ISL8106EVAL1Z User Guide ® Application Note Introduction February 16, 2009 AN1452.0 The value of RSEN can then be calculated by Equation 2: The ISL8106EVAL1Z evaluation board demonstrates the performances of the ISL8106, synchronous buck PWM controller with Intersil’s Robust Ripple Regulator (R3) technology. The ISL8106 features a 1.5ms digital soft-start and can be started into a pre-biased output voltage. The PWM switching frequency can be programmed from 200kHz to 600kHz. The ISL8106 can be configured to operate in Forced-Continuous-Conduction-Mode (FCCM) or in Diode-Emulation-Mode (DEM), which improves light-load efficiency. An audio filter prevents the PWM switching frequency from entering the audible spectrum due to extremely light load while in DEM. Refer to the ISL8106 data sheet for a more detailed operation by clicking on the following link. I P-P I FL + ---------- • OC SP • r DS ( ON ) 2 R SEN = -----------------------------------------------------------------------------I OC (EQ. 2) Where: - RSEN (Ω) is the resistor used to program the overcurrent setpoint - IOC is the ISEN threshold current value sourced from the ISEN pin that will activate the OCP circuit - IFL is the maximum continuous DC load current - IP-P is the inductor peak-to-peak ripple current - OCSP is the desired overcurrent setpoint expressed as a multiplier relative to IFL Power and Load Connections INPUT VOLTAGE ISL8106EVAL1Z Reference Design The PVIN post (J1) is connected to the drain of the upper MOSFET and the VIN pin of the IC. The post (J2) is connected to PGND. The ISL8106EVAL1Z design criteria is listed in Table 1. OUTPUT VOLTAGE LOADING AND MONITORING http://www.intersil.com/data/fn/fn9283.pdf Connect the positive and negative leads of an electronic load to J3 and J4 respectively. Terminal TP4 (PGND) and TP5 (VOUT) can be used to measure the output voltage. TABLE 1. ISL8106EVAL1Z DESIGN CRITERIA PARAMETERS VALUE Input Voltage 7V to 25V Output Voltage 1.8V Rated Output Current 25A Switching Frequency 300kHz Switch Descriptions TABLE 2. ISL8106EVAL1Z SWITCH DESCRIPTIONS TOGGLE SWITCHES FUNCTION SW1 OFF: Shorts the EN pin to GND (Disable the controller) ON: Enable the controller, EN pin is pulled to VIN and clamped by D1. SW2 DEM: FCCM pin is pulled to GND to enable diode-emulation mode FCCM: FCCM pin is pulled to VCC to inhibits diode-emulation mode Setting Switching Frequency The switching frequency of ISL8106EVAL1Z can be adjusted through the resistor, R5, that is connected from the FSET pin to the GND pin. Programming the approximate PWM switching frequency can be estimated from Equation 1: 1 R FSET = -------------------------------------------------------– 12 60 • F OSC • [ 1 ×10 ] (EQ. 1) Test-point Descriptions Setting Overcurrent Protection Threshold TABLE 3. ISL8106EVAL1Z TEST POINT DESCRIPTIONS An overcurrent protection fault will occur when the ISEN pin has measured more than the OCP threshold current IOC (26µA, typ.), on consecutive PWM pulses, for a period exceeding 20µs. It does not matter how many PWM pulses are measured during the 20µs period. If a measurement falls below IOC before 20µs has elapsed, then the timer is reset to zero. A short circuit protection fault will occur when the ISEN pin has measured more than the short-circuit threshold current ISC, in less than 10µs, on consecutive PWM pulses. 