Design Note – DN06055/D Power Supply PSU Device CS51221 Application Input Voltage Output Voltage Output Current Topology Cash Drawer 12 V 24V 4A Boost Table 1: CS51221 Cash Drawer Power Supply Characteristic Output Voltage Output Current Oscillator Frequency Output Voltage Ripple Min 23.56 .5 Max 26.04 20 140 100 Load Regulation Iout = (0.1-8.3A) Vin= 12V Size Typ 24.72 150 300 -1.33 Length 80 Width Height 59 31 Unit V A kHz mVpkpk mV/A mm Figure 1: Demonstration Board Picture Circuit Description The design must minimize the use of through hole components, designed as small as possible on a 4 layer PCB, and only populated on one side. The power supply is required to maintain an 24.7V output while with an input of 12V. Rev 2 - December, 2008 Table 2: CS51221 Cash Drawer Power Supply Compliance Matrix Item 1 2 3 4 5 6 7 8 9 Description Minimum Maximum 23.56 V 26.04 V 24.72 V PASS 21.08 V 26.04 V 24.72 V PASS 100 mV 50 mV PASS 300 mV 26.04 V 149 mV MIN = 24.24 V MAX = 24.95 V PASS Tolerance Line and Load Regulation (USB) Tolerance Line and Load Regulation (Cash Drawer Interface) Ripple Voltage Nominal Current (peak to peak) Noise, HF ripple (peak to peak) Transient Response 1.5A to 4.5A (10 A/us slew rate) Transient Response 1.5A to 7A (10 A/us slew rate) Transient Response 0A to 20A (10 A/us slew rate) Transient Response 2A to 16A (.014 A/us slew rate) Transient Response 0A to 16A (.014 A/us slew rate) 22.8 V 22.8 V 19.84 V 22.32 V 22.32 V 26.04 V 26.04 V 26.04 V 26.04 V The design has the following features: • Adjustable cycle by cycle current limiting • Over voltage Shutoff • Under voltage shutoff • Can be synchronized to a higher frequency • Programmable soft start • Voltage feed forward Rev 2 - December, 2008 Measured Pass/ Fail PASS MIN = 24.24 V MAX = 24.85 V PASS MIN = 21.23 V MAX = 25.65 V PASS MIN = 23.97 V MAX = 25.21 V PASS MIN = 23.8 V MAX = 24.95 V PASS Performance Information The following figures show typical performance of the evaluation board. Dell CS51221 Efficiency 12V to 24V 100 Efficiency (%) 95 90 85 80 75 70 65 60 0 1 2 3 4 5 6 Output Current (A) Figure 2: CS51221 Efficiency at 12V with a 24.7V Output Voltage Output Voltage (V) Dell CS51221 Load Regulation 24.725 24.724 24.723 24.722 24.721 24.72 24.719 24.718 24.717 24.716 24.715 0 1 2 3 4 Output Current (A) Figure 3: CS51221 Load Regulation Rev 2 - December, 2008 5 6 Schematic Figure 4: CS51221 Schematic Rev 2 - December, 2008 Figure 5: CS51221 Top Layout Rev 2 - December, 2008 Figure 6: CS51221 Top Inner Layout Rev 2 - December, 2008 Figure 7: CS51221 Bottom Inner Layout Rev 2 - December, 2008 Figure 8: CS51221 Bottom Inner Layout Rev 2 - December, 2008 Table 3: CS51221 BOM Designator Quantity Description Value Tolerance Footprint Manufacturer Manufacturer Part Number C5 1 Ceramic Chip Capacitor 10V 330n ±20% 805 AVX Corporation 0805ZC334JAT2A C8 1 Ceramic Chip Capacitor 25V 0.1uF ±20% 603 AVX Corporation 06033C104MAT2A C2 1 Ceramic Chip Capacitor 25V 0.1uF ±20% 603 AVX Corporation 06033C104MAT2A C12 1 Ceramic Chip Capacitor 10V 1.5nF ±10% 603 AVX Corporation 0603YC152KAT2A C6 1 Ceramic Chip Capacitor 10V 1nF ±10% 603 AVX Corporation 0603ZC102KA72A C4 1 Ceramic Chip Capacitor 6.3V 1uF ±10% 603 AVX Corporation 06036D105KAT2A C20 1 Ceramic Chip Capacitor 25V 1uF ±20% 603 AVX Corporation 06033D105MAT2A C10 1 Ceramic Chip Capacitor 50V 2.2nF ±5% 603 AVX Corporation 06035C222JAT2A C11 1 Ceramic Chip Capacitor 16V 82nF ±10% 603 AVX Corporation 0603YC823KAT2A C24 