SLYT816 October   2021 TPS548B27 , TPS548B28

 

  1. Introduction
  2. Design considerations
  3. Layout comparison
  4. Thermal comparison
  5. Efficiency comparison
  6. Load transient comparison
  7. Switch-node ringing comparison
  8. Conclusion
  9. Additional Resources
  10. 10Important Notice

Switch-node ringing comparison

The effects of parasitic inductance are visible when observing the switch-note ringing of the power supply’s high-side MOSFET. Under close inspection of Figure 7-1 and Figure 7-2, the voltage overshoot of the Enhanced HotRod QFN package design was 0.1 V lower than the HotRod package design shown in Table 7-1, which is noticeable. It is difficult to ascertain where the difference in voltage ringing originates, but it is safe to assume that the Enhanced HotRod QFN package does not degrade switch-node ringing performance. It is probable, however, that mechanical construction of the Enhanced HotRod QFN package slightly improves switch-node ringing of the high-side MOSFET by reducing the internal parasitic inductance of the IC.

Table 7-1 Switch-node ringing conditions and results
Package VIN VOUT FSW Ringing
Enhanced HotRod QFN package 12 V 1 V 600 kHz 0.7 V
HotRod package 0.8 V
GUID-20210908-SS0I-4QJH-WS0F-VZM41306KZGF-low.jpg Figure 7-1 Enhanced HotRod QFN package high-side FET ringing
GUID-20210908-SS0I-1BKM-5KXQ-KMWWS2JZWFMQ-low.jpg Figure 7-2 HotRod package high-side FET ringing