LED drivers are electrical devices that regulate the power of LEDs. What makes them different from conventional power supplies is their ability to respond to the ever-changing need of LEDs in a circuit by supplying a constant amount of power as electrical properties change with temperature.
The PCA9622 is an I2C-bus controlled 16-bit LED driver optimized for voltage switch dimming and blinking 100 mA Red/Green/Blue/Amber (RGBA) LEDs. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 97 kHz with a duty cycle that is adjustable from 0 % to 99.6 % to allow the LED to be set to a specific brightness value. An additional 8-bit resolution (256 steps) group PWM controller has a fixed frequency of 190 Hz and an adjustable frequency between 24 Hz to once every 10.73 seconds with a duty cycle that is adjustable from 0 % to 99.6 % that is used to either dim or blink all LEDs with the same value.
These LED drivers are based on system-centric, mixed-signal LED driver technology for backlighting and solid-state lighting (SSL) applications. This broad-based and rapidly growing market includes LCD TVs, PC monitors, specialty panels (industrial, military, medical, avionics, etc.) and general illumination for the commercial, residential, industrial and government market segments. LED drivers utilize a proprietary and patented combination of analog and digital circuit techniques and power control schemes.
- PCA9622 I2C-bus controlled 16-bit LED driver
- 2C-BUS/SMBus MASTER
- Resistor 10kΩ ( 27 units)
- LED (88 units)
- Voltage Source 40Vdc
- Voltage Source 5Vdc
I2C Bus Controlled LED Drivers for backlighting and SSL applications – [Link]
The ring counter is useful in hardware logic design such as Application-Specific Integrated Circuit (ASIC) and Field-Programmable Gate Array (FPGA). The ring counter is also ideal in creating simple finite state machines.
The diagram is a circuit of a 4-bit twisted ring counter which can function in 4 different modes, namely: Serial-Input-Serial-Output (SISO), Serial-Input-Parallel-Output (SIPO), Parallel-Input-Serial-Output (PISO), and Parallel-Input-Parallel-Output, by applying Qo to the serial input, the resulting circuit will be a twisted ring or a Johnson Counter. Twisted ring counters are shift registers where the output from the last flip-flop becomes the input of the first flip-flop; it will result in a closed loop circuit which recirculates the data bits around a continuous loop for every sequence state.
The circuit is composed of NAND gates, flip-flops, voltage sources, and clocking system. The NAND gates are incorporated in a Quad-2 input NAND Gate integrated circuit with part number 74ABT00D. The NAND gates receive the inputs from D0, D1, D2, and D3. This device is fully specified for partial power down applications using IOFF. The IOFF circuitry disables the output, preventing the potentially damaging backflow current through the device when it is powered down. The circuit also uses JK flip flops as the memory element. For this circuit, the dual JK flip-flop IC with part number 74HC109D is used. Two 74HC109D chips are used since the circuit needs four JK flip-flops and each IC has two JK flip-flops in it. The 74HC109 is a dual positive-edge triggered, JK flip-flops with individual J, K inputs, clock (CP) inputs, set (SD) and reset (RD) inputs; also complementary Q and Q outputs. The set and reset are asynchronous active LOW inputs and operate independently of the clock input. The supply voltages used to power the ICs are set at 5V for 74ABT00D IC and -1.5V for the 74ABT00D IC. The clocking system connected to the flip-flops provide synchronization pulses and timing for the circuit.
- 74ABT00D Quad-2 input NAND Gate
- 74HC109D Dual Positive-edge triggered JK flip-flops
- Clocking system
- +5V DC Voltage Source
- -1.5V DC Voltage Source
4-bit Twisted Ring Counter using JK Flip Flops – [Link]
Get a free development board from NXP and enter a fun little contest for EEs, with actual prizes running right now. EEWeb.com is running the “NXP/AXP Low Power Design Contest” and it has some interesting (consumer style) prizes. You don’t often see contests like this with quality general interest prizes, and a good chance of winning.
The contest centers around using the the AXP1G57 low-power configurable multifunction gate in your project; the project can be a solution to a real problem or something novel. They’ll send you a free development board, just include it as part of your design project and enter. The board consists of four identical sections, and each section is an independently configurable device.
This contest is very easy to enter, and you can choose your level of commitment, from just answering a 10 question form, a short 1-page (250 word) essay, a reference design project, or creating a schematic/circuit diagram. You can even blog about your project and use that as part of your entry. The contest runs through the end of May.