1 TEST POINTS SIGNALS TP1 VCC TP2 PGND TP3 PGOOD TP4 PGND TP5 VOUT TP6 PVIN TP6 LX 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. 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1452 Typical Performance Curves EN 100 90 VOUT EFFICIENCY (%) 80 DEM 70 LX 60 50 FCCM 40 30 PGOOD 20 10 0 0.1 1 10 OUTPUT CURRENT (A) 100 FIGURE 1. EFFICIENCY (VIN = 12V, VOUT = 1.8V, Fsw = 300kHz) FIGURE 2. SOFT-START: 25A LOAD, FCCM = HIGH VOUT EN VOUT LX LX PGOOD FIGURE 3. PRE-BIASED START-UP (1V PRE-BIASED) VOUT FIGURE 4. STEADY STATE: 25A LOAD VOUT LX LX FIGURE 5. STEADY STATE: NO LOAD (FCCM) 2 FIGURE 6. STEADY STATE: NO LOAD (DEM) AN1452.0 February 16, 2009 Application Note 1452 Typical Performance Curves (Continued) VOUT VOUT LX LX FIGURE 7. STEADY STATE: 1A LOAD (FCCM) VOUT FIGURE 8. STEADY STATE: 1A LOAD (DEM) VOUT IL IL LX LX FIGURE 9. LOAD TRANSIENT: 25A TO 0A (CCM) FIGURE 10. LOAD TRANSIENT: 0A TO 25A (CCM) VOUT VOUT IL IL LX LX FIGURE 11. LOAD TRANSIENT: 25A TO 0A (DCM-CCM) 3 FIGURE 12. LOAD TRANSIENT: 0A TO 25A (CCM-DCM) AN1452.0 February 16, 2009 ISL8106EVAL1Z Schematic VCC J1 TP6 R11 4.7k R16 4.7 RED R3 0 BOOT TP7 TP5 VOUT 2 2 2 1 C22 0.1uF 1 C30 330uF C20 0.1uF 1 C28 330uF R21 DNP 1 TP4 1 2 2 2 2 C26 DNP J3 OUT 1 C21 0.1uF C19 0.1uF C29 330uF 2 C24 DNP C27 330uF 1 1 C25 DNP 2 C23 DNP Q4 C8 1000pF 2 1 0.68uH 2 Q2 VO 8 FSET FB 6 R18 2.2 2 BSOC 9 BSOC BG R12 0 R9 1.69k 1 PGND J4 GND 1 VO 1 1 FSET 7 EP COMP 5 1 C7 1nF D1 4.7V Zener 17 COMP EN 2 R8 10.7K FB VIN 11BGATE 10 PGND 1 2 1 1 1 LX FCCM EN 4 2 Q3 12 PVCC BGATE ISL8106 FCCM 3 SW1 Q1 L1 PVCC U1 2 1nF C4 R17 5.9k C10 0.22uF 1 VCC TGATE VCC 2 PGOOD 1 VIN TG 2 R5 54.9k R15 0 R22 DNP 2 C5 10nF R19 C2 2 VREG 1 R1 68pF C1 10nF 0 2K R2 1 1 2 15.8k 2 C9 10nF R4 1K R20 P1 0 1 GND Intersil Corporation 1001 Murphy Ranch Rd. Milpitas, CA, 95035 Size Title AN1452.0 February 16, 2009 Rev B ISL8106 Application Schematic Date: Thursday, November 13, 2008 Sheet 1 of 1 Application Note 1452 VIN 1 1 2 14 BOOT R14 SW2 10 2 2 0 TGATE 13 2 16 2 4.7uF PGOOD R13 C12 0.1uF C6 15 LX 1 1 2 1 C11 4.7uF TP1 R6 1K J2 TP2 2 2 J5 C17 DNP 2 1 R7 4.7 2 1 3 4 1 C15 560uF C14 3.3uF VCC Q5 BSS123LT1 C16 560uF 1 3.3uF TP3 1 C13 2 D2 GREEN 5365F 1 PVIN 1 R10 4.7k Application Note 1452 I ISL8106EVAL1Z Bill of Materials ID REFERENCE QTY PART NUMBER PART TYPE DESCRIPTION PACKAGE VENDOR 1 U1 1 ISL8106IRZ IC, Linear IC, Single PWM Controller 16Ld QFN Intersil 2 Q1, Q3 2 BSC059N04LS G MOSFET, Single N-Channel, 40V TDSON-8 Infineon 3 Q2, Q4 2 BSC018N04LS G MOSFET, Single N-Channel, 40V TDSON-8 Infineon 4 Q5 1 BSS123LT1G MOSFET N-Channel SOT-23 On Semi 5 D1 1 