SneakPeek: The QA403

Last year at this time, we introduced the QA402 as a successor to the QA401. The rapid switch was required by the AKM fire, which destroyed AKM's factory where they produce their flagship converters that were used in the QA401. 

Here we are a year later, facing a problem that might seem similar but is actually much more severe: the current silicon shortage is an unprecedented event. And it continues to get worse. In the last blog post I outlined a metric (% of TI DCDC converters that are in stock at Digikey) and began tracking that in June of this year. Since that time, we've seen Digikey stock levels continue to fall with no end in site. The graph below shows the deterioration, and the message is simple: Digikey has less than 40% of TI's DCDC converter parts in stock. Normally, in good times, this would be north of 85%. And for the remaining 15% that were out of stock at Digikey, you could get them at another distributor. But parts are out everywhere.

We use several of the SN6505B in most every product we make. Below is Octopart's summary on the availability: Nobody has any parts. Some brokers in Asia will list availability, but they either don't have parts (eg they aren't being truthful in their reporting to Octopart) OR they are expecting to receive $40 for $1 part. 

But this can't last forever, right? How bad can this be? Most distributors never dreamed you'd need visibility into the supply pipeline, and so they don't let you see precisely when they are expecting parts. However, Mouser does give you a snapshot of when they have parts scheduled to arrive.

Here's their take below on when the SN6505B will be arriving--a year from now. Yes, lead time for large orders placed directly from TI today is 81 weeks. Orders placed today will be filled in a year, assuming they are under Mouser's inventory levels.

All of the above is for a simple transformer driver--a simple part used to generate the isolated voltages used in the QA402. The part is unique to TI, but other vendors make something similar though it requires a board re-design to use.

If we go TI's website and use their tools to look at step-down DCDC regulators, we can see they have a huge portfolio of 1332 parts. But when you filter by products for which 10K or more are in stock, just 336 are available. That is, they only have sizable numbers of just 25% of their portfolio. 


Now, all of these problems can usually be worked around. You first find a part that is in-stock that does a similar job, buy those parts NOW, and then re-design the board. And then do a few board iterations to get everything just right. But when you need to do that for 15 parts on the board, the tasks is suddenly on-par with doing an entire re-design. And if we're going to do a board re-design, then we're going to re-do a lot more than  a few problem parts.

And so, work has been underway for some time on a QA403. The QA403 was supposed to live alongside the QA402, but given the landscape it looks like the QA403 will make it to market before parts for the QA402 arrive. And in other cases, we have parts in the inventory (like the SN6505 mentioned above) but would rather use those parts on a higher-performing analyzer such as the QA403 rather than the QA402.

What Is the QA403?

The QA403 will be our next audio analyzer. Externally, the QA403 will appear just like the QA402. Internally, the QA403 moves to the ES9822PRO for the ADC, and the ES9038Q2M for the DAC. Internal signal-paths move to OPA1612 for noise, and the gain switching structure has been improved. 

Benefits include:

* Improved performance (THD, THD+N, noise)

* Reduced power consumption

* 384K sample rate possibility (still TBD)

There is a lot of re-use between the QA403 and QA402. The QA403 will also have the option to be non-isolated. The isolation solution used on the QA402 and QA403 is a major issue, with part lead times rivaling those of the SN6505B outlined above. To work around that, there will be a placement option to build a non-isolated version of the analyzer should the shortage persist. If a person wanted to, it would be easy to convert a non-isolated analyzer to an isolated analyzer: Just remove the 0 ohm jumpers and place the SOIC isolation parts. 

The software used for the QA402 will have the QA403 support added, and the QA402 and QA403 will use the same software (the QA40x application). Applications you have written to run on the QA402 will run the QA403, usually with no or very minor changes. 

Shipping on the QA403 should begin in February 2022. For those that like seeing the internals, below is a near-final board, but there will be probably be two more releases before production. The cost will be similar to the QA402.


The last 18 months have been about as brutal as could be imagined from a supply perspective. And there's really no end in sight. Daily it appears to be getting worse, not better. But, when the supply issues finally do lessen, it will likely happen fairly quickly because so much additional capacity is being built today. And then we'll be staring down a glut of parts. Such is life.

From a schedule standpoint, it looks like the QA451 will be back in stock next month or January 2022, and the QA460 will be back in January or February as the QA461, with improved current sense monitoring. 

So, stay tuned. We'll get through this, but it's going to take some time.

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