FT232H QFN exposed pad... - Page 1
Forum section: electronics / projects

author: Dago
author_rank: Frequent Contributor
timestamp: August 02, 2014, 06:03:20 am
content: I (again...) ran in to the issue that there is no mention of the exposed pad for the QFN packaged version of FT232H in the datasheet nor in the application notes.I'm pretty sure I can connect it to ground with no ill effects but I'd like to hear confirmation from someone who has used it.I have ran in to at least a couple of chips where the EP was not supposed to be grounded but left floating (this was clearly mentioned in the datasheet though). I hate making assumptions...

author: chrisbrown
author_rank: Contributor
timestamp: August 02, 2014, 06:31:30 am
content: Yeah, it would be nice if they would at least acknowledge its existence.You can safely connect it to ground. That's what we do on one of our boards at work.There are also gerbers available for an FT232B eval board where the pad is connected to VCCIO.http://www.ftdichip.com/Support/Documents/Schematics/US232B/US232B-top.pdf

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: August 03, 2014, 03:48:00 am
content: I think it have to be connected to ground. You can stitch the pad with vias so that you can solder it by heating it up with tip of your soldering iron from the bottom (opposite to the chip) side of the board.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 03, 2014, 04:39:10 am
content: I haven't seen a single pad in standard DFN/QFN that isn't either ground explicitly, or just floating and can/should be grounded.Used an FT232R recently, I think it was. The pad is documented (if not the connection, I don't recall). Is the H different?Tim

author: zapta
author_rank: Super Contributor
timestamp: August 03, 2014, 05:20:35 pm
content: Quote from: chrisbrown on August 02, 2014, 06:31:30 amIs this a pad or just a trace?For the Ft232H, did you try to measure tab connectivity to any of the ground pins?

author: chrisbrown
author_rank: Contributor
timestamp: August 03, 2014, 05:39:32 pm
content: Interesting.FT232H, no mention of the pad: pg58http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232H.pdfFT232R, pad may be optionally grounded: pg37http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdfZapta:- Very good point, that copper might not be exposed.- We didn't populate the boards ourselves so I never had a loose chip to test.

author: rob77
author_rank: Super Contributor
timestamp: August 03, 2014, 05:59:08 pm
content: strange that they're not documenting the pad... i was using only FT232BL in 32 Pin LQFP package - and that has no exposed pad obviously.. but the FT232BQ got one and there is not a single mention of it in the datasheet.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 03, 2014, 06:25:05 pm
content: Unless it's needed for heat dissipation or high frequency (latter may be the case for this) , I tend to not even put a pad on the PCB for QFN die pads, as it allows space for routing underneath.But then I'm a cheapskate and hate going to a 4L board.Not soldering the pad also makes rework a whole lot easier.

author: marshallh
author_rank: Unknown
timestamp: August 04, 2014, 01:53:54 am
content: The last board I did has a FT232H and i left the paddle NC... The board brought up and worked with USB no problem