1 Ceramic Chip Capacitor 6.3V 1.2n ±5% 805 AVX Corporation 08056A122JAT2A C16 1 Ceramic Chip Capacitor 100V 1.2nF ±10% 1206 AVX Corporation 12061A122KAT2A 12061C102KAT2A C3 1 Ceramic Chip Capacitor 100V 1nF ±10% 1206 AVX Corporation C21 C23 2 Ceramic Chip Capacitor 50V 1uF ±10% 1206 AVX Corporation 12065C105KAT2A C1 1 Ceramic Chip Capacitor 50V 4.7uF ±20% 1812 TDK Corporation C4532X7R1H475M U1 C7 C9 C13-15 C17-19 1 Mode PWM Controller 3V Ref NA SOIC 16 ON Semiconductor CS51221EDR16G 8 Electrolytic Capacitor 680uF ±20% 12.5X25 United Chemicon EKZE500ELL681MK30S D1 1 Schottky Power Rectifier 40A 100V NA D2PAK 3 LEAD ON Semiconductor MBRB41H100CTT4G Q5 1 NPN Transistor 40V 200mA NA SOT-23 ON Semiconductor MMBT3904TT1G Z1 1 Zener Diode 14V ±5% SOD-123 ON Semiconductor MMSZ5244BT1G U2-3 2 N MOSFET 8.1mOhm 60V 50A NA DPAK Infineon IPB081N06L3G R5 1 SMT Resistor 49.9k ±1.0% 1206 Vishay CRCW120649K9FKEA R14 1 SMD Resistor 1.02k ±1.0% 603 Vishay / Dale CRCW06031K02FKEA CRCW06031K58FKEA R3 1 SMD Resistor 1.58k ±1.0% 603 Vishay / Dale R20 1 SMD Resistor 1k ±5.0% 603 Vishay / Dale CRCW06031K00JNEA R9 1 SMD Resistor 20R0 ±1.0% 603 Vishay / Dale CRCW060320R0FKEA R21 1 SMD Resistor 27.4k ±1.0% 603 Vishay / Dale CRCW060327K4FKEA R2 1 SMD Resistor 3.09k ±1.0% 603 Vishay / Dale CRCW06033K09FKEA R7 1 SMD Resistor 40.2k ±1.0% 603 Vishay / Dale CRCW060340K2FKEA R23 1 SMD Resistor 41.2k ±1.0% 603 Vishay / Dale CRCW060341K2FKEA R13 1 SMD Resistor 49.9k ±1.0% 603 Vishay / Dale CRCW060349K9FKEA R1 1 SMD Resistor 57.6k ±1.0% 603 Vishay / Dale CRCW060357K6FKEA Rev 2 - December, 2008 Designator Quantity Description Value Tolerance Footprint Manufacturer Manufacturer Part Number R26 1 SMD Resistor 6.04k ±1.0% 603 Vishay / Dale CRCW06036K04FKEA R25 1 SMD Resistor 8.2k ±1.0% 603 Vishay / Dale CRCW06038K20FKEA R8 R12 2 SMD Resistor 0R0 ±5.0% 1206 Vishay / Dale CRCW12060000Z0EA R11 R15 2 SMD Resistor 10R0 ±5.0% 1206 Vishay / Dale CRCW120610R0FKEA R10 1 SMD Resistor 4.99k ±1.0% 1206 Vishay / Dale CRCW12064K99FKEA R6 1 SMD Resistor 8.06K ±1.0% 1206 Vishay / Dale CRCW12068K06FKEA R4 1 SMD Resistor 5mOhm ±1.0% 4527 Vishay / Dale WSR55L00F L2 1 SMT Inductor 0.17 mOhm .1 uH ±10% 7.5mmX7.6mm Coilcraft SLC7649S-101KL L1 1 SMT Inductor 1.8 mOhm 10 uH ±10% 27.94mmX27.9mm Coilcraft SER2918H-103 Rev 2 - December, 2008 Figure 9: Vin = 12V Vout =24V Iout = 4A 149 mVpp High Frequency 50mV Fundamental Rev 2 - December, 2008 Figure 10: Transient Response 1.5A to 4.5A with a Slew Rate of 10A/us for a Duration of 300ms and a Period of 1800ms Rev 2 - December, 2008 Figure 11: Transient Response 1.5A to 7A with a Slew Rate of 10A/us for a Duration of 210ms and a Period of 1050ms Rev 2 - December, 2008 Figure 12: Transient Response 0A to 20A with a Slew Rate of 10A/us for a Duration of 2ms and a Period of 10ms Rev 2 - December, 2008 Figure 13: Transient Response 2A to 16A with a Slew Rate of 0.014A/us and a Period of 2ms Rev 2 - December, 2008 Figure 14: Transient Response 0A to 16A with a Slew Rate of 0.014A/us and a Period of 3.4 ms Rev 2 - December, 2008 Figure 15: 12V Frequency Response 1.3 kHz at 51 Degrees of Phase Margin 4A Load Rev 2 - December, 2008 Figure 16: Thermal Image of PCB at 12V with a 4A Load and 25C Ambient Rev 2 - December, 2008 1 © 2009 ON Semiconductor. Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its products at any time, without notice. Design note created by Tim Kaske and Bryan McCoy, e-mail: [email protected] ; [email protected] Rev 2 - December, 2008