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Page <1> V1.010/09/12
Unijunction Transistor
Description:
A PN unijunction transistor in a TO–92 type package designed for use in pulse
and timing circuits, sensing circuits and thyristor trigger circuits
Absolute maximum Ratings :
(Ta = +25°C unless otherwise specied)
Power Dissipation, Pd : 300mW
Derate Above 25°C : 3.0mW/°C
RMS Emitter Current, Ie(rms) : 50mA
Peak Pulse Emitter Current (Note 1) Current, ie : 1.5A
Emitter Reverse Voltage, Vb2e : 30V
Interbase Voltage, Vb2b1 : 35V
Operating Junction Temperature Range, Tj : -65°C to +125°C
Storage Temperature Range, Tstg : -65°C to +150°C
Notes:
1. Duty Cycle <= 1% PRR = 10PPS.
2. Based upon power dissipation at Ta = +25°C
3. Intrinsic standoff ratio is essentially constant with temperature and interbase voltage and is dened by the
equation:
Vp – Vbb + Vd
Where: Vp = Peak Point Emitter Voltage; Vbb = interbase Voltage;
Vd = Junction Diode Drop (~0.5V).
5. Use Pulse techniques: Pulse width ~ 300µS, Duty Cycle <= 2% to avoid internal heating due to inter-
base modulation which may result in erroneous readings
Electrical Characteristics: (Ta = +25ºC Unless otherwise specied)
Parameter Symbol Test Conditions Min Typ Max Unit
Instrinsic Standoff Ratio Vb2b1 = 10V, Note3 0.56 - 0.75 -
Interbase Resistance rbb 4 6 9.1 kΩ
Interbase Resistance Temperature
Coefcient 0.1 - 0.9 %/ºC
Emitter Saturation Voltage Veb1(sat) Vb2b1 = 10V, Ie = 50mA, Note 4 - 2.5 - V
Modulated interbase Current Ib2(mod) Vb2b1 = 10V, Ie = 50mA - 15 - mA
Emitter Reverse Current Ieb20 Vb2e = 30V, Ib1 = 0 - 0.005 1 µA
Peak Point Emitter Current IpVb2b1 = 25V - 1 5 µA
Valley Point Current IvVb2b1 = 20V, Rb2 = 100Ω, Note 4 2 5 - mA
Base-One Peak Pulse Voltage VOb13 6 - V
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Page <2> V1.010/09/12
Unijunction Transistor
Important Notice : This data sheet and its contents (the “Information”) belong to the members of the Premier Farnell group of companies (the “Group”) or are licensed to it. No licence is granted
for the use of it other than for information purposes in connection with the products to which it relates. No licence of any intellectual property rights is granted. The Information is subject to change
without notice and replaces all data sheets previously supplied. The Information supplied is believed to be accurate but the Group assumes no responsibility for its accuracy or completeness, any
error in or omission from it or for any use made of it. Users of this data sheet should check for themselves the Information and the suitability of the products for their purpose and not make any
assumptions based on information included or omitted. Liability for loss or damage resulting from any reliance on the Information or use of it (including liability resulting from negligence or where the
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Multicomp is the registered trademark of the Group. © Premier Farnell plc 2012.
Part Number Table
Description Part Number
Unijunction Transistor, TO-92, PN 2N4870
Dim Min Max
A 4.3 5.33
B 4.45 5.2
C 3.18 4.19
D 0.41 0.55
E 0.35 0.5
F 5º
G 1.14 1.4
H 1.14 1.53
K 12.7 -
Dimensions : Millimetres
