Christchurch, NZ
MReX-PCB User Guide V1.02
LEDs Outputs
Connecting the LEDs using Open Drain (bypassing PCB resistors)
The LED outputs are open drain/collectors suitable for sinking a maximum of 50mA. The example
is being used to drive an LED from an external supply. Should the output be presented to potential
ESD conditions (such as any terminal screw or external connection), ESD devices should be fitted.
If the output is to be used to control a small relay, it is essential that a flyback diode is fitted across
the coil of the relay.
Only the Cathode connections of the LEDS are shown here. They are connected to an open drain
output. As shown in the simplified schematic above, it is the users responsibility to select a resistor
that suits the application, and then connect to a suitable power source that has a common GND.
© WTE Limited, 2021 – Christchurch New Zealand
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