Looking for 1.2V + 3.3V - Page 2

gmarsh · 6th February 2012, 12:07 PM

One thing I'll mention if you're trying this... lots of devices that run off multiple rails have specific power sequencing requirements. I wouldn't be surprised if there's a chip on the board that could suffer damage if 1.2V comes up before 3.3V.

I'd take an inventory of chips on the board and make sure this isn't the case. Enforcing this means whatever power supply you come up with needs power sequencing built in.

marce · 7th February 2012, 04:53 PM

It not damage thats the proplem, but sometimes things wont boot up properly, we use a power sequencer IC to controll how all the various supplies come up. One of the big problems is IO (3V3) coming up before core voltages

UV101 · 8th February 2012, 06:49 AM

What's the 1.2v for? Is it a VRef somewhere? I've not found any 1.2v rails (but then I've not looked yet!!!)

studiostevus · 8th February 2012, 07:17 AM

I think its the processor...
The regulator is under the wifi board on the receiver. The touch doesnt have this voltage i think.

studiostevus · 8th February 2012, 07:19 AM

Quote:

Originally Posted by marce

It not damage thats the proplem, but sometimes things wont boot up properly, we use a power sequencer IC to controll how all the various supplies come up. One of the big problems is IO (3V3) coming up before core voltages

Are you referring specifically to the squeezebox, or a general case where latch-up is a problem?

It have not found (on the web) any references to power up sequencing being a problem on the SB.

UV101 · 9th February 2012, 08:29 PM

What other rails have you identified?

I've done a fair bit but not come across this one so far. The PSU is really quite strange. I dont really understand why the main rail is only 5v.

The internal DAC runs on 5v. The wall wart smps is 5v. Inside the unit goes into another smps up to approx 10v to drive a 5v reg for the dac and touch screen sense.

All looks a bit strange with multiple smps inside!!!

BTW, I've got a total of 5 low noise regs (2 on clocks) and I have no sequencing issues.

8th February 2012, 06:49 AM	#13
UV101 diyAudio Member Join Date: Dec 2008 Location: Oxford	What's the 1.2v for? Is it a VRef somewhere? I've not found any 1.2v rails (but then I've not looked yet!!!) __________________ When Bitstream came out, I thought, “my God, what are we going to do...?” Ken Ishiwata http://www.hifisounds.co.uk Restek Fantasy, Audio Aero Capitole MKII, Focal and Kimber "Leave Nothing as Standard"

9th February 2012, 08:29 PM	#16
UV101 diyAudio Member Join Date: Dec 2008 Location: Oxford	What other rails have you identified? I've done a fair bit but not come across this one so far. The PSU is really quite strange. I dont really understand why the main rail is only 5v. The internal DAC runs on 5v. The wall wart smps is 5v. Inside the unit goes into another smps up to approx 10v to drive a 5v reg for the dac and touch screen sense. All looks a bit strange with multiple smps inside!!! BTW, I've got a total of 5 low noise regs (2 on clocks) and I have no sequencing issues. __________________ When Bitstream came out, I thought, “my God, what are we going to do...?” Ken Ishiwata http://www.hifisounds.co.uk Restek Fantasy, Audio Aero Capitole MKII, Focal and Kimber "Leave Nothing as Standard"

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6th February 2012, 12:07 PM	#11
gmarsh diyAudio Member Join Date: Apr 2004 Location: Halifax, NS, Canada	One thing I'll mention if you're trying this... lots of devices that run off multiple rails have specific power sequencing requirements. I wouldn't be surprised if there's a chip on the board that could suffer damage if 1.2V comes up before 3.3V. I'd take an inventory of chips on the board and make sure this isn't the case. Enforcing this means whatever power supply you come up with needs power sequencing built in.

7th February 2012, 04:53 PM	#12
marce diyAudio Member Join Date: Jun 2007 Location: Blackburn, Lancs	It not damage thats the proplem, but sometimes things wont boot up properly, we use a power sequencer IC to controll how all the various supplies come up. One of the big problems is IO (3V3) coming up before core voltages

8th February 2012, 07:17 AM	#14
studiostevus diyAudio Member Join Date: Oct 2009 Location: The Hague	I think its the processor... The regulator is under the wifi board on the receiver. The touch doesnt have this voltage i think.

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