RELAY-4 is an Input/Output Expander board containing four relays with 10A contact rating. Both Normally Open (NO) and Normally Closed (NC) relay contacts are brought to screw terminals. Relays are controlled by a Philips PCA9554N I/O Expander. Any command to activate or deactivate a relay is sent through the 2-wire (I2C) bus. A jumper block configures a unique 3-bit board address. This allows up to eight RELAY-4 boards to be used at the same time. Thus, it is possible to prepare a controller system with 32 high-current relays.
The 16 control pins and 5V power supply connections are available on a 20-pin (2×10) expansion connector for interfacing to existing microcontroller systems. This board can be connected either as a piggyback daughterboard on a microcontroller board (one with a matching connector) using standoffs or can be placed away from the microcontroller board using a 20-wire ribbon cable.
The expansion connector is plug-in compatible with MicroTRAK, MINI-MAX and BSCB systems. You can use it in your own system too, of course; see the manual for the expansion connector's pinout.
Note: Do not confuse this board with the other board we carry called Relay 4, from a different manufacturer.
Relay Peripheral Board Features
- I2C (2-wire) I/O expander PCA9554N
- 4-channel Darlington drivers (ULN2803) to drive the relay coils
- 4 high-current (10A) relays with Normally Open and Normally Closed contacts
- 4 extra digital I/O
- Address selector jumpers allow stacking up to 8 boards for 32 relays
- Screw terminal blocks for relay contacts
- 20-pin connector for interfacing to a microcontroller board
- Single operating voltage 5V DC, 75mA per energized relay coil
- Dimensions: 2.35 × 2.40 inches (5.97 × 6.10 cm)
- -20° to 85° C operating, -40° to +85° C storage temperature range
If you want to chain multiple add-on boards together, you can purchase cable and connectors separately to construct daisy-chain cables that suit your setup.