From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Raj vu2zap
Sent: Thursday, March 1, 2018 10:38 PM
Subject: Re: [BITX20] TDA2822 ill treatment test!
At 02-03-2018, you wrote:
Good information, that 800ma when shorted.
There is likely a surge that is considerably higher while it charges the cap if you power up the rig
first with no headphones or speaker, then plug in a dead short.
Only there for maybe a couple milliseconds, so would need to use a scope to see it
as a voltage across perhaps 0.1 ohm resistor that is in series with power to the chip.
Was that the stock TDA2822M that came with the uBitx?
Mine has a logo of "FCI" or maybe it's "FOI", where the middle character is filled in to where it is an almost solid circle.
It also says "PI1" and then below it says "TDA2822M".
I have no idea who makes that.
Post 43211 says there's some really bad clones masquerading as TDA2822M's.
There seems to be at least a half dozen different manufacturers of TDA2822 variants.
So any testing had best fully describe manufacturer and markings and such.
Tayda claims to have some ST/SGS-Thomson TDA2822M's and TDA2822L's at cheap prices:
When you click through to the datasheets, you get either a 1995 ST datasheet (for the TDA2822M)
or a UTC datasheet (for the TDA2822L) The "L" just means lead free.
A google search for TDA2822M finds this ST datasheet first, dated 2003 and marked "Obsolete": http://www.st.com/content/ccc/resource/technical/document/datasheet/9e/18/f7/cd/2e/b8/43/62/CD00000134.pdf/files/CD00000134.pdf/jcr:content/translations/en.CD00000134.pdf
I suspect the Tayda parts are not really ST.
Yes, bridge mode would be nice for driving an internal speaker.
But not for driving anything external, were everyone would assume the jack shell is at ground potential.
On Thu, Mar 1, 2018 at 07:22 pm, Raj vu2zap wrote:
Did some more tests.
Normal audio use the current was 60-70mA
Dead short with varied drive the current was 300-800mA. At 800mA the chip got hot!
The current did not go above 1A at any time.
I suspect there are TDA2822Ds masquerading as TDA2822M.
. . .