Application Note 1882 Author: Billy Yang ISL8115EVAL2Z Synchronous Buck Converter User Guide Introduction ISL8115 Key Features ISL8115EVAL2Z is a Synchronous Buck Converter implementing Intersil’s wide input range PWM controller ISL8115. Utilizing voltage mode control with input feed forward, the ISL8115EVAL2Z maintains a constant loop gain for optimal transient response, especially for applications with a wide input voltage range. For a more detailed description of the ISL8115 functionality, refer to the ISL8115 data sheet. • Wide VIN range operation: 2.97V to 36V; up to 5.5V output and 30A load current per phase. • Integrated 5V high speed 4A MOSFET gate drivers - Internal bootstrap diode This application note includes the test setup, typical performance waveforms, schematic, layout and bill of materials (BOM). • Oscillator programmable from 150kHz to 1.5MHz - Frequency synchronization to external clock signal Evaluation Board Specifications • Diode emulation mode for light load efficiency improvement TABLE 1. EVALUATION BOARD ELECTRICAL SPECIFICATIONS SPEC VIN DESCRIPTION Board Input Range MIN TYP 25 28 MAX UNIT 36 • Fast transient response - Voltage-mode PWM leading-edge modulation with non-linear control - Input voltage feed-forward V • Output OVP/UVP; OCP and OTP • Power-good open drain output • Adjustable soft-start VOUT Output Voltage 5 V • Pre-bias start-up function IOUT Output Rated Current 20 A IOC Overcurrent Threshold 22 A Fsw Switch Frequency 220 kHz Input UVP Rising threshold 22.4 V • Excellent output voltage regulation - 0.6V ±1.0% internal reference (-40°C ~ +125°C) - 0.6V ±0.7% internal reference (-40°C ~ +105°C) - Differential voltage sensing Falling threshold 24.2 V Applications 92.53 % • Power supply for datacom/telecom and POL η Efficiency at 50% load • Wide input voltage range buck regulators • High current density power supplies RF power amplifier bias compensation Recommended Equipment • Input power source up to 36V supply voltage with 125W power supply ability. • Electronic load with 100W power sinking ability • Voltmeters and ammeters • 100MHz quad-trace oscilloscope FIGURE 1. ISL8115EVAL2Z EVALUATION BOARD February 5, 2014 AN1882.2 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2013, 2014. All Rights Reserved Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. Application Note 1882 FIGURE 2. ISL8115EVAL2Z TEST SET-UP Quick Test Setup Design Guide 1. Ensure that the Evaluation board is correctly connected to the power supply and the electronic load prior to applying any power. Please refer to Figure 2 for proper set-up. 2. Set the input voltage to 28V, turn on the power supply and observe output voltage. The output voltage should variation should be within 5%. 3. Adjust load current within 20A. The output voltage variation should be within 5%. 