Op amp 4 power supply


#1

Hi all,
I’m going to finish my first project with eeschema.
The project consist of two riia pre stages; each stage use an opa1612.
I design a single filter supply for each pin power .( by an RC net). Then,
I’d connect each single power supply pin to its own filter.
Given that power supply are invisible, what is the right procedure to do?
Thanks in advanced.
Regards
Ros


#2

OPA1612 is a dual opamp.
In Eeschema it is divided into 3 “Units”.
A). Opamp with suffix “A” and pins 1, 2, 3
B). Opamp with suffix “B” and pins 5, 6, 7
C). Power pins section with pins 4 and 5.

You can edit the properties by hovering over a symbol and press “e”.
Then in the symbol Properties window in the top left corner you can change the “Unit” to A, B, or C.

Alternatively, you can also select which unit you want when you get a symbol from the libary directly.
Type “a” in eschema, type “OPA1612” in the search box, and then select either Unit A, B, or C.
image


#3

This does assume @Masca64 uses version 5 libs. In version 4 the op amps really used invisible power pins.


#4

good morning ,
thx for you reply paul and rene.
let me see if I understand everything: in my schematic I used 1 chip (OPA1612) for left channel + 1 chip for right channel (another OPA1612) .
At the beginning:for each channel I used only OPA1612 A unit and OPA1612 B unit : in effect I didnt use in the schematic part C (with power pin section) ; I understant this is the 1st error: I must use , for each chip, unit C too, it’s correct?
ok, continue:
and then,
to minimize intermodulation between channels, I prefered use a separate power supply for each channel.
I means that, Negative and Positive rails go through a low pass rc filter before attach to te negative and positive pins of each chip.
Wich is the procedure to forced power pin of each chip to a different net -instead (as default) Vcc or Vdd ?
I must declare a property in part editor of chip?
Suggest please?
thanks in advanced
Ros


#5

sorry, i forgot:
I downloaded Kicad yesterday, so I’m using Version (5.0.2)-1
thx again
regards
ros


#6

Simply connect the power input pins to the net you want them to be connected to. (unit C of the symbol!) Do not use global labels here unless you really know what you are doing (Power symbols ARE global labels!)

This depends on you having one full IC per channel. If you share the same IC then you only have one supply for that part! (This is not in any way a limitation of kicad. It would be a limitation of your design. The IC simply has one supply for all its sub units combined.)


#7

perfect,
thanks a lot Rene,

during the morning I was trying to use unit C too, connecting it to the output filter, in effect is the right way because the circuit well works …finally I can continue to build pcb …
Thanks again Rene
HAND (Have A Nice Day)
:slight_smile: