DESCRIPTION TO-39 TO-18 INTERNAL SCHEMATIC DIAGRAM 2N2218/2N2219 approved to CECC 50002- 100, 2N2221/2N2222 approved to CECC 50002-101 available on request. The 2N2218, 2N2219, 2N2221 and 2N2222 are silicon planar epitaxial NPN transistors in Jedec TO-39 (for 2N2218 and 2N2219) and in Jedec TO-18 (for 2N2221 and 2N2222) metal cases. They are designed for high-speed switching applications at collector currents up to 500 mA, and feature useful current gain over a wide range of collector current, low leakage currents and low saturation voltages.