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OPEN SOURCE: "CC-Boost" - 2.4 Amp boost driver - RC1
- Thread starter rhd
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Yeah, I was just looking at it and it is definitely 3.6 volts, so if the output is 4.5volts, that had to be the input. Oh well, that happens sometimes.
Yeah, I was just looking at it and it is definitely 3.6 volts, so if the output is 4.5volts, that had to be the input. Oh well, that happens sometimes.
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
ryansoh3, the 3.6 volts is coming from the power supply. The boost is the 4.5 volts and we haven't seen that yet. I would imagine an unloaded boost circuit would last a very short time. In the msec at best.
ryansoh3, the 3.6 volts is coming from the power supply. The boost is the 4.5 volts and we haven't seen that yet. I would imagine an unloaded boost circuit would last a very short time. In the msec at best.
ARG
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Now showing the output
Now showing the output
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
ARG, I didn't want to go hunting for your load, but isn't it into a dummy load? The first 500 microsec the output is everywhere except 4.5 volts. What does it look like at 1 sec? And what does it look like at even longer lengths of time? At the longest time shot you got was 1.8 msec. Even there it was mostly at 5 volts.
ARG, I didn't want to go hunting for your load, but isn't it into a dummy load? The first 500 microsec the output is everywhere except 4.5 volts. What does it look like at 1 sec? And what does it look like at even longer lengths of time? At the longest time shot you got was 1.8 msec. Even there it was mostly at 5 volts.
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ARG
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
4.5V was measured when they were hot.
These tests were done with edge triggering on the scope, so the driver was only on for brief period of time and the diodes were at room temp.
4.5V was measured when they were hot.
These tests were done with edge triggering on the scope, so the driver was only on for brief period of time and the diodes were at room temp.
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
I can't read Oscilloscope data
Is this driver usable or naw?
Crossing my fingers...
I can't read Oscilloscope data
Is this driver usable or naw?
Crossing my fingers...
rhd
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
My thoughts (please chime in if others feel different) is that this needs some cleaning up.
I think a revision would be worthwhile:
- moving the output cap to AFTER the sense resistor/ZXCT
- increasing the output cap to 100uF
- adding a second, smaller, output cap
What do you guys think?
I can't read Oscilloscope data
Is this driver usable or naw?
Crossing my fingers...
My thoughts (please chime in if others feel different) is that this needs some cleaning up.
I think a revision would be worthwhile:
- moving the output cap to AFTER the sense resistor/ZXCT
- increasing the output cap to 100uF
- adding a second, smaller, output cap
What do you guys think?
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Yeah, I see a lot of noise from the short time shots of the driver, but they are all about 1volt p-p either positive going or negative going. At the rate they are coming a smaller cap at the output to ground may help. I don't see a 100mfd cap helping to remove this noise as well as maybe a .01mfd or even a .1 mfd cap. I was concerned about the output voltage as the longest time shot at the top picture shows the output to be closer to 5 volts than 4.5 volt and then the trailing end of the trace seems to be increasing past the 5 volt point, but can't tell much about it from that little bit of information at the end of the trace.
Yeah, I see a lot of noise from the short time shots of the driver, but they are all about 1volt p-p either positive going or negative going. At the rate they are coming a smaller cap at the output to ground may help. I don't see a 100mfd cap helping to remove this noise as well as maybe a .01mfd or even a .1 mfd cap. I was concerned about the output voltage as the longest time shot at the top picture shows the output to be closer to 5 volts than 4.5 volt and then the trailing end of the trace seems to be increasing past the 5 volt point, but can't tell much about it from that little bit of information at the end of the trace.
rhd
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Here's my suggested revision (V11):
For simple components like little 0603 or 0805 capacitors, I'm not going to continually update the parts list (will once we've settled on a final design).
In addition to the revisions for better (hopefully) filtering, I also removed the L- pad. Since this is a continuous ground driver, we can ditch the second GND connection for now.
Weigh in
Here's my suggested revision (V11):
For simple components like little 0603 or 0805 capacitors, I'm not going to continually update the parts list (will once we've settled on a final design).
In addition to the revisions for better (hopefully) filtering, I also removed the L- pad. Since this is a continuous ground driver, we can ditch the second GND connection for now.
Weigh in
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ARG
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Which version is the one I scoped? Need to compare before weighing in.
Which version is the one I scoped? Need to compare before weighing in.
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
rhd, on your revision, I think I would put a very small value resistor between the 100 and 1mfd capacitors and the .01mfd. Maybe something like a 0.56ohm to 0.1ohm resistor to isolate the output a little. The only way to see if it will work is to actually add this and test it again. Since it is on the positive output side, it shouldn't be too hard to do this as a test. But, that or maybe a 0.1mfd capacitor should do the trick IMO.
rhd, on your revision, I think I would put a very small value resistor between the 100 and 1mfd capacitors and the .01mfd. Maybe something like a 0.56ohm to 0.1ohm resistor to isolate the output a little. The only way to see if it will work is to actually add this and test it again. Since it is on the positive output side, it shouldn't be too hard to do this as a test. But, that or maybe a 0.1mfd capacitor should do the trick IMO.
rhd
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
You scoped V08, which is this:
You realize that this would dramatically increase the voltage drop right? Even 0.1ohm would triple the v-drop.
PS, for consistency, lets use the same unit representations. uF is my preference, and seems to be more universal. If we're going to use "mfd" instead, that's fine, but lets just be consistent, and then lets use the correct "MFD", not "mfd". Consistency is key, otherwise it confuses people.
You scoped V08, which is this:
You realize that this would dramatically increase the voltage drop right? Even 0.1ohm would triple the v-drop.
PS, for consistency, lets use the same unit representations. uF is my preference, and seems to be more universal. If we're going to use "mfd" instead, that's fine, but lets just be consistent, and then lets use the correct "MFD", not "mfd". Consistency is key, otherwise it confuses people.
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Yeah, forgot about the current we were working with. I'd decrease it to 0.01 ohms in this case. Didn't think about the amount of current when I suggested the value. But, you are right, you need to keep the value low enough to not cause a dramatic voltage drop across the resistor.
Yeah, forgot about the current we were working with. I'd decrease it to 0.01 ohms in this case. Didn't think about the amount of current when I suggested the value. But, you are right, you need to keep the value low enough to not cause a dramatic voltage drop across the resistor.
rhd
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Okay. It's no big deal to do that if we want to (see below). Is that what you had in mind?
Okay. It's no big deal to do that if we want to (see below). Is that what you had in mind?
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Re: OPEN SOURCE: New Boost Drive, 2.4A capable from one cell, tested and working
Yeah, just a little isolation from the other large capacitors. I'm not sure how it will work out, but it would be worth a test to see if some of the noise could be filtered out. Also, by adding the 100uf and the 1uf you may see a better transition at the start when the output is trying to stabilize and is running from 5 volts to 3 volts and back to 5 volts as well.
Yeah, just a little isolation from the other large capacitors. I'm not sure how it will work out, but it would be worth a test to see if some of the noise could be filtered out. Also, by adding the 100uf and the 1uf you may see a better transition at the start when the output is trying to stabilize and is running from 5 volts to 3 volts and back to 5 volts as well.
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