Systems and methods for controlling relays

A method of controlling a plurality of relays including a first relay and a second relay, the method comprising:

• providing a first relay control signal having one of a first state and a second state to a first switch, wherein during the first state the first relay control signal actuates the first switch and couples the first relay to ground;
• receiving the first relay control signal at an anode of a first diode, a cathode of the first diode being coupled to a pulse generator;
• providing a second relay control signal having one of a first state and a second state to a second switch, wherein during the first state the second relay control signal actuates the second switch and couples the second relay to the ground;
• receiving the second relay control signal at an anode of a second diode, a cathode of the second diode being coupled to the pulse generator, and coupled to the cathode of the first diode;
• outputting a control signal having a first state from the pulse generator to switchably couple a coil voltage input of the first relay to a first voltage that is capable of energizing the first relay from a de-energized state in response to the first relay control signal having the first state;
• outputting the control signal having the first state from the pulse generator to switchably couple a coil voltage input of the second relay to the first voltage in response to the second relay control signal having the first state;
• maintaining the coil voltage inputs of the first and second relays at the first voltage for a period of time sufficient to energize the first and second relays;
• and
• outputting the control signal having the second state from the pulse generator to switchably couple the coil voltage inputs of the first and second relays to a second voltage that is lower than the first voltage in response to expiration of the period of time.

A relay control circuit configured for use with a plurality of relays including a first relay and a second relay, the first relay having a coil voltage input and the second relay having a coil voltage input coupled to the coil voltage input of the first relay, the first relay being coupled to ground through a first switch, and the second relay being coupled to the ground through a second switch, the relay control circuit comprising:

• a first input to receive a first voltage capable of energizing the first relay from a de-energized state;
• a second input to receive a second voltage capable of maintaining the first relay in an energized state, the second voltage being less than the first voltage;
• and
• switching means, responsive to a first relay control signal having one of a first state and a second state, in the first state the first relay control signal actuating the first switch to couple the first relay to the ground, and responsive to a second relay control signal having one of a first state and a second state, in the first state the second relay control signal actuating the second switch to couple the second relay to the ground, the switching means for switchably coupling the coil voltage input of the first relay and the coil voltage input of the second relay to the first input for a period of time sufficient to energize the first relay and the second relay in response to the first relay control signal having the first state and the second relay control signal having the first state, and for switchably coupling the coil voltage input of the first relay and the coil voltage input of the second relay to the second input in response to expiration of the period of time;
• wherein
• the switching means includes a first diode having an anode to receive the first relay control signal and a second diode having an anode to receive the second relay control signal, the first diode having a cathode, and the second diode having a cathode coupled to the cathode of the first diode.