This shunt regulator can protect power supplies from voltage spikes generated by motor drivers they are connected to. This version has a fixed set point of 26.4 V, a shunt resistance of 2.80 ohms, and a total of 32 SMT shunt resistors populated on both sides of the PCB (this is the higher-power version). An external potentiometer can also be added to change the set voltage.
Most motor drivers encounter scenarios (typically when a motor is slowing down) where energy from a motor is returned to the power supply. That power supply is commonly a battery that can tolerate the current fed into it, and the reverse current can be a welcome “regenerative braking” feature that extends the total life of the battery. For applications that do not involve batteries, however, that reverse current can be a problem when the power supply does not deal with the current well. In some cases, the voltage can build up to a high value that kills the motor driver or power supply. In other scenarios, power supplies have “over-voltage protection” features that detect the output voltage going up and shut down the power supply.
Pololu’s shunt regulators are designed for such scenarios, with fixed values available with ±3% accuracy for some common voltages. To use the shunt regulator, install it across (in parallel with) your power supply. Under normal conditions, the supply voltage should be below the set point of the shunt regulator, and the regulator should only draw its quiescent current of less than 0.5 mA. However, any voltage spikes above the set point will cause the shunt regulator to draw substantially more current, dissipating energy and limiting the extent of the voltage change.
Warning: The power ratings are intended primarily to indicate the relative average power-handling capabilities of the boards for up to a few seconds. The boards are designed for clamping occasional short (up to tens of ms) pulses, continuous application of a voltage above the set point will destroy the regulator almost instantly (in less than a second).
Dimension: 28.58mm x 20.32mm
- 1 x 26.4V 2.8Ohm 15W Shunt Regulator