LTC1255IS8_技术文档

LTC1255

Dual 24V High-Side

MOSFET Driver

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DESCRIPTIO

EATURE

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F

■

Fully Enhances N-Channel Power MOSFETs

12µA Standby Current

Operates at Supply Voltages from 9V to 24V

Short Circuit Protection

Easily Protected Against Supply Transients

Controlled Switching ON and OFF Times

No External Charge Pump Components

Compatible With Standard Logic Families

Available in 8-Pin SOIC

The LTC1255 dual high-side driver allows using low

cost N-channel FETs for high-side industrial and auto-

motiveswitchingapplications.Aninternalchargepump

boosts the gate drive voltage above the positive rail,

fully enhancing an N-channel MOS switch with no

external components. Low power operation, with 12µA

standby current, allows use in virtually all systems with

maximum efficiency.

Included on-chip is independent overcurrent sensing

toprovideautomaticshutdownincaseofshortcircuits.

A time delay can be added to the current sense to

prevent false triggering on high in-rush current loads.

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PPLICATI

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Solenoid Drivers

DC Motor Drivers

Stepper Motor Drivers

Lamp Drivers/Dimmers

Relay Drivers

Low Frequency H-Bridge

P-Channel Switch Replacement

The LTC1255 operates from 9V to 24V supplies and is

well suited for industrial and automotive applications.

The LTC1255 is available in both an 8-pin DIP and an

8-pin SOIC.

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TYPICAL APPLICATI

Dual 24V High-Side Switch with Overcurrent Protection

Standby Supply Current

24V

50

+

V

A

= V = 0V

IN2

IN1

45

10µF

T

= 25°C

0.036Ω

40

35

30

V

S

DS1

G1

DS2

G2

IRLR024

LTC1255

GND

25

20

IN1

IN2

12V

15

10

5

FROM

µP, ETC.

FROM

µP, ETC.

24V/0.5A

SOLENOID

24V/0.5A

SOLENOID

1N4001

0

5

15

20

25

30

10

LTC1255 • TA01

SUPPLY VOLTAGE (V)

LTC1255 • TA02

1

LTC1255

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ABSOLUTE AXI U RATI GS

Operating Temperature Range

Supply Voltage ......................................... –0.3V to 30V

Transient Supply Voltage (<10ms) ......................... 40V

Input Voltage ..................... (V_S+ 0.3V) to (GND – 0.3V)

Gate Voltage ...................... (V_S+ 20V) to (GND – 0.3V)

Current (Any Pin)................................................. 50mA

LTC1255C............................................... 0°C to 70°C

LTC1255I........................................... –40°C to 85°C

Storage Temperature Range ................ – 65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

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PACKAGE RDER I FOR ATIO

ORDER PART

TOP VIEW

NUMBER

DS1

GATE 1

GND

1

2

3

4

DS2

8

7

6

5

DS1

GATE 1

GND

1

2

3

4

8

7

6

5

DS2

GATE 2

LTC1255CS8

LTC1255IS8

LTC1255CN8

LTC1255IN8

V

S

V

S

IN1

IN2

IN1

IN2

S8 PART MARKING

N8 PACKAGE

S8 PACKAGE

8-LEAD PLASTIC SOIC

8-LEAD PLASTIC DIP

1255

1255I

T_JMAX= 100°C, θ_JA= 130°C/ W

T_JMAX= 100°C, θ_JA= 150°C/ W

ELECTRICAL CHARACTERISTICS ^V_S^{= 9V to 24V, T}_A^{= 25°C, unless otherwise noted.}

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

I

Quiescent Current OFF

V = 10V, V = 0V (Note 1)

12

40

µA

Q

S

IN

V = 18V, V = 0V (Note 1)

S

IN

V = 24V, V = 0V (Note 1)

S

IN

Quiescent Current ON

V = 10V, V

= 22V, V = 5V (Note 2)

