Gravity Magnetic Latching Relay 3.3V-5V

The Gravity relay from DFRobot is a bistable relay (magnetic latching relay): a permanent magnet holds the contact in the last switched position, even without power. It is switched with a short pulse on one of two inputs, A switches to one position, B to the other. The coil only draws current during the pulse, the relay does not hum and hardly gets warm. It works with 3.3 V and 5 V, for example on Arduino, ESP32 or Raspberry Pi.

Important: For safety reasons, the module is only intended for voltages up to 30 V and not for mains voltage. DFRobot specifies a maximum of 36 V AC and 30 V DC for the module.

Note: The connection cable can be converted to male pins with a Dupont cable M-M, so that it also fits an Arduino UNO.

Recommended Accessories:

Features:

Bistable: the relay stays in the last position without power
Two control inputs A and B, each with a 3-pin Gravity connector
Switching with a HIGH pulse of at least 2 ms (product page), according to the wiki more than 4 ms for reliable switching
Never drive A and B at the same time, do not energise the coil for more than 1 minute (wiki)
Reset state by default, shocks during transport can change the position: switch once deliberately at start-up
Quiescent current 0.73 to 0.8 mA
AgSnO2 contacts, screw terminals contact A, COM and contact B
Keep away from strong magnetic fields (wiki)

Application Examples:

Switching pumps, valves and LED lighting with extra-low voltage
Battery-powered controllers, because holding needs no current
Switching state that survives a power failure

Connection to 5 V Logic (for example Arduino UNO):

+ and − of both Gravity connectors to 5V and GND
A to a digital output, for example pin 3, B to a second one, for example pin 2 (example in the wiki)
To switch, set the output HIGH briefly (at least 2 ms, according to the wiki better more than 4 ms), then LOW again
Load to COM and contact A or contact B

Connection to 3.3 V Logic (for example ESP32, Raspberry Pi):

+ and − of both Gravity connectors to 3.3 V and GND, supply and signal are then both at 3.3 V
A and B to two GPIOs, pulses as with 5 V
During the pulse about 137 mA flow through the coil at 3.3 V, the 3.3 V pin of the board must supply this

Documentation:

Technical Data:

Manufacturer: DFRobot
Manufacturer SKU: DFR0996
Relay: bistable (magnetic latching) with driver chip
Permitted voltage on this module: up to 30 V
Ratings according to DFRobot: max. 36 V AC and 30 V DC, 10 A, 36 VA / 300 W
Contact load according to DFRobot: 10 A at 36 V AC (resistive), 15 A at 36 V AC (incandescent lamp)
Contact resistance: max. 100 mΩ (1 A, 6 V DC)
Contact material: AgSnO2
Supply voltage: 3.3 V to 5 V DC
Signal level: 3.3 V and 5 V
Quiescent current: 0.73 mA to 0.8 mA
Coil current: 137 mA (3.3 V), 93 mA (5 V)
Coil rated power: 0.4 W
Pulse width: at least 2 ms (wiki note: more than 4 ms)
Operate time: max. 8 ms, reset time: max. 5 ms
Humidity: 5 % to 85 % RH
Operating temperature: -40 °C to 85 °C
Dimensions: 42 × 32 × 18 mm
Weight: 28 g