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Posts by Nick Alexeev‭

51 posts
80%
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Q&A Is ESD overhyped?

ESD precautions can save a lot of tedious failure analysis. A very inconvenient thing about ESD is that a failure can be attributed to ESD only by ruling out every other possible cause. ESD failu...

posted 4y ago by Nick Alexeev‭

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Q&A What component is this (a +/- labeled symbol)?

This type of symbol isn't standard or common. Those are electrolytic capacitors. The short bar is the positive terminal.

posted 1y ago by Nick Alexeev‭

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Q&A Are LDOs more efficient than switching regulators in very low currents?

The efficiency of the LDO is a function of the input and output voltages. $$\eta = \frac {P_{out}} {P_{in}} = \frac {I_{out} V_{out}} {I_{in} V_{in}}$$$I_{out} \approx I_{in}$ for a series linear ...

posted 2y ago by Nick Alexeev‭  ·  edited 2y ago by Nick Alexeev‭

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Q&A Essential safety features of an EMG/medical grade device?

What are the essential safety features of such types of hardware? One option to make such hardware safer is to make it battery powered. What other safety features are generally recommended? ...

posted 3y ago by Nick Alexeev‭  ·  edited 3y ago by Nick Alexeev‭

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Q&A Correct way to think about thermal noise?

If a data sheet gives the thermal noise (of +3/-3 standard deviations) as 1 uVpp does it mean that out of every thousand samples, 3 will have noise more than ±1 uV at any sample rate? 1000 sps wi...

posted 3y ago by Nick Alexeev‭  ·  edited 3y ago by Lorenzo Donati‭

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Q&A Low-pass filter after the output DAC in CD players

[Disclaimer. This is not for an academic class. I'm self-studying.] I’m reading an introductory book on DSP for audio and computer music [Steiglitz 1996, ISBN 0-8053-1684-1 p. 287]. One of the ...

4 answers  ·  posted 4y ago by Nick Alexeev‭  ·  last activity 3y ago by Lorenzo Donati‭

Question filter audio DAC
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Q&A Rigid-Flex vs Flex with stiffeners - What is the practical difference?

Flex with stiffeners The main purpose of flex with stiffeners is to be able to place SMT components onto the flex board. Without a stiffener a flex has a somewhat undetermined shape, and pick&amp...

posted 8mo ago by Nick Alexeev‭

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Q&A ADE7933 layout guidelines - Lazy Y capacitor?

I have a hunch that the AC which flows through the isolation transformer has quite a bit higher frequency than 1 MHz. The first piece of evidence is this sentence in the datasheet. Each time a ...

posted 10mo ago by Nick Alexeev‭  ·  edited 10mo ago by Nick Alexeev‭

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Q&A What fabrication process is being used for jellybean parts

[I used to work at Microchip.] Is it [node size] at all important [for power management ICs] ? For power conversion ICs cutting edge MOSFETs on the scale of 5nm aren't important, because powe...

posted 3y ago by Nick Alexeev‭  ·  edited 3y ago by Nick Alexeev‭

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Q&A Communication with microcontroller via usart - using strings a good idea?

Command protocols which use strings are a norm. They use more bytes compared to binary protocols, but they are human readable. If the UART itself isn’t a bottleneck, then command strings are a go...

posted 1mo ago by Nick Alexeev‭  ·  edited 1mo ago by Nick Alexeev‭

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Q&A Altium IPC Footprint Options: Which One Should I Choose for Best DFA and Assembly Yield?

I normally use the IPC A footprints because they have the largest pads, and they lend themselves to manual rework. I tend to use 0603 for resistors and capacitors. My boards with IPC A are machin...

posted 5mo ago by Nick Alexeev‭

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Q&A Is inductor winding insulation rating important for a high-voltage application if the voltage is not across inductor itself?

