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24 Apr 2013

article-2013april-buck-boost-converters-fig2

Publitek European Editors writes:

Many security and motion detector systems rely on small, semi-autonomous nodes that are easy and simple to install. This implies the use of a battery-based power source and low-power operation in order to minimize the number of battery changes during the lifetime of the product.

Over its lifetime, the output voltage of a battery falls, with the biggest decline when the charge is nearing full depletion. A converter type that can accommodate this change in voltage but can still provide relatively high voltages for sensors and RF transmitters is the buck-boost converter – it operates the buck part of the circuit when the battery is fresh, moving to boost operation when the voltage falls below the threshold of the electronic circuitry it powers. A number of vendors have developed integrated buck-boost converters optimized for battery systems

Buck-Boost Converters Help Extend Battery Life for Motion Detection - [Link]

28 Feb 2013

IMG_20120729_1801342

Zak Kemble build an AVR based PWM fan controller. He writes:

So this is a bit of a continuation on my 555 timer based PWM controllers, but now using microcontrollers and MOSFETs instead of 555 ICs and transistors. I made 2 versions, one with switches for speeding up and down and the other with a potentiometer like the previous controllers. I used ATtiny25 controllers running at 31.25KHz (8MHz internal RC / 256 prescaler) with a 3.3V supply, the MOSFETs I used are STP36NF06L with 0.045Rds and 2.5Vgs max, perfect for 3.3V, the MOSFETs only generate ~180mW of heat at 2A ((0.045Rds * (2A * 2)) = 0.18W) so no heatsink needed, you can barely feel them getting warm.

AVR microcontroller based PWM fan controller - [Link]

8 Feb 2013

MBI5030-SOP24_starter-board__front_purple-640x473

Macroblock MBI5030, 16-ch constant current LED driver with PWM, SPI-like interface, requires external e clock.

The problem: you need the chip to figure out if your code actually works. And you also need the LEDs to see what’s going on – if at all. You could use a logic analyzer, but that is overkill. Just looking at the LEDs is a much more suitable way. Your code might have insidious bugs, or the datasheet might simply be crap / outdated / obsolete – of course without your knowledge. BUT you surely don’t want to fight wires, at least not during the coding / debugging phase. All you need is the chip + onboard LEDs as indicators.

MBI5030 – 16ch LED constant current LED driver starter board - [Link]

15 Dec 2012

DSC00050

This is a nice switchmode power supply with the following characteristics:

• Input Voltage 80-275 VAC
• Operating frequency. 47 -63 Hz 47 -63 Hz
• Maximum output power 320W
• Frequency of operation 130 KHz
• Adjustable Output Voltage 0 – 40V
• Output current adjustable from 0 – 20A at 15V
• Over temperature protection with indicator
• Automatic fan control with indicator
• 0-40V voltmeter and ammeter 0-40A LCD programmable USB
• Ammeter without resistive elements with Hall sensor 50A

- PWM module for this PSU

Switchmode Laboratory Power Supply - [Link]


9 Nov 2012

The TPS92510 by Texas Instruments is a 1.5-A constant current DC/DC buck converter with a combo of frequency synchronization, pulse-width modulation (PWM) dimming and thermal foldback firsts. Used with the WEBENCH LED Architect, users rapidly design a power management circuit to drive a string of up to 17 high-brightness LEDs at up to 97% power efficiency in automotive, industrial, and general lighting applications.

The TPS92510 operates with fixed frequency by using its internally generated clock or via synchronization to an external PWM clock source. Thermal foldback ensures light output remains even in an LED over-temperature condition, adding safety.  [via]

Features include:

  • 3.5-V to 60-V input voltage operating range supports a wide variety of DC LED lighting applications, including area and street lighting.
  • Fixed switching frequency range from 100 kHz to 2.5 MHz can be synchronized to optimize for efficiency or solution size.
  • LED thermal foldback with external negative temperature coefficient (NTC) protects LED array from over-temperature while maintaining reduced light output.
  • Dedicated PWM dimming input from 100 Hz to 1 kHz adjusts LED brightness without color shift or perceivable flicker.

Buck converter drives high-brightness LEDs - [Link]

7 Oct 2012

LT series LED drivers with 10-100W power represent a complete solution with wide possibilities of control. Exceptionally narrow and slim design, remained even at high-power versions, provides a high flexibility of use.