160

350

600

400

800

1200

µA

S

GATE

IN

V = 18V, V

= 30V, V = 5V (Note 2)

S

IN

V = 24V, V

S

= 36V, V = 5V (Note 2)

IN

V

Input High Voltage

Input Low Voltage

Input Current

Input Capacitance

Drain Sense Threshold Voltage

●

2

V

µA

pF

mV

µA

V

µA

INH

INL

0.8

±1

I

0V ≤ V ≤ V

S

IN

C

V

5

100

IN

80

75

120

125

±0.1

SEN

●

I

Drain Sense Input Current

Gate Voltage Above Supply

Gate Output Drive Current

0V ≤ V

≤ V

SEN

S

V

– V

V = 9V

S

7.5

5

10.5

20

23

12

GATE

S

I

V = 18V, V

V = 24V, V

S

= 30V

= 36V

●

GATE

S

GATE

2

LTC1255

ELECTRICAL CHARACTERISTICS

V_S= 9V to 24V, T_A= 25°C, unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

t

Turn-ON Time

V = 10V, C

Time for V

= 1000pF (Note 3)

ON

S

GATE

> V + 2V

30

75

100

250

300

750

µs

S

> V + 5V

S

V = 18V, C

Time for V

= 1000pF (Note 3)

S

GATE

> V + 5V

40

75

120

250

400

750

µs

S

> V + 10V

S

V = 24V, C

Time for V

= 1000pF (Note 3)

S

GATE

> V + 10V

50

180

500

µs

S

t

Turn-OFF Time

V = 10V, C

= 1000pF, (Note 3, 4)

10

5

24

21

19

16

60

30

µs

OFF

SC

S

GATE

V = 18V, C

S

V = 24V, C

S

Short-Circuit Turn-OFF Time

V = 10V, C

S

GATE

V = 18V, C

S

V = 24V, C

S

The

●

denotes specifications which apply over the full operating

Note 3: Zener diode clamps must be connected across the GATE-SOURCE

temperature range.

of the power MOSFET to limit V . 1N5242A (through hole) or

GS

MMBZ5242A (surface mount) 12V Zener diodes are recommended. All

Turn-ON and Turn-OFF tests are performed with a 12V Zener clamp in

Note 1: Quiescent current OFF is for both channels in OFF condition.

Note 2: Quiescent current ON is per driver and is measured independently.

The gate voltage is clamped to 12V above the rail to simulate the effects of

protection clamps connected across the GATE-SOURCE of the power

MOSFET.

series with a small-signal diode connected between V and the GATE

S

output to simulate the effects of a 12V protection Zener clamp connected

across the GATE-SOURCE of the power MOSFET.

Note 4: Time for V

to drop below 1V.

GATE

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TYPICAL PERFOR A CE CHARACTERISTICS

Standby Supply Current

Supply Current per Driver (ON)

Gate Voltage Above Supply

2.0

1.8

50

45

20

18

ONE INPUT = 0N

V

= 12V

V

A

= V = 0V

IN2

CLAMP

IN1

OTHER INPUT = OFF

T

= 25°C

T

= 25°C

A

1.6

1.4

1.2

40

35

30

16

14

12

25

20

1.0

0.8

10

8

15

10

5

0.6

0.4

0.2

0

6

4

2

0

5

15

20

25

30

0

5

15

20

25

30

0

5

15

20

25

30

10

SUPPLY VOLTAGE (V)

LTC1255 • TPC01

LTC1255 • TPC02

LTC1255 • TPC03

3

LTC1255

TYPICAL PERFOR A CE CHARACTERISTICS

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Input Threshold Voltage

Drain Sense Threshold Voltage

Gate Clamp Current

2.4

2.2

125

120

50

45

T

A

= 25°C

V

A

= 12V

CLAMP

= 25°C

T

2.0

1.8

1.6

115

110

105

40

35

30

V

ON

1.4

1.2

100

95

25

20

OFF

1.0

0.8

0.6

0.4

90

85

80

75

15

10

5

0

5

15

20

25

30

0

5

15

20

25

30

10

0

5

15

20

25

30

10

SUPPLY VOLTAGE (V)

