Cool-Running MOSFETs Deliver High-Efficiency For Class D

A new generation of trench MOSFETs offers high efficiency, cool running temperatures, and quality audio reproduction needed for Class D output stages. The n- and p-channel devices in the ZXM N/P 7 series are rated at 70 V and come in SOT223 and DPAK packages. The MOSFETs’ higher drain-source voltage gives designers extra “headroom,” compared to 60-V parts, allowing them to accommodate significant supply and gate ringing. On-resistances typically are a low 130 mΩ for the n-channel devices and 160 mΩ for the p-channel transistors. This results in low losses, which combine with switching and low gate-charge characteristics to enable output stage efficiencies of better than 90%.

Turn-off time and gate drain charge for the n- and p-channel versions, operating at 10 V, are specified as 17 ns/1.8 nC and 35 ns/3.6 nC, respectively. The ability to handle high drain current allows the MOSFETs to achieve high power delivery in a one-FET circuit, while the low gate drive requirement also lets designers parallel FETs in applications needing higher power levels. Maximum drain currents in SOT223 package are 3.8 A for the n-channel device and 3.7 A for the p-channel version. In the DPAK package, maximum drain currents are 6.1 A and 5.7 A, respectively.