2N4870 Unijunction Transistor (UJT) TO-92 Type Package Description: The 2N4870 is 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 = +25C unless other specified) RMS Power Dissipation, PD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300mW Derate Above 25C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0mW/C RMS Emitter Current, IE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA Peak-Pulse Emitter Current (Note 1), IE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5A Emitter Reverse Voltage, VB2E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30V Interbase Voltage (Note 2), VB2B1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35V Operating Junction Temperature Range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to +125C Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to +150C Note 1. Duty cycle 1%, PRR = 10 PPS Note 2. Based upon power dissipation at TA = +25C Electrical Characteristics: (TA = +25C unless other specified) Parameter Min Typ Max 0.56 - 0.76 4.0 6.0 9.1 k VB2B1 = 3V, IE = 0, TA = -65 to +125C 0.1 - 0.9 %/C Emitter Saturation Voltage VBE1(sat) VB2B1 = 10V, IE = 50mA, Note 4 - 2.5 - V Modulated Interbase Current IB2(Mod) VB2B1 = 10V, IE = 50mA - 15 - mA VB2E = 30V, IB1 = 0 - 0.005 1.0 A - 1.0 5.0 A 2.0 5.0 - mA 3.0 6.0 - V Intrinsic Standoff Ratio Interbase Resistance Interbase Resistance Temperature Coefficient Emitter Reverse Current Symbol Test Conditions VB2B1 = 10V, Note 3 RBB RBB IEB2O Peak-Point Emitter Current IP VB2B1 = 25V Valley-Point Current IV VB2B1 = 20V, RB2 = 100, Note 4 Base-One Peak Pulse Voltage VOB1 Unit Note 3. Intrinsic standoff ratio, is defined in terms of peak-point voltage, VP, by means of the equation: VP = VB2B1 + VF, where VF is approximately 0.49 volts at +25C @ IF = 10A and decreases with temperature at approximately 2.5mV/C. Components R1, C1, and the UJT form a relaxation oscillator, the remaining circuitry serves as a peak-voltage detector. The forward drop of Diode D1 compensates for VF. To use, the "call" button is pushed, and R3 is adjusted to make the current meter, M1, read full scale. When the "call" button is released, the value of is read directly from the meter, if full scale on the meter reads 1.0. Note 4. Use pulse techniques: PW 300s, duty cycle 2.0% to avoid internal heating, which may result in erroneous readings. .135 (3.45) Min .210 (5.33) Max Seating Plane .021 (.445) Dia Max .500 (12.7) Min B E B2 .100 (2.54) .050 (1.27) .165 (4.2) Max .105 (2.67) Max .205 (5.2) Max .105 (2.67) Max