AN3290 STMICROELECTRONICS | Alldatasheet

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  • PDF pages: 34

Technical content

Datasheet sections

  • 1 Test board design and eval uation
  • 2 Output voltage characteristics
  • 3 Efficiency and no load measurement s
  • 4 Typical board waveforms
  • 5 Protection features
  • 5.1 Overload and short-circuit protection
  • 5.2 Auxiliary winding disc onnection (brownout)
  • 6 Conducted noise measurement s
  • 7 Modifications for ultra wide- range operations
  • 8 Conclusions
  • 9 Demonstration tools and documentation
  • 10 Revision history

April 2011 Doc ID 18038 Rev 1 1/34 AN3290 Application Note Reference design for double output SMPS for power line modem applications using ALTAIR04-900 primary controller Introduction This application note introduces a new “all-primary sensing” switching regulator ALTAIR04- 900, used to build an innovative solution to supply a power line communication. A demonstration board, implementing a wide-range double-output power supply, has been developed and the results of its bench evaluation are reported in this document. The board uses the new ALTAIR04-900, a quasi-resonant (QR) current-mode controller IC specifically designed for QR ZVS (zero voltage switching at switch turn-on) flyback converters, which combines a high-performance low-voltage PWM controller chip and a typical 16 R DSon, 900 V, avalanche-rugged power MOSFET in the same package. The device is capable of providing constant output voltage regulation using primary-sensing constant voltage loop (CV loop). This eliminates the need for the optocoupler and the secondary voltage reference while still maintaining quite accurate regulation. Also, using the primary constant current loop (CC loop), it is possible to set the maximum deliverable output current without any secondary components or current sensor.

1 Test board design and evaluation

communication based on ST7580 (by STMicroelectronics). shown in Figure 2 and the PCB layout in Figure 3 and 4. Table 1. ALTAIR04-900 power supply: electrical specification

Figure 3. Demonstration board image: power supply board

Figure 4. Demonstration board image: complete (power supply and PLM boards) Table 2. ALTAIR04-900 power supply - bill of material

Note: If not otherwise specified, all resistors are 5%, ¼ W.

744612101 Wurth

Table 2. ALTAIR04-900 power supply - bill of material (continued)

Figure 5. ALTAIR04-900 power supply: transformer characteristics Table 3. ALTAIR04-900 power supply: transformer characteristics Leakage inductance 1.42% nom.

2 Output voltage characteristics

charged with 40 mA and 80 mA respectively. All output voltages have been measured on the output connector of the board. Figure 6. Output voltage characteristics with 3V3 @ 40 mA Figure 7. Output voltage characteristics with 3V3 @ 80 mA

3 Efficiency and no load measurements

on VOUT1 and VOUT2 fixed at 40 mA and 80 mA. The figures below show the results. Figure 8. Efficiency vs. output power with 3V3 @ 40 mA Figure 9. Efficiency vs. output power with 3V3 @ 80 mA

4 Typical board waveforms

and 60% duty cycle. Output 2 is loaded at 100 mA. different input voltage values. order to simulate the widest possible operative conditions. specification with very good margin. Figure 10. Normal operations in TX mode at 85 V

Figure 21. Normal operation in TX mode at 264 V AC and IOUT2=80 mA

5 Protection features

secondary rectifier detection, and transformer saturation protection. protection against overload and short-circuit. In the following paragraphs all protections are tested and the results are presented.

5.1 Overload and shor t-circuit protection

the output is shorted with good precision. At the same time, the overload also coincides with the maximum operative output current. voltage values and output 1 shorted. Figure 22. Short-circuit mode: 13 V shorted at 115 V

Figure 23. Short-circuit mode: 13 V shorted at 230 V AC

5.2 Auxiliary winding disconnection (brownout)

compared with an internal reference, IZCDON (50 µA). present, the protection is maintained active. This feature has been tested and the results are shown in Figure 24. Figure 24. Brownout protection activation

5.3 Secondary winding short-circu it and transformer saturation

The ALTAIR04-900 is equipped with a hiccup mode overcurrent protection level. and the MOSFET is no longer allowed to switch on. the device again enters auto-restart mode. extremely low, resulting in very safe and reliable protection. behavior of the system during fault. Figure 25. Hiccup mode OCP: protection tripping at V IN=115 VAC and full load

Figure 28. Hiccup mode OCP: operating condition at VIN=230 VAC

6 Conducted noise measurements

test conditions there is a good margin for the measurements with respect to the limits. Figure 29. CE average measurement at 115 V

Figure 32. CE average measurement at 230 V AC and full load: neutral

7 Modifications for ultra wide-range operations

modification, thanks to the 900 V rated power section BVDss of the ALTAIR04-900. modifications are needed for the transformer and the IC. specified in this table, the bill of material in Table 2 is still valid. Figure 33. Electrical schematic for 440 V

Note: If not otherwise specified, all resistors are 5%, ¼ W. Table 4. ALTAIR04-900 power supply: bill of material for 440 V AC input voltage

8 Conclusions

A double-output flyback converter using the new ALTAIR04-900, specifically designed for power line modem systems based on ST7580 (by STMicroelectronics), has been introduced and the results are presented. The demonstration board shows good performances in terms of load and line regulation and the overall efficiency is very good also at light load conditions. The pre-compliant tests on conducted noise show that the QR mode of operation of the IC helps to meet the standards, therefore it is possible to reduce the size and the cost of the EMI filter compared to a fixed frequency IC. The all-primary sensing control loop circuitry makes this device very competitive in terms of performance and price thanks of the absence of the optocoupler and any specific secondary circuitry for CV regulation and overload protection, including a secondary voltage reference and sense resistor. Moreover, the 900 V avalanche-rugged power section, and the several protections that this device has onboard, makes this IC the device of choice for energy metering, 3-phase auxiliary power supplies and for all applications where the ultra wide-range is required.

Demonstration tools and documentation AN3290 32/34 Doc ID 18038 Rev 1

9 Demonstration tools and documentation

The ALTAIR04-900 demonstration board order code is: EVLALTAIR900-M1. In order to get a complete PLM system, the power supply can be connected with the EVALKITST7580-1. Further information about these products are available in the ALTAIR04-900 datasheet at www.st.com.

Table 5. Document revision history