Application Note 1766 Author: Jun Liu ISL85402EVAL2Z Evaluation Board Setup Procedure Recommended Equipment The ISL85402EVAL2Z board is used to demonstrate the compact size and operations of synchronous buck using ISL85402. The ISL85402 supports an input voltage range of 3V to 36V. Note that the input voltage of this board is limited by the input capacitor C2(25V rating). When an input voltage higher than 20V is desired, replace C2 with capacitors with higher voltage ratings. The output voltage is set to 5V and can be changed by voltage feedback resistors. Note that in order to change to a higher output voltage, the output capacitors’ voltage ratings have to be checked. The board output current is 2A typical. The board is set to a default overcurrent threshold of 3.6A. the OC threshold can be programmed by a resistor at the ILIMIT pin. The ISL85402EVAL2Z board has configuration options of forced PWM mode or PFM mode. • 0V to 36V power supply with at least 5A source current capability • Load capable of sinking current up to 3A • Multimeters • Oscilloscope Quick Startup 1. Connect test point MODE to ground when forced PWM mode (no PFM) is desired; leave MODE floating if PFM mode is desired. 2. Connect the power source to the input terminals VIN+ and VIN-. Connect the load terminals to the buck outputs VO+ and VO-. Make sure the setup is correct prior to applying any power or load to the board. 3. Adjust the power source to 12V and turn it on. 4. Verify the output voltage is 5V and use oscilloscope to monitor the phase node waveforms. The board is set to a default frequency of 500kHz. The frequency can be programmed by a resistor at R1. The board can be synchronized to external clock. Multiple ISL85402EVAL2Z boards can be synchronized simply by connecting their SYNC pins together. 0.9’’ 0.39’’ BOTTOM TOP FIGURE 1. ISL85402EVAL2Z BOARD IMAGE July 26, 2012 AN1766.1 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 Inc. 2012. 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 1766 TABLE 1. CONNECTORS/TEST POINTS DESCRIPTIONS TEST POINT DESCRIPTION VIN+ Positive terminal of buck inputs. VIN- Ground terminal of buck inputs. VO+ Positive terminal of buck outputs. VO- Ground terminal of buck outputs. VCC Test point to monitor the VCC. EN Use this connector to control IC ON/OFF. ILIMIT Use it to set up the overcurrent limit threshold. With the ILIMIT pin connected to VCC or GND, or left open, the IC has a default 3.6A OC threshold. The OC threshold can be programmed by a resistor from the ILIMIT pin to ground. MODE Mode setup connector. Connecting the MODE pin to GND will set the IC in forced PWM mode; leaving the MODE pin open or connected to VCC will set the IC to have PFM available under light load conditions. The IC’s default PFM current threshold is 0.7A. R16 is a placeholder for a resistor to program the PFM current threshold. PGOOD Test point to monitor PGOOD. SYNC Used for synchronization configuration. Option 1: to apply external clock for the IC to be synchronized with. Option 2: to synchronize multiple ISL85402s, simply connect the SYNC pins together. 2 AN1766.1 July 26, 2012 ISL85402EVAL2Z Board Schematic VIN+ E C1 4.7UF VCC E C2 VO+ COMP 16 18 17 VIN VIN 19 VCC SGND 12 EXT BOOST SYNC 11 E C3 PHASE PHASE ISL85402IRZ PGOOD EP 13 SYNC 10 9 PGOOD 8 6 ILIMIT 7 E E C8 R2 C10 3.92K 150PF R4 R3 44.2K 232K 1 8 2 7 3 6 4 5 BSZ100N06LS3G FIGURE 2. ISL85402EVAL2Z BOARD SCHEMATIC VO+ 10UH Q1 E 1000PF VO+ L1 C6 5 14 LGATE 10UF FB 15 C5 4 U1 BOOT PGND 10UF SS E 1UF FS 3 MODE 10PF 2K EN 2 21 C9 C7 100PF R7 C4 E 1 VIN- +5V/2A VO- E Application Note 1766 0.015UF E DNP EN ILIMIT MODE 3 R1 AUXVCC 20 10UF AN1766.1 July 26, 2012 Application Note 1766 TABLE 1. BILL OF MATERIALS REF DES PART NUMBER QTY DESCRIPTION MANUFACTURER C9 C0402COG500-100JNE 1 CAP, SMD, 0402, 10pF, 50V, 5%, NP0, ROHS VENKEL C7 VARIOUS 1 CAP, SMD, 0402, 100pF, 25V, 10%, C0G, ROHS VARIOUS C3 ECJ-OEB0J105M 1 CAP, SMD, 0402, 1µF, 6.3V, 20%, X5R, ROHS PANASONIC C10 VARIOUS 1 CAP, SMD, 0402, 150pF, 50V, 5%, NP0, ROHS VARIOUS C4 VARIOUS 1 CAP, SMD, 0402, 0.015µF, 16V, 10%, X7R, ROHS VARIOUS C8 VARIOUS 1 CAP, SMD, 0402, 1nF, 25V, 10%, X7R, ROHS VARIOUS C5,C6 VARIOUS 2 CAP, SMD, 0805, 10µF, 6.3V, 10%, X5R, ROHS VARIOUS C1 0805ZD475KAT2A 1 CAP, SMD, 0805, 4.7µF, 10V, 10%, X5R, ROHS AVX C2 TMK316B7106KL-TD 1 CAP, SMD, 1206, 10µF, 25V, 10%, X7R, ROHS TAIYO YUDEN L1 SD8350-100-R 1 COIL-PWR INDUCTOR, SMD, 9.5X8.3, 10µH, 20%, 4A, 31.4mΩ, ROHS COILTRONICS U1 ISL85402IRZ 1 IC-SWITCHING REGULATOR, 20P, QFN, 4X4, ROHS Q1 BSZ100N06LS3G 1 TRANSIST-MOS, N-CHANNEL, 8P, PG-TSDSON-8, 60V, 20A, ROHS 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 R1 N/A 0 RES, SMD, 0402, DNP, DNP, DNP, TF, ROHS 4 INTERSIL INFINEON TECHNOLOGY N/A AN1766.1 July 26, 2012 Application Note 1766 Board Layouts FIGURE 3. SILKSCREEN TOP COMPONENTS FIGURE 4. TOP LAYER FIGURE 5. 2 nd LAYER FIGURE 6. 3 rd LAYER FIGURE 7. BOTTOM LAYER FIGURE 8. SILKSCREEN BOTTOM COMPONENTS 5 AN1766.1 July 26, 2012 Application Note 1766 Board Layouts (Continued) FIGURE 9. TOP COMPONENT ASSEMBLY FIGURE 10. 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 6 AN1766.1 July 26, 2012