Undervoltage-lockout
（重定向自UVLO）
″ The Undervoltage-Lockout or UVLO is an electronic circuit used to turn off the power of an electronic device in the event of the voltage dropping below the operational value. For instance, in embedded devices, UVLOs can be used to monitor the battery charge or turn off the circuit if the battery voltage drops below a specific threshold, thus protecting the associated equipment. Some variants may also have an upper threshold. Undervoltage lockout is an integral part of many electronic devices. For instance, it is widely used in many Electrical ballast circuits to switch them off in the event of voltage falling below the operational value.