Power supplies for LED lighting (so called drivers) are available from many producers, in a various qualitative level. Why to decide just for the LT series from German company Friwo? Here are few reasons:

  • precise design, safe operation and a long lifetime
  • voltage and current regulation in one device
  • high efficiency and a possibility of dimming in a range of 0-100% directly via a CTRL pin
  • modules are available in 10-100W power, with a possibility of customization by laser directly at production also available a module for dimming – so called DIMMbox, further expanding possibilities of control (switch, 1-10V, DALI) and with a possibility of synchronization with up to 1000 slave units
  • very small cross section of modules (21x30mm, resp. 24x30mm at LT100) – applicable even in very tiny conditions

Wide control possibilities of LT series modules are perhaps the most interesting. Modules contain a galvanically isolated CTRL input, by which it is possible to switch on/ off the module without disconnecting from 230V mains. CTRL pin also serves for regulation of an output current. For this purpose, only one resistor (or a potentiometer) is necessary – connected between SEC+ and CTRL pins, with a value counted by a simple formula in the datasheet. The output current can also be controlled by an external voltage in the range of 0-1,8V connected to SEC- and CTRL, as well as by means of a PWM TTL (0/5V).

Further possibilities of control are provided by a standalone additional module DIMMbox. DIMMbox operates as an (almost) lossless PWM regulator with a MOSFET switched at f=600Hz. DIMM-BOX connected to any series LT driver enables to regulate an output current in a range of 10-100% or 0% (OFF) via a usual switch (switch-dimm“ mode), via a linear voltage 1-10V and also a DALI interface. DIMMbox tests after switching on, which of three methods of control is used and consequently accepts only signals from a given input – until switching off the module. DIMMboxes can be connected through SYNC inputs, ensuring the same level of dimming for all modules. Enclosed pictures will provide you the best idea about possibilities of connection.

Friwo drivers not only drive your LEDs but even control them - [Link]

29 Sep 2012

The concept for this small birthday present was to create a small heart shape with red LEDs and then to draw a heart shape underneath it on the PCB as a backdrop. Then a small processor was added to control the heart shape of LEDs for both fade and pattern control. The method of control that we use (PWM) allows us to save precious battery life, control the exact brightness of each specific LED and create this tiny but awesome project.

LED Heart PWM Fading – [Link]

25 Sep 2012

The LM3463 by Texas Instruments is a six-channel LED driver with dynamic headroom control for high-power applications that accurately drives up to six strings of LEDs. The biggest cost reductions in LEDs today come from improvements in efficacy (fewer LEDs needed for the same light output), and the LM3463 is no exception.

It is the industry’s first wide-input voltage LED driver featuring multiple dimming control modes—PWM input signals, analog-to-PWM input control, or 4-byte data control—to maximize system efficiency and reduces complexity in LED area lighting. The driver targets such bright-light applications as street, high-bay and ceiling lighting. When designers require PWM, the LM3463 is particularly useful as it accepts a simple serial data stream and the LED driver creates the PWM signals internally. It can, therefore, be used with a fairly inexpensive MCU and it easily adjusts brightness. [via]

High-power LED driver features multiple dimming control modes - [Link]

25 Aug 2012

embedded-lab.com writes:

Pulse width modulation (PWM) is a technique of controlling the amount of power delivered to an electronic load using an on-off digital signal. The key idea behind this technique is that the average DC value of the digital signal, and hence the power delivered to the load, can be varied by varying the duty cycle of the signal. This method is commonly used for controlling speeds of DC motors and brightness of lamps. The switching mode power supplies are also based on the PWM technique. In this tutorial, we will discuss about the PWM pins of the chipKIT Uno32 board and illustrate the concept by controlling the brightness of two external LEDs.

chipKIT Tutorial 5: Pulse width modulation (PWM) - [Link]

9 Aug 2012

FTDI released the FT311D USB host IC for easy communication with Android devices. It features 7 GPIOs, one I2C peripheral, one UART, one SPI, and 4 PWM peripherals.

The device acts as a USB host to an Android device, while the Android’s app directly controls the peripherals on the IC. The device is configurable trough 3 CFG pins. [via]

FT311D USB host IC provides easy communication with Android devices - [Link]



 
 
 

 

 

 

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