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Old 15th November 2012, 08:40 AM   #1501
glt is offline glt  United States
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AR2, Finally got a change to look at all the photos. Incredible! I like the photo of your lab, looks like inside the space shuttle...
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Old 15th November 2012, 09:49 AM   #1502
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Originally Posted by glt View Post
AR2, Finally got a change to look at all the photos. Incredible! I like the photo of your lab, looks like inside the space shuttle...
+1

That's far beyond I can imagine from the word of "D.I.Y" 
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Old 15th November 2012, 10:25 AM   #1503
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+1

That's far beyond I can imagine from the word of "D.I.Y" 
Totally agree but that is also most of the D.I.Y.er's dream : Knowledge, time and money
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Old 15th November 2012, 10:30 AM   #1504
syklab is offline syklab  Hong Kong
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It can only be a dream, cannot afford that much space in HK.
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Old 16th November 2012, 02:12 AM   #1505
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Default TPS7A4700 low noise PSU PCB

I got TPS7A4700 PCB last weekend. I assembled two of them tonight. One is MLCC version, the other is TAN version. I know there is piezoelectric effect connected to MLCC capacitors which can introduce mechanical vibration into noise. But Iím not quite sure by how much it will affect the power supply of an oscillator. Is there anybody has experience on this issue?

TPS7A4700 is a jumper programmable bipolar RF regulator. It can be easily set into 3.3V, 5V and etc with steps each 0.1V. Max input range goes to 36V. 4.17 μVRMS (10 Hz, 100 kHz) output noise level makes it industrial best so far. Another good thing is the max output current goes up to 1A. This feature makes it very suitable for powering Si570 which needs a very low noise power supply running at 100mA level.

One of the PCB caught fire during test because the TAN caps were reversing assembled by mistake. Whole board became black. I threw it into garbage bin and re-assemble a new one. So, please always be aware of TAN caps. Sometimes they are dangers. Never reverse of over voltage.

After that, both of them ran right away. Without load, one outputs 3.321V and the other 3.331V. It seems I can start testing the Si570 clock board now.

Ian
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File Type: jpg PCBs.JPG (648.2 KB, 470 views)
File Type: jpg MLCCversion.JPG (439.2 KB, 446 views)
File Type: jpg TANversion.JPG (450.1 KB, 439 views)
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Old 16th November 2012, 03:22 AM   #1506
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That looks like a lot of fun there Ian! Seems you needed the Lego fire department earlier though

A question that has just struck me is ... with that VQFN package, where is the index marking? How do you know which way it should sit on the pcb?!
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Old 16th November 2012, 04:00 AM   #1507
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That looks like a lot of fun there Ian! Seems you needed the Lego fire department earlier though

A question that has just struck me is ... with that VQFN package, where is the index marking? How do you know which way it should sit on the pcb?!
Thermal pad has a cut corner so it's not difficult to indicate pin 1 .

Ian
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Old 16th November 2012, 07:15 AM   #1508
glt is offline glt  United States
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Quote:
Originally Posted by iancanada View Post
I got TPS7A4700 PCB last weekend. I assembled two of them tonight. One is MLCC version, the other is TAN version. I know there is piezoelectric effect connected to MLCC capacitors which can introduce mechanical vibration into noise. But Iím not quite sure by how much it will affect the power supply of an oscillator. Is there anybody has experience on this issue?

TPS7A4700 is a jumper programmable bipolar RF regulator. It can be easily set into 3.3V, 5V and etc with steps each 0.1V. Max input range goes to 36V. 4.17 μVRMS (10 Hz, 100 kHz) output noise level makes it industrial best so far. Another good thing is the max output current goes up to 1A. This feature makes it very suitable for powering Si570 which needs a very low noise power supply running at 100mA level.

One of the PCB caught fire during test because the TAN caps were reversing assembled by mistake. Whole board became black. I threw it into garbage bin and re-assemble a new one. So, please always be aware of TAN caps. Sometimes they are dangers. Never reverse of over voltage.

After that, both of them ran right away. Without load, one outputs 3.321V and the other 3.331V. It seems I can start testing the Si570 clock board now.

Ian
Beautiful!
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Old 16th November 2012, 08:18 AM   #1509
qusp is offline qusp  Australia
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I dont think the piezo effect is anything to worry about, otherwise why would they be used internally in the chrystek clock under the can? I prefer the panasonic special polymer for bulk decoupling though. at these low voltages you may find a large enough DC link polymer, which acts like a small battery
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Old 16th November 2012, 11:28 AM   #1510
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AR2:

Would the real Tony Stark, please stand up.
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