BST52C4V7-7-F Zener Diode 4.7V, 500mW Zener Diode SOD-123 Diode Inc. 6 D2 1 SSL-LXA3025IGC-TR LED RED/GREEN SMD LED SMD 3mmx2.5mm Lumex 7 L1 1 IHLP-5050FD-01-R68M01 Inductor 0.68µH Power Inductor SMD Vishay CAPACITORS 8 C15, C16 2 EKZE350ELL561MJ25S Capacitor, Alum. Elec. 560µF, 20%, 35V RAD 10x25 United Chemi-con 9 C13, C14 2 C3225X7R1H335M Capacitor, Ceramic, X7R 3.3µF, 10%, 50V SM_1210 TDK/Generic 10 C4, C7, C8 3 Capacitor, Ceramic, X7R 1000pF, 10%, 50V SM_0603 Generic 11 C1, C5, C9 3 Capacitor, Ceramic, X7R 0.01µF, 10%, 50V SM_0603 Generic 12 C12, C19, C20, C21, C22 5 Capacitor, Ceramic, X7R 0.1µF, 10%, 50V SM_0603 Generic 13 C10 1 Capacitor, Ceramic, X7R 0.22µF, 10%, 25V SM_0603 Generic 14 C6, C11 2 Capacitor, Ceramic, X5R 4.7µF, 10%, 6.3V SM_0603 Generic 15 C27, C28, C29, C30 4 Capacitor, POSCAP 330µF, 20%, 6.3V, 0.009Ω Case D3L SANYO 16 C2 1 Capacitor, Ceramic, X5R 68pF, 10%, 50V SM_0603 Generic 17 C17, C23, C24, C25, C26 0 6TPF330M9L Do Not Populate RESISTORS 18 R1 1 Resistor, Film 2kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 19 R2 1 Resistor, Film 15.8kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 20 R4,R6 1 Resistor, Film 1kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 21 R21, R22 0 22 R5 1 Resistor, Film 54.9kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 23 R7, R16 1 Resistor, Film 4.7Ω, 1%, 1/16W SM_0603 Panasonic/Generic 24 R8 1 Resistor, Film 10.7kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 25 R3, R12, R13, R15, R19, R20 6 Resistor, Film 0Ω, 1%, 1/16W SM_0603 Panasonic/Generic 26 R9 1 Resistor, Film 1.69kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 27 R10, R11 2 Resistor, Film 4.7kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 28 R14 1 Resistor, Film 10Ω, 1%, 1/16W SM_0603 Panasonic/Generic 29 R17 1 Resistor, Film 5.9kΩ, 1%, 1/16W SM_0603 Panasonic/Generic 30 R18 1 Resistor, Film 2.2Ω, 1%, 1/16W SM_0603 Panasonic/Generic Do Not Populate 5 SM_0603 AN1452.0 February 16, 2009 Application Note 1452 ISL8106EVAL1Z Bill of Materials (Continued) ID REFERENCE QTY PART NUMBER PART TYPE DESCRIPTION PACKAGE VENDOR OTHERS 31 SW1, SW2 2 GT11MSCKE 32 P1 1 Do Not Populate 33 TP1-TP6 6 5002 34 TP7 0 Do Not Populate 35 J1, J2 2 Blinding Post 36 J5 1 1X2 Header 37 J3, J4 2 TEST POINT vertical, white KPA8CTP Toggle Switch SMD C&K PC test jack PTH Keystone Cable Terminal BERG/FCI ISL8106EVAL1Z Printed Circuit Board Layers FIGURE 13. ISL8106EVAL1Z - TOP LAYER (SILKSCREEN) FIGURE 14. ISL8106EVAL1Z - TOP LAYER (COMPONENT SIDE) 6 AN1452.0 February 16, 2009 Application Note 1452 ISL8106EVAL1Z Printed Circuit Board Layers (Continued) FIGURE 15. ISL8106EVAL1Z - LAYER 2 FIGURE 16. ISL8106EVAL1Z - LAYER 3 7 AN1452.0 February 16, 2009 Application Note 1452 ISL8106EVAL1Z Printed Circuit Board Layers (Continued) FIGURE 17. ISL8106EVAL1Z - BOTTOM LAYER (SOLDER SIDE) FIGURE 18. ISL8106EVAL1Z - BOTTOM LAYER (SILKSCREEN) 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 8 AN1452.0 February 16, 2009