Direct current undervoltage release and circuit breaker

The invention discloses a direct current undervoltage release and a circuit breaker. The direct current undervoltage release comprises a release mechanism and a control circuit, wherein the control circuit comprises an undervoltage detection module, a release control module and a power supply module, wherein the undervoltage detection module is connected with a voltage detection input end; the release control module is coupled with the undervoltage detection module and can carry out pulse width control; the power supply module is connected with the release control module and is used for providing work voltage for the release control module; the release control module comprises a release controllable switch and a PWM (Pulse Width Modulation) control chip; the release controllable switch is connected with the release mechanism; and the PWM control chip is coupled with the release controllable switch and is used for controlling the release controllable switch to be opened or closed. The duty ratio of an output pulse signal is controlled by the PWM control chip capable of carry out pulse width control, so that low power consumption is realized; and the release mechanism is controlled by the PWM control chip to trigger a release operation, so that the possibility of mistaken action caused by fuzzy intermediate state is avoided and the accuracy and the reliability are improved.