digitron semiconductors 144 market street kenilworth nj 07033 usa phone +1.908.245-7200 2N4948, 2n4949 pn unijunction transistors maximum ratings rating symbol value unit rms power dissipation (1) p d 360 mw rms emitter current i e 50 ma peak pulse emitter current (2) i e 1.0 amp emitter reverse voltage v b2e 30 volts storage temperature range t stg -65 to 200 c note 1: derate 2.4mw/c increase in ambient temperature. total power dissipation must be limited by external circuitry. interba se voltage limited by power dissipation: v b2b1 = ( r bb *p d) note 2: capacitance discharge current must fail to 0.37a within 3.0ms and prr 10pps. electrical characteristics (t a = 25c unless otherwise noted) characteristic symbol min typ max unit intrinsic standoff ratio (v b2b1 = 10v) (1) 2N4948 2n4949 0.55 0.74 - - 0.82 0.86 - interbase resistance (v b2b1 = 3.0v, i e = 0) r bb 4.0 7.0 12.0 kohms interbase resistance te mperature coefficient (v b2b1 = 3.0v, i e = 0, t a = -65 to 100c r bb 0.1 - 0.9 %/c emitter saturation voltage (v b2b1 = 10v, i e = 50ma) (2) v eb1(sat) - 2.5 3.0 volts modulated interbase current (v b2b1 = 10v, i e = 50ma) i b2(mod) 12 15 - ma emitter reverse current (v b2e = 30v, i b1 = 0) (v b2e = 30v, i b1 = 0, t a = 125c) i eb20 - - 5.0 - 10 1.0 na a peak point emitter current (v b2b1 = 25v) 2N4948 2n4949 i p - - 0.6 0.6 2.0 1.0 a valley point current (v b2b1 = 20v, r b2 = 100ohms) (2) i v 2.0 4.0 - ma base-one peak pulse voltage (3) 2n4949 2N4948 v ob1 3.0 6.0 5.0 8.0 - - volts maximum oscillation frequency f (max) - 1.25 - mhz note 1: intrinsic standoff ratio: = (v p -v eb1 )/v b2b1 , where v p = peak point emitter voltage, v b2b1 = interbase voltage, and v eb1 = emitter to base-one junction diode drop ( 0.45v @ 10a) note 2: use pulse techniques: pw 300s 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 ampl itude for applications in scr firing circuits and other types of pulse circuits. sales@digitroncorp.com fax +1.908.245-0555 www.digitroncorp.com rev. 20121019
digitron semiconductors 144 market street kenilworth nj 07033 usa phone +1.908.245-7200 2N4948, 2n4949 pn unijunction transistors available non-rohs (standard) or rohs compliant (add pbf suffix). available as ?hr? (high reliability) screened per mil-prf- 19500, jantx level. add ?hr? suffix to base part number. sales@digitroncorp.com fax +1.908.245-0555 www.digitroncorp.com rev. 20121019
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