Modem for Home Appliance Automation
Created: Feb 18, 2014
No description available.
The circuit design is part of the famous power supply network technology for home automation and in advanced metering infrastructure (AMI). It is an application of the TDA5051A modem IC that is dedicated to ASK transmission by means of the home power supply network with 600 baud or 1200 baud data rate. It is with power line insulation, with improved sensitivity of the system typically 68 dBμV.
The transmission and reception stages are controlled either by the master clock of the microcontroller or by the on-chip reference oscillator connected to a crystal. This ensures the accuracy of the transmission carrier and the exact trimming of the digital filter, thus making the performance totally independent of application disturbances such as component spread, temperature change, supply drift, and other unwanted signals. The interface with the power network is made by means of an LC network. The device includes a power output stage that feeds a 120 dBμV (RMS) signal on a typical 30Ω load. The 250V AC input of the modem IC includes a fuse with a current rating of 630mA that serves as the protection of the network. The HF signal transformer is used for the power-line insulation. The Modem IC is supplied by a stable 5V DC from a complete package of power supply elements that includes a transformer, a bridge rectifier, and a regulator. The output of the power stage (TX_OUT) is connected to a decoupling capacitor which serves as the protection against overvoltage, negative transient signals, and presence of 0.5VDD voltage on the channel even when the device is not transmitting. The TDA5051A has a power-down pin (PD) that reduces power consumption because it disabled the modem IC during the reception stage.
The circuit design is ideal for advance power monitoring and control. It can handle the instrumentation and control facility of industrial plant and also electric usage metering for residential and commercial consumer.