Hello everyone!
I have a problem with the TRB142.
I have set the power pin 3 and 4 as output.
The TRB142 receives 9V and ground. As a control, I have an LED lamp that receives 9V externally and is grounded in either pin 3 or 4.
Regardless of whether output 3 or 4 is on or off, the LED is always on. Check with multimeter is “On 9.23 V” and “Off 9.17 V”. So there is a small difference, but not what I would expect.
Am I wrong in assuming that the voltage should actually be 0V at Off, as the pin is deactivated? What am I doing wrong?
Thanks and best regards
Peter
Hello,
you’re encountering an issue with the TRB142’s output pins not fully switching off. Based on the behavior you described, here are a few points to consider:
Open Collector Outputs: The TRB142’s output pins are likely configured as open collector (OC) outputs. In this configuration, the output pin does not actively drive a voltage but instead acts as a switch to ground. When the output is “off,” it may not fully disconnect, leading to a small residual voltage. This could explain why you’re seeing 9.17V instead of 0V.
Pull-Up Resistors: Open collector outputs often require external pull-up resistors to function correctly. Without a proper pull-up resistor, the voltage may not drop to 0V when the output is off. Check if your setup includes pull-up resistors and ensure they are appropriately rated.
LED Behavior: LEDs can be sensitive to even small currents. If there is any leakage current through the output pin when it is “off,” the LED may still light up faintly. This could be due to the internal circuitry of the TRB142 or the characteristics of your LED.
Best Regard,
violeta
Thank you very much for your reply!
So, would this setup (see picture) work?
As I wrote above:
- When output 3 is open (high), LED3 should light up.
- When output 3 is closed (low), LED3 should be out.
- Same with output 4/LED 4.
- LED1 is indicating, that there is 12V alive.
I need this setup, because the TRB142 will be stored in a box and I want the three LEDs to see the status from the outside:
- LED1: 12V is available
- LED3: Output 3 is open according to rule
- LED4: Output 4 is open according to rule