LTC1255 • TPC04

LTC1255 • TPC05

LTC1255 • TA06

Turn-ON Time

Turn-OFF Time

Short-Circuit Turn-OFF Delay Time

1000

900

50

45

50

45

C

A

= 1000pF

C

= 1000pF

C

= 1000pF

GATE

TIME FOR V

T

= 25°C

< 1V

TIME FOR V

< 1V

GATE

800

700

600

40

35

30

40

35

30

500

400

25

20

25

20

300

200

100

0

15

10

5

15

10

5

V

= 5V

15

GS

V

= 2V

5

GS

0

20

25

30

0

5

15

20

25

30

0

5

10

15

20

25

30

10

SUPPLY VOLTAGE (V)

LTC1255 • TA09

LTC1255 • TA07

LTC1255 • TA08

Supply Current per Channel (ON)

Standby Supply Current

Input ON Threshold

50

45

2.0

1.8

2.4

2.2

40

35

30

1.6

1.4

1.2

2.0

1.8

1.6

V

= 10V

= 24V

S

25

20

1.0

0.8

1.4

1.2

V

= 24V

S

V

= 18V

= 24V

S

15

10

5

0.6

0.4

0.2

0

1.0

0.8

0.6

0.4

V

= 18V

= 10V

S

V

S

= 10V

S

0

–50 –25

25

50

75

100

–50 –25

25

50

75

100

–50 –25

25

50

75

100

0

TEMPERATURE (°C)

LTC1255 • TA10

LTC1255 • TA11

LTC1255 • TA12

4

LTC1255

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PI FU CTIO S

Input Pin

The LTC1255 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 reapply it, the input pin should be

cycled (low to high) a few milliseconds after the power

is reapplied to reset the input latch and protection

circuitry. Also, theinputpinshouldbeisolatedfromthe

controllinglogicbya10kresistorifthereisapossibility

that the input pin will be held high after the supply has

been removed.

The LTC1255 input pin is active high and activates all of

theprotectionandchargepumpcircuitrywhenswitched

ON. The LTC1255 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 input pin should be

held low during the application of power to properly set

the input latch.

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 of relatively

high impedance when driven above the rail (the equiva-

lent 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

inputtoresettheshort-circuitlatchandturntheMOSFET

back on.

This pin is also a high impedance CMOS gate with ESD

protection and therefore should not be forced outside

of the power supply rails. To defeat the overcurrent

protection, short the drain sense pin to the supply pin.

Supply Pin

The supply pin of the LTC1255 serves two vital pur-

poses. The first is obvious; it powers the input, gate

drive, regulation and protection circuitry. The second

purposeislessobvious;itprovidesaKelvinconnection

to the top of the drain sense resistor for the internal

100mV reference.

Some loads, such as large supply capacitors, lamps or

motors require high in-rush 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 startup. This time constant can

be set from a few microseconds to many seconds.

However, very long delays may put the MOSFET at risk

of being destroyed by a short-circuit condition (see

Applications Information section).

The supply pin of the LTC1255 should never be forced

below ground as this may result in permanent damage

to the device. A 100Ω resistor should be inserted in

series with the ground pin if negative supply voltage

transients are anticipated.

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OPERATIO

The LTC1255 is a dual 24V MOSFET driver with built-in

protection and gate charge pump. The LTC1255 consists

of the following functional blocks:

olds are set at about 1.3V with approximately 100mV of

hysteresis. A low standby current regulator provides

continuous bias for the TTL-to-CMOS converter.

The input/protection latch should be set after initial

power-up, or after reapplication of power, by cycling

the input low to high.

