Awareness | Open Collector (200 mA) - LED Output Circuit configuration and behavior for QIO-GP8x8
Learn how to configure and analyze the behavior of an open collector (200 mA) configuration in the QIO-GP8x8 system.
Information
The following is an example of general configuration and behavior for Open Collector (200 mA) - LED Output Circuit setup on the QIO-GP8x8.
This type of setup is typically used as a microphone mute indicator.
Simple LED Output Circuit
LED Off
(DC) Voltmeter across +12VDC and GPIO output pin should measure about 12V.
LED On
(DC) Voltmeter across +12VDC and GPIO output pin should measure about 0.6V, meaning current is flowing to ground.
Note
The power can be external, or supplied via the 12 Volts DC pin. GPIO allows current to ground when the LED is active and can handle 200mA.
External Power with Current Limiting Resistor
When using external power with a current limiting resistor to power very large or very bright LEDs that require higher voltage and current, you may need to use a current limiting resistor. This ensures proper operation to prevent burn out due to overcurrent.
Expected Measurements
LED Off
(DC) Voltmeter across GPIO output pin and ground should measure Vdiode.
LED On
(DC) Voltmeter across GPIO output pin and ground should measure about 0.6V, meaning current is flowing.