13.25.5 Motor Current Sense Circuitry

A sense resistor in series with the bridge ground return provides a current signal for feedback. This resistor should be non-inductive to minimize ringing from high di/dt. Any inductance in the power circuit represents potential problems in the form of additional voltage stress and ringing, as well as increasing switching times. While impractical to eliminate, careful layout and bypassing will minimize these effects. The output stage should be as compact as heat sinking will allow, with wide, short traces carrying all pulsed currents. Each half-bridge should be separately bypassed with a low-ESR/ESL capacitor, decoupling it from the rest of the circuit. Some layouts will allow the input filter capacitor to be split into three smaller values and serve double duty as the half-bridge bypass capacitors.