Difference between revisions of "Senoko PVT ECO List"

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(ECO 1: Improve inductor clearance)
(ECO 2: Route power switch to mainboard)
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! scope="col" | Notes
! scope="col" | Notes
| add || R120 330, 1% ||
| add || R120 330, 1% || ballast resistor

Revision as of 09:46, 1 July 2014

This is a list of all the changes applied to the board from DVT to PVT (Crowd Supply initial campaign) release. If it's not on this list, it didn't happen.

Each change has the format of issue summary/resolution, and specific change

ECO 1: Improve inductor clearance

The ferrite MSS1260 used as the primary power inductor is a bit too tall and large. Use a composite molded core XAL7030 which is a bit more compact.

Pros/cons: XAL7030 has a better rated Irms than MSS1260, but seems mostly due to better heat conduction out of the package, not due to better electrical performance. The DCR of XAL7030 is 19.5mOhm, MSS1260 is 12.60mOhm, so conduction losses are greater. Isat of the XAL7030 is better due to soft-saturating characteristic of the composite core. Overall, I expect there to be very little change in practical circuit performance, perhaps a little extra heat during peak battery charging situations.

The MSS1260 isn't removed from the PCB layout. Instead, XAL7030 shall be fitted inside the footprint of the MSS1260. This allows for going back to the original inductor in case there is a design issue with the XAL7030.

This change is coordinated onto Novena BOM as well.

L200 3.3uH, MSS1260-332NL L200 3.3uH, MSS1260-332NL (DNP) remove from BOM but leave footprint
add L200B 3.3uH, XAL7030-332MEC add inductor within old footprint

ECO 2: Route power switch to mainboard

Power switch pin is routed to mainboard for pass-through to front panel.

Pin 14 (previously an NC 3.3V pin) is now dedicated to CHG_PWRSWITCH.

add R120 330, 1% ballast resistor