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SWITCHES AND MULTIPLEXERS

May 03, 2004

SWITCHES AND MULTIPLEXERS
May 03, 2004
IC Drives Up to Four Single-Coil Latching Relays
Relay-driver IC allows a 3-bit parallel interface to independently open or close each of four latching relays. Single-coil latching relays, with applications in signal routing, audio, and automotive systems, can pose a design challenge because coil current must flow in both directions through a single coil. Current flowing in one direction latches the relay in its "set" position. Current in the opposite direction latches it in the "reset" position. The relay maintains its position even when the coil current is removed. Power is saved by removing coil current after the relay latches. In Figure 1, current flowing from pin 1 to pin 8 latches the relay in the set position, while current from pin 8 to pin 1 resets it.
Figure 2. This circuit easily drives four single-coil latching relays.
More Information MAX4821: QuickView - Full (PDF) Data Sheet - Free Samples