XR2206 Chip Overheats? - Page 1
Forum section: electronics / beginners

author: Legal_Planet
author_rank: Newbie
timestamp: March 24, 2018, 04:53:22 pm
content: Hello,I purchased 10 XR2206 chips from ebay in hopes to make a wave generator for some synth projects. I followed this guide (https://makezine.com/projects/make-a-wave-shaper-multifunction-sound-synthesizer/) and made two different boards from perf but each resulted in the chip getting very hot. I'm 100% the boards I'd soldered follow the instructions. I'm using a 16v 700mA AC-DC adapter so it's within the range of the chip's specs. Even if I run Vcc to a new chip's pin 4 and ground to pin 12 while the remainder remain open the chip still gets hot. Is this normal, am I doing something wrong, or have I possibly received a lot of dead chips?

author: Buriedcode
author_rank: Super Contributor
timestamp: March 24, 2018, 05:17:33 pm
content: Possible, but its hard to say without a schematic and a layout (even on perf board).Standard debugging with a continuity tester, checking each pins resistance to ground and V+ to check for shorts/bridges/layout mistakes would help.

author: Audioguru
author_rank: Super Contributor
timestamp: March 24, 2018, 05:18:52 pm
content: The XR2206 is obsolete and not made anymore. You bought cheap Chinese fakes or defective copies from ebay so of course they do not work.

author: Legal_Planet
author_rank: Newbie
timestamp: March 24, 2018, 05:43:00 pm
content: Was hoping they wouldn't be knockoffs but I'm beginning to think they're rejects that the seller sold off in bulk. Going to try contacting the seller about the issue. Ohhhh boy.

author: ocw
author_rank: Regular Contributor
timestamp: March 24, 2018, 05:45:23 pm
content: Have you measured to actual voltage coming from that adapter? Unregulated adapters typically have voltages much higher than their ratings when they are only lightly loaded (as yours would be feeding the just the XR2206).How good is the filtering on that adapter? It might have too small, defective or no capacitive filtering. A high AC ripple on the adapter's output could cause problems.The schematic which you point to does not have the recommended 1uF capacitor to ground on the positive voltage input pin (4).There are three possible causes.

author: Legal_Planet
author_rank: Newbie
timestamp: March 24, 2018, 05:57:27 pm
content: I'll try out the 1uF cap but as for the voltage from the adapter I'm getting 17.52v and and and its output appears to be perfectly linear.

author: sourcecharge
author_rank: Regular Contributor
timestamp: March 25, 2018, 03:46:02 am
content: Quote from: Audioguru on March 24, 2018, 05:18:52 pmMy XR2209 chips have a 1 MHz max frequency, 1000:1 frequency sweep, and has a square wave and a triangle wave output.The XR2206 is the same except with a sine wave output.The EXAR chips are great I think, and the ones I got work great.What I don't get is why the manufacturer decided to stop making them.Don't want to use digital microprocessors with DACs and post waveform processing opamps, that just way too complex compared to a 1 chip solution.I wish I knew of a replacement VCXO type that did the same thing but with maybe greater capability.Got any Ideas?

author: coromonadalix
author_rank: Super Contributor
timestamp: March 25, 2018, 03:57:45 am
content: you had max038 managed to get 2 sample of them never used lollthe xr2206 may heat if the output load is too much, normally you had somme push pull amplifier to add more gain and load possibility

author: BradC
author_rank: Super Contributor
timestamp: March 25, 2018, 04:49:33 am
content: Most of the knockoffs get funky at around 12V or thereabouts. I recently bought a couple of genuine parts from Jameco. They were bordering on unreasonably expensive, but they don't exhibit the issues that plague the clones.I now have no idea why I bought them, let alone why I paid that much for the parts + shipping.

author: Jwillis
author_rank: Super Contributor
timestamp: March 25, 2018, 08:44:26 pm
content: Quote from: Legal_Planet on March 24, 2018, 05:43:00 pmThe XR2206/11/12EB which is the equivalent is not obsolete according to Mouser.A lot of the stuff you get from Ebay is new old stock and not necessarily fake .

author: wraper
author_rank: Unknown
timestamp: March 25, 2018, 09:59:00 pm
content: Quote from: Jwillis on March 25, 2018, 08:44:26 pmIt is "just" not in stock and not available at any reputable distributor. Not every part which is no longer produced is necessarily listed as obsolete at Mouser.QuoteNot all, but most of what is no longer produced is fake.

author: wraper
author_rank: Unknown
timestamp: March 25, 2018, 10:07:43 pm
content: Quote from: sourcecharge on March 25, 2018, 03:46:02 amIf you don't make a million of chips annually, most likely it does not make economic sense. This chip no longer has any significant market. On top of that production technology/equipment gets obsolete. Often it makes more economic sense to get rid of old equipment and replace it with new which in not suitable for producing old designs.QuoteReal industry don't care about your needs.

author: drussell
author_rank: Super Contributor
timestamp: March 26, 2018, 07:50:43 am
content: Quote from: Jwillis on March 25, 2018, 08:44:26 pmHuh? I think you're confused. That was a dev board that used to be available when Exar made that chip family.What does that have to do with availability of the actual chips?

author: bd139
author_rank: Super Contributor
timestamp: March 26, 2018, 08:39:56 am
content: A point to note: most of the problems at the high end of the frequency range are due to bad decoupling of the supply rails. The Exar manufactured devices suffer from the same problems as well. I wouldn't be so quick to blame fakery. They're pretty good. I built an FSK modulator with a £1 from aliexpress which was clearly fake as it was marked up differently to the Exar ones and it was rock solid.As for alternative solutions, there aren't really any one chip ones. For better or worse, most likely the latter, it's something a microcontroller or DDS can do now at merely the added cost of capital complexity, time and money. Bah humbug.You can build your own though with the usual combination of integrator and schmitt trigger. If you want sine you can add a diode shaper on the output or a switched capacitor filter. See attachment. Works with most opamps.

author: CJay
author_rank: Super Contributor
timestamp: March 26, 2018, 10:56:55 am
content: I abhor the 'it's from China so it's fake' or 'Its from China so it's crap' mentality, while I'd not buy from eBay for a commercial project, as a hobbyist, it's an excellent way to get a huge variety of parts way cheaper than you can buy them anywhere else.Yes there are fakes, there always have been even before eBay made it easy to buy from China.There are plenty of NOS parts, there are plenty of 'refurbs' or pulls for sale and yes, there are fakes which aren't always easy to spot because sellers use pictures of genuine parts in a lot of cases.Now, the XR2206, first thing, I suspect your PSU as it sounds like it'd be unregulated and possible even very poorly smoothed so chances are it's a *lot* higher output on low current draw.Try it with a battery pack instead and see how it performs but before you do that, unplug the chip, grab a copy of the datasheet and measure the voltages where the chip will be fitted to ensure your power supply is correct polarity, correct voltage and on the correct pins.