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A note on small-signal modeling of SEPIC CM CCM

CAD/CAM *Circuit design *Manufacture and development of electronics *DIY Electronics for beginners

Knowing parameters of small-signal control-to-output transfer functions makes it easier for engineers to design compensation networks of DC/DC converters. The equations for SEPIC can be found in different works and Application Notes, but there are differences. A work has been done to solve this problem.

Simplified design equations for SEPIC with Current Mode control (CM) in Continuous Conduction Mode (CCM) suitable for practical design of compensation networks are shown.

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Total votes 3: ↑3 and ↓0 +3
Views 503
Comments 0

System-on-Chip bus: AXI4 simplified and explained

FPGA *Robotics development *Programming microcontrollers *Circuit design *Manufacture and development of electronics *

Protocol AXI4 was developed for High-bandwidth and low latency applications. It is designed to allow communication between master and slave devices. Master is typically a DMA or CPU and slaves are DRAM controllers, or other specific protocol controllers: UART, SPI, and others. Sometimes one component can implement multiple instances of this protocol. Usually, a prefix is used to differentiate between multiple AXI4 interfaces.

For example, Ethernet MAC can integrate DMA and slave interface used to command MAC. MAC can accept commands on the slave interface that contain data about the location of the next ethernet packet and MAC can start fetching this packet using the separate master interface instance.

This article was motivated by common design mistakes AXI4 designers make when they are designing their Digital IP. (Looking at you Xilinx)

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Total votes 10: ↑10 and ↓0 +10
Views 864
Comments 0

DSO138 upgrade

Programming microcontrollers *Circuit design *DIY Electronics for beginners

On Ali, an interesting toy – an oscilloscope called DSO138 is sold for a very inexpensive price. It has already gained quite a lot of popularity among electronics lovers, but the parameters of this device, alas, allow it to be more or less fully used only for debugging very low-frequency circuits. Actually, it is not positioned as a tool, but rather as a DIY-kit for novice electronics engineers.

This "toy" oscilloscope is assembled on the STM32F103 microcontroller, and with a fairly competent circuit design of the digital part, the presence of a fairly decent 320X240-dot color display, and not the most rotten analog path, everything, alas, is ruined by very weak ADCs on board the 32F103. The claimed band of 200 kHz can be recognized as such only with a very large stretch. Yes, it will show the presence or absence of a signal with such a frequency, but it will not be possible to really look at something beyond this.

At the same time, the 103-series has a slightly more powerful brother - the STM32F303, it is almost completely compatible with the legs, but it is significantly better in terms of the parameters we are interested in, there are 4 ADCs on board with a conversion frequency of 5 MHz (6 MHz with a 10-bit resolution). In this scenario, if you use all 4 ADCs in parallel with a 10-bit resolution, you can get a effective resolution of up to an honest 24 MSPS (millions of samples per second). The microcontroller is also inexpensive; you can easily find it on the same Ali for very reasonable money again. It is clear that the idea to change the microcontroller arose almost immediately after I tried this DSO138.

At the same time, if upgraded the toy can turn out to be a completely full-fledged tool that even professionals, not just novice amateurs, could already use. With these thoughts in mind, I decided to try to do something with a Chinese toy in my free time.

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Total votes 5: ↑5 and ↓0 +5
Views 685
Comments 0

RS485 — a standard for industrial networks. What are the main features of the transceiver microcircuit?

Миландр corporate blog Circuit design *Manufacture and development of electronics *Electronics for beginners Systems engineering

When building a network for communication between a large number of devices, one may think: what interface to choose? Each interface has its own pros and cons that determine its application: CAN — Automotive, RS485 / RS232 — Industrial, Ethernet — Consumer Electronics / Server. What features of the transceiver microcircuit help to protect against many problems during installation and operation? How is the process of measuring and researching of transceiver microcircuits going on? New RS485 microcircuit is ready to get to market!
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Total votes 4: ↑4 and ↓0 +4
Views 609
Comments 0


Circuit design *Manufacture and development of electronics *DIY Electronics for beginners

Gyrators are impedance converters usually used to simulate inductance in circuits. Though they are rarely used in discrete electronics, they are interesting circuits looking like pole dancers in pictures. There are studies on gyrators, but still something is missing, so it is interesting to do another one.
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Total votes 4: ↑4 and ↓0 +4
Views 960
Comments 0

Active Termination Drivers

Circuit design *Manufacture and development of electronics *DIY Electronics for beginners

The easiest way to build a driver with specified output impedance is to use an amplifier with high load compatibility and add a resistor to its output. The penalty is a voltage drop across this resistor, so there is power loss and we need a higher supply voltage. If our driver is able to deliver the same voltage and current to the same load, but the extra resistor will have a lower value, our device will be able to deliver the same output power at a lower supply voltage. Less power losses, less heat, and longer working time when a battery is used.
There is an idea how to solve this problem: active termination. We can synthesize the output impedance!