TTL and CMOS Compatible Inputs and Latches

The LTC1255 inputs have been designed to accommo-

date a wide range of logic families. Both input thresh-

5

LTC1255

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OPERATIO

Internal Voltage Regulation

Drain Current Sense

The output of the TTL-to-CMOS converter drives two

regulated supplies which power the low voltage CMOS

logicandanalogblocks.Theregulatoroutputsareisolated

from each other so that the noise generated by the charge

pump logic is not coupled into the 100mV reference or the

analog comparator.

The LTC1255 is configured to sense the current flowing

into the drain of the power MOSFET in a high-side applica-

tion. 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 relatively

large N-channel transistor.

Gate Charge Pump

Gate drive for the power MOSFET is produced by an

adaptive charge pump circuit which generates a gate

voltage substantially higher than the power supply volt-

age.Thechargepumpcapacitorsareincludedon-chipand

thereforenoexternalcomponentsarerequiredtogenerate

the gate drive. The charge pump is designed to drive a 12V

Zener diode clamp connected across the gate and source

of the MOSFET switch.

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 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 (typi-

cally a few microseconds) by a large N-channel transistor.

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BLOCK DIAGRA

(One Channel)

DRAIN

SENSE

ANALOG SECTION

V

S

10µs

DELAY

COMP

LOW STANDBY

CURRENT

REGULATOR

100mV

REFERENCE

GATE CHARGE

AND DISCHARGE

CONTROL LOGIC

GATE

ANALOG

DIGITAL

R

S

OSCILLATOR

AND CHARGE

PUMP

FAST/SLOW

GATE CHARGE

LOGIC

TTL-TO-CMOS

CONVERTER

VOLTAGE

REGULATOR

INPUT

LATCH

INPUT

ONE

SHOT

LTC1255 • BD

GND

6

LTC1255

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APPLICATIO S I FOR ATIO

MOSFET AND LOAD PROTECTION

Large inductive loads (>0.1mH) may require diodes con-

nected directly across the inductor to safely divert the

stored energy to ground. Many inductive loads have these

diodes included. Ifnot, adiode ofthe propercurrent rating

should be connected across the load, as shown in

Figure 2, to safely divert the stored energy.

The LTC1255 protects the power MOSFET switch by

removing drive from the gate as soon as an overcurrent

condition is detected. Resistiveandinductiveloadscanbe

protected with no external time delay in series with the

drain sense pin. Lamp loads, however, require that the

overcurrentprotectionbedelayedlongenoughtostartthe

lampbutshortenoughtoensurethesafetyoftheMOSFET.

12V

+

R

100µF

SENSE

0.036Ω

V

S

DS1

1/2 LTC1255

IN1

Resistive Loads

Loads that are primarily resistive should be protected with

asshortadelayaspossibletominimizetheamountoftime

that the MOSFET is subjected to an overload condition.

The drain sense circuitry has a built-in delay of approxi-

mately 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.

IRFZ24

G1

GND

12V

12V, 1A

SOLENOID

1N5400

LTC1255 • F02

Figure 2. Protecting Inductive Loads

18V

Capacitive Loads

+

R

10µF

SENSE

0.036Ω

Large capacitive loads, such as complex electrical sys-

tems 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 startup cur-

rent flowing into the supply capacitor(s) which, in turn,

reduces supply transients and allows for slower activation

V

S

DS1

1/2 LTC1255

IN1

IRFZ24

G1

GND

12V

C

LOAD

R

LOAD

18Ω

≤ 1µF

LTC1255 • F01

Figure 1. Protecting Resistive Loads

15V

+

C

R

DELAY

470µF

SENSE

R

DELAY

0.01µF

0.036Ω

V

S

100k

Inductive Loads

DS1

1/2 LTC1255

IN1

D1

1N4148

Loads that are primarily inductive, such as relays, sole-

noids 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.

MTP3055E

G1

GND

R1

100k

R2

100k

12V

+

C1

0.33µF

C

LOAD

100µF

LTC1255 • F03

Figure 3. Powering Large Capacitive Loads

7

LTC1255

APPLICATIO S I FOR ATIO

of sensitive electrical loads. (Resistor R2, and the diode

D1, provide a direct path for the LTC1255 protection

circuitry to quickly discharge the gate in the event of an

overcurrent condition.)

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Selecting R_DELAYand C_DELAY

Figure5isagraphofnormalizedovercurrentshutdown

time versus normalized MOSFET current. This graph is

used to select the two delay components, R

and

DELAY

The RC network, R_DELAYand C_DELAY, in series with the

drain sense input should be set to trip based on the

expected characteristics of the load after startup, i.e., 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:

C

, which make up a simple RC delay between the

DELAY

drain sense input and the drain sense resistor.

The Y axis of the graph is normalized to one RC time

constant. The X axis is normalized to the set 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

boundsestablishedbythemanufacturerforsafeopera-

tion. (See MOSFET data sheet for further S.O.A.

information.)

dV/dt = (V_GATE– V_TH)/(R1 × C1)

Therefore, the current flowing into the capacitor during

startup is approximately:

I_STARTUP= C_LOAD× dV/dt

Using the values shown in Figure 3, the startup current is

lessthan100mAanddoesnotfalsetriggerthedrainsense

circuitry which is set at 2.7A with a 1ms delay.

10

1

Lamp Loads

The in-rush 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 a short period

of time while the bulb is turned on. The current limit then

dropsdownto2.7Aafterthein-rushcurrenthassubsided.

0.1

0.01

0.1

1

10

100

NORMALIZED MOSFET CURRENT (1 = SET CURRENT)

LTC1255 • F05

12V

+

10k

470µF

R

SENSE

0.036Ω

Figure 5. Normalized Delay Time vs MOSFET Current

100k

V

S

DS1

1/2 LTC1255

IN1

Using a Speed-Up Diode

VN2222LL

0.1µF

Another way to reduce the amount of time that the

power MOSFET is in a short-circuit condition is to

“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,

providingadirectpathtothesensepinanddramatically

reducing the amount of time the MOSFET is in an

overload condition. The drain sense resistor value is

selected to limit the maximum DC current to 4A.

MTP3055EL

G1

GND

1M

9.1V

12V/1A

BULB

LTC1255 • F04

Figure 4. Lamp Driver With Delayed Protection

8

LTC1255

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APPLICATIO S I FOR ATIO

The large output capacitors on many switching regula-

tors, on the other hand, may be able to hold the supply

pinoftheLTC1255above3.5Vsufficientlylongthatthis

extra filtering is not required.

18V

+

C

R

DELAY

100µF

SENSE

0.01µF

0.036Ω

R

DELAY

V

S

100k

DS1

1/2 LTC1255

IN1

1N4148

BecausetheLTC1255ismicropowerinboththestandby

and ON state, the voltage drop across the supply filter

is very small (typically <6mV) and does not signifi-

cantly alter the accuracy of the drain sense threshold

voltage which is typically 100mV.

IRF530

G1

GND

12V

LOAD

LTC1255 • F06

AUTOMOTIVE APPLICATIONS

Reverse Battery Protection

Figure 6. Using a Speed-Up Diode

Current Limited Power Supplies

The LTC1255 can be protected against reverse battery

conditions by connecting a resistor in series with the

groundleadasshowninFigure8.Theresistorlimitsthe

supply current to less than 120mA with –12V applied.

Since the LTC1255 draws very little current while in

normal operation, the drop across the ground resistor

is minimal. The 5V µP (or controlling logic) is protected

by the 10k resistors in series with the input.

The LTC1255 requires at least 3.5V at the supply pin to

ensure proper operation. It is therefore necessary that

the supply to the LTC1255 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 LTC1255 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 added as shown in

Figure 7 which holds the supply pin of the LTC1255

high long enough for the overcurrent shutdown cir-

cuitry to respond and fully discharge the gate.

