2SD1681-S Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 18 V
• Collector-Base Voltage, max: 20 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 1.2 A
• Collector Dissipation: 10 W
• DC Current Gain (h_fe): 140 to 280
• Transition Frequency, min: 150 MHz
• Operating and Storage Junction Temperature Range: -55 to +125 °C
• Package: TO-126

Here is an image showing the pin diagram of this transistor.The 2SD1681-S transistor can have a current gain of 140 to 280. The gain of the 2SD1681 will be in the range from 70 to 400, for the 2SD1681-Q it will be in the range from 70 to 140, for the 2SD1681-R it will be in the range from 100 to 200, for the 2SD1681-T it will be in the range from 200 to 400.Sometimes the "2S" prefix is not marked on the package - the 2SD1681-S might only be marked "D1681-S".The complementary PNP transistor to the 2SD1681-S is the 2SB1141-S.The BCX68 (SOT-89) is the SMD version of the 2SD1681-S transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the 2SD1681-S with the 2SC1162, 2SC1368, 2SD1380, 2SD1685, 2SD439, 2SD793, 2SD826, 2SD882, BD185, KSD882, KSH882, KTD882 or MJE520.