AND9004/D Use of NCP1529 Pspice Model Prepared by: Gang Chen ON Semiconductor http://onsemi.com APPLICATION NOTE Overview applications, a Pspice model of the NCP1529 has been developed. There are two typical applications using the NCP1529. Figure 1 shows a typical simulation circuit for a DC−DC application. Figure 2 shows another typical simulation circuit for a LED driver application. This simulation note is to illustrate how to use the NCP1529 Pspice model. The NCP1529 is a synchronous step−down DC−DC converter for portable applications powered by one cell Li−ion or three cell Alkaline/NiCd/NiMH batteries. The device is able to deliver up to 1.0 A on an output voltage range externally adjustable from 0.9 V to 3.9 V. The device also has a built−in 1.7 MHz (nominal) oscillator. Automatic switching PWM/PFM mode offers improved system efficiency. To provide simulation results and an initial design of system parameters before a real board design in VIN R1 360k FB V1 C4 10uF 3.6Vdc C3 18pF FB network R2 180k 0 2 Input Supply NCP1529 VIN EN 4 FB GND 0 U1 5 SW SW 1 L1 R9 2 2.2uH 3 1 VOUT 70m R3 10m Output Filter 0 EN V1 = 0 V2 = 5 TD = 0u TR = 10u TF = 10u PW = 1 PER = 2 C1 10uF 0 0 EN control T1 = 0 T2 = 400u T3 = 400.01u Iout T4 = 450u T5 = 450.01u T6 = 500u T7 = 600u T8 = 950u Output Loading I1 = 0.2 I2 = 0.2 I3 = 0.7 I4 = 0.7 I5 = 0.2 I6 = 0.2 I7 = 0.2 I8 = 0.2 0 Figure 1. Typical Simulation Circuit of NCP1529 for DC−DC Applications © Semiconductor Components Industries, LLC, 2011 April, 2011 − Rev. 0 1 Publication Order Number: AND9004/D AND9004/D VOUT R11 1k R1 0.1 VLED Q1 BC857B Q2 BC857B Q4 BC847B Q3 BC847B VIN FB network V1 FB C4 10uF 2 Input Supply NCP1529 VIN EN FB GND 1 0 U1 SW C3 1nF 4 R2 7.5k 0 5 SW 1 L1 0 2 2.2uH VOUT 70m R3 10m Output Filter 0 EN V1 = 0 V2 = 5 TD = 0u TR = 10u TF = 10u PW = 1 PER = 2 C1 1uF 0 0 VLED EN control D1 MBR130P V12 2.5Vdc R10 0.57 LED Model 0 Figure 2. Typical Simulation Circuit of NCP1529 for LED Driver Applications http://onsemi.com 2 R12 7.5k 0 R9 3 5Vdc AND9004/D DETAILED DESCRIPTION Download Pspice Model Users can download the NCP1529 Pspice model from ON Semiconductor website, which is a zipped file (NCP1529_PSPICE.ZIP) including one Pspice model lib file (NCP1529_PSPICE.LIB), one schematic symbol olb file (NCP1529_PSPICE.OLB), and two design dsn files (NCP1529_DCDC.DSN and NCP1529_LED.DSN). Save all the extracted files in a folder. Model Installation and Simulation 1. Create New Project Users need to run ORCAD Capture or Allegro Design Entry CIS first, and then create a new blank project in Capture as shown in Figure 3. Figure 3. Create New Blank Simulation Project 2. Import Design File Depending on the application to be simulated, users need to select either the design file “NCP1529_DCDC.DSN” or “NCP1529_LED.DSN” and add it into the Design Resources to replace the blank design. Figure 4. Import Design File into Design Resources 3. Import Symbol File Add the symbol file “NCP1529_PSPICE.OLB” into the Design Resources as shown in Figure 5. http://onsemi.com 3 AND9004/D Figure 5. Import Symbol File into Design Resources 4. Open Schematic Open the schematic in the “Schematic1” under the design file as shown in Figure 6. Users can edit the schematic according to real applications. Figure 6. Open Schematic in Design File 5. Create Simulation Profile and Run Simulation In order to run simulation, a simulation profile has to be created as shown in Figure 7. In the simulation setting of the simulation profile, users need to use browser to add the Pspice lib file “NCP1529_PSPICE.LIB” into the design library of the simulation configuration files, as shown in Figure 8. Figure 7. Create a New Simulation Profile Figure 8. Add Pspice LIB File into Library of Configuration Files http://onsemi.com 4 AND9004/D To reduce simulation time, a 100 ms (instead of 310 ms in the NCP1529 datasheet) internal soft start has been implemented in the model. A typical time−domain simulation profile setting is shown in Figure 9. Users can review simulation waveforms in Pspice A/D after running a simulation. Figure 9. Simulation Setting for a Time Domain Simulation. 5.1 Simulation with DC−DC Application Circuit Figure 1 shows the schematic included in the design file “NCP1529_DCDC.DSN”, which is a typical simulation circuit for a DC−DC application. To get detail application information, please refer to datasheet “NCP5219−D”. An IPWL current source “Iout” is employed to simulate a load current variation in the output of the DC−DC converter. Figure 10 shows an example of the simulation results regarding to a load transient event. Figure 10. Typical Simulation Results of Time Domain Simulation in DC−DC Application http://onsemi.com 5 AND9004/D 5.2 Simulation with LED Application Circuit Figure 2 shows the schematic included in the design file “NCP1529_LED.DSN”, which is a typical simulation circuit for a LED driver application. The NCP1529 operates with an external current mirror to regulate LED current. To get detail application information, please refer to application note “AND8465/D”. In this simulation circuit, a LED diode is modeled by a circuitry incorporating a diode “D1”, a DC voltage source “V12”, and a resistor “R10”. Figure 11 shows an example of the simulation results regarding to the regulation of the LED current I(D1). Figure 11. Typical Simulation Results of Time Domain Simulation in LED Application 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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