Enter the 2014 AXP Logic Design Contest! – [Link]
Freescale Freedom Boards are a series of ultra-low-cost development platforms featuring the Kinetis family of MCUs based on the ARM Cortex M Series Cores. The boards are compact In a size a little bit bigger than a credit card. It can provide easy access to the MCU I/O pins, low-power operation and an open standard embedded serial and debug adapter (Open SDA). Other added features include two USB Mini-B type connectors where one is labeled K20 that acts as a USB host and the other is labeled SDA for a built-in debug interface for flash programming and run-control.
In the video is the K20D50M Evaluation Board that comprises a K20 Processor based on the ARM Cortex-M4 processor. Some other features of the board include an accelerometer, ambient light sensor, RGB LED and a capacitive touch slider. K20D50M I/O pins are also routed out in such a way that it is compatible with Arduino Shields, a third-party expansion board. This also means that K20D50M can be supported by a range of Freescale and third-party development software. Read the rest of this entry »
International Rectifier’s IR3846 is a member of the Gen3 SupIRBuck family of highly integrated synchronous voltage regulators. IR3846 is a compact DC-DC regulator with a single input supply without the need of an external VCC with its internal LDO and has a high current output of up to 35 A. Being part of the Gen3 SupIRBuck family, it has a corrective and unique modulation feature that gives a jitter-free and noise-free operation allowing higher frequency and higher bandwidth operation for better transient response. The device is very efficient and ideal for power applications of enterprises requiring space such as netcom server/storage, distributed point-of-load power architecture, and embedded telecom systems that involve high power density.
With a market price of $29, IRDC3846 evaluation board is highly efficient and cost-effective having multiple features. The PCB is a 200 mm^2, 6-layer board mounted with few passive components. Some of the important features of the board include: digital soft-start up, power good operation, overvoltage protection, thermal shutdown, and programmable switching frequency, which is flexible for different applications ranging from 300 kHz-1.5 Mhz. It is designed to a well-regulated input supply of +12V and configured for remote differential sensing.
The IRDC3846 evaluation board is very easy-to-use. Simply connect a +12V input supply at VIN+ and VIN- and a maximum of 35 A load should be connected to VOUT+ and VOUT-. If external VCC is required in an operation, Vin and VCC pins should be shorted together by installing a 0 ohm resistor. Other than remote sensing, the board can also be configured for local sensing by changing the resistors needed for operation. The length of the on-board power ground is minimized for better efficiency. Using separate power ground and analog ground, both can be connected together using a 0 Ohm resistor.
If you need a low voltage, high current regulator, IR3846 definitely should be considered. Having a small footprint, the device has exceptional capability offering high density. It is likely suitable for many applications in network communication and storage systems.
International Rectifier SupIRBuckTM IRDC3846 Evaluation - [Link]
RIGOL DSA1030A is a 9 kHz to 3 GHz Performance Spectrum Analyzer with advanced measurement capabilities. At only $4999 market price, DSA1030A has USB and Ethernet connectivity as well as a VGA outlet. It features a minimum resolution bandwidth of 10 Hz and comes with an all-digital IF design technology to meet the needs for reliability and precision for some of the most demanding RF applications. DSA1030A offers other optional features such as the Advanced Measurement option attainable for applications either in low noise or in narrow resolution and also a built-in pre-amplifier to help on low level signals. The interface is also comparable to other rated analyzers with a large display at 21.6 cm with a resolution of 800 x 480 pixels that in return allows good viewing and easy navigation.
The DSA1030A Spectrum Analyzer offers readily accessible frequency settings. The span control for functions like zooming in/out or even for zero and full span can be attained readily in one click. All the menus can be set quickly and easily. The configuration of the analyzer is also made simple. Just access the marker functions, press the marker buttons and you will see exactly what you expect.
One thing about the DSA1030A Spectrum Analyzer is that changing most of its settings in effect also automatically updates the display settings on the screen to match your desired options. The status indicator is readily available and is always on the screen. No matter where you are on the spectrum analyzer, the status indicator is always provided. Correction settings are also integrated to the analyzer to allow file corrections for antenna, cable or similar as long as it comes with the correct format. Data can be corrected by these settings live in real time.
The RIGOL DSA1030A Spectrum Analyzer comes with standard accessories such as the Advance Measurement Kit (AMK) and USB cable and power cord. It weighs 6.2 kg without the optional battery that can be used for portable operation. In addition, it has a user-friendly preset function that enables users to load their previous measurements. With an exceptional market price, it is safe to say that the DSA1030A Spectrum Analyzer can be used for broad electronics applications present today.
