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Forum Index : Microcontroller and PC projects : IC orientation
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palcal Guru  Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
I am building a Buck Boost converter, Silicon Chip June 2022. One of the ICs is a 1NA282AIDR SOIC-8, I want to make sure of the orientation, the layout diagram just shows pin 1 and the picture of the board is not clear. This IC is shown with pin 1 top right. I could not get a good picture of the chip even using super macro and it does not have any marking to indicate pin 1. Looking at the chip with the writing the right way up it does have a line market top to bottom on the left hand side. Can I assume that pin one is bottom left in which case the chip will mount upsidedown on the PCB. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1646 |
The board layout on page 45 shows a grey line down one side indicating that pin one is top left with the line running down the left side. Does that help? Bill Keep safe. Live long and prosper. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
I saw that but on my chip there is a stripe of 5 thin lines but the lines run at 90 degrees to the one marked in the layout. So if that were my chip in the layout the line would run from pin 1 to pin 8. I don't feel safe mounting it and Silicon Chip are probably on holidays but I will email them anyway. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2833 |
Yes P45 shows the stripe going from pin 1 to pin 4, TI data sheet doesn't show the stripe but google images seems to suggest it goes from pin 1 to pin 8. Perhaps there is an errata in a later issue - often the last page. |
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bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2971 |
G’day Palcal, All, In almost all ICs if you have the letttering in correct orientation the pin 1 will be the bottom left. If you want to make sure. Looking at the data sheets it appears that pin 4 in not connected (NC) try buzzing out to other pins. The one that’s pin 8 will probably have some connectivity to other pins but pin 4 will not. To identify the PCB layout, it appears that pins 1 and 8 connect across a current sense resistor so simply determine the orientation by where the sense resistor connects to. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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| Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1646 |
I found this which looks something like you describe. https://www.ebay.com.au/itm/302556799276 I can only make out one line in the photo. There are similar modules listed below too. Bill Keep safe. Live long and prosper. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
Well I'll mount it, but like I said it is unusual for their designs to have one chip upsidedown, larger pin count ones sometimes vertical but not upside down. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2833 |
"https://www.ebay.com.au/itm/302556799276" That pic shows clearly the stripe is next to the current shunt, so it it goes from 1 to 8 as they connect to the shunt. |
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| Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1646 |
I'm worried that you'll blame me if it's wrong now  But look at the picture on page 40 it shows a line across the top and a dot on the PCB to indicate pin 1 at the left end of that line. Looking closely at the other picture I can sort of see a line across the top. Normally they have a little illustration of the components on the schematic but they've missed this one. Bill Keep safe. Live long and prosper. |
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Justplayin Guru Joined: 31/01/2014 Location: United StatesPosts: 330 |
Pin 2 of the chip is ground. Do a continuity check on the two pads that might be ground to a known ground location on the board. That will tell you the proper orientation of the chip. I am not a Mad Scientist... It makes me happy inventing new ways to take over the world!! |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
Looking at the EBay picture I'm happy that I have it the correct way around. Thanks all. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| TrevorH Senior Member  Joined: 06/04/2018 Location: United KingdomPosts: 145 |
I think the chip is "INA282Axxx" NOT "1NA282Axxx". See https://www.hitechcat.com/products/ina282aidr bottom pin is 1, bevelled side is 1-4, hope this helps. its the way I see it anyway. |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
Thanks for that Trevor, you are correct. The chip just has 282 but looking closely at the magazine it is an "I". It does have the stripe on the left and looking under the microscope it does have a bevel though not very pronounced. I just assumed a one because a lot of other diodes begin with "1N" All good, thanks. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
Thanks everyone finished the board and all works as it should. BTW I'm using it as a DC-DC battery charger. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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