Spring 2023 UV Cutoff Validation Plan

Owned by Nita E
Last updated: Aug 10, 2023 by Jenna Kong
4 min read

Plan written by: Jonathan Xie

  • Follow the validation plan in the order provided, it’s not necessary but was written in a sequential order

  • If anything is sus PLEASE question it, don’t trust me 100% I didn’t design or assemble the board

  • Plan assumes you only have 1 power supply to work with. If you have 2, you can simplify some of the processes

Comparator Logic

As an overview, the comparator should function as follows:

  • Comparator calculation assumes that PD_12V is 12V

  • If the comparator output is HIGH, then FUSED_VBAT+ must be 11.8V or lower in order to change output to LOW

  • If the comparator output is LOW, then FUSED_VBAT+ must be 13V or higher in order to change the output to HIGH

To verify this:

  1. Connect a 12V power source to act as PD_12V

  2. Connect an adequately charged battery (>13V) into the circuit

    1. (can be a power source)?

  3. Measure the voltage of the comparator output. It should be around 12V

  4. Replace the >13V battery with a low-charged battery (<11V). Repeat the above step, and verify that the voltage is now 0V.

 

===================================================================FOR EACH OF THE FOLLOWING STEPS WITHIN THE DIVIDER, REPEAT FOR BOTH THE FAN AND HORN!! (Instruction images correlate to the fan, repeat with the horn afterwards)

Enable Logic

  1. Follow the steps in ‘comparator logic’ to drive the output of the comparator to 12V

  2. With the controller board plugged in, set PB14 / pin 11 and PB15 / pin12 to HIGH

    1. (can this be done with a 3.3V power supply?)

  3. For BOTH the fan and horn circuits, verify that the voltage at the following points are all HIGH (~12V)

    1. Output of the AND gate:

    2. Output of the low-pass filter capacitor:

Load Switch Enabling

Direct power test:

  1. Follow the above <Enable Logic> steps to ensure that the capacitor output voltage is HIGH (12V)

    1. (alternatively, you can use a 12V power supply to drive the output high):

  2. Measure the voltage of the FAN_12V trace and the positive terminals of the connectors. Both should be around 12V (signifying that the fan is receiving power when enabled)

Load Switch Current Output

For full detail on how the IS pin of the load switch works, read the datasheet:

Since DEN is always HIGH when IN is HIGH, there should always be some current at pin IS (and thus, a voltage across R35 and R37) if the input pin (IN) is HIGH.

To verify this:

  1. Follow the steps in <Load Switch Enabling> to drive the input of the load switch to HIGH

  2. Measure the voltage at any of the following points, and look for a non-zero value

    1. It may be useful to record these values, especially the voltage at the lowest highlighted point in the picture below, because that’s the voltage at the ‘sense’ pins of the MCU

You can also verify that a current is being detected by allowing the MCU to read the voltage at its sense pin

The magnitude of this ‘sense current’ ( IIS or IIS(FAULT) ) is unknown

Load Switch Current Sensing

 

 

END OF REPEAT FAN + HORN SECTION
=======================================================

 

In-rush current limiting

Reverse Polarity Protection

 

 

(Junkyard, ignore)

Load Switch Enabling

Direct power test:

  1. Connect a 12V power supply to the output of U5A (fan comparator)

  2. Measure the voltage of the FAN_12V trace and the positive terminals of the connectors. Both should be around 12V (signifying that the fan is receiving power when enabled)

  3. Repeat steps 1 & 2 with the comparator and load switch of the horn (U5B, U4B)