Now when we know what we want, go to design our drivers!
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Total votes 6: ↑6 and ↓0 +6
Views 1.6K
Comments 0

Compensation for Error Caused by Limited Gain-Bandwidth of Operational Amplifiers in Low-pass Filters

Circuit design *Manufacture and development of electronics *DIY Electronics for beginners
Amateur vs Pro

An operational amplifier has the internal compensation circuit for stability which limits its working bandwidth. Frequency response of the compensated Op Amp has slope of −6 dB/octave or −20 dB/decade. Unity gain frequency defines the bandwidth where the Op Amp is able to amplify a signal. If we multiply the gain and frequency at any point, the result is the same, allowing us to use this parameter to select the appropriate Op Amp. It is called Gain-Bandwidth Product, GBW or GBP. The limited open-loop gain introduces a closed-loop gain and phase error.

But we want to optimize our circuits, right?
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Total votes 8: ↑8 and ↓0 +8
Views 1.7K
Comments 0

Common misconceptions about space-grade integrated circuits

Circuit design *Manufacture and development of electronics *Popular science Astronautics Electronics for beginners

Space exploration was always fascinating, and recent developments have reignited the interest to the heights never seen since the last man stood on the Moon. People argue about Mars exploration and features of spaceships as their grandparents would’ve done if the internet existed fifty years ago. I’m an electronics engineer working in the aerospace industry, so I know a thing or two about the technical background of this stuff — and I see that these things aren’t common knowledge, and people often have significantly skewed ideas about the reasons behind many things and decisions. Namely, I’d love to speak of some misconceptions about radiation hardened integrated circuits and the means of protection from radiation-induced damage.

So, let's start our journey
Total votes 15: ↑15 and ↓0 +15
Views 15K
Comments 35

How to verify Switching-Mode Power Supply circuits

CAD/CAM *Circuit design *Manufacture and development of electronics *DIY
It is always good practice to verify a circuit before using.

Switching-Mode Power Supplies are the most used circuits nowadays. But there are some difficulties with verifying their circuits: vendors do not publish models for all controllers; a model can be locked to be used with some tool; there can be errors in a model; average models want correct parameters and you need some practice of using them; transient models take a lot of time to get small-signal response and also can have errors.

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Total votes 5: ↑5 and ↓0 +5
Views 1.2K
Comments 0

Reverse engineering a high-end soldering station

Reverse engineering *Circuit design *Manufacture and development of electronics *DIY

(This is the translation of the original article performed by baragol)

We had a bunch of photographs of the main PCB, a YouTube video with drain-voltage waveforms of MOSFETs, a forum post with a breakdown of the capacitance values of LC circuit capacitors and also a number of unboxing videos showing the heating-up of the soldering tip. The only thing that really worried me was the video with the measurement of the peak power consumption during the heating-up. There is nothing in the world more helpless and irresponsible and depraved than burned cartridge newly bought for 60 bucks from Amazon. But let me start from the beginning.
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Total votes 24: ↑23 and ↓1 +22
Views 14K
Comments 1

System in Package, or What's Under Chip Package Cover?

FPGA *Circuit design *Manufacture and development of electronics *Computer hardware CPU
Transistor feature size is decreasing despite constant rumors about the death of Moore’s law and the fact that industry is really close to physical limits of miniaturisation (or even went through them with some clever technology tricks). Moore’s law, however, created user’s appetite for innovation, which is hard to handle for the industry. That’s why modern microelectronic products aren’t just feature size scaled, but also employ a number of other features, often even more complicated than chip scaling.

Disclaimer: This article is a slightly updated translation of my own piece published on this very site here. If you're Russian-speaking, you may want to check the original. If you're English-speaking, it's worth noting that English is not my native language, so I'll be very grateful for the feedback if you find something weird in the text.
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Total votes 38: ↑38 and ↓0 +38
Views 3.3K
Comments 0

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