Power board v3 - Githubissues

thanasipantazides commented 6 days ago

Overview

This issue will track changes to the v3 power board design to address FOXSI-4 hardware errata, documented here.

[ ] Connect LT8612 BST to SW via 0.1 µF capacitor.
[ ] Connect LT8612 SYNC to INTVCC.
[ ] Route SPI.SDO to J1.7 and SPI.SDI to J1.9 (swapping them).
[ ] Change R58 value to 3 kΩ.
[ ] Timepix_5V_out and Timepix_12V_out naming or placement in header should be swapped. They carry one another's voltage. (Error was introduced by module-level wiring in the hierarchical schematic).
[ ] The MAX7317 SPI.SDO line needs external circuitry to be hi-Z when inactive (when nCS3 is high).
[ ] Confirm feedback resistor values for all converters (measure on board).
[ ] Something needs to be done to address the CMOS 2 always-on issue that emerged during sequence testing in Alaska. Consider new SRRs, input-side (+28V_clean) circuit protection, or output-side circuit protection. Overvoltage protection? Fuses?
[ ] Increase the MAX7317 pullup resistor value to ~47 kΩ. The output ports are weak (max ~10 mA drive). Don't waste effort when they are sinking to ground.

thanasipantazides commented 6 days ago

For the MAX7317 SPI.SDO fix, can use the TI SN74AHC1G125 inline, switched by SPI.nCS3, to toggle.

thanasipantazides commented 6 days ago

Implemented these locally:

[x] Connect LT8612 BST to SW via 0.1 µF capacitor.
[x] Connect LT8612 SYNC to INTVCC.
[x] Route SPI.SDO to J1.7 and SPI.SDI to J1.9 (swapping them).
[x] Change R58 value to 3 kΩ.
[ ] Timepix_5V_out and Timepix_12V_out naming or placement in header should be swapped. They carry one another's voltage. (Error was introduced by module-level wiring in the hierarchical schematic).
[x] The MAX7317 SPI.SDO line needs external circuitry to be hi-Z when inactive (when nCS3 is high).
[ ] Confirm feedback resistor values for all converters (measure on board).
[ ] Something needs to be done to address the CMOS 2 always-on issue that emerged during sequence testing in Alaska. Consider new SRRs, input-side (+28V_clean) circuit protection, or output-side circuit protection.

thanasipantazides commented 6 days ago

For voltage spike suppression, consider the LittleFuse SMCJ36CA which was used on the CMOS boards.

thanasipantazides commented 6 days ago

Or the SMBJ36CA, which is slightly smaller.