RIGOL DSA1030A Spectrum Analyzer - [Link]
12V Lead acid battery low voltage indicator, to monitor battery condition during long term storage.
This is a simple circuit that will indicate a low voltage on a 12V lead acid battery. Many that have golf carts, small EV’s, RV’s, or solar power banks for homes have a number of 12V lead acid batteries to maintain and this circuit will help protect your investment while not using these batteries. When stored, batteries will self discharge, and if left for too long, will self-discharge to a damaging level. This circuit will light an LED when the battery voltage decreases to 11.6V. When the LED turns on, charge the battery to prevent the battery from dying on the shelf.
Only a few parts are needed in the small but useful circuit. The BC557 PNP transistor controls the lighting of the LED. The BC557 transistors base is biased by the 10V zener diode. As long as the battery voltage stays above 11.6V, the zener keeps the base of the BC557 transistor high. When the battery becomes discharged, the zener stops conducting and the base bias goes low, and BC557 begins conducting, and the LED alerts you to the low battery voltage. You can use a variable resistor to fine tune the low voltage indication, and/or use a set resistor when you have a good value figured out.
Battery Self Discharge Indicator – [Link]
Lightning detector that flashes when lightning strikes nearby.
This circuit picks up and amplifies signals in the 300 kHz range, where lightning makes a lot of noise that can be picked up with a radio. The antenna and receiver are tuned to 300 kHz, with the receiver’s output connected to an amplifier that drives the lamp flashing circuit, alerting you to lightning in the area.
Use the potentiometer to reduce the sensitivity to noise and still be able to detect lightning strikes. In addition to lightning, this circuit will also respond to noise from motors inside appliances like refrigerators, washers, and air-conditioners. Another easy way to affect the sensitivity is to take off the antenna, or lengthen it depending on the conditions. To get some confirmation while tuning the detector, you can tune an AM radio to the bottom the of the dial as well.
You can use this circuit to track weather, and be prepared for it. The circuit is small enough and can be placed in a project box or waterproof container to use, on a boat for instance. The lamp can be replaced or even used alongside a buzzer in this circuit to give an audible alert as well, so that constant monitoring of the circuit is not necessary.
Simple Lightning Detector - [Link]
An IR detector that sounds a buzzer when an IR beam is broken, meaning the IR signal is lost. A pulsed IR signal generator is necessary, but not included in this post. This project would be ideal for doorways or hallways to alert when someone enters or exits an area.
The IR sensor responds to pulsed IR, not ambient or continuous IR. This means that another transmitter project is necessary in order to complete this one! Note though that some forms of lighting like fluorescent lighting may interfere with the sensor. For convenience, the the buzzer is internally driven so that a only Vdc is needed to make a sound. In this case, the IR sensor senses 38kHz pulsed infrared light.
Pin 3 of the IR sensor is actually low (0V) while receiving a signal. When the sensor is blocked from receiving the IR signal, the sensor outputs a high signal to the comparator, which then allows current through the LED/Buzzer circuit, and alerting you that the beam is broken. In the Scheme-It drawing the LM311 IC is a grouping of three components, in a functional block diagram style, to show how it functions in the circuit beyond what the pinouts would show normally.
IR Beam Breaker Alarm Circuit - [Link]
A small, simple AM receiver project. This AM receiver can pick up medium wave stations in your area
This circuit can use general purpose transistors, and in this example there are 3 BC109C transistors. In this schematic and BOM there is a 200uH inductor and a trimmer 150-500pF capacitor, though these parts can be salvaged from an old AM radio, to preserve the directional nature of a tuning coil, and an adjustment knob (plate capacitor) that work well for radio reception.
The 120k resistor is for regenerative feedback between the Q2 NPN transistor and the input to the tank circuit. The value of this resistor is important to the performance of the entire circuit. In fact, it may be better to replace the fixed value with a variable resistor paired with a fixed resistor to adjust the oscillation and sensitivity of the circuit. All the connections in this circuit should be short to minimize interference.
Performance of the circuit will vary depending on stray capacitance in your layout, the inductor winding/core/length, etc. Changing values of some of the capacitors, or adding them, as well as a potentiometer in the feedback loop can help with the performance of the receiver. With such a small circuit that is affected so much by its construction and its environment, a lot of hand tuning and experimentation will be fun, instructive, and possibly necessary to make it work best.
Simple AM Receiver Project - [Link]