Undervoltage-lockout

Undervoltage Lockout (UVLO) is a protective feature commonly found in power supply devices and integrated circuits. This feature is designed to prevent electronic devices from operating at inadequate power supply voltages.

Overview

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A typical undervoltage lockout circuit

The undervoltage lockout function is crucial in the operation of many electronic devices. It ensures that the device does not operate under a condition where the supply voltage is below a specified minimum. This is important because operating a device below its minimum supply voltage can lead to unpredictable behavior or even damage to the device.

The UVLO circuit monitors the input voltage and turns off the device when the voltage falls below the UVLO threshold. The device remains off until the voltage rises above the UVLO threshold plus some hysteresis voltage. This hysteresis prevents the device from turning on and off rapidly when the voltage is near the UVLO threshold.

Applications

Undervoltage lockout is used in a wide range of applications, including:

• Power converters and inverters
• Battery-operated devices
• Microcontroller systems
• Automotive electronics
• Industrial control systems

Design Considerations

When designing a system with undervoltage lockout, several factors need to be considered:

• UVLO Threshold: The UVLO threshold should be set above the minimum operating voltage of the device. This ensures that the device is not operating in an undervoltage condition.
• Hysteresis Voltage: The hysteresis voltage should be set to prevent the device from rapidly turning on and off when the voltage is near the UVLO threshold.
• Response Time: The UVLO circuit should respond quickly to changes in the input voltage to protect the device from undervoltage conditions.

See Also

• Overvoltage protection
• Brownout
• Voltage regulator
• Power supply