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Post-Assembly

  • Check all required components are assembled and DNP components are not assembled
  • Verify components oriented correctly (polarity, pin 1 designators, etc.)
  • Verify there are no bridges between parts/pins creating unwanted shorts
  • Verify general soldering quality - no stray solder, burns, etc., all pins and pads connected with enough solder

Unpowered Tests

  • Verify power rails are not shorted to GND or with each other
  • Verify EN/RST/SHDN pins are not shorted to either GND or a power rail, unless it is supposed to be
  • Verify communication protocol lines (i.e. SDA & SCL for I2C, MISO MOSI SCLK & CS for SPI, etc.) are not shorted with each other, with a power rail, or GND

Basic Powered Tests

General Tests:

  • Program microcontroller
  • Verify the TVS diode function protects against overvoltage on analog lines
  • Do a full system test with all of the rails powered and make sure nothing explodes

48V Power

  • Power onboard + touch test, verify components and the board itself does not get too hot
  • Verify all ICs, details, LEDs, etc. are powered on successfully. Communicate with all peripherals

STM:

  • Verify the enable pins (N-CH MOSFET gate) can be driven high and low (PC1, PC3, PC5, PA6)
    • Gate and source pins are reversed in the footprint
  • Verify the analog read of the current sense amplifier outputs (PC0, PC2, PA5, PA7)
  • Verify the analog read of the VBAT rail (PC4)

Electrical:

  • Verify the 48V outputs can be enabled and disabled via N-CH FET (can draw load from the output when enabled, can’t otherwise)
  • Verify the analog output of the amplifier matches expectations

5V Power:

  • Power onboard + touch test, verify components and the board itself does not get too hot
    • 5V_1
    • 5V_2
  • Verify all ICs, details, LEDs, etc. are powered on successfully. Communicate with all peripherals
    • 5V_1
    • 5V_2

STM:

  • Verify the enable pins can be driven high and low (PC14, PC11, PB9, PD2)
  • Verify the STM can read the state of the OC pins accurately (PC13, PC12, PC10, PB8)
  • Verify the analog reads of both of the 5V rails (PB7, PC15)
    • Both of the pins for this are not analog capable, but was able to read from a peripheral

Electrical

  • Verify enable condition on all 4 switches (can draw load from the output when enabled, can’t otherwise)
  • Verify output current limit (2.4A)
    • The current limit is actually 2A not 2.4A
    • Verify the OC pin goes low in this condition

Problems:

  • at 1A load, the 5V output is dropping to 4.3V

    • Actually even at the power supply input it is 4.3V, so maybe it’s the power supply

    • Does it even when connecting power supply directly to the reload, maybe power drop through wires

      • Ya it is, its 5v right at the power supply terminal but

  • Highside switched shut down the output at 2A not 2.3 or whatever

17V Power

  • Power onboard + touch test, verify components and the board itself does not get too hot
    • Current sense amplifier blew up when powerd
  • Verify all ICs, details, LEDs, etc. are powered on successfully. Communicate with all peripherals

STM:

  • Verify the enable pin (N-CH MOSFET gate) can be driven high and low (PB2)
  • Verify the analog read of the current sense amplifier output (PB1)
  • Verify the analog read of the 17V rail (PB0)

Electrical:

  • Verify the 17V output can be enabled and disabled vis N-CH FET (can draw load from the output when enabled, can’t otherwise)
    • N-CH footprint has source and drain pins reversed
  • Verify the analog output of the amplifier matches expectations
  • Verify the TVS diode function protects against an oversimplification of signal

Problem:

  • When 17V was powered without 48V, there was a leakage to 48V, only 100 ohms between the rails

    • IC VCC is 48, though it is measuring at 17

  • When 48V was supplied without 17V, nothing

  • When both 17V and 48V were connected, IC blew up, shorted 48V though the IC,

  • I think pull resistors on N-CH/P-CH load switch has the output enabled by default

    • No, they are off by default

Changes for Next Rev

  • R44 and R45 are 0603 and should be 0805

  • Change 0.1uF 10V to 50V for consistency (5V high side switched)

  • 3.3k (r2) 0603 part number

  • There are 16V, 50V and 100V 1uF caps on the board

  • It should probably double the power rating on the current sense resistors for the 24V buck

  • Add label to 3v3 led

  • N-Ch fet description says 340mS instead of 340 mA

  • Add polarity indicators to terminals

  • STM reset button footprint is wrong, shorts itself out

  • Add testpoint labels where convenient

  • SHDN on CAN should have a test point

  • RST pin on microcontroller should have testpoint w label

  • Add clippy testpoints to all of the voltage rails

  • reduce the small terminal through hole size for better alignment

  • Both 5V rail ADC pins do not go to ADC capable pins

  • Current sens +/- pin name wrong

  • N-CH footprint is wrong

  • LED doens’t work

  • 17V current sense should be supplier by 17V so it doesn’t blow up

  • Either combine the 5V rails or make sure all of the start up conditions are on the same 5V rail

  • Make the current gain max out at 1.8V, change out the TVs diode for one that hopefully works,

    • In the firmware, the STM should shutdown the output when the voltage reaches 1.8V so it has a margin of error to shut down the output before it becomes dangerous to the stm

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