This application note describes the main features and applications of the Zetex FMMT618 and FMMT619 transistor series. These devices are SOT23 packaged, and offer high current, high gain and low voltage drop, making them ideal for switching 6A loads.
The note introduces the new Zetex FMMT618 and FMMT619 SOT‑23 transistors, which deliver up to 6 A peak current, low saturation voltage and a power rating of 625 mW in a compact package. It explains the custom SOT‑23 frame and Matrix chip technology that enable the high current capability and low VCE(sat).
Several application examples are shown, including IR remote‑control drivers, LED matrix displays, step‑up converters, stepper‑motor drivers and hybrid DC‑DC converters. The document also compares the devices with standard SOT‑89 and SOT‑223 parts, highlighting the reduced PCB area and improved efficiency.
| VCE0 (breakdown voltage) | up to 50 V |
|---|---|
| Maximum collector current (continuous) | 6 A peak |
| Maximum collector current (on‑state) | 2.5 A |
| Power dissipation (Ptot) | 625 mW |
| VCE(sat) (typical) | 200 mV max @ 2.5 A |
| Thermal resistance (Zetex SOT23) | ~100 °C/W |
| Saturation voltage (FMMT618) | 130 mV @ 2.5 A |
| Saturation voltage (FMMT619) | 125 mV @ 1 A |
Both transistors can handle up to 6 A peak current.
The FMMT618 typically shows a saturation voltage of about 130 mV at 2.5 A.