Hi All,
I have a radio with this IC in it https://www.digikey.ca/en/products/detail/onsemi/LA4425A-E/3536126 but it is obsolete. I am wondering if someone can tell me if there is an alternative?
I have the room to install a fairly large/different IC so if it functions the same I can most likely make it work.
Thanks for your help.
Hi Byron,
I could not find any through hole IC amps with that same type of package case, the 5-SIP seems to be obsolete.
In the link you gave there are some similar ones suggested to check out. You can scroll to the bottom of that page to see the opions and click on each on to see if it might work for you.
Hi Irfan,
How would I use one like this for example: https://www.digikey.ca/en/products/detail/texas-instruments/LM4991MA-NOPB/1871789
It says it is similar, but it has different input pins etc. Do I just tie all inputs together?
Also could something like this work: https://www.digikey.ca/en/products/detail/stmicroelectronics/TDA2030AV/599619
I am not too familiar with amplifier ICs and don’t know how inverting and non inverting inputs work.
Byron
Hi @ByronT ,
Although not direct crosses, please review the “most similar” options i’ve found 2368-NTE1376-ND | 2156-LM383T-NS-ND. Please review datasheet specifications before ordering to verify if they will be suitable for your application.
Hi again Byron,
The data sheet of the LA4425A-E gives info on pins 1 through 5 as such in image below taken from the data sheet.
Unfortunately I found nothing with the similar configurations. The ones you listed like LM4991MA/NOPB is 8 pin and it is also a surface mount not through hole. It may be possible to incorporate something like this but its not going to be a form fit solution where you can just solder it on an go.
The TDA2030AV is also 5 pin but it is obsolete and we have none in stock. This is more similar in the pinout and fit properties but the pinouts are designated a bit differently.
Basically looking through the data sheets and verifying pinout along with pin functions is what you will have to end up doing. Maybe someone else can offer more assistance on how to utilize some similar products we have listed, in place of the one you have.
Just my two cents worth, but I would try the LM383T. Check out the datasheet and make any necessary changes. If you have the room mount the package rotated 90 degrees and use wire to change the pinout as needed and solder the wire to the PCB.
If you are simply trying to fix something and not looking for production- I’d just buy this 5 pack and be done with it. Hopefully you don’t have something else wrong that caused your amplifier IC to die in the first place.
Kind regards,
Brian
Not sure we still carry them, but we used to have SURF boards, which is basically a breakout board with SMT solder pads, adapting to a SIP , but really , at this point any option of modifying by using your own board, is probably difficult.
Using any other part would require adding additional components, as your part is fairly unique in that it does not require feedback resistors plus a few extra capacitors for setting the gain of the amplifier (that’s what goes on the inverting input of most of those other amps). Yours has a fixed gain of about 45dB, or 178 volts per volt. Therefore @Brian_German has the best answer, just snatch up those ebay parts.
Hi Brian,
Have you had good luck ordering these types of items off of ebay? I am leery of getting face chips.
Byron
Hi Irfan,
I have a couple TDA2030AV in stock in my shop, but I am unsure of how I would connect it up in place of the LA4425A-E.
Any chance you could help with that?
Byron
Hi ByronT,
I suspect that if you ordered that 5-pack of parts off of ebay, it would most likely work out, but it’s always a bit of a risk there. However, if you want to try to use a TDA2030AV in its place, you would want to compare the circuits between the two and make a custom board with the TDA2030AV and all of the extra parts it needs and then run wires to the main circuit board from the appropriate points on your custom board.
I assume you’ve found a datasheet for the LA4425A-E online somewhere. I presume your board has it wired in similarly to the example circuit provided on page 2 of that datasheet, which looks like this:
LA4425A-E sample circuit:
Note that there are only 3 external caps and the speaker around the part.
Single supply schematic for the TDA2030AV from page 4 of the datasheet:
After you make your custom circuit board as shown, you’ll want to run wires from your board to the main board. I have shown where you would connect between the custom board and the main board below using green “wires”.
Additionally, you’ll likely need a heatsink to adequately cool the TDA2030A.
Wow, OK so I assumed that was a test circuit for those chips on the datasheet. Missed that it was what was required to run the chip.
I really appreciate that sir!
I think for the chance on some learning I will try to set it up to work on the TDA2030AV and as backup I will order the ebay chips.
Thank you for your help!
That seller has a 99.7% positive feedback rating on eBay. I’d have no problem buying from him, but that is me.
As stated previously, there is always a chance they are not OEM LA4425A chips (fake). It may be worth the risk or you could try this seller: LA78040A BY SANYO 1 Piece | eBay He is in New Jersey, USA.
OK. Might be fun!
A few points about the example circuit:
Since the TDA2030AV is designed to work with dual supply rails (positive and negative voltages on pins 5 and 3, respectively), to operate on a single rail, you have to shift your input signal to around 1/2 of the positive rail. That is why the two 100kΩ resistors on the input side are connected between the positive rail and ground. Except for some small AC signals, the voltage at that point between them will remain at nearly 1/2 the supply voltage at all times. The 22uF cap next to the lower one acts as a buffer to help keep it stable at that voltage.
The 2.2uF input capacitor blocks any DC portion of the input signal (your board should already have this cap, though it may not be the exact same value) but allows the AC audio signal to pass. The 100kΩ resistor placed after the input capacitor and between the non-inverting input of the op-amp and the center point between the other two 100kΩ resistors is there to tie that mid-voltage rail to the input of the op-amp. With this in place, the voltage at the op-amp input will wiggle around the mid-point of the supply rail.
The combination of the 100kΩ resistor and the 4.7kΩ resistor connected as shown between the output and the inverting input of the op-amp control the gain of the amp. For discussion’s sake, I’ll call the 100k resistor R1 and the 4.7k resistor R2. The formula for calculating the gain is:
So, the gain of this circuit is about 21 volts per volt, which can also be referred to as 27dB. As mentioned above, the gain of the LA4425A-E is given as 45dB, which translates to a gain of 178 volts per volt. To increase the gain of the TDA2030AV, you would increase the value of R1.
To get to the same 45dB level as the LA4425A-E, R1 would need to be approximately 831kΩ. The datasheet gives most of its specifications assuming a gain of around the 20-27dB range, so it is not clear what the effect of increasing the gain that much would be. I would recommend you use a 1MΩ multiturn trim pot for R1 and test your circuit at around 100kΩ first. Once it’s working, then you can start to increase the resistance incrementally and test as you go to make sure it still operates without excessive distortion.
The other components are there to properly filter the output and to protect the amp from oscillations and voltage spikes on the output.
Finally, most of the specifications given for the TDA2030AV assume a power supply of +/-16V, which equates to 32V between +Vs and ground on a single supply topology. The recommended minimum supply is +/-6V, which equates to a 12V single supply rail. It shouldn’t hurt it to go below this by a little bit, but it’s output power would be reduced, and if too low, it simply won’t operate.