14V

+

5V

28V

10µF

R

SENSE

0.036Ω

V

S

DS1

1/2 LTC1255

IN1

µp OR

CONTROL

LOGIC

10k

MTP12N06E

G1

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.

GND

12V

LOAD

100Ω

LTC1255 • F08

12V/2A

15V

REGULATOR

+

10Ω*

0.01µF

Figure 8. Reverse Battery Protection

10µF

R

SENSE

0.1Ω

+

V

S

100k

47µF*

Transient Overvoltage Protection

DS1

1/2 LTC1255

IN1

A common scheme used to limit overvoltage transients

on a 14V nominal automotive power bus is to clamp the

supply to the module containing the high-side MOSFET

switches with a large transient suppressor diode, D1 in

Figure 9. This diode limits the supply voltage to 40V

underworsecaseconditions. TheLTC1255isdesigned

to survive short (10ms) 40V transients and return to

normal operation after the transient has passed.

1N4148

MTP12N06E

G1

GND

12V

SHORT

CIRCUIT

*SUPPLY FILTER COMPONENT

LTC1255 • F07

Figure 7. Supply Filter for Current Limited Supplies

9

LTC1255

APPLICATIO S I FOR ATIO

U U

W

U

The switches can either be turned OFF by the controlling

logic during these transients or latched OFF above 30V by

holding the drain sense pin low as shown in Figure 9.

14V

+

D1

1µF

50V

MR2535L

R

SENSE

0.036Ω

V

S

1k*

DS1

1/2 LTC1255

IN1

Switch status can be ascertained by means of an XNOR

gate connected to the input and switch output through

100k current limiting resistors (see Typical Applications

sectionformoredetailonthisscheme).Theswitchisreset

after the overvoltage event by cycling the input low and

then high again.

10k

FROM

µP, ETC.

IRF530

G1

12V

GND

1N5242B

30V*

1N5256B

LOAD

100Ω

LTC1255 • F09

The power MOSFET switch should be selected to have a

breakdown voltage sufficiently higher than the 40V supply

clampvoltagetoensurethatnocurrentisconductedtothe

load during the transient.

*OPTIONAL OVERVOLTAGE (30V) LATCH-OFF COMPONENTS

Figure 9. Overvoltage Transient Protection

U

TYPICAL APPLICATIO S

Dual Automotive High-Side Switch with Overvoltage Protection,

XNOR Status and 12µA Standby Current

14V

+

1µF

MR2535L*

50V

0.036Ω

V

S

DS1

G1 LTC1255 G2

IN1 IN2

DS2

10k

10k** MTD3055E

MTD3055E

10k**

12V

MMBZ5242B

12V

MMBZ5242B

100k

GND

14V/1A

SOLENOID

14V/1A

SOLENOID

1N5400

1/4 74C266^†

100Ω

FAULT FROM

TO µP µP, ETC.

FROM FAULT

µP, ETC. TO µP

LTC1255 • TA03

TRUTH TABLE

IN OUT

*LIMITS V TRANSIENTS TO <40V. SEE MANUFACTURER DATA SHEET FOR

S

CONDITION

SWITCH OFF

OVERCURRENT

OPEN LOAD**

SWITCH ON

FAULT

FURTHER DETAIL.

0

1

0

1

0

1

0

1

**OPTIONAL OPEN LOAD DETECTION REQUIRES 10k PULL-UP RESISTORS.

(ULTRA LOW STANDBY QUIESCENT CURRENT IS SACRIFICED)

†

POWER FROM 5V LOGIC SUPPLY.

