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8 Apr 2014

Home automation is the residential extension of building automation. It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC (heating, ventilation and air conditioning), appliances, security locks of gates and doors and other systems.  This provides better convenience, comfort, energy efficiency and security. Home automation for the elderly and disabled can provide better quality of life for persons who might otherwise require caregivers or institutional care. Nowadays, semiconductor companies develop IC that integrates the system as a whole. One of which is NXP Semiconductors which they develop Home automation modem IC TDA5051A.

The TDA5051A is a modem IC, specifically dedicated to ASK transmission by means of the home power supply network, at 600 baud or 1200 baud data rate.  Its single chip power line modem is equipped with protection of its output power stage and AGC (Automatic Gain Control) of input signal. With simple coupling network, this power line modem is compliance with EN50065-1 power line communication standard. This power line modem circuit uses ASK (Amplitude Shift Keying) for the modulation, and operates on 5V supply.

A home automation system integrates electrical devices in a house with each other.  Devices may be connected through a computer network to allow control and may allow remote access from the Internet. Through the integration of information technologies with the home environment, systems and appliances are able to communicate in an integrated manner, which results in convenience, energy efficiency, and safety benefits.


  • TDA5051AT modem IC
  • Schottky Diode
  • 68Ω Resistor
  • 2.2MΩ Resistor
  • 7.3728Mhz Oscillator Clocks
  • T 630mA Fuse
  • General Diode (2 units)
  • 2uF Capacitor
  • 47 nF/X2 Capacitor (3 units)
  • 470 µF Capacitor
  • 100 µF Capacitor
  • 1 uF Capacitor
  • 10 nF Capacitor
  • 5 µF Capacitor (2 units)
  • 1 mH Inductor
  • 47 µH Inductor (2 units)
  • 1N4006 Diode
  • 250 Supply Vac
  • Microcontroller
  • Positive Voltage Regulator

Power Line Modem for home Automation - [Link]

2 Apr 2014

The PCA9508 is a CMOS integrated circuit that supports hot-swap with zero offset and provides level shifting between low voltage (down to 0.9 V) and higher voltage (2.7 V to 5.5 V) for I2C-bus or SMBus applications. While retaining all the operating modes and features of the I2C-bus system during the level shifts, it also permits extension of the I2C-bus by providing bidirectional buffering for both the data (SDA) and the clock (SCL) lines, thus enabling two buses of 400 pF. Using the PCA9508 enables the system designer to isolate two halves of a bus for both voltage and capacitance, and perform hot-swap and voltage level translation. Furthermore, the dual supply pins can be powered up in any sequence; when any of the supply pins are unpowered, the 5 V tolerant I/O are high-impedance.

PCA9508 has B-side and A-side bus drivers. The 2.7 V to 5.5 V bus B-side drivers behave much like the drivers on the PCA9515A device, while the adjustable voltage bus A side drivers drive more current and incur no static offset voltage. This results in a LOW on the B-side translating into a nearly 0 V LOW on the A side.

The hot swap feature allows an I/O card to be inserted into a live backplane without corrupting the data and clock buses. Control circuitry prevents the backplane from being connected to the card until a stop command or bus idle occurs on the backplane without bus contention on the card. Zero offset output voltage allows multiple PCA9508s to be put in series and still maintains an excellent noise margin.


  • PCA9508D CMOS integrated circuit (3 units)
  • BUS Master
  • Slave 400kHz (3 units)
  • 10kΩ Resistor (6 units)
  • Ground Source

Hot swap level translating I2C repeater - [Link]

27 Mar 2014

We are always vulnerable to thieves but we don’t know when will they strike. When they do, it will be too late for us to notice that our property was already taken. This project helps alert the owner if a thief is picking a lock. It can be used on doors, luggage or anything else with a lock.

The concept is simple, if the lock is opened without our consent, an alarm will be turned on indicating an intruder. This circuit is based on a NAND gates configuration that will turn the switching side on or off.

