Activity for DeadMouse
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Comment | Post #291038 |
You are right about R18. I think it should be lower at around 1K.
Regarding the 3.2mA it is fine. I have tested that already and it worked without issues. I could also make it a bigger value.
Another issue is how to merge the TX and RX lines so I can have only one but also maintain the protecti... (more) |
— | about 1 month ago |
| Edit | Post #291027 |
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— | about 1 month ago |
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— | about 1 month ago |
| Edit | Post #291027 | Initial revision | — | about 1 month ago |
| Question | — |
1-wire interface overvoltage protection I'm designing a robust 1-wire output for an IoT board. The interface should be able to withstand high voltage. Mainly the same voltage level as the board power supply. That's 12V to 36V DC. The protection is intended for the board only, not the devices connected to it. Consider the protect... (more) |
— | about 1 month ago |
| Comment | Post #288784 |
Would you mind to elaborate the reasons why you would not add a ground pour on top/bottom layers? (more) |
— | 10 months ago |
| Edit | Post #288763 |
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— | 10 months ago |
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— | 10 months ago |
| Comment | Post #288784 |
I posted some pictures that show how bypass capacitors are placed around the chip. Notice that some of them cannot have direct connection to their relative ground pins of the chip cause sometimes the ground pins are not physically close to the power pins and other gpio pins there are in between them.... (more) |
— | 10 months ago |
| Edit | Post #288763 |
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— | 10 months ago |
| Comment | Post #288784 |
Regarding bypass capacitors you mean to avoid connecting them directly to the internal ground plane using a via?
Do you mean that they should be connected to the ground pins directly using traces or local planes and connect all of it together to the internal ground plane? (more) |
— | 10 months ago |
| Comment | Post #288784 |
I'm not sure I understand your point about the ground plane being a center-fed patch antenna.
I didn't mean there's only one via that connects every ground from the top layer to the internal ground plane.
I have placed vias close to every pad that is connected to ground and using a trace or a ... (more) |
— | 10 months ago |
| Edit | Post #288763 |
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— | 10 months ago |
| Edit | Post #288763 |
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— | 10 months ago |
| Edit | Post #288763 | Initial revision | — | 10 months ago |
| Question | — |
Ground pour on outer layers on 4-layer PCB I'm designing a board that contains a cortex-M4 mcu working at 120MHz, and an ethernet bus with a wiznet chip that communicates with SPI. The ethernet chip gives me a phy output that goes directly to a connector with internal magnetics. All circuits are powered by a DC to DC buck converter.... (more) |
— | 10 months ago |
| Comment | Post #288515 |
Why do you prefer a voltage divider over a zener diode? (more) |
— | 10 months ago |
| Comment | Post #288515 |
NPN version.
Thanks, Olin.
I concluded you like more the NPN version versus the MOSFET version.
Regarding your last schematic.
R1-R2 form a voltage divider and the threshold is around 11V at the input. At this voltage, the Vbe will be around 0.7V and it is enough for the BJT to star... (more) |
— | 10 months ago |
| Edit | Post #288504 |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
| Edit | Post #288504 | Initial revision | — | 10 months ago |
| Question | — |
Sensing 3 states in a single mcu pin using firmware I want to sense 3 different states in the same mcu pin (GND, Hi-Z and PWR). PWR is typical +24V but I would like to have a wide margin from +17V to +40V just to be safe. The values can change but the typical will still be +24V I need 32 different (physical) inputs. I designed the following c... (more) |
— | 10 months ago |
| Comment | Post #288474 |
Thanks! That's helpful (more) |
— | 10 months ago |
| Edit | Post #288440 |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
| Comment | Post #288440 |
Also, a simple inversion won't do the trick. I added a truth table that shows the output with 3 differnt types of input for each option.
For example, if you just put a NOT gate on Option 1, you will not get Option 2. (more) |
— | 10 months ago |
| Edit | Post #288440 |
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— | 10 months ago |
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— | 10 months ago |
| Comment | Post #288440 |
Adding the inversion in the firmware would require one more pin from the chip.
I need total 36 inputs that would be able to invert independently. That is 72 pins total. One for the input and one for its selection control. That's why I want to handle this in the hardware side (more) |
— | 10 months ago |
| Edit | Post #288440 |
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— | 10 months ago |
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— | 10 months ago |
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— | 10 months ago |
| Edit | Post #288440 | Initial revision | — | 10 months ago |
| Question | — |
How to change the polarity of an input using a single switch? I have an mcu pin and I want to sense a voltage up to 24V to 36V. I want to connect some outputs on the board I'm designing and I don't know whether those outputs will provide a voltage or will be open collector outputs. Also, some outputs will be just relays and the other terminal will be at G... (more) |
— | 10 months ago |
| Edit | Post #287295 | Initial revision | — | over 1 year ago |
| Question | — |
Energy harvesting from non-invasive current sense transformer I have a non-invasive current sense transformer (SCT-013-030) which according to its datasheet it is voltage output type. I want to harvest energy and supply a wireless sensor that consumes 5-6 uA current average. The most common approach is a rectifier on the output of the transformer. But I'm... (more) |
— | over 1 year ago |
| Comment | Post #287265 |
I'm not sure I can achieve such steep skirts with discrete components.
I'd aim for 100KHz bandwidth but 300kHz is much easier to achieve with discrete parts.
Would there be any problem if the skirts were not that steep?
And yes, I noticed that ceramic resonators are very hard to find at a f... (more) |
— | over 1 year ago |
| Comment | Post #287263 |
Thank you very much for your answer.
I am pretty sure that my problem is the tight bandwidth of the Murata part as you mention.
I'll try out a bandpass filter using discrete components and maybe find another suitable part. I'll also try a direct communication off of power line by connecting t... (more) |
— | over 1 year ago |
| Comment | Post #287262 |
You probably mean connecting the outputs (right part of C4) together and off of DC line, right?
Thank you! I'll try it.
Regarding the main question, what's the difference between those two components above (a ceramic filter and a ceramic resonator)?
Is the part I found suitable for that ... (more) |
— | over 1 year ago |
| Edit | Post #287262 |
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— | over 1 year ago |
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— | over 1 year ago |