10

LTC1255

U

TYPICAL APPLICATIO S

10 to 12 Cell Battery Switch and 5V Ramped Load Switch with

12µA Standby Current and Optional 3A Overcurrent Shutdown

18V TO 30V

FROM

1N5400

BATTERY

CHARGER

9.1V

0.033Ω*

MMBZ5239BL

IRFR024

SWITCHED

BATTERY

V

10 TO 12

CELL

BATTERY

PACK

IN

100k*

10k

0.22µF*

HIGH^†

EFFICIENCY

SWITCHING

REGULATOR

+

V

OUT

12V

MMBZ5242BL

100µF

2N2222

10k

5V/1A

+

V

S

DS1

G1

100µF

V

LOGIC

LTC1255

GND

1N4148

100k

µP OR

CONTROL

LOGIC

IN1

IN2

DS2

G2

100k

1k

MTD3055EL

0.1µF

5V/1A

(SWITCHED)

LTC1255 • TA04

*OPTIONAL 3A OVERCURRENT SHUTDOWN

^†SEE LTC1149 DATA SHEET FOR CIRCUIT DETAILS

Automotive Motor Direction and Speed Control with

Stall-Current Shutdown

14V

+

0.1µF

100k

10µF

50V

MR2535L

0.02Ω

V

S

DS1

G1

30k

5V

MTD3055E

12V

MMBZ5242B

LTC1255

GND

DIRECTION

IN1

IN2

DS2

G2

30k

MOTOR SPEED

AND DIRECTION

CONTROL LOGIC

OR µP

MTD3055E

14V

DC MOTOR

12V

MMBZ5242B

PWM 1

PWM 2

100Ω

MTD3055EL

LTC1255 • TA05

11

LTC1255

TYPICAL APPLICATIO S

U

Low Frequency (f_O= 100Hz) PWM Motor Speed Control with

Current Limit and 22V Overvoltage Shutdown

14V

+

1N4148

10µF

50V

MR2535L

OFF

0.1µF

50V

0.47µF

0.01Ω

60k

SLOW

MED

FAST

10k

V

9.1k

S

DS1

G1

10k

30k

15k

+

22V

5.6V

LTC1255

GND

1µF

MMBZ5251BL

IN1

IN2

DS2

G2

8

4

100k

6

2

IRFR024

22V

MMBZ5251BL

LMC555

1k

5

3

100Ω

1N4148

14V

MOTOR

1

0.1µF

0.01µF

MR750

LTC1255 • TA06

Dual Automotive Lamp Dimmer with Controlled Rise and Fall Times

and Short-Circuit Protection

14V

+

10µF

50V

MR2535L

1N4148

0.1µF

0.05Ω

9.1k

+

100k

12V

V

5.6V

S

10µF

PULSE

WIDTH

ADJUST

DS1

G1

30k

MTD3055E

8

4

6

2

100k

LTC1255

GND

100k

MMBZ5242B

IN1

IN2

DS2

G2

LMC555

30k

5

3

MTD3055E

1N4148

12V

MMBZ5242B

1

0.1µF

0.01µF

1k

100Ω

#53

14V

BULBS

LTC1255 • TA06

12

LTC1255

U

TYPICAL APPLICATIO S

18V to 32V Operation with Overcurrent Shutdown and Optional

Overvoltage Shutdown

18V TO 32V

R

SEN

1k

0.10Ω

1W

+

(I

= V /R

BE SEN

)

MAX

24V

1N5252B

1µF

50V

10k

2N3906

V

36V*

1N5258B

S

DS1

2N3904

1/2 LTC1255

10k

FROM

µP, ETC.

IRF530

IN1

G1

GND

12V

1N5242B

*OPTIONAL 36V OVERVOLTAGE SHUTDOWN

18V TO 32V

LOAD

LTC1255 • TA08

Bootstrapped Gate Driver (100Hz < f_O< 10kHz)

High-Side Switch with Thermal Shutdown (PTC Thermistor)

9V TO 24V

+

10µF

1N4148

10µF

PTC*

0.036Ω

THERMISTOR

(100°C)

V

S

DS1

100k

0.1µF

1/2 LTC1255

G1

2N2222

G1

IRF530

FROM

µP, ETC.

FROM

µP, ETC.

