Audio Power Transistors Improve Sound Quality and Reliability With On-Chip Compensation

For high-performance audio amplifiers that use bias trimming to prevent output transistors overheating, ON Semiconductor ThermalTrak™ transistors implement bias compensation internally to save part count and improve temperature stability.

With compensation on-chip, the NJL4281D N-type and NJL4302D P-type bipolar power transistors respond instantly to die-temperature changes, reducing bias levels to stabilise temperature variations that can distort the output signal. Amplifiers using discrete bias-correction circuitry, which is normallymounted on the heatsink near the transistors, have inherently slower temperature response. The faster response of ThermalTrak transistors not only prevents harmonic distortion due to transistor overheating, but also results in smaller adjustments to bias levels leading to greater bias stability. Both advantages contribute to improved audio performance in the end product.

Also, by reacting faster to prevent overheating, the integrated bias-control circuitry prevents the output transistors fromentering thermal runaway and thereby enhances the amplifier’s reliability. All external components for bias control are also eliminated, delivering a valuable bill-of-materials saving.

 

FEATURES 230W, 15A bipolar power transistor Thermally-matched bias diode Absolute thermal integrity High Safe Operating Area (SOA)

APPLICATIONS High-end consumer audio amplifiers and receivers Professional audio amplifiers Theatre and stadium sound systems Public Address (PA) systems

 

 

ON Semiconductor / NJL428D/NJL4302D