Designing with the Power Line Smart Transceiver A Successful Power Line Network A PL 31xx Device A power line device: PL 31xx chip Reference design Coupling circuit Power supply Application electronics Proper device design is imperative to maintain high communication performance of PL 31xx transceiver Non-Isolated vs Isolated nodes First decide if isolated power and coupling are needed Coupling Circuit Choices Residential consumer applications worldwide C-band 1-phase Line-to-Neutral Utility applications A-band 1-phase Line-to-Neutral for CENELEC meters A-band 3-phase Line-to-Neutral for substation devices A-band 2-phase L1&L2-to-N for North American devices Commercial Applications C-band 1-phase Line-to-Neutral for CENELEC devices C-band 1-phase Line-to-Earth for North American devices C-band 3-phase for panel devices worldwide Coupling Circuit Requirements Be sure EVERY component meets ALL User’s Guide Specifications Optional “Example Vendor/Part #s” are supplied to reduce selection time Example Coupling Circuit Cost 100VAC - 240VAC C-band Non-Isolated 3-phase Applications Signal loss between phases is typically 10dB-20dB To avoid cross-phase loss to/from a central device: Use a 3-phase coupling circuit in the central device Use a PL 31xx reference design with the optional 2Ap-p amplifier (Separate PLA-21 Amplifier not required) PL 31xx Power Supply Design Power supply requirements Power supply considerations Power supply options Reference Design Power Supply Requirements Power Supply Options Wall-Plug Power Supply and Power Line Communications Coupler Tamura isolated 400mA power supply and coupler Powers PL 31xx chip and discrete interface circuitry plus ... Supports application current of ~100mA ~ $4 in 50k quantity European and North American versions available CE mark and UL listed Energy Storage Power Supplies Small and low-cost power supply with an energy storage capacitor Takes advantage of ~10X difference between transmit and receive current requirements Power management feature of transceiver automatically regulates transmit duty cycle A Pre-designed Switching Supply Bias Power Technology, Inc. Isolated 14V and 5V, 1 watt power supply Use with energy storage capacitor Powers PL 31xx chip and discrete interface circuitry plus ... Supports application current of ~25mA Universal input (90VAC - 254VAC) ~ $3 in 50k qty Power Management Feature PL 31xx power management circuit monitors VA voltage If VA droops too low, then transmission is inhibited … until ... The node’s energy storage capacitor is recharged If a packet was interrupted it is automatically retransmitted Capacitor-Input Power Supply A Complete Node Power Supply Induced Signal Attenuation Line-to-Neutral EMC capacitors are low impedance at power line communication frequencies A capacitor in a receiver is more significant than loading buffered by meters of mains wiring If a mains capacitor is used to meet EMC regulations, then a series inductor must be added to raise the input impedance of the supply Switching Power Supply Noise Noise at communication frequencies can limit performance Noise from local node power supply is more significant Power supply noise requirements are in the data book Filtering may be required to maintain full communication performance A Power Supply Filter Both Inductors must be rated to handle power supply peak current Inductors must either be toriodal, shielded or separated by >10cm from each other and the switching supply  Why Linear Power Supplies are Benign Transformer leakage inductance results in high series impedance at power line communication frequencies There are no oscillators generating noise at power line communication frequencies Custom Switching Power Supplies Design using controller chips can be very challenging Detailed design requirements are in the PL 3120/PL 3150 Smart Transceiver Data Book Recommended only if experienced switching supply expert or consultant is employed Expect to iterate the design based on lab testing Conducted Emissions Measurements Many spectrum analyzers cannot make this measurement without the addition of a high pass preselection filter Must use enough input attenuation to prevent overload Changing the input attenuation should not change the reading With attenuation set for no overload, noise floor should have 20dB headroom Rhode & Schwarz ESHS series can make the measurement A file with proper Rhode & Schwartz settings is on Echelon’s website: www.echelon.com/support/downloads under OEM components Design Verification Proper node design is imperative to maintain the high communication performance of the PL 31xx transceiver Faulty nodes work in typical environments but fail to communicate under corner conditions in the field Design of ALL PL 31xx based products must be verified Start with a PL 31xx Reference Design for discrete circuitry Then verify checklist in Smart Transceiver Data Book Appendix B Then check performance using the procedure given in Chapter 7 of the Smart Transceiver Data Book Chapter 7 tests check 4 critical performance areas Unintentional output noise (usually from switching supplies) Excessive loading (low receiver input impedance) Transmit output impedance Receive sensitivity Verification Test Equipment Unintentional Output Noise Verification Monitor signal level without any packet transmission Primary and secondary -72dB LEDs should NOT be on solid Primary and secondary -66dB LEDs should NOT flash PKD LED should flash no more than once per minute Excessive Loading Verification Send 10Vpp packets through 88.7W resistor Receiver’s -3 dB primary LED should be ‘on’ or flashing Transmit Performance Verification Transmit into “5W Load” by pressing service pin on UUT Monitor primary signal strength LEDs on PLCA-22 0dB LED should flash 6 out of 10 times Receive Sensitivity Test Send attenuated packets Complete Resources for Success Pre-verified reference designs Design review services The PL 3120 /PL 3150 Smart Transceiver data book Low-cost coupling circuits Power supply recommendations Comprehensive design checklist Performance verification guidelines Worldwide team of Field Application Engineers