Datasheet TEA1501 (NXP) - 4

Philips Semiconductors TEA1501 GreenChip SMPS controller IC
V V in out np ns load Vzener on/off (1) SOURCE DRAIN OOD n.c.
TEA1501
BURST GND REF AUX R n SOURCE CBURST RREF a mgm823 (1) The secondary earthing point is isolated from the primary earthing points.
Fig 3. Basic flyback configuration 7.1 System operation 7.1.1 On/off
The system of the TEA1501 can be switched on and off by means of a low cost, low voltage switch. In the Off mode the start-up current source and power switch are disabled. In the On mode, the TEA1501 delivers the start-up current for the supply capacitor and after the supply voltage reaches the start-up level, the TEA1501 activates the power switch.
7.1.2 Start-up
The start-up is realized with a high voltage start-up current source instead of a dissipative bleeder resistor which is commonly used by low voltage control ICs. When the TEA1501 is switched on, the start-up current source is enabled and starts charging the AUX capacitor. The start-up current level is high and accurate (typical 1.8 mA) which results in a well-defined and short start-up time, within 0.25 s. After the supply voltage reaches the start-up level the current source is switched off and the AUX capacitor supplies the chip. Reducing the power dissipation in the current source to zero after start-up is one of the green features of the TEA1501.
7.1.3 Operation
After start-up the flyback converter starts delivering energy to the secondary and auxiliary winding. The system of the TEA1501 works with fixed switching frequency and fixed peak current. As all the windings of the flyback transformer have the same flux variation, the secondary voltage and the auxiliary voltage are related via the turns-ratio (ns : na). Therefore, the isolated secondary voltage is controlled by the non-isolated auxiliary voltage. TEA1501_2 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet Rev. 02 — 31 March 2006 4 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