LT1431

0

1431fd

Typical applicaTions

5V Power Supply Monitor with ±500mV

Window and 50mV Hysteresis

Transfer Function

High Efficiency Buck Converter E = 85% to 89%

COLL

REF

GND-F

GND-S

10**

“HIGH” FOR

OVER VOLTAGE OR

UNDER VOLTAGE

5k

1N4148

COLL

REF

GND-F

GND-S

10**

5k

4k*

1k

6k*

1k

*DETERMINES WINDOW SIZE

V = (R – 5k)(0.5mA)

**SETS HYSTERESIS

LT1431 TA13

LT1431

LT1431

0

0

1

2

3

4

6

1

2

3

4

LT1431 TA14

5

6

5

COLL

1

2

6

5

REF

3

Q3

2N3904

4

8

7

R8*

24.9k

COMP

GND-F

GND-S

LT1431CN8

+

+

R2

1k

C3

0.1µF

C5

0.047µF

C4

0.033µF

R6*

23.7k

5V

2.5A

C6

470µF

16V

0.12

ESR

R7*

24.9k

1431 TA15

Q2

2N3904

D2

BAT85

D4

BAT85

R1

470k

C2

4.7µF

35V

TANT

L1

50µH 3A

R5

680

Q1

VN2222LL

RUN = 0

SHUTDOWN > 3V

R4

100

R3

10k

NOTES: UNLESS OTHERWISE SPECIFIED

1. ALL RESISTANCES ARE IN , 0.25W, 5%

2. ALL CAPACITANCES ARE IN µF, 50V, 10%

3. SHUTDOWN LOGIC STATE MUST BE DEFINED BY A LOGIC GATE OR BY TYING TO GND

1

2

RTN

OFF

1

D1

BAT85

C1

220µF

35V

D3

MBR330

BOLD LINES INDICATE HIGH CURRENT PATHS

*1% FILM RESISTORS

C1: NICHICON UPL1V221MPH

C3, C4, C5: WIMA MKS-2

C6: NICHICON UPL1C471MPH6

D1, D2: PHILIPS BAT85

D3: MOTOROLA MBR330

L1: COILTRONICS CTX50-3-MP

LT1170

GND

FB

3

1

2

4

5