Unijunction Transistors (UFT)

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Manufacturers
    • Motorola
    • Nte Electronics
    • Onsemi
    • Texas Instruments
Configuration
    • SINGLE
Surface Mount
    • NO
Maximum Power Dissipation (Abs)
    • .3 W
    • .36 W
    • .45 W
Package Body Material
    • METAL
    • PLASTIC/EPOXY
Transistor Application
    • SWITCHING
Maximum Emitter Current
    • 50 mA
    • 70 mA
Terminal Form
    • WIRE
Package Shape
    • ROUND
No. of Elements
    • 1
Maximum Inter-base Voltage
    • 25 V
    • 35 V
    • 55 V
    • 65 V
No. of Terminals
    • 3
Package Style (Meter)
    • CYLINDRICAL
Sub-Category
    • Unijunction Transistors
Maximum Operating Temperature
    • 125 Cel
    • 140 Cel
    • 150 Cel
    • 200 Cel
Transistor Element Material
    • SILICON
Minimum Operating Temperature
    • -55 Cel
    • -65 Cel
Terminal Finish
    • TIN LEAD
    • Tin/Lead (Sn/Pb)
Minimum Intrinsic Stand-off Ratio
    • .47
    • .51
    • .54
    • .55
    • .56
    • .62
    • .68
    • .7
    • .72
    • .74
Maximum Static Inter-Base Resistance
    • 12 kohm
    • 6.8 kohm
    • 8 kohm
    • 8.5 kohm
    • 9.1 kohm
Terminal Position
    • BOTTOM
JESD-30 Code
    • O-MBCY-W3
    • O-PBCY-W3
Case Connection
    • BASE2
    • ISOLATED
Qualification
    • Not Qualified
Maximum Intrinsic Stand-off Ratio
    • .62
    • .67
    • .68
    • .69
    • .75
    • .8
    • .82
    • .85
    • .86
Minimum Static Inter-Base Resistance
    • 4 kohm
    • 4.7 kohm
    • 6 kohm
    • 6.2 kohm
JEDEC-95 Code
    • TO-18
    • TO-206AA
    • TO-39
    • TO-5
    • TO-92
JESD-609 Code
    • e0
Minimum Valley Point Current
    • 1 mA
    • 12 mA
    • 2 mA
    • 4 mA
    • 6 mA
    • 8 mA
Maximum Time At Peak Reflow Temperature (s)
    • NOT SPECIFIED
Peak Reflow Temperature (C)
    • NOT SPECIFIED
Maximum Peak Point Current
    • .4 mA
    • 1 mA
    • 12 mA
    • 15 mA
    • 2 mA
    • 25 mA
    • 4 mA
    • 5 mA
    • 6 mA
Reset All
Part RoHS Manufacturer Configuration Surface Mount Maximum Power Dissipation (Abs) Package Body Material Transistor Application Maximum Emitter Current Terminal Form Package Shape No. of Elements Maximum Inter-base Voltage No. of Terminals Package Style (Meter) Sub-Category Maximum Operating Temperature Transistor Element Material Minimum Operating Temperature Terminal Finish Minimum Intrinsic Stand-off Ratio Maximum Static Inter-Base Resistance Terminal Position JESD-30 Code Case Connection Qualification Maximum Intrinsic Stand-off Ratio Minimum Static Inter-Base Resistance JEDEC-95 Code JESD-609 Code Minimum Valley Point Current Maximum Time At Peak Reflow Temperature (s) Peak Reflow Temperature (C) Maximum Peak Point Current

2N2419A

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.56

6.8 kohm

BOTTOM

O-MBCY-W3

.68

4.7 kohm

TO-18

e0

8 mA

12 mA

2N494C

Onsemi

SINGLE

NO

.45 W

METAL

SWITCHING

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.62

9.1 kohm

BOTTOM

O-MBCY-W3

.75

6.2 kohm

TO-5

e0

8 mA

2 mA

W4893

Onsemi

NO

Unijunction Transistors

.55

12 kohm

.82

4 kohm

2 mA

2 mA

2N2421A

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.62

6.8 kohm

BOTTOM

O-MBCY-W3

.75

4.7 kohm

TO-18

e0

8 mA

12 mA

P2647

Onsemi

NO

Unijunction Transistors

.68

9.1 kohm

.82

4.7 kohm

4 mA

5 mA

2N2417B

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.51

6.8 kohm

BOTTOM

O-MBCY-W3

.62

4.7 kohm

TO-18

e0

8 mA

6 mA

P2646

Onsemi

NO

Unijunction Transistors

.56

9.1 kohm

.75

4.7 kohm

4 mA

5 mA

2N2418A

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.51

9.1 kohm

BOTTOM

O-MBCY-W3

.62

6.2 kohm

TO-18

e0

8 mA

12 mA

2N1671C

Onsemi

SINGLE

NO

.45 W

METAL

SWITCHING

50 mA

WIRE

ROUND

1

35 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.47

9.1 kohm

BOTTOM

O-MBCY-W3

.62

4.7 kohm

TO-5

e0

8 mA

2 mA

2N2417A

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.51

6.8 kohm

BOTTOM

O-MBCY-W3

.62

4.7 kohm

TO-18

e0

8 mA

12 mA

2N490C

Onsemi

SINGLE

NO

.45 W

METAL

SWITCHING

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.51

9.1 kohm

BOTTOM

O-MBCY-W3

.62

6.2 kohm

TO-5

e0

8 mA

2 mA

2N2418B

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.51

9.1 kohm

BOTTOM

O-MBCY-W3

.62

6.2 kohm

TO-18

e0

8 mA

6 mA

2N2420A

Onsemi

SINGLE

NO

.3 W

METAL

70 mA

WIRE

ROUND

1

65 V

3

CYLINDRICAL

Unijunction Transistors

140 Cel

SILICON

-65 Cel

Tin/Lead (Sn/Pb)

.56

9.1 kohm

BOTTOM

O-MBCY-W3

.68

6.2 kohm

TO-18

e0

8 mA

12 mA
Unijunction Transistors (UFT)

Unijunction Transistors (UJT) are three-terminal semiconductor devices that are used in a variety of applications such as timing, triggering, and oscillation circuits.

A UJT consists of a lightly doped n-type silicon bar with a p-type material implanted in the center, forming two p-n junctions. The two outer ends of the n-type bar are the emitter (E) and collector (C) terminals, while the p-type material in the center is the base (B) terminal. The UJT has a high input impedance and a low output impedance.

When a voltage is applied to the emitter terminal, it causes a small forward bias on the emitter-base junction, which allows a small current to flow into the base region. As the voltage across the UJT increases, the emitter-base junction reaches a point where the current into the base region increases rapidly. This point is known as the "peak-point voltage" or Vp. Once the emitter-base junction is forward biased, the UJT behaves like a negative resistance device, with the current increasing as the voltage decreases.

UJTs are often used in relaxation oscillator circuits and as voltage-controlled switches. In oscillator circuits, the UJT is used to provide a timing signal that can be used to trigger other devices, such as thyristors or triacs. In switching applications, the UJT is used to control the turn-on and turn-off of other devices, such as transistors or SCRs.