4. Use oscilloscope to observe output ripple voltage and phase node ringing. For accurate measurement, please refer to Figure 3 for proper set-up. Note: Test points TP1; TP3; TP8; TP9 are for voltage measurement only. Do not allow high current through these test points. The ISL8115EVAL2Z is optimized for 25V to 36V input voltage range. However, the evaluation board can be modified to support multiple applications due to the customer requirements. Please refer to the datasheet for the detailed information. Output Voltage Adjustment The output voltage can be set by the resistor R4, R1. In order to keep the existing compensation parameters unchanged, adjust R4 to set the output voltage by the following Equation 1: R4 = 0.6 V × R1 Vout − 0.6 V (EQ. 1) VMON monitors the output for UVP and OVP, the resistor divider value of R11/R8 should be the same with the R1/R4. Synchronization Probe Set-up ISL8115EVAL2Z board can be synchronized with an external clock. Apply a clock signal (10% to 90% duty cycle) in the range of 150kHz to 1.5MHz to the FSET pin makes the internal frequency synchronized with the external clock. Please remove R27 when the sync function is implemented. FIGURE 3. OSCILLOSCOPE PROBE SET-UP 2 AN1882.2 February 5, 2014 Application Note 1882 Typical Performance Curves Unless otherwise specified, the input voltage is 28V. 95 95 90 90 VIN = 24V 85 VIN = 28V 80 EFFICIENCY (%) EFFICIENCY (%) 85 VIN = 36V 75 VIN = 24V 80 VIN = 28V 75 70 70 65 65 60 0 2 4 6 8 10 12 14 16 18 60 20 VIN = 36V 0 1 2 3 4 5 6 OUTPUT CURRENT (A) OUTPUT CURRENT (A) FIGURE 4. EFFICIENCY vs LOAD CURRENT AT CCM MODE FIGURE 5. EFFICIENCY vs LOAD CURRENT AT DEM MODE 5.0080 5.0058 5.0075 5.0057 5.0056 VOUT (V) VOUT (V) 5.0070 VIN = 28V 5.0065 5.0055 VIN = 28V 5.0054 5.0060 5.0053 5.0055 5.0050 5.0052 5.0051 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 FIGURE 6. VOUT LOAD REGULATION AT CCM MODE 12 14 16 18 20 DEM MODE 5.0068 5.0066 5.0070 5.0064 5.0068 NO LOAD 5.0066 5.0062 NO LOAD 5.0060 5.0064 VOUT (V) VOUT (V) 10 FIGURE 7. VOUT LOAD REGULATION AT DEM MODE CCM MODE 5.0072 5.0062 5.0060 5.0058 5.0056 5.0054 5.0058 5.0052 5.0056 5.0050 5.0054 5.0048 5.0052 24 8 LOAD CURRENT (A) LOAD CURRENT (A) 26 28 30 32 34 36 5.0046 24 26 28 30 32 34 36 VIN (V) VIN (V) FIGURE 8. LINE REGULATION AT NO LOAD CONDITION 3 AN1882.2 February 5, 2014 Application Note 1882 Typical Performance Curves Unless otherwise specified, the input voltage is 28V. (Continued) CCM MODE 5.00562 5.00560 5.0056 5.00558 5.0055 5.0054 VOUT (V) VOUT (V) 5.00556 5.00554 FULL LOAD 20A 5.00552 5.00550 5.0053 5.0052 FULL LOAD 20A 5.0051 5.0050 5.00548 5.0049 5.00546 5.00544 24 DEM MODE 5.0057 5.0048 26 28 30 32 34 36 5.0047 24 26 28 VIN (V) 30 32 34 36 VIN (V) FIGURE 9. LINE REGULATION AT FULL LOAD CONDITION VOUT 50mV/DIV PH 20V/DIV 2µs/DIV FIGURE 10. OUTPUT VOLTAGE RIPPLE AT 20A LOAD CONDITION 10A/DIV OUTPUT LOAD VOUT 10A/DIV 100mV/DIV OUTPUT LOAD VOUT 100mV/DIV 200µs/DIV 200µs/DIV FIGURE 11. 