Varistor Products

©2010 Littelfuse, Inc.

Revision: May 11, 2010

SM20 Series Varistor

Surface Mount Varistors > SM20 Series

Specifications are subject to change without notice.

Please refer to www.littelfuse.com/series/sm20.html for current information.

Repetitive Surge Capability

V175SM20 - V320SM20

10,000

2,000

200

100

50

20

10

5

2

500

20

100

1,000

10,000

IMPULSE DURATION (μs)

1

2

MODEL SIZE 20mm

V175SM20 - V320SM20

INDEFINITE

1,000

10

5,000

1

For applications exceeding 85ºC ambient temperature, the peak

surge current and energy ratings must be reduced as shown below

Peak Pulse Current Test Waveform for Clamping Voltage

Peak Current, Energy and Power Derating Curve

0

T = Time from 10% to 90% of Peak

T

T

Example - For an 8/20 μs Current Waveform:

8μs = T

20μs = T

0

50

100

TIM E

t

1

t

t

O

1

100

90

80

70

60

50

40

30

20

10

0

-55

50

60

70

80

90

100 110

120 130 140 150

SM20 Series Ratings & Specifications

Maximum Rating (85°C)

Specifications (25°C)

Continuous

Transient

Varistor Voltage

at 1mA DC

Test Current

Maximum

Clamping

Voltage

8 x 20 μs

Typical

Capacitance

f = 1MHz

V

RMS

V

DC

Energy

10 x 1000μs

Peak Current

8 x 20μs

Part

Number

Branding

V

M(AC)

V

M(DC)

W

TM

1x pulse

I

TM

1x pulse

V

V

V

C

I

PK

C

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(A)

(pF)

V26SM20

26SM20

20

26

20

160 (note 1)

2000

32

(10mA)

40

(10mA)

63

20

12000

V175SM20

175SM20

175

225

90

6500

247

303

455

100

1400

V230SM20

230SM20

230

300

122

6500

324

396

595

100

1100

V250SM20

250SM20

250

330

130

6500

354

429

650

100

1000

V275SM20

275SM20

275

369

140

6500

389

473

710

100

900

V300SM20

300SM20

300

405

165

6500

420

517

775

100

800

V320SM20

320SM20

320

420

150

6500

462

540

810

100

750

1. Energy rating for impulse duration of 30ms minimum to one half of peak current (automotive load dump).