| Equivalent | BUT21 | |
| Type | Transistor Silicon NPN | |
| Case | TO220 | |
| Manufacturer | Generic | |
| Vbr CEO | 450 | |
| Max. PD (W) | 20 | |
| t(f) Max. (S) | 700n | |
| Min hFE | 6.0 | |
| Ic Max. (A) | 5.0 | |
| @Ic (test) (A) | 3.0 | |
| Icbo Max. @Vcb Max. (A) | 1.0m | |
| Polarity | NPN | |
| Derate Above 25°C | 570n | |
| Oper. Temp (°C) Max. | 140 | |
| @VCE (V) | 1.5 | |
| Pinout Equivalence Number | 3-15 | |
| Surface Mounted Yes/No | NO | |
| Maximum Collector Power Dissipation (Pc) | 100 W | |
| Maximum Collector-Base Voltage |Vcb| | 850 V | |
| Maximum Collector-Emitter Voltage |Vce| | 450 V | |
| Maximum Emitter-Base Voltage |Veb| | 1.5 V | |
| Maximum Collector Current |Ic max| | 5 A | |
| Max. Operating Junction Temperature (Tj) | 200 °C | |
| Forward Current Transfer Ratio (hFE), MIN | 25 | |
| SKU | 1272458 | |