Hercules LaunchPad and GaN FETs - Side Note B: Look at the PCB

RE: Hercules LaunchPad and GaN FETs - Side Note B: Look at the PCB

Jan Cumps — Mon, 12 Dec 2016 15:47:22 GMT

Captures annotated with the hysteresis info.

The orange cursor (B) for the rising edge

The white cursor (A) for the falling edge

[View:/resized-image/__size/744x277/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188795.png:744:277]

Typical IC:

[View:/resized-image/__size/320x234/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188796.png:320:234]

Lowest in bell curve:

[View:/resized-image/__size/320x234/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188797.png:320:234]

Highest in bell curve:

[View:/resized-image/__size/320x234/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188798.png:320:234]

Extreme Low and High (this is hypothetical. hysteresis is always 400 mV):

[View:/resized-image/__size/320x234/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188799.png:320:234]

And the frequency of the ringing. 100 MHz as indicated by Jon.

[View:/resized-image/__size/320x234/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188800.png:320:234]

RE: Hercules LaunchPad and GaN FETs - Side Note B: Look at the PCB

Jan Cumps — Fri, 09 Dec 2016 14:58:03 GMT

The board is built up, not tested yet.

Reflow worked ok, except for 0402 and some 0603s.

C22(0402) toombstoned, I had to rework C15, C21 and LED D2 too.

I'm happy that the (somewhat) complex footprint of quadrature encoder - with one oval and two round mounting holes fitted perfectly.

The two screw terminals however, P2 and P3, are a complete goof-up. The holes are too small, the distance between them is wrong and the total size of the footprints doesn't match the component.

I have to check how that happened, because I made this footprint myself from the data sheet. (wrong part ordered or delivered, wrong drawing selected in the sheet, inch/cm switch, I don't know yet)

[View:/resized-image/__size/620x465/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/3817.contentimage_5F00_188774.jpg:620:465]

[View:/resized-image/__size/623x467/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/3821.contentimage_5F00_188775.jpg:623:467]

RE: Hercules LaunchPad and GaN FETs - Side Note B: Look at the PCB

Jan Cumps — Thu, 08 Dec 2016 21:25:53 GMT

Seeed has a new Gerber viewer since today. Compare it with the image at the beginning of this blog.

[View:/resized-image/__size/628x288/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/6825.contentimage_5F00_188773.png:628:288]

(downside is that their cost calculator and 'add to basket' button don't work anymore [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/7485.contentimage_5F00_1.png:16:16])

RE: Hercules LaunchPad and GaN FETs - Side Note B: Look at the PCB

Jan Cumps — Thu, 08 Dec 2016 13:25:25 GMT

First error found: wrong footprint for C30:

[View:/resized-image/__size/1150x577/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/contentimage_5F00_188772.png:1150:577]

RE: Hercules LaunchPad and GaN FETs - Side Note B: Look at the PCB

Jan Cumps — Wed, 07 Dec 2016 21:53:25 GMT

The two difficult components are soldered.

I've measured for solder bridges, all OK...

[View:/resized-image/__size/620x549/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-05466bce-0011-4907-b053-e645da1a56c3/5707.contentimage_5F00_188768.jpg:620:549]