This note explains some of the major problem areas in selecting devices and circuits for automobile use, and demonstrates the use of the Zetex Super E-Line range of transistors in some practical examples.
The note introduces the growing use of electronics in automobiles and the need for power transistors that can handle high‑current loads such as relays, solenoids, lamps and motors. It describes the mechanical and electrical hazards of automotive environments and highlights the advantages of Zetex’s Super E‑Line devices, which use a silicone‑plastic package to allow junction temperatures up to 200 °C.
Several application examples are provided, including reverse‑battery protection, load‑dump clamping, and four‑phase stepper‑motor drivers. Design tables and parameter charts for the ZTX6xx and ZTX7xx series are given, showing voltage, current and power ratings, as well as recommended protection techniques for common automotive transients.
| Maximum junction temperature | 200 °C |
|---|---|
| Power dissipation (copper‑area mounted) | 1.5 W per 1 sq in copper |
| Continuous current rating | 2 A |
They can operate from -40 °C up to a junction temperature of 200 °C.
The ZTX653 is rated for a continuous current of 2 A.