LT1158CS View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LT1158CS

Half Bridge N-Channel Power MOSFET Driver

Linear Technology 

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LT1158

APPLICATIONS INFORMATION

from a true short. This is done by using the current limit to

control cold filament current in conjunction with the self-

protection circuit of Figure 9. The reduced cold filament

current also extends the life of the filament.

A good guideline is to choose RSENSE to set ISC at approxi-

mately twice the steady state “on” current of the lamp(s).

tSHUTDOWN is then made long enough to guarantee that the

lamp filaments heat and drop out of current limit before the

enable capacitor discharges to the enable low threshold.

For a short circuit, the enable capacitor will continue to

discharge below the threshold, shutting down the top

MOSFET. The LT1158 will then go into the automatic

restart mode described in Self-Protection with Automatic

Restart above.

The time constant for an incandescent filament is tens of

milliseconds, which means that tSHUTDOWN will have to be

longer than in most other applications. This places in-

creased SOA demands on the MOSFET during a short

circuit, requiring that a larger than normal device be used.

A protected high current lamp driver application is shown

in Figure 18.

TYPICAL APPLICATIONS

100k

×

VP0300

INSERT FOR

ZERO POWER

SHUTDOWN

100k

+

CMOS

2N2222

ON/OFF

1N4148

1

BOOST DR

16

BOOST

2 V+

0.01µF

3

BIAS

15

T GATE DR

14

T GATE FB

10µF

4 ENABLE

5

FAULT

13

T SOURCE

LT1158 SENSE+ 12

6 INPUT

SENSE– 11

7

GND

V+ 10

Q1, Q2: IRLZ44 (LOGIC-LEVEL)

IRFZ44 (STANDARD)

L1: HURRICANE LAB

HL-KK122T/BB

8

B GATE FB

9

B GATE DR

24k

1000pF

RS: VISHAY/DALE TYPE LVR-3

VISHAY/ULTRONIX RCS01, SM1

ISOTEK CORP. ISA-PLAN SMR

CONSTANT OFF TIME CURRENT MODE CONTROL LOOP

( ) FREQUENCY = 1

tOFF

1

–

VOUT

VIN

WHERE tOFF ≈ 10µs

5V TO 10V INPUT (USE LOGIC-LEVEL Q1, Q2)

8V TO 20V INPUT (USE STANDARD Q1, Q2

AND CONNECT BOOST DIODE TO PIN 1)

Q1 + 500µF

LOW ESR

0.1µF 680k

100Ω

100Ω

Q2

SHORT-CIRCUIT

L1

22µH

RS CURRENT = 8A

0.015Ω

+3.3V/6A

+

–

OUTPUT

1000µF

LOW ESR

510Ω 1N4148

1

8

0.05µF 1k 2

7

LT1431

3

6

4

5

1.62k

1%

4.99k

1%

200pF

LT1158 F10

Figure 10. High Efficiency 3.3V Step-Down Switching Regulator (Requires No Heatsinks)

15

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