5A-15A; 2A/µs AT CCM MODE FIGURE 12. 10A -20A; 2A/µs AT CCM MODE 4 AN1882.2 February 5, 2014 Application Note 1882 Typical Performance Curves Unless otherwise specified, the input voltage is 28V. (Continued) 2V/DIV 2V/DIV VOUT VOUT OUTPUT LOAD VIN 10A/DIV OUTPUT LOAD 10A/DIV 20V/DIV VIN 20V/DIV 10ms/DIV 10ms/DIV FIGURE 13. START-UP AT 0A LOAD CONDITION FIGURE 14. START-UP AT 20A LOAD CONDITION VOUT VOUT OUTPUT LOAD 2V/DIV 2V/DIV OUTPUT LOAD 10A/DIV 10A/DIV VIN VIN 20V/DIV 20V/DIV 50ms/DIV 2ms/DIV FIGURE 15. SHUTDOWN AT 0A LOAD CONDITION FIGURE 16. SHUTDOWN AT 20A LOAD CONDITION VOUT VOUT 500mV/DIV OUTPUT LOAD 500mV/DIV OUTPUT LOAD 10A/DIV PH 20V/DIV 10A/DIV PH 20V/DIV 5ms/DIV 5ms/DIV FIGURE 17. OCP AT 27A LOAD FIGURE 18. SHORT PROTECTION 5 AN1882.2 February 5, 2014 Schematic TP9 RGND PVCC R31 4.99K R30 4.99K R10 0 R8 2K 2K 3 1 6 R4 3.3n R11 14.7k 133 R9 0 Q5 2N7002LT1 1 2 PGOOD R1 14.7k C3 R3 3 4 2 TP4 PGOOD C37 1uF TP8 VOUT_S LED1 Average OCP: 22A Peak current limit: 25A C17 0.22uF C1 4.7nF C2 100p R17 3k J4 23 R38 0 R26 24 113K R27 VIN R29 10k R6 10 JP5 C22 2.2uF R35 174k 8 1 2 3 DNP Q1 4 C34 DNP C32 5 1 L1 2.6uH J3 1 2 Big Lug 7443556260 2.6uH 31.5A 1.58mohm Q2 4 0.22uF D2 C24 100uF 7 C23 100uF DNP R14 2 C21 2.2uF C26 100uF C25 100uF C11 1uF C15 1uF 33.2K R12 3k R34 2.2 TP3 PVIN C30 10uF Output: 5V/20A C29 10uF C35 100uF C36 100uF J1 VIN 36V TP1 GND C13 1uF C10 1uF Upper MOS: BSC039N06NS Lower MOS: BSC039N06NS PVCC EVAL2Z Input: 24V - 36V Frequency: 220KHz 6TPF330M9L C31 DNP 1 2 3 5 1 2 3 C16 C33 6TPF330M9L R13 DNP 10 R33 0 Big Lug R28 7.15k JP7 0 9 DNP 4 R20 R36 140K input rising shreshold: 22.4V input falling shreshold: 21.2V 1 2 3 13 ISENA 14 ISENB 16 15 VMON FB BOOT SS 1 R37 0 UGATE CLKOUT FSET 18.2K CLK_IN PHASE ISL8115 CONF Q4 5 11.8K CLK_OUT PLL_COMP Q3 4 5 22 U1 R43 1 C6 11 PVCC VFF R23 PVCC RAMP 21 LGATE ISHARE R16 DNP C20 4.7uF 12 6 R25 0 ISET PGOOD 20 5 390pF 5.11K ISHARE_BUS GND PGOOD 4 19 RGND 18 25 17 R18 10.5k 1n VCC JP6 C19 R21 EN C12 DNP 3 DNP COMP R24 JP3 2 JP4 JP1 VOUT C4 C14 2.2nF J2 GND Application Note 1882 R2 13k R22 0 AN1882.2 February 5, 2014 Application Note 1882 Bill of Materials QTY REFERENCE VALUE DESCRIPTION 1 C1 4.7nF CAP CER 4700pF 50V 10% X7R 0603 Generic Generic 1 C2 100p CAP CER 100pF 50V 5% NP0 0603 Generic Generic 1 C3 3.3n CAP CER 3300pF 50V 10% X7R 0603 Generic Generic 1 C4 1n CAP CER 1000pF 50V 5% NP0 0603 Generic Generic 5 C6, C12, R13, R16, R24 DNP 5 C10, C11, C13, C15, C37 1µF CAP CER 1µF 10V 10% X5R 0603 Generic Generic 1 C14 2.2nF CAP CER 2200pF 50V 10% NP0 0603 Generic Generic 2 C16, C17 0.22µF CAP CER 0.22µF 16V 10% X7R 0603 Generic Generic 1 C19 390pF CAP CER 390pF 50V 5% NP0 0603 Generic Generic 1 C20 4.7µF CAP CER 4.7µF 6.3V 10% X5R 0805 Generic Generic 1 C21 2.2µF CAP CER 2.2µF 25V 10% X7R 1210 C3225X7R1E225K/1.60 TDK 1 C22 2.2µF CAP CER 2.2µF 6.3V 20% X5R 0603 Generic Generic 4 C23, C24, C25, C26 