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too 20th May 2007 09:33 AM

How many maximum Vcc for TIP2955 & TIP3055?
I plane to use TIP2955 & 3055 for O/P of my Amp,but I see different data beetween ECG book and internet.
From ECG tell Vceo = 100 v,but from internet (Mospec) tell Vceo = 60 V,Vcer = 70 V.Which is real value. And How many max. Vcc for it if use RE = 0.22 ohm.

jaycee 20th May 2007 09:43 AM

ECG have probably misprinted Vceo with the figure for Vcbo. The Vceo for 2955/3055 pairs is 60V.

I would not go beyond 35V rails with these, you are looking at about 45W into an 8 ohm load.

Workhorse 20th May 2007 09:49 AM

+/-30VDC is max recommended Rail voltage for these devices

AndrewT 20th May 2007 10:48 AM

the TIP data I have to hand specifies 100Vcb0 and 60Vce0 (but they are advertised as 100V devices).
This implies that supply rails should be less than +-30Vdc.
However the transistor never feels the full rail to rail voltage and you may get away with +-35Vdc. Try it and see if they are reliable.

Keep in mind that the rail voltage changes with mains input voltage. +6% (in the UK) takes +-30Vdc to +-31.8Vdc and +-35Vdc becomes +-37.1Vdc. That stresses the transistor even more.

But, worst of all is increase in temperature. Keeping the output device cases (Tc) cool will bring the biggest improvement in reliability.

jaycee 20th May 2007 10:57 AM

I've seen the TIP 2955/3055 used in plenty of 35V rail amps. I think the Arcam A60 was one of them.
(ok, so the Arcam only used the 3055, but it still used the TIP version)

The thing with the TIP devices is that one pair isn't going to be safe in anything but 8 ohm loads - you really need two.

I would question WHY use the TIP devices at all, but I understand that this may be because they are all you can get hold of.

destroyer X 20th May 2007 12:15 PM

Fully agreement with Jaycee...and i have used for long time

So, this was worked fine using 35V symetrical supplies.. and 8 ohms loads.

Also i have compared "how much worst" it is compared to modern units....not too much...increasing your treble control a little, the result is almost the same....small losses in hi end...not quality losses...volume (level, amplitude) losses only.

As some people do not know me...when i talk about compared, i mean A to B controled tests...blind testing.

When i talk to quality, sonics or losses...this is something you can listen, perceive, during audition.....nothing related my ears cannot "read" waveshapes.

A myth that old parts sound bad....of course have some losses related high end...also smaller gain...also lower dissipation capacity...but small losses, easy to compensate into the speakers treble control, listening environment or tone controls.



djQUAN 20th May 2007 12:59 PM

can the TIP2955/3055 pairs be replaced by TIP35/36?

would be using it in an amp..... a quick look at their datasheets and I think it is possible?

jaycee 20th May 2007 01:10 PM

Yep, don't see why not...

john_ellis 20th May 2007 04:41 PM

Hi all

The 2N3055 - derivatives spec has changed a few times. The original 2N3055 spec. had BVceo of 60 and BVcbo of 100. WHen TI brought out the original TIP 3055 the spec. was 70V for both if I recall correctly. The 70V rating for the 2N3055 was Vcer. So 35 V is no problem for the ORIGINAL TIP3055 and original and current 2N3055's. But the spec. I saw for another supplier TIP3055 was 60V....but I don't recall if the BVcer or BVcbo was met.

In reality this means that the liklihood of failure of an original TIP3055 at +/- 35V is low but check the latest spec. sheets for anyone else. TI don't make them anymore- the power device group was Power Innovations, and they've been bought out too.

You might consider a (parallel) pair of BD911/912's - same power (90W) but 100V.


john_ellis 20th May 2007 04:52 PM

Hi all

*** Update ***

Just checked the ST and Bourns spec sheets for TIP3055.

They're both rated at 100V BVcbo, so as long as the amp is switching them off use of 35V rails ought to be fine. This is usually OK for Class (A)B amps.

I routinely used 2N3055's from a 37.5V rail (off/light load) but I check BVcex for the devices beforehand. Haven't found any failing yet.


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