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7 Feb 2014


In a paper published in Nature Communications researchers at IBM describe how they have built a silicon-based receiver chip incorporating GFETs or Graphene Field Effect Transistors (the purple structure in the photo) into the circuit. The multi-stage receiver integrated circuit consists of 3 graphene transistors, 4 inductors, 2 capacitors, and 2 resistors.

“This is the first time that someone has shown graphene devices and circuits to perform modern wireless communication functions comparable to silicon technology,”

said Supratik Guha, Director of Physical Sciences at IBM Research. In a test the team successfully used the graphene-based receiver to process a digital transmission on 4.3GHz. The binary sequence received was 01001001 01000010 01001101, which represents ASCII coding of the letters IBM.

IBM Chip uses Graphene FETs - [Link]

27 Nov 2013


Industry’s Only 60V, 2.5A Internal FET Synchronous Buck Converter

The MAX17503 high-efficiency, high-voltage, synchronously rectified step-down converter with dual integrated MOSFETs operates over a 4.5V to 60V input. It delivers up to 2.5A and 0.9V to 90%VIN output voltage. Built-in compensation across the output voltage range eliminates the need for external components. The feedback (FB) regulation accuracy over -40°C to +125°C is ±1.1%. The device is available in a compact (4mm x 4mm) TQFN lead(Pb)-free package with an exposed pad. Simulation models are available.

The device features a peak-current-mode control architecture with a MODE feature that can be used to operate the device in pulse-width modulation (PWM), pulse-frequency modulation (PFM), or discontinuous-conduction mode (DCM) control schemes. PWM operation provides constant frequency operation at all loads, and is useful in applications sensitive to switching frequency. PFM operation disables negative inductor current and additionally skips pulses at light loads for high efficiency. DCM features constant frequency operation down to lighter loads than PFM mode, by not skipping pulses but only disabling negative inductor current at light loads. DCM operation offers efficiency performance that lies between PWM and PFM modes. The low-resistance, on-chip MOSFETs ensure high efficiency at full load and simplify the layout.

4.5V-60V, 2.5A, High-Efficiency, Synchronous Step-Down DC-DC Converter with Internal Compensation - [Link]

6 Sep 2013


TraId – is a Transistor type & pinout identifier:

TraId is a really low cost version of the Part Ninja. It’s made to only identify the pinout and type (NPN/PNP) of a transistor and display the results on eight LEDs. Currently the firmware only handles BJTs but I think FETs should be possible as well.

TraId – Transistor type & pinout identifier - [Link]

22 Mar 2013


This DC-DC Converter start-up from as low as 330mV input!  Marian Stofka writes:

The bq25504 from Texas Instruments is a good candidate to become a milestone on the road to micro-power management and energy harvesting. A prominent feature of this IC is its ability to start up at a supply voltage as low as 330 mV typically, and 450 mV guaranteed. With an SMD inductor and a few capacitors and resistors, it forms a dc-dc converter with a high power efficiency that is unprecedented, especially in the ultralow-power region.

DC-DC converter starts up and operates from a single photocell - [Link]

26 Feb 2013


Fully depleted silicon transistor are much promising for future developments. Xavier Cauchy writes:

To date, transistor scaling has continued in accordance with Moore’s Law down to 32 nm. Engineering challenges, however, are forcing chipmakers to compromise performance and power efficiency in order to reach smaller nodes – unless they switch to new technologies that help better solve these challenges. Today, the semiconductor industry is starting to deploy such new technologies, largely relying on “fully-depleted” transistors for continued scaling and performance gains.

Fully depleted silicon technology to underlie energy-efficient designs at 28 nm and beyond - [Link]

18 Jan 2013


Re:load is an adjustable constant current load with the following properties:

  • No external power supply required – powered by the device under test
  • Wide range of input voltages, from 3.3 volts to 32 volts
  • Adjustable load from 0 to 3.5 amps
  • Up to 14 watts power dissipation (with design heatsink)
  • Virtually indestructable: The power FET, BTS117, has built in overtemp, ESD, and overcurrent protection
  • Load remains constant under different input voltages – 40 milliamp variation over input voltage range
  • Screw terminal and banana plug footprints
  • Low BoM cost, and easy to solder thru-hole parts
  • Test points for reading current with a voltmeter

A simple, flexible adjustable dummy load - [Link]

5 Oct 2012

BF245, a JFET transistor produced for many decades by several companies, has joined the list of discontinued components. However an equivalent replacement exists in an SMT package and its name is BF545.

BF245 in a TO-92 package has been one of the first transistors, which were mass-used. That’s why it’s no wonder, that the BF 245 is nowadays familiar to every experienced technician. As a transistor with a very high input resistance (tens of MOhm) and a relativlely low noise, it’s gained a global popularity and served to many beginning technicians at an assembly of their first radio-receivers. There are many other FET transistors on the market nowadays, thus the usage of BF245 is substantially smaller. Moreover, a majority of electronics is produced with SMT components, what probably was one of more reasons why all main producers have discontinued the BF245.

However, BF245 is still an interesting transistor, that’s why it will be henceforward available in a SOT23 SMT package as the BF545. It is available in 3 groups A, B, C – sorted according to IDSS at VGS=0. Directly from our stock are available BF545A, BF545B and BF545C from company NXP (originally Philips). Detailed information can be found in the BF545 datasheet, as well as in the RF Manual document.

BF245 – the legend is leaving, the successor comes - [Link]

2 Jun 2012

Here is a reference design from Maxim how to built a circuit that would seamlessly switch to the secondary power supply if the primary fails. [via]

This power-supply sequencer senses a loss of the main supply voltage and, by controlling the two FETs, automatically switches the load to the secondary (backup) supply.

The FET-OR connection for power supplies - [Link]

29 May 2012

scd writes:

I designed this controller for my Crystalite Sparrow 48V electric bicycle hub motor. The core function of a DC motor controller is to periodically read the throttle setting and adjust the current being supplied to the motor. It does this with a technique called pulse-width modulation or PWM (more on this later). Other functions of the controller include: 1) low-voltage cutoff .. monitor the battery voltage and shut down the motor if the battery voltage is too low .. this protects the battery from over-discharge. 2) over-temperature cutoff .. monitor the temperature of the FET power transistors and shut down the motor if they become too hot .. this protects the FET power transistors. 3) over-current cutoff .. reduce the current to the motor if too much current is being supplied .. this protects both the motor and the the FET power transistors. 4) brake cutoff .. shut down the motor when the brake is applied .. this is a safety feature .. if the user applies brake and throttle, the brakes win.

DC Motor Controller for Electric Bicycle - [Link]

9 May 2012

www.adafruit.com writes:

Having a hard time trying to figure out whether that FET can handle enough current for your project? AN11158 from NXP might help clarify some of the many parameters that you need to take into account that are often overlooked.  The Safe operating area, for example, is an important one that often gets skipped and people just look at the best-case scenario marketing numbers on the front page of the datasheet: “The Safe Operating Area (SOA) curves are some of the most important on the data sheet. The SOA curves show the voltage allowed, the current and time envelope of operation for the MOSFET. These values are for an initial Tmb of 25°C and a single current pulse. This is a complex subject which is further discussed in the appendix (Section 3.1).”

Understanding power MOSFET data sheet parameters - [Link]





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