Application Note 1960 ISL85403DEMO1Z Demonstration Board User Guide Description Key Features The ISL85403DEMO1Z board allows quick evaluation of the ISL85403 in the synchronous buck configuration. It also demonstrates the compact size solution for the wide input voltage range point-of-load DC/DC converter using ISL85403. • Small, compact design • VIN range of 7V to 40V • VOUT adjustable from 0.8V to 5V • Convenient power connection Specifications The design specifications of the ISL85403DEMO1Z are shown in Table 1. References ISL85403 Datasheet TABLE 1. SPECIFICATIONS Ordering Information PARAMETERS VALUES Input Voltage (VIN) 7V to 40V Output Voltage (VOUT) 5.0V Max. Output Current (IOUT_MAX) 2.5A Switching Frequency 500kHz Output Ripple 50mV at 2.5A Load Peak Efficiency 93% at 50% Load, 12V Input FIGURE 1. TOP VIEW March 13, 2015 AN1960.1 1 PART NUMBER ISL85403DEMO1Z DESCRIPTION ISL85403 Evaluation kit, synchronous buck configuration 5V output FIGURE 2. BOTTOM VIEW 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 2014, 2015. 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 1960 Functional Description Quick Test Setup The ISL85403 is a flexible switching regulator with an integrated 127mΩ high-side MOSFET. It can be used as a synchronous buck converter, a 2-stage boost-buck converter, or a noninverting buckboost converter. +- - LOAD + A The ISL85403DEMO1Z board demonstrates the compact size and operations of the ISL85403 in the synchronous buck configuration. The ISL85403DEMO1Z board is shown in Figures 1 and 2. The schematic is shown on page 3, bill of materials on page 4, and PCB layers for reference start on page 7. Figures 4 through 12 show performance data taken from the demo board. Operating Range The board input voltage range is 7V to 40V. The output voltage is set to 5V and can be changed by voltage feedback resistors R3 and R4, as shown in Equation 1: V ref R 4 = R 3 ---------------------------V out – v ref (EQ. 1) FIGURE 3. ISL85403DEMO1Z BOARD SETUP NOTE: In order to change to a higher output voltage, the output capacitors have to be changed for the higher voltage rating. The board is set to a default frequency of 500kHz (FS pin/R1 is open). The switching frequency can be programmed to other values by a resistor at R1. Refer to the ISL85403 datasheet for the resistor value and the switching frequency. The switching frequency can also be synchronized to external clock by connecting the external clock to the SYNC terminal (J7). PCB Layout Guidelines 1. If PWM mode is desired, connect test point MODE (J5) to ground. Otherwise leave the J5 open for PFM mode. 2. Connect the power supply to the input terminals VIN (J8) and GND (J9). Connect the load terminals to the buck outputs VOUT (J10) and GND (J11). Make sure the setup is correct prior to applying any power or load to the board. 3. Adjust the power supply to 12V and turn it on. 4. Verify the output voltage is 5V and use oscilloscope to monitor the phase node waveforms. 1. Place the input ceramic capacitors as closely as possible to the IC VIN pin and power ground connecting to the power MOSFET or Diode. Keep this loop (input ceramic capacitor, IC VIN pin and MOSFET/Diode) as tiny as possible to minimize the voltage spikes induced by the trace parasitic inductance. 2. Keep the phase node copper area small but large enough to handle the load current. 3. Place the output ceramic and aluminum capacitors close to the power stage components as well. 4. Place vias (at least 9) in the bottom pad of the IC. The bottom pad should be placed in ground copper plane with an area as large as possible in multiple layers to effectively reduce the thermal impedance. 5. Place the 4.7µF ceramic decoupling capacitor at the VCC pin (the closest place to the IC). Put multiple vias close to the ground pad of this capacitor. 