IN1

12V

1N5242B

*

GND

IRFZ44

12V

1N5242B

LOAD

*V = V – 0.6V

GS

*KEYSTONE RL2006-100-100-30-PT

S

(CLAMPED AT 12V)

RISE AND FALL TIMES

ARE BETA TIMES FASTER

LOAD

2N3906

LTC1255 • TA10

LTC1255 • TA09

13

LTC1255

U

TYPICAL APPLICATIO S

H-Bridge DC Motor Driver

(Direction and ON/OFF Control)

9V TO 24V

+

10µF

50V

0.33µF

0.036Ω

100k

V

S

DS1

G1

100k

5V

1N4148

LTC1255

GND

IN1

IN2

DS2

G2

100k

1/4 74C02

MTD3055E

12V

MMBZ5242B

12V

MMBZ5242B

1N4148

DC MOTOR

1/4 74C02

100k

MTD3055EL

1N4148

LTC1255 • TA11

100k

DIRECTION

DISABLE

MTD3055EL

1N4148

High-Side DC Motor Driver With Electronic Braking and

Stalled Motor Shutdown

18V

+

100µF

0.47µF

0.02Ω

100k

5V

1/4 74C02

V

S

DS1

G1

30k

1/4 74C02

IRFZ34

12V

1N5242B

IN1 LTC1255

RUN/COAST

DS2

G2

BRAKE

IN2

1Ω*

GND

18V

DC MOTOR

IRFZ34

1N5400

12V

1N5242B

*SIZE RESISTOR TO DISSIPATE ENERGY

REGENERATED BY MOTOR DURING BRAKING.

LTC1255 • TA12

14

LTC1255

U

TYPICAL APPLICATIO S

Stepper Motor Driver with Overcurrent Protection

12V

+

0.01µF

100k

0.036Ω

100µF

0.036Ω

100k

0.01µF

V

S

V

S

DS1

G1

DS1

5V

IRFR024

12V

G1

A

B

C

D

STEPPER MOTOR WINDINGS

12V

IN1 LTC1255

LTC1255 IN1

A

C

MMBZ5242BL

DS2

G2

DS2

G2

IRFR024

STEPPER

MOTOR

CONTROL

LOGIC

IN2

GND

1N4001

B

1N4001

D

12V

MMBZ5242BL

12V

MMBZ5242BL

1N4001

LTC1255 • TA13

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-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

15

LTC1255

U

Dimensions in inches (millimeters) unless otherwise noted.

PACKAGE DESCRIPTIO

N8 Package

8-Lead Plastic DIP

0.400

(10.160)

MAX

8

7

6

5

4

0.250 ± 0.010

(6.350 ± 0.254)

1

2

3

0.130 ± 0.005

0.300 – 0.320

0.045 – 0.065

(3.302 ± 0.127)

(1.143 – 1.651)

(7.620 – 8.128)

0.065

(1.651)

TYP

0.009 – 0.015

(0.229 – 0.381)

0.125

0.020

(0.508)

MIN

(3.175)

MIN

+0.025

0.045 ± 0.015

(1.143 ± 0.381)

0.325

–0.015

+0.635

8.255

(

)

–0.381

0.100 ± 0.010

(2.540 ± 0.254)

0.018 ± 0.003

(0.457 ± 0.076)

N8 0393

S8 Package

8-Lead SOIC

0.189 – 0.197

(4.801 – 5.004)

7

5

8

6

0.228 – 0.244

0.150 – 0.157

(5.791 – 6.197)

(3.810 – 3.988)

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)

SO8 0393

LT/GP 0493 10K REV 0

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7487

16

●

LINEAR TECHNOLOGY CORPORATION 1993

(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977


型号：	LTC1255IS8
厂家：	Linear
描述：	Dual 24V High-Side MOSFET Driver 双路24V高侧MOSFET驱动器驱动器
文件：	总16页 (文件大小：340K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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