MIKROE Relay Click is a dual relay Click board™, which can be operated by the host MCU. This Click board™ offers an elegant and easy solution for controlling a wide range of high power applications. Since it is able to operate on mains voltage level, it can even be used control the power for a number of small home appliances. It can also be used to activate various electromotors, switch on the lights, or power on the entire embedded system.
Relay Click features two G6D-1A-ASI DC5 mini-relays, from Omron. Omron micro switches and relays are well known among enthusiasts and professionals alike, for their reliability and durability. Despite its size, the G6D-1A-ASI DC5 relay is able to withstand up to 5A and 220V AC/30V DC. It can endure up to 300,000 operations, with 30V DC and 2A. This relay has a single pole only - when the coil is energized, it will attract the internal switching elements and close the circuit, similarly to a switch.
These relays are designed so that their coils can be easily activated by relatively low currents and voltages. For the G6D-1A-ASI DC5 relay operated at 5V, the coil current is 40mA. This makes them a perfect choice for activating them by an MCU. However, some additional components have to be included for a proper operation:
A small NPN RET (Resistor Equipped Transistor) is used to provide enough current for the relay coil. Two resistors are already integrated into the RET, providing it with the correct biasing, so using RETs simplify the design. Since the MCU drives the relay coils through these RETs, their bases are routed to CS and PWM pins of the mikroBUS™.
There is a LED (in a different color for each relay) which signalizes the state of the relay. When the current flows through the RET, the coil will be energized, and the relay will be in the closed switch state. This current also flows through this LED, which will indicate that the relay switch is closed.
The Schottky diode is connected across the relay coil, preventing the NPN RET to become inversely polarized by the inert nature of the coil.
Two varistors are used to prevent voltage peaks when the load is connected or disconnected, protecting the relay contacts that way.
DO NOT TOUCH THE BOARD WHILE THE EXTERNAL POWER SUPPLY IS ON!
Note: MIKROE RELAY Click has exposed pins/pads. To stay safe take precaution when applying high voltage to the Click. The Click is to be used by trained personnel only when applying high voltage.
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