Design Note – DN06073/D 24V Input, 5A DC-DC PWM Buck Controller + FET Device NCP3020 Application 16W Industrial Application Input Voltage Output Voltage Output Current Topology 21.6-26.4V 3.3V 0.01-5A Buck Table 1: Buck Power Supply Characteristic Input Voltage Output Voltage Output Current Oscillator Frequency Output Voltage Ripple Load Regulation Iout = 0.02-10A / Vin= 24V NCP3020 Circuit Description This circuit is proposed for a +24V input industrial application where there is a need to step-down the voltage to +3.3V @ 5A. The requirement specified a large electrolytic input capacitance and also to utilize electrolytic capacitors on the output. Target efficiency is >85%. The PCB for the NCP3020 is a 2-layer board for use in applications up to 50W. The synchronous buck converter uses voltage mode control, which can be compensated externally with a transconductance amplifier. The soft start time is fixed. The NCP3020 demonstration board is a flexible design allowing the use of electrolytic capacitors or ceramic capacitors. Min 9 3.20 .01 270 Typ 12 3.326 1 300 86 Max 18 3.34 5 330 1.53 Unit V V A kHz mVpk-pk mV/A Key Features High Efficiency Adjustable Current Limit Output Overvoltage and Output Undervoltage protection Short Circuit Protection Fixed Switching Frequency Rev 0, January 2011 Electrolytic Capacitor Version Performance The following figures show typical performance of the NCP3020 demonstration boards. Efficiency (%) Efficiency Vs I-Out 90 87 84 81 78 75 72 69 66 63 60 21.6 V-In 24.0 V-In 26.4 V-In 0 1 2 3 4 5 I-Out (A) Figure 1: NCP3020 Efficiency at 21.6-26.4 V with a 3.3V Output Voltage V-Out (V) Load Regulation 3.37 3.36 3.35 3.34 3.33 3.32 3.31 3.3 3.29 21.6 V-In 24.0 V-In 26.4 V-In MIN MAX 0 1 2 3 4 I-Out (A) Figure 2: NCP3020 Load Regulation Rev 0, January 2011 5 Line Regulation 0A 3.37 0.5A 3.36 V-Out (V) 1.0A 3.35 1.5A 3.34 2.0A 2.5A 3.33 3.0A 3.32 3.5A 3.31 4.0A 4.5A 3.3 5.0A 3.29 21.6 MIN 22.6 23.6 24.6 V-In (V) Figure 3: NCP3020 Line Regulation Rev 0, January 2011 25.6 MAX ON Semiconductor Schematics Figure 4: NCP3020 Schematic Rev 0 - January, 2011 ON Semiconductor Figure 5: NCP3020 Top Layout Rev 0 - January, 2011 ON Semiconductor Figure 6: NCP3020 Bottom Layout Rev 0 - January, 2011 ON Semiconductor Item 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 19 20 21 22 23 24 25 26 27 28 29 30 31 Qty 1 1 1 1 1 1 1 1 2 2 1 1 2 1 1 1 2 1 1 1 1 1 1 2 1 1 1 1 1 Reference D1 C3 C4 C1 C2 C13 C7 C5 C8-9 C10 C14 L1 C6 C11-12 U1 Q2 Q1 R12 R15 R7 R3 R1 R5 R14 R6 R2 R4 R13 R9 R11 R10 R8 Manufacturer Part Name ON Semiconductor AVX AVX Taiyo Yuden AVX Vishay/Dale Vishay Vishay AVX Corporation TDK TDK Corporation SANYO United Chemi-Con ON Semiconductor Infineon Infineon Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay/Dale Vishay / Dale Vishay / Dale Vishay / Dale Vishay / Dale Manufacturer BAT54T1G 06036C104JAT2A 06035C153KAT2A UMK107C5105KA 0603ZC271KAT2A VJ0603Y103KXACW1BC 08053G104ZAT2A 08055A471JAT2A 1210ZC106KAT2A GRM32DF51H106ZA01L SLF12575T-6R8N5R9-PF 10SP270M EMVH350GDA681MMH0S NCP3020 BSZ105N04NSG BSZ165N04NSG CRCW06030000Z0EA CRCW06030000Z0EA CRCW06031K47FKEA CRCW06031K82FKEA CRCW060310K0FKEA CRCW060320R0FKEA CRCW060322K1FKEA CRCW0603402RFKEA CRCW060310K0FKEA CRCW12060000Z0EA CRCW12060000Z0EA CRCW1206100RFKEA CRCW120639R2FKEA Description Schottky Barrier Diodes Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor Ceramic Chip Capacitor SMT Inductor OS-CON Capacitor Electrolytic Capacitor 300 kHz PWM Controller 40V N-MOSFET 40V N-MOSFET SMT Resistor SMT Resistor SMT Resistor SMT Resistor SMT Resistor SMT Resistor SMT Resistor SMT Resistor SMT Resistor Resistor Resistor Resistor Resistor Table 2: NCP3020 BOM Rev 0 - January, 2011 FootPrint SOD123 603 603 603 603 603 805 805 1210 2210 (12.50x12.50x7.50)mm (11.5x 8)mm (13.0x 13.0 x16.0)mm SOIC8 8-TSDSON 8-TSDSON 603 603 603 603 603 603 603 603 603 1206 1206 1206 1206 Value 0.35 Vf 100nF 15nF 1uF 50V 270pF NI 0.1 uF 470pF 10uF 10V 10uF 50V 6.8uH 270 uF 10V 680 uF 35V 300 kHz 10.5m 40 V 16.5m 40 V 0R0 0R0 1.47k 1.82k 10k 20R0 22.1k 402 NI 0OHM 0R0 100 39R2 Tolerance NA 10% 10% 10% 10% 10% 10% 20% 20% 20% 10% 20% 20% NA NA NA 1% NA 1% 1% 1% 1% 1% 1% 1% NA ±5.0% ±1.0% NA ON Semiconductor Figure 7: Input = 24V, Output = 3.3V, Load = 5A, Red = VOUT, Yellow = VSW Blue = VIN Figure 8: Input = 18V, Output = 3.3, Load = 10A, Transient Response Red = VOUT, Green = IOUT Figure 9: Input = 24V, Output = 3.3V, Load = 5A Crossover Frequency = 22.09kHz at 48 deg Rev 0 - January, 2011 ON Semiconductor © 2011 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 Jim Hill, e-mail: [email protected] ; [email protected] Rev 0 - January, 2011