Glossary · Motion control and drives
Undervoltage lockout (UVLO)
Also known as: UVLO, Undervoltage protection
German: Unterspannungsabschaltung
In power electronics, undervoltage lockout (UVLO) is a built-in function of a driver or IC that keeps the power stage switched off while the supply voltage is below a defined threshold, and switches it off when the voltage falls below it, so that the circuit doesn't operate in an undefined state.
- Motion control
In one sentence
Undervoltage lockout keeps a driver's power stage off while the supply voltage is below a threshold, avoiding undefined operation.
Example
When a battery-powered inspection robot's supply sags below 7 V during a load peak, the motor driver's UVLO disables the outputs until the voltage recovers.
How it applies
- Engineering: UVLO thresholds have hysteresis, so the output doesn't toggle around the threshold. Many ICs monitor both the motor supply and the logic supply.
- Commissioning: Supplies that sag at acceleration peaks trigger UVLO intermittently; check the supply under load, not only at idle.
- Operation: A UVLO event disables the motor, which may lose its position and holding torque; after recovery, homing may be needed.
- Documentation: Give the supply voltage range and state what happens below it (outputs off, position lost). UVLO is equipment protection, not a safety function, and doesn't bring the machine into a defined safe state on its own.