AND8285/D NCP1521B Adjustable Output Voltage Step−Down Converter Simulation Procedure http://onsemi.com Prepared by: Bertrand Renaud On Semiconductor SIMULATION NOTE Overview Additional features include integrated soft−start, cycle−by−cycle current limiting and thermal shutdown protection. The NCP1521B is available in space saving, low profile TSOP5 and UDFN6 packages. The NCP1521B step−down PWM DC−DC converter is optimized for portable applications powered from one cell Li−ion or three cell Alkaline/NiCd/NiMH batteries. The part is available in adjustable output voltage versions ranging from 0.9 V to 3.3 V. It uses synchronous rectification to increase efficiency and reduce external part count. The device also has a built−in 1.5 MHz (nominal) oscillator which reduces component size by allowing smaller inductors and capacitors. Automatic switching PWM/PFM mode offers improved system efficiency. VIN 1 VIN 2 GND 3 EN LX 5 CIN OFF ON L Model Package NCP1521B model has been developed on ORCAD Capture & Pspice 15.7. It includes NCP1521B typical application schematic (NCP1521B.DSN), NCP1521B simulation library (NCP1521B.LIB) and NCP1521B package (NCP1521B.OLB). R2 VOUT OFF ON COUT R1 FB Cff 4 R2 March, 2007 − Rev. 0 FB 6 2 GND LX 5 3 VIN GND 4 2.2 mH R1 18 pF VOUT 10 mF 4.7 mF VIN Figure 1. Typical Application − TSOP−5 © Semiconductor Components Industries, LLC, 2007 1 EN 1 Figure 2. Typical Application − UDFN6 Publication Order Number: AND8285/D AND8285/D Model Installation This procedure describes one method to correctly simulate this model. 1. Run ORCAD Capture and start a new blank project development. 2. Delete the current blank design http://onsemi.com 2 AND8285/D 3. Import NCP1521.DSN schematic 4. Import NCP1521B.OLB package too http://onsemi.com 3 AND8285/D 5. Your hierarchical project looks like the following pictures http://onsemi.com 4 AND8285/D 6. To simulate the device, a new time domain simulation must be created: http://onsemi.com 5 AND8285/D 7. NCP1521B.LIB simulation library file must be added to the current design. http://onsemi.com 6 AND8285/D 8. NCP1521B typical application circuit can be now simulated. Input Voltage Enable Signal Output Voltage Additional Information NCP1521B model is only a behavioral model which cannot fully reproduce NCP1521B device electrical characteristics. For further information on NCP1521B, visit our website http://onsemi.com. http://onsemi.com 7 AND8285/D ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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