In this project we used the HEF4011B, a quad 2-input NAND gate. The outputs are fully buffered for the highest noise immunity and pattern insensitivity to output impedance. The configuration of the IC HEF4011B produces a HIGH output if the input is HIGH. Based on the figure, when the wire loop is closed, the IC HEF4011B will have a LOW input, and when the wire loop is triggered, the IC HEF4011B will have a HIGH input which will make its output also HIGH. The HIGH output of the IC HEF4011B will then be inputted to the base of the BC547 transistor allowing the current to flow on the relay switching the indicator or the buzzer ON.


  • HEF4011B quad 2-input NAND gate
  • BC547 transistor
  • 1N4007 diode
  • 1kΩ resistor
  • 4.7kΩ resistor
  • 0.1µF capacitor
  • Relay
  • 5V dc power source

Anti-theft Security Alarm Circuit – [Link]

20 Mar 2014

This is another common device people use everyday, in which a circuit drives the motor found in our watches or clocks to determine the time.

The circuit is mainly operated by PCA1462U IC, specially suited for battery-operated quartz-crystal controlled wrist watches. The quartz crystal is used to input an oscillated signal to the PCA1462U IC then produces an output of pulses that drives the stepping motor ON.

The IC used in this circuit is specialized for this application featuring an amplitude regulated 32KHz oscillator, with excellent frequency stability resulting in a high immunity from oscillator-to-leakage currents. The loss of motor steps is not possible because of an on-chip detection on the induced motor voltage, this output is applicable for different types of bipolar stepping motors. This IC also has a very low current consumption; typically 170 nA, and the time calibration of the pulses is electrically programmable and reprogrammable (via EEPROM).


  • PCA1462U CMOS integrated circuit
  • 1.55V dc power source
  • Quartz Crystal Oscillator
  • Stepper Motor

Quartz-crystal Controlled Wrist Watch - [Link]

10 Mar 2014

With the rapid development of GPS (Global Positioning System) techniques, GPS gets wider application in many fields. GPS has features such as high precision, global coverage, convenience, high quality, and low cost. Recently, the use of GPS extends speedily from military to civilian applications such as automobile navigation systems which combine the GPS system, e-map, and wireless network. GPS is getting popular, and the market for GPS techniques is extending continuously.

UARTs provide serial asynchronous receive data synchronization, parallel-to-serial and serial-to-parallel data conversion for both the transmitter and receiver sections. These functions are necessary for converting the serial data stream into parallel data that is required with digital systems. Synchronization for the serial data stream is accomplished by adding start and stop bits to the transmit data to form a data character. Data integrity is ensured by attaching a parity bit to the data character. The parity bit is checked by the receiver for any transmission bit errors.

The circuit describes how to combine GPS into a navigation system by using a Philips 2-channel UART, the SC16C2552B.  The SC16C2552B is a two channel Universal Asynchronous Receiver and Transmitter (UART) used for serial data communications. Its principal function is to convert parallel data into serial data, and vice versa. The UART can handle serial data rates up to 5 Mbit/s.


  • SC16C2552BIA44 Dual UART, 5 Mbps (max.), with 16-byte FIFOs
  • 80C51 CMOS 0 to 42 MHz Single-Chip 8 Bit Microcontroller
  • 12 MHz Oscillator Clock
  • 1.8432 MHz Oscillator Clock
  • 22pF Capacitor – 2 Units
  • 33pF Capacitor – 2 Units
  • 0.1µF Capacitor – 2 Units
  • 10 µF Capacitor – 2 Units
  • 74LV04 Hex Inverter – 2 Units

UART in GPS navigation system – [Link]

5 Mar 2014

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
  • Resistor 10kΩ ( 27 units)
  • LED (88 units)
  • Voltage Source 40Vdc
  • Voltage Source 5Vdc

I2C Bus Controlled LED Drivers for backlighting and SSL applications – [Link]

1 Mar 2014

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]

9 Jan 2014

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]

3 Jan 2014

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 »

21 Dec 2013

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]





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