Where is pin 1 on this SMD LF351??

[Ricardus]

It isn't obvious to me even though the spec sheet says there should be a dot at one of the corners.

 

[Khron]

Usually it's on the lower left, with the markings the readable way around. Worst case though, you could try to confirm by taking some reverse-diode-drop readings with your meter.

 

[user 130681]

Bottom left as you read the ID.

 

[Newmarket]

Also, there's often a drawing in the datasheet showing an end-on view. There is usually a greater bevel on one side of the IC with pin one identified on the drawing.

 

[JohnRoberts]

another vote for pin 1 being lower left corner while printed legend is "right reading" oriented.

A VOM will measure a couple diode drops when reverse polarity between +v (7) and -v (4), but not good practice to reverse op amp PS polarity. So correct polarity will NOT measure a couple diode drop between PS pins.

JR

[edit- looking at schematic of the innards https://media.digikey.com/pdf/Data Sheets/Fairchild PDFs/LF351.pdf it may be more than a couple volts reverse, but again don't do that, look for no breakdown in correct polarity. /edit]

 

[moamps]

The simplest method for detecting IC LF351 pins is to use the DMM in the resistance position and measure the resistance between pin 4 (-Ve) and other pins. Only to pins 1 and 5 an ohmmeter (not diode checker) will show a value of a few or about kohms while to all the others pins it will show a value greater than a Mohm. Pins 1 and 5 are offset nulling resistors pins.

 

[JohnRoberts]

likewise there will be resistance between pins 1 and 5 to each other pin 8 is supposed to be NC

JR

 

[Newmarket]

It could be more explicitly stated but the information is in the data sheet on page 12 (refer to the bevel).
https://www.st.com/resource/en/datasheet/lf351.pdf

 

[Ricardus]

The spec sheet says there should be a dot near pin one, but there is so much texture to the surface of these I can't tell a dot from anything. But upon reading farther down the spec sheet, they mention that the pin-1 side has a larger 45 degree angle bevel than the other side.

I had to use my special soldering glasses with a magnifying glass to see it, but it's there.

Remind me to punch the guy who invented SMD the next time I see him!

 

[Newmarket]

The spec sheet says there should be a dot near pin one, but there is so much texture to the surface of these I can't tell a dot from anything. But upon reading farther down the spec sheet, they mention that the pin-1 side has a larger 45 degree angle bevel than the other side.

I had to use my special soldering glasses with a magnifying glass to see it, but it's there.

Remind me to punch the guy who invented SMD the next time I see him!

Yeah - It's not always easy - and as my need for spectacles and magnification increases with age I feel it more
And the "texture" thing doesn't help. But ime more than that - Print on ICs used to be bright white but "These Days"* it's often a "grey on black" laser etch where you need the right light to read it properly.
* A reference to a popular UK comedian that may not translate internationally

 

[Ricardus]

Yeah - It's not always easy - and as my need for spectacles and magnification increases with age I feel it more
And the "texture" thing doesn't help. But ime more than that - Print on ICs used to be bright white but "These Days"* it's often a "grey on black" laser etch where you need the right light to read it properly.
* A reference to a popular UK comedian that may not translate internationally

What's the reference?

 

[Newmarket]

What's the reference?

Stewart Lee (I've done no research though )