Speaker Protection Board

MOST of those chip amps have the diodes. Explicitly says so in the LM1875 data sheet, and on every generation since. Early single supply stuff often didn’t have this, but those were only a handful of watts.

All IRF type mosfets have them, as do general purpose darlingtons. Be careful, as audio-specific darlingtons from Sanken do not have the diodes.
 
  • Like
Reactions: 1 users
All power MOSFETs have body diodes, its an inherent part of the structure, not a separate device, as the substrate bonds direct to the middle pin and tab. Small signal MOSFETs don't usually have them because the substrate isn't pinned out. Darlington's rarely have extra diodes unless designed specifically for inductive switching. IGBT's don't have body diodes but commonly come packaged with a diode as they are normally used for inductive switching.

Lateral power MOSFETs are different to most in that the substrate is the source (not the drain), but they still have a diode built in the structure.
 
  • Like
Reactions: 1 users