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13

307C Overcurrent Thermistors

Vishay Cera-Mite

Document Number: 23089

Revision 14-May-02

ceramite.support@vishay.com

PTCR Overcurrent Protection

VISHAY

CURRENT CURRENT

TEMP. NOMINAL

PART

mA

mA

Ohms

°C

mm

NUMBER

110

220

30

105

6.5

307C1127

100

200

15

70

8

307C1128

100

200

20

80

8

307C1126

110

220

18

80

8

307C1268

120

240

15

80

8

307C1129

140

280

15

105

8

307C1435

110

220

15

70

9.5

307C1134

130

260

15

80

9.5

307C1130

140

280

9

70

9.5

307C1436

150

300

10

80

9.5

307C1437

Note 1

Note 2

Note 3

Fig P-5

Fig P-6

PTC THERMISTORS FOR

TELECOMMUNICATIONS

PTC Thermistors provide protection

for large digital switches. Vishay Cera-

Mite has pioneered this field with

ceramic PTC thermistors working

closely with major telephone equip-

ment and telephone protection

manufacturers. The requirements are

dynamic, as switch makers continually

strive to protect at lower levels. Vishay

Cera-Mite participates with industry

standard technical committees to

establish common definitions and

understanding of this new tech-

nology.

Over-voltage

Pressure

Contact

Line

Tip

C.O.

Tip

Ground

C.O. Ring

Over-Current

Pressure

Contact

PTCR

C.O. Ring

To Battery

OV

PTCR

C.O. Tip

Leaded PTCR

PTCR

C.O. Tip

C.O. Ring

Line Ring

Line Tip

OV

PTCR

PTC THERMISTOR PELLETS FOR TELECOMMUNICATIONS

Table 2

Fig P-7

Rated Voltage = 60 V

DC

Rated Current = 3A

Maximum Voltage = 220 Vr m s

Fig P-8

Time-Trip Curves for Popular Telecom Pellets

Note 1

Hold and trip currents

are specified at

25°C ambient.

Note 2

resistance at 25°C with

tolerance of ± 20%.

Note 3

All pellets have silver elec-

trodes suitable for pressure

contact mounting.

INTERRUPTING CAPACITY ESTIMATES

Under unusual circumstances, telecommunication lines may

be subjected to high surge currents as might occur from

lightning effects or accidental crossing with power lines or

transformer primaries.

Fig P-10 shows trip time curves for higher currents. Estimated

interrupting capability data is also shown in Table 3 and

is expressed as “I

conducted in accordance with UL 497A and CSA 22.2 No.

0.7-M1985.

The data shown is for reference. Specific short circuit data or

interrupting capability is partially determined by the mounting

means and circuit application.

Fig P-9

Fig P-10

Time VS. Current Curves for High Current Surges (25°C)

D

Base

Electrode

T

Silver

Electrode

Solid Ceramic

Disc

2.5mm

Current (Amperes)

Operating Time to 50% Current

0

.05

1

1.5

2

2.5

3

307C1130

307C1129

307C1128

307C1126

307C1127

PTCR

Scope

Time

To

1/2

Current (Amperes)

2

4

6

8

10

12

14

16

18

20

10,000

1,000

100

10

10 ohm, 80°C Pellets for

Diameters (mm

14.5mm

12.5mm

11.0mm

9.5mm

8.0mm

6.5mm

Variable

Voltage

Source

0-600V

60Hz

Current

Probe or

26 AWG

Pair

A = 1.5 sec.

B = 5 sec.

C = 30 min.

A

B

C

PTCR

Current

Limiter

15

85

275

Timed Interrupter

100

10

1

0.1