Price Difference between Digikey and Aliexpress

[aimthiazz]

Hi,

I'm planning to design a simple buck converter using LM2596. I was estimating the Bill of Material cost using Digikey and Aliexpress and I noticed that there is a huge cost difference between them.

Digikey : https://www.digikey.com/product-detail/en/texas-instruments/LM2596S-ADJ-NOPB/LM2596S-ADJ-NOPB-ND/363705
Cost : $5.41 per IC

Aliexpress : https://goo.gl/4sTsKP    (I have shortened the URL)
Cost : $7 for 50 IC, which roughly comes around $0.14 per IC

I understand that the Aliexpress vendor might be selling counterfeit IC's which are prone to high defective rates. But the cost difference between them is huge. Any Idea on why I should prefer Digikey over Aliexpress? Any Input / Insight will be helpful. TIA

P.S. Cost specified are in USD
Also I'm relatively new to this forum, I'm not sure whether this is the right channel to post my question. Let me know if I need to post it in different channel.

[MagicSmoker]

Yeah, $7/50 means those are almost certainly counterfeit or reject parts, but for that price why not try them out?

I, personally, won't use ICs from Alibaba or Aliexpress, but that is more because I value my time and having to rework a board to remove a dodgy IC that didn't meet its specs is way more costly than the IC itself.

[mdszy]

Probably most certainly fake/bad chips. I almost always order from DigiKey, never had any problems and while it might cost more, stuff gets to me in 2-3 days and I know it's good, quality stuff.

[Monkeh]

There are substantially cheaper, faster switchers available, which will not only save you money on the IC, but on the inductor and board area as well. Upgrade to 21st century parts and save money at the same time!

[JPortici]

probably they are NOT LM2596
i've read somewhere that all those cheap regulators marked to have a LM2596 actually uses another regulator which is functionally compatible albeit being far worse in specs

[jonovid]

how many units? 
Saving of just 1.59 USD not worth the customer backlash. but for the hobbyist, its more fun and games

[anishkgt]

Well Lets put it this way if you intent to sell your design Digi-Key would be more reliable as you don't want your customers buying stuff that blows up after a week or so. After all,
your selling 'Trust' also. If your just a hobbiest and have enough time to play around. Then give AliExpress a try.


Sent from my iPhone using Tapatalk

[rea5245]

If you buy the ones from AliExpress, let us know if they're any good.

- Bob

[schmitt trigger]

I second the opinions of previous posters.
If these chips are for your own personal use, and/or they are not used on a critical application, then you can purchase the lower cost devices.

However, if you are planning the sale of these units, the cost of replacing the defective components and the bad customer feelings you will create is simply not worth the cost differential.

I speak from experience. I have gotten badly burned before by counterfeit devices.

[anishkgt]

Myself having said that, I had bought 100 ATmega from ebay, 100 diodes, 100 LM7805, 100 H11AA1 etc. but I knew what I was buying. The 7805 was Chinese but worked so far. So it's all about luck.

Basically small stuffs like resistors are ok as long as the tolerance of these is not a factor to you. 


Sent from my iPhone using Tapatalk

[Kjelt]

You answered your own question:
Digikey: proven TI 2596
Aliexpress: unknown chinese brand mislabeled 2596 who knows what it is and will do.

So the question is how much is it going to cost you if the regulator dies and the input voltage will be on the output frying the product ?
I have read a lot of sad stories about the cheap fake 2596s enough to only use them at 750mA max.
Same with the so called HV versions.
Good luck with your lotery.

[anishkgt]

Some ic's like the 7805 would have CN marked on them instead of ON or ST. Comparatively ebay is more reliable than AliExpress because buyer feedback is very much valued by eBay and the seller too. So what you can do is mail them via eBay messages and enquirer if it is genuine and latter if 'the item is not as described' you are cover by 'eBay buyer protection' where you can either opt for a replacement or a refund.


Sent from my iPhone using Tapatalk

[Muxr]

Only stuff I order on Aliexpress are either unique tabaoo contraptions. hard to find parts, or expensive salvaged pieces I am willing to take a chance on (for instance, mini solar panels I'll order from Ali). But for for everything else I actually use Mouser.. I often find they tend to have better prices for the majority of parts I am looking for, the price brakes on quantity orders are well laid out as well.. they just seem to cater more towards the hobbyist or small run guys. If you need a specialty part and the largest selection Digikey is still the best place, although occasionally I've found new parts on Mouser that haven't made it to digikey yet.

If I am desperate for a part (for a repair) I will also use octopart.com metasearch and ebay as well.

