link to page 9 link to page 10 link to page 10 ST662AB - ST662ACDescription6 Description The ST662 is an IC developed to provide a 12V regulated output 30mA from voltage input as low as 4.75 without any inductors. It is useful for a wide range of applications and its performances makes it ideal for flash memory programming supply. An evaluation kit is provided to facilitate the application. This include a single-side demo board designed for surface-mount components.The operating principle of ST662 (see Figure 12.) is to charge C1 and C2 capacitor by closing the S1 switch (while S2 is opened) at the VCC voltage. After S1 will be opened and S2 closed so that C1 and C2 capacitors are placed in series one to each other, and both are in series with VIN. The sum of VC1 and VC2 and VI is applied to the capacitor C4. This works as voltage triple. An amplifier error checks the output voltage and blocks the oscillator if the output voltage is greater than 12V. The shutdown pin is internally pulled to VCC. When it is held low the output voltage rises to +12V. Figure 13. shows the transition time of the shut down pin when the VSHDN goes from 5V to 0V. Input logic levels of this input are CMOS compatible Applying a logic high at this input, the VOUT oscillator will be blocked and the VOUT will reach the VI value by D1. In this condition ICC will be. low as 1µA. The Figure 14. shows the transition time of the shut down pin when the VSHDN goes from 0V to 5V. Figure 12.Operating principle circuit 9/20 Document Outline Table 1. Device summary 1 Application circuit Figure 1. Typical application circuit 2 Pin configuration Figure 2. Pin connections (top view) Table 2. Pin description 3 Maximum ratings Table 3. Absolute maximum ratings Table 4. Thermal data 4 Electrical characteristics Table 5. Electrical characteristics (Refer to the test circuits, VCC = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise specified. Typical value are referred at TA = 25˚C) 5 Typical performance characteristics Figure 3. Output voltage vs temperature Figure 4. Output voltage vs temperature Figure 5. Supply current vs temperature Figure 6. Supply current vs supply voltage Figure 7. SHDN pin current vs temperature Figure 8. Output voltage vs shutdown input Figure 9. Output voltage vs shutdown input voltage Figure 10. Output voltage vs shutdown input voltage Figure 11. Test circuit 6 Description Figure 12. Operating principle circuit Figure 13. Exiting shutdown Figure 14. Entering shutdown 7 Application circuit Figure 15. KIT Lay-out Figure 16. Electrical schematic Table 6. List of component 7.1 ST662A output performance Figure 17. Output voltage vs output current Figure 18. Efficiency vs output current Figure 19. Load transient response Figure 20. Load transient response 8 How to increase output current or output voltage capability Figure 21. Application circuit for two ST662A in parallel Table 7. List of component Figure 22. Application circuit for output voltage greater than 12V Figure 23. Output voltage for the application with two device in parallel Figure 24. Output voltage for application with output voltage greater than 12V 9 Package mechanical data 10 Revision history Table 8. Revision history
