This part is a kind of semiconductor called B1721.

Function of this product has Silicon Power Transistors.

Manufacturers : NEC

Image and pinout :

Some of the text within the PDF file :

Silicon Power Transistors 2SB1721 PNP 2SB1721 IC OA FA 2SB1721 2SB1721-Z TO-251 MP-3 TO-252 MP-3Z hFE 100 VCE = –5.0 V, IC = –0.5 A Z TA = 25°C - VCBO - VCEO - VEBO IC(DC) IC(pulse) PW 10 ms, Duty Cycle 50% IB(DC) PT Tj Tstg TC = 25°C TA = 25°C –60 –60 –7.0 –3.0 –6.0 V V V A A –1.0 20 1.0 150 –55 +150 A W W °C °C (TO-251) (TO-252) D16287JJ2V0DS00 July 2006 NS CP(K) PDF 2 2002 TA = 25°C PW ICBO hFE1 hFE2 VCE(sat) VBE(sat) fT Cob ton tstg tf 350 μs, Duty Cycle VCB = −60 V, IE = 0 A VCE = −5.0 V, IC = −0.5 A VCE = −5.0 V, IC = −3 A IC = −3.0 A, IB = −300 mA IC = −3.0 A, IB = −300 mA VCE = −5.0 V, IC = −0.5 A VCB = −10 V, IE = 0 A, f = 1.0 MHz IC = −2.0 A, RL = 15 Ω, IB1 = –IB2 = −200 mA, VCC –30 V 2% ton tstg tf [ ... ]

B1721 PDF Datasheet Download