Is it a good SE to Diff PCB ? ( link below )That's ridiculous.
Edit: PCBs arrived.
http://www.ti.com/lit/ug/tidu038/tidu038.pdf
thank Dr
https://www.google.co.uk/url?sa=t&s...fhW9oji85vyzqJNRQ&sig2=EZcZ8hLhObEYMe89DclseA
Might be of use if the link works.
Might be of use if the link works.
You guys might want to maximize gain up front and drop gain at the pwr amp. > source to end gain distribution, max S/N.
DC coupled is harder, I wouldn't unless a cleaned up reference V is available from the pwr amp inputs , that way it tracks with Vdd & temp. but maybe it's just too noisy. The 1st diff amp app. note is more generic so you don't have to use their $tuff.
TL431 maybe good enough to supply both Vcc and Vref. (with a resistor divider)
DC coupled is harder, I wouldn't unless a cleaned up reference V is available from the pwr amp inputs , that way it tracks with Vdd & temp. but maybe it's just too noisy. The 1st diff amp app. note is more generic so you don't have to use their $tuff.
TL431 maybe good enough to supply both Vcc and Vref. (with a resistor divider)
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It's alive, actually in a "worst case" setup.
This means:
- noname Low-ESR-Caps
- no Step-Down-Converter (PVDD linked to linear regulators, so actually 18V max)
- X5R high-capacity MLCCs
- LM4562 opamps (the good ones)
- no EMI-snubbers
- no 0612 100nF direct decoupling
Things only can get better.
It works without heatsink at moderate levels, gain-stage and amp are dead-silent, really. It's actually "no-noise". Fault/Overtemp works, 2-stage fan works, no power-on-plop but power-off-plop when not muted. Setup is one-channel-only at the moment, other channel will get different inductors. Heatsink is getting done next. Power-in is fused at 6.3A fast.
All in all, success!
(Sorry for the bad pictures, it's late)
This means:
- noname Low-ESR-Caps
- no Step-Down-Converter (PVDD linked to linear regulators, so actually 18V max)
- X5R high-capacity MLCCs
- LM4562 opamps (the good ones)
- no EMI-snubbers
- no 0612 100nF direct decoupling
Things only can get better.
It works without heatsink at moderate levels, gain-stage and amp are dead-silent, really. It's actually "no-noise". Fault/Overtemp works, 2-stage fan works, no power-on-plop but power-off-plop when not muted. Setup is one-channel-only at the moment, other channel will get different inductors. Heatsink is getting done next. Power-in is fused at 6.3A fast.
All in all, success!
(Sorry for the bad pictures, it's late)
Attachments
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If they do carry your rms/peak current without dropping (too much) every inductor is fine. So your Bourns are fine if they are rated for the current demands of the 3116 and your listening levels. These Coilcrafts just carry more current before they drop in inductance. I'll test them against another Coilcraft inductor (molded) and some Bourns. To say at last, the Coilcrafts are overbuilt even for this application, smaller ones will also do. Will have to check the thermal aspects as well.
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Thanks to doc's generosity, by providing me with one of his samples, I now have two of my channels up and running. The chip arrived early on this morning.
The pictures aren't fantastic as the lighting here is pretty dire, nevertheless have some pics.
I am currently running these from 7 Li-ion cells in series, giving about 26 volts. The high efficiency of these chips allows battery operation without needing vast amounts of capacity. If these pan out I will add in 2 more cells to bump the voltage up to around 36 volts and implement a charger that keeps things topped off when the amps aren't in use.
As doc says these do run cool, the idle losses are no joke, you can use these without a heat sink at low power levels. They are also quiet. Quieter than the TAS5630 that I have used in the past. This was one of my concerns as you need low noise for use with higher efficiency loudspeakers.
Measurements will hopefully be coming up in the not too distant future.
The pictures aren't fantastic as the lighting here is pretty dire, nevertheless have some pics.
I am currently running these from 7 Li-ion cells in series, giving about 26 volts. The high efficiency of these chips allows battery operation without needing vast amounts of capacity. If these pan out I will add in 2 more cells to bump the voltage up to around 36 volts and implement a charger that keeps things topped off when the amps aren't in use.
As doc says these do run cool, the idle losses are no joke, you can use these without a heat sink at low power levels. They are also quiet. Quieter than the TAS5630 that I have used in the past. This was one of my concerns as you need low noise for use with higher efficiency loudspeakers.
Measurements will hopefully be coming up in the not too distant future.
Attachments
those Li 18650 unprotected cells. what's your charging strategy?
FWIW series batteries the cell balancing may be an issue if not using matched* cells.
*same make, same date codes, and shared life history. or can simply go out of whack as they age >check each cell
really cant stress this enough guys for safety always fuse a battery!
the wires maybe red hot and smoking so you cant turn it off
FWIW series batteries the cell balancing may be an issue if not using matched* cells.
*same make, same date codes, and shared life history. or can simply go out of whack as they age >check each cell
really cant stress this enough guys for safety always fuse a battery!
the wires maybe red hot and smoking so you cant turn it off
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Yep these are unprotected 18650s harvested them out of a dead Dell laptop replacement battery a couple of weeks ago.
Cell balancing was something I was concerned about but as these are identical I'd be surprised if it would cause a problem.
I was going to use a constant current/constant voltage, dual control loop, switching regulator from LT in combination with a micro controller for battery monitoring.
@infinia,
What's the point about unprotected cells? Every RC is running from unprotected Lipo-Bags without issues at very high surge discharge current, way more than this amp.
@5th,
nice to see your amp up and running.
If you're thinking of using 8 cells max, you could use a BC8 charger, which charge/balance up to 8 cells at once.
Got an email from Intersil today about a highly integrated bms ic for up to 8 cells, it's the ISL94203.
Or you get your bms from this shop:
http://www.aliexpress.com/store/1821822
I'd go for a fresh pack made of Panasonic NCR18650B. Sure, bit more expensive but long lasting and excellent quality. We use those in 1s4p configuration with pcb from an assembler here in Germany in quantities. (They also do packs from prismatic Panasonics)
To play around with, used cells are okay if you match them again from measured performance. Doing so frequently with several step up-converters in portable soundsystems.
@infinia,
I usually use them fused when they got fixed to a system with "medium fast" fuse and tempswitch or electronic current limiter.
What's the point about unprotected cells? Every RC is running from unprotected Lipo-Bags without issues at very high surge discharge current, way more than this amp.
@5th,
nice to see your amp up and running.
If you're thinking of using 8 cells max, you could use a BC8 charger, which charge/balance up to 8 cells at once.
Got an email from Intersil today about a highly integrated bms ic for up to 8 cells, it's the ISL94203.
Or you get your bms from this shop:
http://www.aliexpress.com/store/1821822
I'd go for a fresh pack made of Panasonic NCR18650B. Sure, bit more expensive but long lasting and excellent quality. We use those in 1s4p configuration with pcb from an assembler here in Germany in quantities. (They also do packs from prismatic Panasonics)
To play around with, used cells are okay if you match them again from measured performance. Doing so frequently with several step up-converters in portable soundsystems.
@infinia,
I usually use them fused when they got fixed to a system with "medium fast" fuse and tempswitch or electronic current limiter.
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