6. Keep the bootstrap capacitor close to the IC. 7. Keep the LGATE drive trace as short as possible and try to avoid using via in the LGATE drive path to achieve the lowest impedance. 8. Place the output voltage sense trace close to the place that is to be strictly regulated. 9. Place all the peripheral control components close to the IC. Submit Document Feedback 2 AN1960.1 March 13, 2015 Submit Document Feedback ISL85403DEMO1Z Circuit Schematic J2 J8 1 1 1 VCC 2 3 R6 1 VOUT 1 C1 4.7uF 2 1 C11 10uF VIN C2 10uF 2 J9 1 2 0 2 16 VIN VIN2 17 18 SGND VCC PHASE2 PHASE EP EXT_BOOST 13 12 11 J7 1 1 SYNC 2 C3 1uF L1 J10 10 COMP PGOOD SYNC 9 R7 2k LGATE FB MODE 21 DNP 2 1 C8 470pF C9 PGND ISL85403 SS 8 1 5 C7 1 150pF 2 4 FS 15 14 VOUT 1 10uH 2 VOUT 1 2 3 1 0.015uF BOOT U1 6 R8 750 1 2 EN 1 1 2 AUXVCC 20 DNP 1 1 C4 ILIMIT 2 1 R1 J5 J6 ILIMIT MODE PGOOD Q1 NTTFS5826NLTAG J4 1 1 R5 4.7k 2 2 5Vout 5 VOUT 2.5A 2.5A 1 C5 10uF 2 C6 10uF J1 1 GND R2 C10 1 2 2 3.92k R3 1 1 2 AN1960.1 March 13, 2015 I 150pF 2 232k R4 44.2k 1 Application Note 1960 1 7 J3 EN 19 GND Application Note 1960 Bill of Materials REF DES PART NUMBER QTY C9 DESCRIPTION MANUFACTURER 0 DNP VARIOUS 2 CAP, SMD, 0402, 150pF, 50V, 10%, C0G, ROHS C3 ECJ-OEB0J105M 1 CAP, SMD, 0402, 1µF, 6.3V, 20%, X5R, ROHS C4 VARIOUS 1 CAP, SMD, 0402, 0.015µF, 16V, 10%, X7R, ROHS VARIOUS C8 VARIOUS 1 CAP, SMD, 0402, 470pF, 50V, 10%, X7R, ROHS VARIOUS C5, C6 GRM21BR71A106KE51K 2 CAP, SMD, 0805, 10µF, 10V, 10%, X7R, ROHS Murata C1 GRM21BR71A475KA73L 1 CAP, SMD, 0805, 4.7µF, 10V, 10%, X7R, ROHS Murata C3216X5R1H106K 2 CAP, SMD, 1206, 10µF, 50V, 10%, X5R, ROHS TDK L1 SD8350-100-R 1 COIL-PWR INDUCTOR, SMD, 9.5x8.3, 10µH, 20%, 4A, 31.4mΩ, ROHS U1 ISL85403IRZ 1 IC-SWITCHING REGULATOR, 20P, QFN, 4X4, ROHS INTERSIL Q1 NTTFS5826NLTAG 1 TRANSIST-MOS, N-CHANNEL, 8P, PG-TSDSON-8, 60V, 8A, ROHS ON SEMI R2 VARIOUS 1 RES, SMD, 0402, 3.92k, 1/16W, 1%, TF, ROHS VARIOUS R3 VARIOUS 1 RES, SMD, 0402, 232k, 1/16W, 1%, TF, ROHS VARIOUS R7 VARIOUS 1 RES, SMD, 0402, 2k, 1/16W, 1%, TF, ROHS VARIOUS R4 ERJ-2RKF4422X 1 RES, SMD, 0402, 44.2k, 1/16W, 1%, TF, ROHS VARIOUS R5 VARIOUS 1 RES, SMD, 0402, 4.7k, 1/16W, 1%, TF, ROHS VARIOUS R6 VARIOUS 1 RES, SMD, 0402, 0Ω, 1/16W, 1%, TF, ROHS VARIOUS R1 N/A 0 Do not populate C7, C10 C2, C11 Submit Document Feedback 4 VARIOUS PANASONIC COILTRONICS N/A AN1960.1 March 13, 2015 Application Note 1960 Typical Performance Curves 5.2 100 VIN = 7V 95 85 80 VIN = 24V 75 VIN = 12V 70 65 60 OUTPUT VOLTAGE (V) EFFICIENCY (%) 90 VIN = 24V 5.1 VIN = 7V 5.0 4.9 VIN = 12V 55 50 0.01 0.10 1.00 4.8 0.01 0.10 1 10 OUTPUT CURRENT (A) OUTPUT CURRENT (A) FIGURE 5. LINE REGULATION FIGURE 4. EFFICIENCY vs LOAD VOUT (AC-COUPLE) VOUT (AC-COUPLE) IL IL PHASE PHASE FIGURE 7. OUTPUT RIPPLE AT 2.5A LOAD FIGURE 6. OUTPUT RIPPLE AT 0A LOAD VOUT VOUT IL IL PHASE FIGURE 8. SOFT-START AT 0A LOAD Submit Document Feedback 5 PHASE FIGURE 9. SOFT-START AT 2.5A LOAD AN1960.1 March 13, 2015 Application Note 1960 Typical Performance Curves (Continued) VOUT (AC-COUPLE) VOUT (AC-COUPLE) IL IL PHASE PHASE FIGURE 10. LOAD TRANSIENT RESPONSE FIGURE 11. LOAD TRANSIENT RESPONSE VOUT (AC-COUPLE) IL PHASE FIGURE 12. LOAD TRANSIENT RESPONSE Submit Document Feedback 6 AN1960.1 March 13, 2015 Application Note 1960 Board Layout FIGURE 13. SILKSCREEN TOP COMPONENTS FIGURE 14. TOP LAYER FIGURE 15. 2nd LAYER FIGURE 16. 3rd LAYER FIGURE 17. BOTTOM LAYER FIGURE 18. SILKSCREEN BOTTOM COMPONENTS Submit Document Feedback 7 AN1960.1 March 13, 2015 Application Note 1960 Board Layout (Continued) FIGURE 19. TOP COMPONENT ASSEMBLY FIGURE 20. BOTTOM COMPONENT ASSEMBLY (MIRRORED) 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 Submit Document Feedback 8 AN1960.1 March 13, 2015