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Rant: Top View vs Bottom View on Datasheets.
JoeN:
Why would anyone do a bottom view on a datasheet as the primary source of the pinout diagram? It doesn't seem common, but Linear still has it on some of their components (LTZ1000, LT1029, etc.) Maybe it is for the TO packages only? I don't understand why you would want it under any circumstances, it is just confusing to me. Does anyone like it like this? Here is an example where they mix and match views:
On the LM399, they have gone with a top view:
LTZ1000, which is a similar can, bottom view.
No rhyme or reason...
Berni:
Yeah it makes no sense. The bottom view only confuses people.
I have a worse one tho. Its a Gyro/Accelerometer/Compas IMU chip from Bosh:
https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMX055-DS000-02.pdf
Check page 155. For some reason they number all the pins in the clockwise direction! :palm:
I had already drawn its annoying LGA footprint in Altium and then i also wanted to mark down the axies directions inside the footprint so i know where to point it on my PCB. But as i read the diagram on Page 161 nothing seams to come together, how is pin one on that side? Have they accidentally mirrored the picture of the chip in that diagram? Hmm it looks like that on the front page too... Whats going on here? Wait... the pins go the other way around? YOU CHEEKY BASTARDS! |O
Have i not tried to mark down the accelerometer axies on my footprint i probably would have not realized this and went on to produce a PCB with a mirrored footprint for it.
CatalinaWOW:
Look at the bright side. It is labeled. And makes some sense for TO-3 and similar since you can't see or easily access the pins from the top. You will probably be coming from the side or bottom when probing, unlike the various flat paks, DIPs and so on where you will be coming from the top. BGA would be the one to break that pattern. And at least a few do, by showing both top and bottom views - labeled.
JoeN:
--- Quote from: Berni on March 28, 2017, 05:30:33 am ---Check page 155. For some reason they number all the pins in the clockwise direction! :palm:
--- End quote ---
Yeah, that is a pretty weird screwup. The rule for quad packages is simple, you put the dot in a corner, the pin next to it is 1, and then you go counterclockwise. Hard to screw that up.
I also don't like that the first pinout is on page 155. Pinouts are usually much closer to page 1 for every manufacturer I have ever seen, even for really complex devices.
Berni:
--- Quote from: JoeN on March 28, 2017, 05:44:28 am ---
I also don't like that the first pinout is on page 155. Pinouts are usually much closer to page 1 for every manufacturer I have ever seen, even for really complex devices.
--- End quote ---
Yeah that's also one of my gripes about some manufacturers datasheets that don't stick to the standard datasheet formula of where things are,
That reminds me of another documentation failure. There is a pressure sensor that marks the pinout on the mechanical drawing. Its a bit odd but hey it works fine, but the problem arises that there are two possible pinouts marked simply as A or B and despite going trough the entire datasheet multiple times i could not find if i am supposed to use the A or B one. What made things worse is that the A and B one had power supply pins in different locations. In the end i got fed up and soldered some wires to the sensor and applied power according to the A pinout using a low current limit, PSU went in to over current so i changed it around to the B pinout and it was drawing normal current and it had a output signal so i used that pinout. :palm:
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