2N4948, 2N4949 PN UNIJUNCTION TRANSISTORS High-reliability discrete products and engineering services since 1977 FEATURES Available as “HR” (high reliability) screened per MIL-PRF-19500, JANTX level. Add “HR” suffix to base part number. Available as non-RoHS (Sn/Pb plating), standard, and as RoHS by adding “-PBF” suffix. MAXIMUM RATINGS Rating RMS power dissipation(1) RMS emitter current Peak pulse emitter current (2) Symbol Value Unit PD 360 mW Ie 50 mA ie 1.0 Amp Emitter reverse voltage VB2E 30 Volts Storage temperature range Tstg -65 to 200 °C Note 1: Derate 2.4mW/°C increase in ambient temperature. Total power dissipation must be limited by external circuitry. Interbase voltage limited by power dissipation: V B2B1 = √(RBB*PD) Note 2: Capacitance discharge current must fail to 0.37A within 3.0ms and PRR ≤ 10PPS. ELECTRICAL CHARACTERISTICS (TA = 25°C unless otherwise specified) Characteristic Intrinsic standoff ratio (VB2B1 = 10V)(1) 2N4948 2N4949 Symbol Min Typ Max Unit η 0.55 0.74 - 0.82 0.86 - 4.0 7.0 12.0 0.1 - 0.9 - 2.5 3.0 12 15 - Interbase resistance (VB2B1 = 3.0V, IE = 0) RBB Interbase resistance temperature coefficient (VB2B1 = 3.0V, IE = 0, TA = -65° to 100°C αRBB kohms %/°C Emitter saturation voltage (VB2B1 = 10V, IE = 50mA)(2) VEB1(sat) Modulated interbase current (VB2B1 = 10V, IE = 50mA) IB2(mod) Emitter reverse current (VB2E = 30V, IB1 = 0) (VB2E = 30V, IB1 = 0, TA = 125°C) IEB20 - 5.0 - 10 1.0 nA µA IP - 0.6 0.6 2.0 1.0 µA 2.0 4.0 - VOB1 3.0 6.0 5.0 8.0 - Volts f(max) - 1.25 - MHz Peak point emitter current (VB2B1 = 25V) 2N4948 2N4949 Valley point current (VB2B1 = 20V, RB2 = 100ohms)(2) IV Volts mA mA Base-one peak pulse voltage (3) 2N4949 2N4948 Maximum oscillation frequency Note 1: Intrinsic standoff ratio: η = (VP-VEB1)/VB2B1, where VP = peak point emitter voltage, VB2B1 = interbase voltage, and VEB1 = emitter to base-one junction diode drop (≈ 0.45V @ 10µA) Note 2: Use pulse techniques: PW ≈ 300µs duty cycle ≤ 2% to avoid internal heating due to interbase modulation which may result in erroneous readings. Note 3: Base-one peak pulse voltage is measured in circuit of Figure 3. This specification is used to ensure minimum pulse amplitude for applications in SCR firing circuits and other types of pulse circuits. Rev. 20150520 High-reliability discrete products and engineering services since 1977 2N4948, 2N4949 PN UNIJUNCTION TRANSISTORS MECHANICAL CHARACTERISTICS Case TO-18 Marking Alpha-numeric Polarity See below Dim CD CH HD LC LD LL LU L1 L2 P Q TL TW α TO-18 Inches Millimeters Min Max Min Max 0.178 0.195 4.520 4.950 0.170 0.210 4.320 5.330 0.209 0.230 5.310 5.840 0.100 TP 2.540 TP 0.016 0.021 0.410 0.530 0.500 0.750 12.700 19.050 0.016 0.019 0.410 0.480 - 0.050 0.250 0.100 0.040 0.028 0.048 0.036 0.046 45°TP - 1.270 6.350 2.540 1.020 0.710 1.220 0.910 1.170 45°TP Rev. 20150520