Using the ISL6440 Evaluation Board ® Application Note January 8, 2007 AN1219.1 Using the Evaluation Board Soft-start and Shutdown The ISL6440 is a high performance triple-output controller offering control and protection features for 2 synchronous buck PWMs. The soft-start capacitors can be adjusted for sequencing of the output voltages, PWM startup tracking, and/or to adjust the startup current required to charge the output capacitors. The ISL6440 evaluation board highlights the operation of the IC in an embedded DC/DC converter application. Table 1 shows the available evaluation board. 0.8V t SS ( PWM1 ) = C 5 ⋅ -----------5μA TABLE 1. EVALUATION BOARDS BOARD NAME ISL6440EVAL1Z IC ISL6440IAZ PACKAGE 24 Ld QSOP Power and Load Connections Input Voltage - To connect a +12V power supply to the evaluation board, connect the positive lead of the power supply to VIN (P1) post and the ground lead of the supply to the GND (P2) post. Output Adjustment Change the respective output voltage feedback resistors to modify the output voltage: R 7⎞ ⎛ V OUT2 = 0.8 ⋅ ⎜ 1 + -------⎟ R 8⎠ ⎝ (EQ. 1) 1 To independently shutdown the PWMs, the SD1 or SD2 pin can be pulled to GND using the on board posts, P7 and P8 respectively. When both PWMs are within ±10% of their set value, the PGOOD signal will go high. The open drain PGOOD pin is pulled HIGH to VCC_5V on the board. The PGOOD circuitry monitors the FBx pin of each regulated output to determine if the outputs are in regulation. PGOOD can be monitored at post P9. A 12V, 5A capable power supply An electronic load Four channel oscilloscope with probes Precision digital multimeters R 5⎞ ⎛ V OUT1 = 0.8 ⋅ ⎜ 1 + -------⎟ R 6⎠ ⎝ (EQ. 2) Power Good Recommended Test Equipment • • • • 0.8V t SS ( PWM2 ) = C 3 ⋅ -----------5μA Overcurrent Protection The overcurrent thresholds can be adjusted on the ISL6440 evaluation board. The current sense resistors, ISENSE, are set at 1.0k. The overcurrent set resistor is 95.3k. The overcurrent trip point can be adjusted by modifying ROCSET, R3 and R4: 7 ⋅ R CS R OCSET = ------------------------------------I OC ⋅ r DS ( ON ) (EQ. 3) ROCSET is the overcurrent set resistor, RCS is the current sense resistor, IOC is the desired overcurrent trip point, and rDS(ON) is the on resistance of the respective PWM’s lower MOSFET. Refer to the ISL6440 datasheet for more information on how to select the current sense and overcurrent select resistors. CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2006. All Rights Reserved All other trademarks mentioned are the property of their respective owners. ISL6440EVAL1Z Schematic 2 Application Note 1219 AN1219.1 January 8, 2007 Application Note 1219 ISL6440EVAL1Z Bill of Materials ITEM REFERENCE QTY PART NUMBER 1 P1-P9 9 1514-2 Test Point Turret 0.281 Height Keystone 2 D1, D2 2 BAT54HT1G Diode, Schottky 30V, 200mA On Semi 3 C4 1 H1045-00105-6R3V10- Cap, Ceramic, X5R T 1µF, 10V, 0603, X5R Panasonic 4 C9, C10 2 10TPB220M Cap, POSCAP 220µF, 10V Sanyo 5 C1, C2 2 C3225X7R1E106 Cap, Ceramic, 1210 10µF, 10%, 25V, 1210, X7R TDK 6 L1, L2 2 DO3316P-682ML-T SMT Power Inductor 6.8µH, ±20%, 4.6A, 27mΩ Coilcraft 7 C3 1 H1045-00105-16V20-T Capacitor, Ceramic 1µF, 20%, 16V, Y5V, 0603 MURATA 8 Q1, Q2 2 FDS6912A Dual NFET 6A, 30V, Dual NFET, SO8 Fairchild 9 C5, C6, C7, C8 4 H1045-00104-25V10-T Cap, Ceramic, 0603 0.1µF, 10%, 6.3V MURATA/Generic 10 R1, R2, R5, R7 5 Resistor, Film 1kΩ, 0603, 1%, 1/16W Any 11 R6 1 Resistor, Film 324Ω, 0603, 1%, 1/16W Any 12 R3, R4 1 Resistor, Film 95.3kΩ, 0603, 1%, 1/16W Any 13 R9 1 Resistor, Film 5.11kΩ, 0603, 1%, 1/16W Any 14 R8 1 Resistor, Film 806Ω, 0603, 1%, 1/16W Any 15 U1 1 ISL6440IAZ PART TYPE DESCRIPTION 300kHz, Dual PWM Controller VENDOR Intersil ISL6440EVAL1Z Layout TOP SILK 3 LAYER 1 AN1219.1 January 8, 2007 Application Note 1219 ISL6440EVAL1Z Layout (Continued) LAYER 2 LAYER 3 LAYER 4 BOTTOM SILK 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 4 AN1219.1 January 8, 2007