I’m looking to buy a couple of Attiny 13a ICs to replace non-programmable ones on a couple of drivers i have and have both the SSU and SSH variants on ‘good’ drivers that i have.
I’m fairly sure either will work fine but i’m curious as to the difference between the two as i can’t see it from looking at the datasheets.
Anyone know?
Hi Marc, I believe the U/H designates the material of the pins/legs. Either will be fine. See my posts discussing the same thing but about the attiny85.
Thanks, that’s what i needed. Where did you get your Attinys from? I was looking at Mouser.
If I recall correctly it’s about package size/shape. One is rectangular and fits our pads easily, the other is square and only fits our pads by bending the legs. The SSU is what fits our boards unless I am mistaken…
Arrow, but that was back when they had free shipping. You could try rs-online , not sure if they have 13s but they had 85s when I was looking. Only used them once before but didn’t have any problems.
I don’t think so. The package is not defined in the part number, you need to check the datasheet to find what package it is based on the part number.
Best go for SU anyway as that’s what seems to be most prevalent in our drivers.
SU is square, SSU is rectangular… I accidentally bought SU 85’s once and they are square, requiring the legs to be bent to fit.
This not from memory but after looking in my parts bin. 
Actual Mouser label on 13’s…
Typo, meant SSU. SU is for the 85.
The H and U are for the finish type on the pins, H is a lead finish while U is a matte tin finish. This from the data sheet.
While I see the rectangular and square packages in the data sheet I really can’t determine what signifies this in the part number, too many numbers and too much head cold…
Cheers DB and Hodor, i clearly need to improve my datasheet reading skills:, i’ll give them a “B- Could do better” 
It’s all because i noticed the 13A on my Mountain Electronics drivers were the H version, all the others i have are U. I shall let price dictate my choice 
Hope your cold clears soon DB.
Edit: And at the moment the Hs are cheaper!
While the U and H designations answered the question about the ATTiny13, I did learn that for the 25,45,and 85 series the P designation is rectangular while the S is the 4mm square package. So PU fits, SU has to be bent to fit. For whatever that’s worth to anyone…
It’ll come in handy to someone at some point, when i go searching for info i glean a lot of other useful info when people talk around the specific topic (as long as it’s not too far off topic).
With that in mind i just looked up the 13A package sizes in the datasheet and… spotted the ‘U’ ‘H’ leg info, d’oh!
But packagewise:
PU comes in what Atmel call the 8P3 package, which they specify as: 8-lead, 0.300” Wide, Plastic Dual Inline Package (PDIP).
The legs go straight down at 90 degrees to the body so would need to be bent to fit on a driver board. The size of the body, not including legs is: 0.365 x 0.25 inches (nominal).
SU and SH come in the 8S2 package which is specified as: 8-lead, 0.209” Wide, Plastic Small Outline Package (EIAJ SOIC).
The legs are shaped to fit a driver board and the body size is: 5.35 x 5.40 mm (maximum). (Handily the datasheet switches from inches to mm for the measurements and omits the nominal stat.)
SSU and SSH come in the 8S1 package which is specified as: 8-lead, 0.150” Wide, Plastic Gull-Wing Small Outline (JEDEC SOIC).
The legs are again shaped to fit a driver board (as the gull-wing moniker would indicate) and the body size is: 0.4 x 0.5 mm (maximum).
There is also an MU which comes in a 20M1 package (20-pad, 4 x 4 x 0.8 mm Body, Lead Pitch 0.50 mm, Micro Lead Frame Package (MLF) )
and an MMU which comes in a 10M1 package (10-pad, 3 x 3 x 1 mm Body, Lead Pitch 0.50 mm, Micro Lead Frame Package (MLF) ).
Further, there is SN in an 8S2 package, SS7 in an 8S1 package, SF in an 8S2 package, and MMF in a 10M1 package. These are all rated to handle slightly higher temps than the above.
The leg info is:
H or 7: NiPdAu lead finish
U, N or F: matte tin
And if there is an ‘R’ on the end it denotes: tape & reel.
Phew!
Yup, that’s what the datasheet says 
Oh yeah!
I had to look long to find that on page 207 of 234! Man there’s some lengthy data on these little things!