Peak Pull-Down
LTC4441/LTC4441-1
N-Channel MOSFET Gate Driver
Up to 25V Supply Voltage, 5V ≤ VCC ≤ 25V, 6A Peak Output Current
LT1910
Protected High Side Gate Driver
Up to 48V Supply Voltage, Short Circuit Protected
LTC4446
High Voltage Synchronous N-Channel MOSFET
Driver without Shoot Thru Protection
Up to 100V Supply Voltage, 7.2V ≤ VCC ≤ 13.5V, 3A Peak Pull-Up/0.55Ω
Peak Pull-Down
LTC4444/LTC4444-5
High Voltage Synchronous N-Channel MOSFET
Driver with Shoot Thru Protection
Up to 100V Supply Voltage, 4.5V/7.2V ≤ VCC ≤ 13.5V, 3A Peak Pull-Up/
0.55Ω Peak Pull-Down
LTC4442/LTC4449
High Speed Synchronous N-Channel MOSFET
Driver
Up to 38V Supply Voltage, 4.5V/6V ≤ VCC ≤ 9.5V, 3.2A Peak Pull-Up/
4.5A Peak Pull-Down
1154fb
18 Linear Technology Corporation
LT 0411 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1992
Similar pages