Abstract: A load switching circuit includes a supply power availability (SPA) detector, a rail voltage detector, a swell detector, a surge detector, control logic, make and break timers, and a relay driver. The detectors detect various conditions, and generate signals in response to some detected conditions. The control logic is configured to: (1) release a relay within 300 ms after receiving a power-up signal; (2) start the make timer upon receiving a “rail voltage present” signal and wait for a first delay time, then operate the relay; (3) start the break timer upon receiving a “swell detected” signal to wait for a second delay time, then release the relay; (4) cause a shunt switch to conduct within 10 ms after receiving a “surge detected” signal; and (5) release the relay within 10 ms after receiving a “rail fail” signal.

Abstract: A method for switching power supplied by a powerline to a load includes coupling a current sense device and a pulse-controllable bistable switch between the powerline and the load. A sense signal, representative of the current through the load, is applied to a condition detector. The condition detector compares the sense signal value with a threshold to detect a first overcurrent condition. In response to detecting the first overcurrent condition, a second shaped pulse is applied to the pulse-controllable bistable switch to deassert it. The second shaped pulse has an amplitude of at least 110% of a maximum continuous energization voltage and a duration shorter than a predetermined maximum duration. The second shaped pulse may begin at least fifty milliseconds (50 ms) after a prior second shaped pulse ended.

Abstract: A power switch controller includes a condition detector, a zero crossing detector, a retimer, and a driver. The condition detector detects a change in a sense signal towards a first or second condition. The zero crossing detector detects zero crossings in an AC powerline signal. The power switch controller drives a latching relay that connects a load to powerlines. The power switch controller activates or deactivates the latching relay based on the sensed condition, and retimes activation and deactivation pulses to align the relay contact opening and closing times to coincide with the AC powerline zero crossings, compensating for contact travel times. The activation and deactivation pulses have a duration of max 20 ms, and an amplitude of at least 110% of the maximum sustainable voltage for the relay coil(s). A power-on reset deactivates the relay, aligned with a second AC zero crossing.

Abstract: An electronic protection system includes an electronic protection IC, mains power lines including a line rail and a neutral rail, a power switch, and a current sense device. A load is coupled with the mains power lines via the power switch and the current sense device. The electronic protection circuit turns off the power switch within eighty (80) milliseconds from a zero crossing in power delivered by the mains power lines when a load current is too high. A dummy DAC supplies a dummy current to prevent instability resulting from positive feedback during a change between a first state and a second state. The system may include an overcurrent detection circuit with a sense input, a comparator, a latch, and a pulse generator, configured to output a train of pulses with a low duty cycle when a current amplitude exceeds a reference value.

Abstract: A protection IC protects an external load connected to mains supply lines from dangerous or undesired conditions such as overvoltage, undervoltage, and overcurrent, by disconnecting the external load for at least the duration of such a condition. The IC has a range detector, a zero-crossing detector, a control unit, a switch driver, and a dummy DAC. The range detector senses the presence of an unwanted condition. The control unit then waits for a zero crossing, upon which it disconnects the load. A lockout timer may introduce a minimum wait time before reconnecting the load. To prevent instabilities around the switching points, hysteresis in the window thresholds prevents impact from noise. The dummy DAC regulates a dummy current that linearizes the IC's current consumption around the switching points to prevent instabilities caused by positive feedback in non-linear transitions.

Abstract: A powerline load monitor has a voltage sense input, a current sense input, a clock input and a data output. It includes first and second ADCs coupled with the voltage sense and current sense input, and coupled with a serial interface. A power manager is coupled with the clock input, the ADCs, and the serial interface. When the power manager receives a first clock, it puts the powerline load monitor in active mode and starts a first timer with a first timeout time. The first and second ADC convert a sensed voltage and a sensed current to digital values for the serial interface. When the serial interface receives a trailing edge of a clock pulse, it outputs a data bit of the digital values. When the first timer times out, the power manager puts the powerline load monitor in a standby mode to save power.

Abstract: A protection IC protects an external load connected to mains supply lines from dangerous or undesired conditions such as overvoltage, undervoltage, and overcurrent, by disconnecting the external load for at least the duration of such a condition. The IC has a range detector, a zero-crossing detector, a control unit, a switch driver, and a dummy DAC. The range detector senses the presence of an unwanted condition. The control unit then waits for a zero crossing, upon which it disconnects the load. A lockout timer may introduce a minimum wait time before reconnecting the load. To prevent instabilities around the switching points, hysteresis in the window thresholds prevents impact from noise. The dummy DAC regulates a dummy current that linearizes the IC's current consumption around the switching points to prevent instabilities caused by positive feedback in non-linear transitions.