ASRock B550M-ITX/ac - Need help with SOT23

[gurj1979]

Hi guys.

So I've got hold of a board mentioned above.
Need help finding a suitable replacement Transistor/MOSFET of SOT23-3. 2 are blown.
SMD Marking is A3OAK but I can't find this anywhere on the internet, not even AliExpress.
What can I use instead of these.

Multimeter continuity shows it connects to the LED RGB Header.
So these are LED Drivers, but are they Transistors, Diodes, or MOSFET's ?

Anyone please help.

See pics.

Thanks

[DynaxSC]

Re: ASRock B550M-ITX/ac - Need help with SOT23

Hi, looked into some similar generation Asrock boarview's for the same application part, it could be the N-Channel Enhancement Mode MOSFET from Sinopower -> SM2430NSANC-TRG (SM2430NSAN).
It has the marking code A30XX, where XX is date code, which makes it highly probable it's this device, also as vendors tend to use similar devices over the product palette for lower purchasing prices.

However you could use here any similar mosfet, with ESD protection and at least the same ratings regarding RDS(on), Vdss voltage (30V) and Id (1,49A), voltage can be even lower, as the maximum voltage present here is 12V, so 20V would also do the job. I would even recommend to use some device with much higher Id eg. 3A and and lower RDS(on), as LED strips can generate really high currents, and probably the reason for the failure was a higher current, than these devices can handle (BTW 1,49A is a fairly weak current, so I would say ASRock has done a bad job with savings here). I know there are devices out there in same package which can handle up to 6-7 Amps, but probably w/o the ESD protection, which BTW is not very critical here (once the mobo is mounted in the case, the risk for electrostatic surges is marginal inside the case - it's in fact a faradaic case).

Especially lower RDS(on) is better as it reduces the dissipation power in the device, and automatically increases the Id current tolerance, hence also the reliability.

I would also recommend to check, whether the nearby 2N7002 mosfets (K72 marking) driving these swithes are not broken/shorted (probably they are not, but it's better to check before replacing the SM2430NSAN swithces).

The datasheet you will find easily in the net.

[krsta]

Re: ASRock B550M-ITX/ac - Need help with SOT23

Site for smd markings says it :

A3*** SOT-23 Si2303DS Vishay P-Channel MOSFET

[DynaxSC]

Re: ASRock B550M-ITX/ac - Need help with SOT23

The problem with markings is they are most of the cases not unique and can stand for several different devices. Usually also the date codes in markings are only 2 letters/digits long.

Anyway, one way is just to try both types of devices, and see what works, much bad except another 3 low cost devices burned, if at all, cannot happen. Mosfet device is sure.

[gurj1979]

Re: ASRock B550M-ITX/ac - Need help with SOT23

Yes you might be right there. I just happened to stumble across the same too. SM2430NSAN (https://alltransistors.com/mosfet/tr...ansistor=25189)

The only thing I'm not too sure about is the 0 (zero) or O (letter o). A30AK or A3OAK.

I'll see if I can find it locally in UK.

Thanks dude.

Hi, looked into some similar generation Asrock boarview's for the same application part, it could be the N-Channel Enhancement Mode MOSFET from Sinopower -> SM2430NSANC-TRG (SM2430NSAN).
It has the marking code A30XX, where XX is date code, which makes it highly probable it's this device, also as vendors tend to use similar devices over the product palette for lower purchasing prices.

However you could use here any similar mosfet, with ESD protection and at least the same ratings regarding RDS(on), Vdss voltage (30V) and Id (1,49A), voltage can be even lower, as the maximum voltage present here is 12V, so 20V would also do the job. I would even recommend to use some device with much higher Id eg. 3A and and lower RDS(on), as LED strips can generate really high currents, and probably the reason for the failure was a higher current, than these devices can handle (BTW 1,49A is a fairly weak current, so I would say ASRock has done a bad job with savings here). I know there are devices out there in same package which can handle up to 6-7 Amps, but probably w/o the ESD protection, which BTW is not very critical here (once the mobo is mounted in the case, the risk for electrostatic surges is marginal inside the case - it's in fact a faradaic case).

Especially lower RDS(on) is better as it reduces the dissipation power in the device, and automatically increases the Id current tolerance, hence also the reliability.

I would also recommend to check, whether the nearby 2N7002 mosfets (K72 marking) driving these swithes are not broken/shorted (probably they are not, but it's better to check before replacing the SM2430NSAN swithces).

The datasheet you will find easily in the net.

[gurj1979]

Re: ASRock B550M-ITX/ac - Need help with SOT23

Just checking now, and it looks like different text used than the SM2430NSAN
I doubt it is this one.
Thanks for checking.

Site for smd markings says it :

A3*** SOT-23 Si2303DS Vishay P-Channel MOSFET

[gurj1979]

Re: ASRock B550M-ITX/ac - Need help with SOT23

I found this out for all 3 of those SMD's.
Gate (Pin 1) comes from 3 x K72 transistors.
Source (Pin 2) goes to Ground.
Drain (Pin 3 goes to R G B pins, respectively of each A30AK/A3OAK).
So from this, is there any way of telling if it's N or P Channel ? Then I guess we can say if if its Vishay (P Chanel) or SinoPower (N Chanel).

[gurj1979]

Re: ASRock B550M-ITX/ac - Need help with SOT23

I guess its N Channel by studying this video.
Therefore it's SM2430NSAN

https://www.youtube.com/watch?v=a30Rm7UQLss

[gurj1979]

Re: ASRock B550M-ITX/ac - Need help with SOT23

I could probably get away with 2N7002 - easily salvageable from donor boards I have.
What are your thoughts ?

https://alltransistors.com/mosfet/cr...s=SOT23N&cf=on

[DynaxSC]

Re: ASRock B550M-ITX/ac - Need help with SOT23

2N7002 is a typical low power mosfet widely used for logic networks on mobos, it will not have enough power handling (drain amperage), I would not recommend this but you can try, for a very short LED strip it may by sufficient. Longer LED stripes can even need several amperes for driving. The issue in this LED driving network is, there is completely no power limitation, eg a recoverable fuse or so. So the driving mosfet will be the fuse as the weakest element in the loop. But all mobo vendors do it same bad way, and I've seen already many boards with the same issue of burned drivers.

[DynaxSC]

Re: ASRock B550M-ITX/ac - Need help with SOT23

Here I found a similar ASRock boardview with same chipset (B550) and even same part numbers, it confirms the SM2430NSAN:



As a good replacement you could use eg an Alpha & Omega AO3434A:
https://www.tme.eu/pl/en/details/ao3...semiconductor/

Id is rated 4A (see the datasheet, on the page they say only 3A), has a very low Rdson - 74 miliohms resistance in conducting mode (so low dissipation power), it has also a shottky diode and reverse diode ESD protection, and I think it should be also easier to buy in your country.

This polish site you can also very easily search for other replacements - it has an extremely good parametric search implemented, much better than mouser or other big distributors, it is also in english. They send also abroad. On Aliexpress it is also available.