Patent ID: 11881849
Assignee: LITTELFUSE, INC.
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 4:
5. A method, comprising:
coupling a first end and a second end of a solid state relay switch to a charging capacitor, via a first diode and a second diode, respectively;
receiving at the solid state relay switch, an ON control signal based upon an enable HIGH signal generated over an enable line from an external load device;
maintaining the solid state relay switch in an ON state when a switch control voltage is above a preset value, the switch control voltage being derived from a low threshold for a capacitor voltage of the charging capacitor; and
maintaining the solid state relay switch in an OFF state when the switch control voltage is below the low threshold;
wherein the solid state relay switch comprises a first transistor and a second transistor, wherein when an enable LOW signal is received over the enable line, the first transistor and the second transistor are maintained in an OFF state, and wherein the charging capacitor is coupled to receive a charging voltage from the external load device;
wherein during the ON state, a capacitor voltage at the charging capacitor decreases over time, wherein at a second instance during the ON state, the capacitor voltage drops below the low threshold value;
wherein the switch control voltage is received from a voltage divider circuit coupled to the charging capacitor, wherein the switch control voltage is fed to a first input of a comparator, and wherein a reference voltage having a voltage level at a preset value, based upon the capacitor voltage, is fed to a second input of the comparator; and
wherein the solid state relay switch is disposed in a solid state relay circuit that further comprises an AND gate, having a first input coupled to an output of the comparator, and having a second input coupled to the enable line, and wherein at the second instance, an output of the comparator switches to logic LOW, wherein the solid state relay switch is changed to the OFF state.