Since the inductor never sees the full 500V across its terminals (This is an assumption, please correct if this is not true) The inductor sees $ V_{out} - V_{in} + V_{diode} $ during the part ...

posted 9mo ago by Nick Alexeev‭  ·  edited 9mo ago by Nick Alexeev‭

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Q&A High side current sense

The sensed current may be at a +90V potential (VIN). The LTC2063 op-amp power supply range goes only to +5.25V . It's not a high voltage op-amp. So, the op-amp in this circuit floats just below ...

posted 1y ago by Nick Alexeev‭  ·  edited 1y ago by Nick Alexeev‭

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Q&A Power polygon and matching ground

If it is important, how crucial is it that the polygon completely overlaps the ground plane beneath it? A power polygon can hang off the side a of a power plane. Complete overlap isn't crucia...

posted 1y ago by Nick Alexeev‭  ·  edited 1y ago by Nick Alexeev‭

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Q&A Photodiode transimpedance amplifier with single supply

synopsis Achievable by using a rail-to-rail op-amp. A small bias on the non-inverting input improves the transient response of the op-amp. That’s the second circuit in the O.P. I use such top...

posted 2y ago by Nick Alexeev‭  ·  edited 2y ago by Nick Alexeev‭

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Q&A STM32. What should be done in firmware for VBUS detection through a GPIO pin?

I've got a is self-powered USB device, which means that I have to do VBUS detection. The device is built around STM32G474. Unlike some other STM32s, the STM32G4 don't have a dedicated pin for VBUS...

2 answers  ·  posted 2y ago by Nick Alexeev‭  ·  last activity 2y ago by Nick Alexeev‭

Question USB firmware STM32
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Q&A Altium. Reusing schematic symbols for pin-compatible parts.

I want to create a schematic symbol and reuse it for multiple ICs which have identical pinouts. For example, op-amps, or the venerable SN74LS00, SN74HC00, SN74HCT00. How can I do this in an Altiu...

1 answer  ·  posted 4y ago by Nick Alexeev‭  ·  edited 5mo ago by Nick Alexeev‭

Question schematic Altium symbol
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Q&A Why is the ACK (acknowledge bit) in the CAN bus frames dominant? What could have been the rationale behind that design decision?

[I’m asking this question out of curiosity. I understand that this aspect of the CAN bus specification is what it is, and can not change.] The ACK bit in any CAN data frame is dominant. Each rece...

2 answers  ·  posted 6y ago by Nick Alexeev‭  ·  last activity 6y ago by Olin Lathrop‭

Question CAN-bus
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Q&A Why there is a body diode in mosfets?

A MOSFET has its gate, source and drain on the top side [1]. These structures are sitting on top of the substrate, which is also called body or bulk. The source and drain are n-doped, while the...

posted 6y ago by Nick Alexeev‭  ·  edited 3y ago by Lorenzo Donati‭

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Q&A What exactly is a HAL and how would I write my own?

So is a HAL really just a collection of functions that when called set/reset specific register bits for my specific microcontroller? The HAL created by ST for the STM32 is a relatively thin wr...

posted 28d ago by Nick Alexeev‭  ·  edited 28d ago by Nick Alexeev‭

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Q&A AD5941 GPIO2 cannot act as general-purpose output — any workaround without a board respin?

There may be workaround, potentially, although I haven't done it. Neither have I used the AD5941. The GPIO2 has an output function for synchronizing external device. Configure it for synchroniza...

posted 3mo ago by Nick Alexeev‭  ·  edited 3mo ago by Nick Alexeev‭

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Q&A Assembly challenges for shared pad between mounting hole and resistor

Here's how I usually lay out optional grounding through a mounting hole. The connections are wide copper pours which reduces the connection inductance. Multiple vias to GND also reduce inductance...

posted 6mo ago by Nick Alexeev‭  ·  edited 6mo ago by Nick Alexeev‭

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Q&A Need clarification on SWDIO/SWCLK length‑matching and “shielding” for STM32WBA5MMG debug connector

Length matching the SWDIO and SWCLK doesn't make sense, as @Lundin have mentioned already. What about shielding? MB2131 is a radio module. Maybe they were concerned that unshielded SWD lines can...

posted 8mo ago by Nick Alexeev‭

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Q&A Understanding of basic semiconductors

From my own thinking, I guess "x+" and "x-" denote over- and under- doped semiconductors, is that correct? "+" stands for heavy doping. "-" stands for light doping. n+ and p+ are heavily dop...

posted 10mo ago by Nick Alexeev‭

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Q&A Purpose of resistance between SENSE/FORCE line of power supply

Furthermore, an amplifier symbol called "gm" is labeled as transconductor. What does it do? Transconductors are voltage-controlled current sources, but what are they doing here? The diagram lo...

posted 2y ago by Nick Alexeev‭

Answer