100µF CAP CER 100µF 6.3V 20% X5R 1210 C3225X5R0J107M250AC TDK 2 C29, C30 10µF CAP CER 10µF 50V 10% X5R 1206 C3216X5R1H106K160AB TDK 2 C31, C34 DNP CAP TANT 330µF 6.3V 20% 2917 6TPF330M9L Panasonic 2 C32, C33 6TPF330M9L CAP TANT 330µF 6.3V 20% 2917 6TPF330M9L Panasonic 2 C35, C36 100µF CAP ALUM 100µF 50V 20% SMD PCV1H101MCL2GS nichicon 1 D2 DNP 4 JP1, JP3, JP4, JP5 Jumper JUMPER PLUG 2POS DOUBLE ROW XG8T-0231 Omron 2 JP6, JP7 DNP JUMPER PLUG 2POS DOUBLE ROW 1 J1 VIN POST BINDING BANANA INSULATED RE 111-0707-001 Johnson Components 1 J2 GND POST BINDING BANANA INSULATED BL 111-0703-001 Johnson Components 2 J3, J4 Big Lug CONN- Big Lug TERMINAL POST KPA8CTP Burndy 1 LED1 VENDOR LNJ162C3XRA Panasonic 1 L1 2.6µH 7443556260 WE-Midcom 1 Q1 DNP 3 Q2, Q3, Q4 1 Q5 2N7002LT1 MOSFET N-CH 60V 115MA SOT-23 2N7002LT1 ON Semiconductor 2 R1, R11 14.7k RES 14.7kΩ 1/10W 1% 0603 SMD Generic Generic 1 R2 13k RES 13.0kΩ 1/10W 1% 0603 SMD Generic Generic 1 R3 133 RES 133Ω 1/10W 1% 0603 SMD Generic Generic 2 R4, R8 2k RES 2.00kΩ 1/10W 1% 0603 SMD Generic Generic 1 R6 10 RES 10.0Ω 1/10W 1% 0603 SMD Generic Generic 8 R9, R10, R22, R25, R33, R37, R38, R43 0 RES 0.0Ω 1/10W JUMP 0603 SMD Generic Generic 2 R12, R17 3k RES 3.00kΩ 1/10W 1% 0603 SMD Generic Generic 1 R14 2 RES 2.00Ω 1/4W 1% 1206 SMD Generic Generic 1 R18 10.5k RES 10.5kΩ 1/10W 1% 0603 SMD Generic Generic 1 R20 33.2k RES 33.2kΩ 1/10W 1% 0603 SMD Generic Generic 1 R21 5.11k RES 5.11kΩ 1/10W 1% 0603 SMD Generic Generic DIODE SCHOTTKY 40V SOD123 LXA3025IGC-TR LED INDUCTOR POWER 2.6µH 31.5A SMD MOSFET N-CH 60V 19A TDSON-8 BSC039N06NS MOSFET N-CH 60V 19A TDSON-8 7 PART # BSC039N06NS AN1882.2 February 5, 2014 Application Note 1882 Bill of Materials (Continued) QTY REFERENCE VALUE 1 R23 11.8k RES 11.8kΩ 1/10W 1% 0603 SMD Generic Generic 1 R26 18.2k RES 18.2kΩ 1/10W 1% 0603 SMD Generic Generic 1 R27 113k RES 113kΩ 1/10W 1% 0603 SMD Generic Generic 1 R28 7.15k RES 7.15kΩ 1/10W 1% 0603 SMD Generic Generic 1 R29 10k RES 10kΩ 1/10W 1% 0603 SMD Generic Generic 2 R30, R31 4.99K RES 4.99kΩ 1/10W 1% 0603 SMD Generic Generic 1 R34 2.2 RES 2.2Ω 1/10W 1% 0603 SMD Generic Generic 1 R35 174k RES 174kΩ 1/10W 1% 0603 SMD Generic Generic 1 R36 140k RES 140kΩ 1/10W 1% 0603 SMD Generic Generic 1 TP1 GND Test point SPCJ-123-01 Jolo 1 TP3 PVIN Test point SPCJ-123-01 Jolo 1 TP4 PGOOD Test point SPCJ-123-01 Jolo 1 TP8 VOUT_S Test point SPCJ-123-01 Jolo 1 TP9 RGND Test point SPCJ-123-01 Jolo 1 U1 ISL8115 Sync Buck PWM Controller 24Ld QFN ISL8115FRTZ Intersil 8 DESCRIPTION PART # VENDOR AN1882.2 February 5, 2014 Assembly Drawing 9 Application Note 1882 AN1882.2 February 5, 2014 Application Note 1882 PCB Layout FIGURE 19. TOP LAYER FIGURE 20. LAYER 2 10 AN1882.2 February 5, 2014 Application Note 1882 PCB Layout (Continued) FIGURE 21. LAYER 3 FIGURE 22. LAYER 4 Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 11 AN1882.2 February 5, 2014