2SD1666-S Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 60 V
• Collector-Base Voltage, max: 60 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 3 A
• Collector Dissipation: 25 W
• DC Current Gain (h_fe): 140 to 280
• Transition Frequency, min: 40 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-220F

Here is an image showing the pin diagram of this transistor.The 2SD1666-S transistor can have a current gain of 140 to 280. The gain of the 2SD1666 will be in the range from 70 to 280, for the 2SD1666-Q it will be in the range from 70 to 140, for the 2SD1666-R it will be in the range from 100 to 200.Sometimes the "2S" prefix is not marked on the package - the 2SD1666-S might only be marked "D1666-S".The complementary PNP transistor to the 2SD1666-S is the 2SB1133-S.The BDP949 (SOT-223) is the SMD version of the 2SD1666-S transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the 2SD1666-S with the 2SC1826, 2SC1985, 2SC1986, 2SC2075, 2SC3179, 2SC3252, 2SC3252-S, 2SC3253, 2SC3253-S, 2SC3254, 2SC3254-S, 2SC3255, 2SC3255-S, 2SC3746, 2SC3746-S, 2SC3747, 2SC3747-S, 2SC3748, 2SC3748-S, 2SC3851, 2SC3851A, 2SC4007, 2SC4008, 2SC4550, 2SC4551, 2SC4552, 2SD1134, 2SD1266, 2SD1266A, 2SD1274, 2SD1274A, 2SD1274B, 2SD1354, 2SD1406, 2SD1761, 2SD1913, 2SD1913S, 2SD2012, 2SD2061, 2SD2394, 2SD313, 2SD613, 2SD823, 2SD880, BD203, BD241A, BD241B, BD241C, BD243A, BD243B, BD243C, BD303, BD535, BD537, BD539A, BD539B, BD539C, BD539D, BD543A, BD543B, BD543C, BD545A, BD545B, BD545C, BD797, BD799, BD801, BD807, BD809, BD949, BD951, BD953, BD955, BDT81, BDT81F, BDT83, BDT83F, BDT85, BDT85F, BDT87, BDT87F, BDX77, D44H11, D44H11FP, D44H8, KSD1406, KSD2012, KSD2058, KSD880, KTC2016, KTC2026, KTD1351, MJE15028, MJE15028G, TIP41D or TIP42D.