Datasheet TEA1501 (NXP) - 9

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Philips Semiconductors TEA1501 GreenChip SMPS controller IC
regulation level AUX (V) 20 SAUX 17.5 0 CPAUX 0 40 100 burst duty cycle (%) mgm826
Fig 6. Regulation level AUX as a function of burst duty cycle 7.3.13 Counter
The power delivered to the load (auxiliary and secondary) is a function of the number of energy pulses per burst, according to the following formula 2 P = η 1 × - × L × I × f × N load 2 p prim burst Where η is the efficiency, Lp is the primary inductance, Iprim is the primary peak current, fburst is the burst frequency and N is the number of pulses in one burst period. The counter counts the number of pulses in each burst period and detects if the Ndata threshold is passed. The counter state is used for the data transfer function and for the supply current tracking.
7.3.14 Supply current tracking
For obtaining good load regulation, especially with low cost transformers, a tracking circuit is included. The tracking circuit makes the supply current of the TEA1501 a function of the secondary load. This makes the voltage drop across the series resistance of the auxiliary winding proportional to the voltage drop across the series resistance of the secondary winding. Therefore, the secondary output voltage tracks with the AUX regulation voltage. The tracking starts at a counter state of 28. For a counter state from 28 up to 112 (typical values) the supply current of the TEA1501 rises linearly with the counter state according to the following formula, see Figure 7. I = k × N AUX tracking For counter states of 112 and higher the supply current remains on its maximum value. TEA1501_2 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet Rev. 02 — 31 March 2006 9 of 21
Document Outline 1. General description 2. Features 2.1 Distinctive features 2.2 Green features 2.3 Protection features 3. Quick reference data 4. Ordering information 5. Block diagram 6. Pinning information 6.1 Pinning 6.2 Pin description 7. Functional description 7.1 System operation 7.1.1 On/off 7.1.2 Start-up 7.1.3 Operation 7.1.4 Data transfer 7.2 Waveforms in the Off mode, Start-up mode and Operation mode 7.3 Circuit block description 7.3.1 On/off/data section 7.3.2 VAUX management 7.3.3 Start-up current source 7.3.4 Reference block 7.3.5 Temperature protection 7.3.6 Switch oscillator 7.3.7 Burst oscillator 7.3.8 Gate driver 7.3.9 Power switch 7.3.10 Primary current comparator 7.3.11 Leading edge blanking 7.3.12 Modulator 7.3.13 Counter 7.3.14 Supply current tracking 7.4 Design Equations 7.4.1 Primary peak current 7.4.1.1 Minimum value of RSOURCE 7.4.2 Switch oscillator 7.4.2.1 Range of RREF values 7.4.3 Leading edge blanking 7.4.4 Burst oscillator 7.4.4.1 Minimum value of CBURST 8. Limiting values 9. Thermal characteristics 10. Characteristics 11. Test information 11.1 Quality information 12. Package outline 13. Soldering 13.1 Introduction to soldering surface mount packages 13.2 Reflow soldering 13.3 Wave soldering 13.4 Manual soldering 13.5 Package related soldering information 14. Revision history 15. Legal information 15.1 Data sheet status 15.2 Definitions 15.3 Disclaimers 15.4 Trademarks 16. Contact information 17. Contents