[aimthiazz]

Thank you all for your responses. I guess I should experiment it for the sake of science. Will post my observation later. 😀

[Kjelt]

First test: switching frequency original is much higher than the fakes
Second Test: input voltage 30V drop down to 5V and 2,5A current, stopwatch when it fails.

[mikeselectricstuff]

There are cheaper options from reputable suppliers via Digikey -cheak out Richtek and Alpha Omega Semiconductor for example

[wraper]

Yeah, $7/50 means those are almost certainly counterfeit or reject parts, but for that price why not try them out?

Because they work at much lower frequency and when they will fail, very likely will destroy the load by overvoltage as well.

[DerekG]

Any Idea on why I should prefer Digikey over Aliexpress?

Digikey have built their business by only purchasing from 1st tier suppliers (normally direct from the manufacturer themselves).

The counterfeits are normally very good with their "remarking" but the differences can normally/often/sometimes be spotted under the microscope.

You can purchase both the OEM part from Digikey & the cheap parts from Aliexpress & have a good look yourself.

In this case there is a huge difference in price, however excess/no longer used 1st tier stock does turn up on Aliexpress. As a "rough rule" these "real OEM" parts are priced at somewhere between 50% & 70% of the volume OEM price. In these cases the vendor will normally state the actual manufacturer of the parts ie On Semi, Fairchild etc & you can ask (& often receive) for a copy of the invoice from the 1st tier supplier. Often these invoices are 3 to 10 years old which indicates how long these parts have been held in stock.

We are currently doing a stock take of our excess stock & will list volume numbers of micros such as some old ST6 micros, PIC16F72, PICF73 on Aliexpress shortly.

Our stores are however based in Australia

[Kjelt]

ST6 really? I worked with ST7s in 2004 so these chips must be over a decade old?

[thm_w]

For sure some of those aliexpress LM2596 are genuine, the hard part is figuring out which ones.
btw if anyone is buying TI parts, just buy direct from TI, their prices are lower than Digikey and they use Digikey to send out the parts: https://store.ti.com/LM2596S-ADJ/NOPB.aspx

As Mike says AOS make good cheap switchers, should be much more compact than the LM2596, if you are designing one into a product.
Or you could even get something like this and solder it onto your board: https://www.aliexpress.com/item/5-pcs-Mini-360-DC-DC-Buck-Converter-Step-Down-Module-Ultra-Small-Power-Supply-Module/32412017021.html (assuming specs are within your requirement).

[DerekG]

ST6 really? I worked with ST7s in 2004 so these chips must be over a decade old?

Correct: circa 1998-2004 (they sold side by side against the ST7 for many years).

We should have cleaned out our stores much earlier!

Whilst we have been mainly using PIC16 parts for the past 15 years, we are now moving back to the ST8 parts from ST Microelectronics for our lower end products as Microchip can no longer compete.

Take a look at the pricing for an STM8 part with 8K Flash & 1K RAM - both available with 16 I/O (US$0.36) & 28 I/O (US$0.52) (Digikey pricing, if you order from Arrow etc your would save a further 10% on these prices).

https://www.digikey.com/product-detail/en/stmicroelectronics/STM8S003F3P6TR/STM8S003F3P6TR-ND/4357536

https://www.digikey.com/product-detail/en/stmicroelectronics/STM8S003K3T6CTR/STM8S003K3T6CTR-ND/3455602

[krho]

There is also stm32l0 which in some configurations comes to ~1$@1000pcs and has half the consumption of stm8s003

[Smallsmt]

Semiconductor suppliers sell parts to big production runs like automotive components at very low prices.
Most of the microcontrollers costs below 1 usd we pay normally 4 to 5 times more sometimes 10x.

Some parts on Aliexpress are pre owned or second hand parts so take care.

Fake parts are possible to0 but if you check the electrical parameters against a reference part it should be safe to use.

[DerekG]

There is also stm32l0 which in some configurations comes to ~1$@1000pcs and has half the consumption of stm8s003

Yes, ST Microelectronics have been sharpening their pencils these past couple of years with their "Value Line" micros, in both 8 bit & 32 bit.

Atmel AVR's (the under dog) always looked to be bit better value than Microchip ............ but all that is changing now with STM competing hard in the same space, often coming in at half (or one-third) the cost of a similar PIC part.

[Kjelt]

Take a look at the pricing for an STM8 part with 8K Flash & 1K RAM - both available with 16 I/O (US$0.36) & 28 I/O (US$0.52) (Digikey pricing, if you order from Arrow etc your would save a further 10% on these prices).

Been working since 2008 to 2011 with those chips when they were only prototypes 
nice chips for small products but they lack the processing power of the arm 32 bits that use less power.