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Old 22nd August 2007, 01:47 PM   #11
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by AndrewT
they do a low power To92 version of this transistor with what appear to be identical characteristics.

Hi Lumba,
go and have a look at the Hitachi 2sb647a datasheet.
Most of the data is very close to that for 2sb649, except for the voltage, current and power derating to match the To92 package.

I contend that this same chip could well be used in both devices with just the copper backplate increased to allow the extra dissipation.
But, I could be wrong.
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Old 22nd August 2007, 05:09 PM   #12
ilimzn is offline ilimzn  Croatia
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You are probably right, it wouldn't be the first time this was done. just look at the venerable BD139/140 and it's TO92 version, BC639/640.

The chip looks small, but I doubt the real thing is very big, perhaps a bit over 1mm square. The writing is odd, looks like laser cut or etched, the genuine devices are similar but very shallow (almost like print).
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Old 23rd August 2007, 08:30 AM   #13
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Hi Andrew,
OK, now I understand what you mean and YES you are very much right. Manufacturers use often transistor chip designs in several different packages resulting in recognizable similarities.
The package of 2SB647 is TO-92L
Other nice devices from Hitachi I would like to mention: 2SD756 2SC1213 2SC1775 2SD1609 and their complementary pairs.
- That`s superior Japanese technology.
Kindly regards
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Old 24th August 2007, 06:24 AM   #14
Zeljko is offline Zeljko  Croatia
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Quote:
Originally posted by AndrewT
Hi,
they do a low power To92 version of this transistor with what appear to be identical characteristics.
If this is indeed a high power version, then we would expect the chip to be smaller than the norm, but that does strike me as very small.
Yes you are right, look at attachment, but now I am so confused, is it genuine Hitachi transistor or not
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File Type: pdf 2sb649_a_unisonic.pdf (77.0 KB, 74 views)
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Old 24th August 2007, 06:33 AM   #15
Zeljko is offline Zeljko  Croatia
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I still cant believe it that small silicon chip can deliver Ic current of 1A .
What is very strange, look how i got it.

Zeljko
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File Type: jpg pict0248.jpg (95.5 KB, 308 views)
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Old 24th August 2007, 06:36 AM   #16
Zeljko is offline Zeljko  Croatia
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And this is one another 2SB649A which looks the same as jackinnjs.
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Old 24th August 2007, 06:37 AM   #17
Zeljko is offline Zeljko  Croatia
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And how it look inside, look at that size of silicon chip!
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Old 24th August 2007, 09:27 AM   #18
AndrewT is offline AndrewT  Scotland
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Hi,
have you seen Zetec's 3A transistors built into the Eline package?
Some SMDs have similar spec in the sot23 and 223 packages.

It appears that the chips can cope if the heat can get out.

Think about the relative size of a big power transistor and the much bigger heatsink to keep it cool. Same philosophy, but on a different scale.
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Old 24th August 2007, 11:06 AM   #19
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Zeljko,
Quote:
now I am so confused
Do not be. UTC is a Taiwanese pirate.
Only Hitachi`s manufacturing technology should be trusted.
Quote:
I still cant believe it that small silicon chip can deliver Ic current of 1A
Actually 1.5A
The operating area and dissipation level of devices in audio use, in general terms and especially versus data sheets, would be another issue.
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Old 24th August 2007, 11:11 AM   #20
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Andrew,
Quote:
It appears that the chips can cope
Maybe it can for a while, but I would not like to listen to the sound produced.
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