ISL8502EVAL1Z: 2A Synchronous Buck Regulator with Integrated MOSFETs ® Application Note February 15, 2008 AN1277.1 The ISL8502 is a synchronous buck controller with internal MOSFETs packaged in a small 4mmx4mm QFN package. The ISL8502 can support a continuous load of 2A and has a very wide input voltage range. With the switching MOSFETs integrated into the IC, the complete regulator footprint can be very small and provide a much more efficient solution than a linear regulator. Features The ISL8502 is capable of standalone operation or it can be used in a master slave combination for multiple outputs that are derived from the same input rail. Multiple slave channels can be individually programmed such that the internal clocks are out-of-phase. This method minimizes the ripple on the input rail. • Wide Input Voltage Range, 5V ±10% or 5.5V to 14V The switching PWM controller drives two internal N-Channel MOSFETs in a synchronous-rectified buck converter topology. The synchronous buck converter uses voltage-mode control with fast transient response. The switching regulator provides a maximum static regulation tolerance of ±1% over line, load, and temperature ranges. The output is user-adjustable by means of external resistors down to 0.6V. The output is monitored for undervoltage events. The switching regulator also has over current protection. Thermal shutdown is integrated. The ISL8502 features a bidirectional Enable pin that allows the part to shut itself down and pull the enable pin low at the same time. • 2A Continuous Output Current • Integrated MOSFETs for Small Regulator Footprint • Adjustable Switching Frequency, 500kHz to 1.2MHz • Tight Output Voltage Regulation, ±1% Over-Temperature • Wide Output Voltage Range, from 0.6V • Simple Single-Loop Voltage-Mode PWM Control Design • Input Voltage Feed-Forward for Constant Modulator Gain • Fast PWM Converter Transient Response • Lossless rDS(ON) High Side and Low Side Overcurrent Protection • Undervoltage Detection • Integrated Thermal Shutdown Protection • Power-Good Indication • Adjustable Soft-Start • QFN Package - Compliant to JEDEC PUB95 MO-220 QFN (Quad Flat No Leads) package outline - Near Chip Scale Package footprint, which improves PCB efficiency and has a thinner profile • Pb-Free (RoHS Compliant) Pinout ISL8502 (24 LD QFN) TOP VIEW Applications VCC PVCC BOOT VIN VIN VIN • Point of Load Applications • Graphics Cards - GPU and Memory Supplies 24 23 22 21 20 19 • ASIC Power Supplies PGOOD 1 18 VIN • Embedded Processor and I/O Supplies SGND 2 17 PHASE • DSP Supplies EN 3 16 PHASE Ordering Information SYNCH 4 M/S 5 14 PHASE FS 6 13 PGND GND 29 7 8 9 10 11 12 COMP FB SS PGND PGND PGND 15 PHASE 1 PART NUMBER (Note) ISL8502IRZ* PART MARKING TEMP. RANGE (°C) PACKAGE (Pb-free) PKG. DWG. # 85 02IRZ -40 to +85 24 Ld 4x4 QFN L24.4x4D *Add “-T” suffix for tape and reel. Please refer to TB347 for details on reel specifications. NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate PLUS ANNEAL - e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. 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. 2007, 2008. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1277 What’s Inside Evaluating Other Output Voltages The Evaluation Board Kit contains the following materials: • The ISL8502 datasheet The ISL8502EVAL kit outputs are preset to 2.5V. For a quick evaluation of output voltages between 0.6V and VIN -1.7V, the following resistors need to be changed in the feedback network as shown in Equations 1 and 2: • This EVAL KIT document R 111 = ( R 108 ) ⁄ [( V OUT ⁄ V FB1 ),– 1] Recommended Equipment where R108 = 17.4kΩ; and VFB1 = 0.6V The following materials are recommended to perform testing: R 211 = ( R 208 ) ⁄ [( V OUT2 ⁄ V FB2 ),– 1] • 0V to 15V power supply with at least 5A source current capability, battery, notebook AC adapter where R208 = 17.4kΩ; and VFB2 = 0.6V • The ISL8502 EVAL REVD board • Two Electronic Loads capable of sinking current up to 5A • Digital Multimeters (DMMs) • 100MHz quad-trace Oscilloscope (EQ. 1) (EQ. 2) However, for reliable operation over the entire load and temperature range, it is highly recommended to follow the output filter and loop compensation network design guidelines as listed in the ISL8502 datasheet. • Signal generator (only if the SYNC function needs to be evaluated) http://www.intersil.com/data/fn/fn6389.pdf Quick Setup Guide The ISL8502EVAL can operate at switching frequencies from 500kHz to1.2MHz. R104 and R204 are used to program the switching frequency through Equation 3: 1. Ensure that the circuit is correctly connected to the supply and loads prior to applying any power. 2. Connect the bias supply to VIN. Plus terminal to J1(VIN) and negative return to J2(GND). 3. Verify that all positions are ON for S1, EN_all, EN_1, EN_2. Frequency R 104 and ( R 204 ) = 48000 ⁄ ( fosc [ kHz ] ) (EQ. 3) TABLE 1. SWITCH 1 SETTINGS SW1 SKIP 4. Turn on the power supply. 1 NC 5. Verify the outputs voltages are 2.5V for VOUT1 and VOUT2. 2 EN_ALL 3 EN1 Enable or disable VOUT1 4 EN2 Enable or disable VOUT2 2 OPERATING MODE No Connect Enable or disable VOUT1 and VOUT2 AN1277.1 February 15, 2008 ON ON ON ON ENABLE 8 7 6 5 GROUND CONNECTIONS FOR SCOPE PROBES IKN0403000 25 EP 1 470PF 24 PIN PACKAGE 18 17 16 15 14 13 17.4K C210 R210 R208 2 174 4.7UH R205 0 C206 2 OPEN 1 100UF TP203 10UF 2 C200B 1 10UF 2 C200A 1 1 TP212 1 J4 3 4 J8 1 2 J6 1 1 L200 2 C204 1 1 4 J9 22UF 1 2 2 C205 1 J5 18 17 16 15 14 13 3 0.1UF 2 C202 1 TP200 100UF 1 2 C104 1 22UF 2 C105 1 1 J3 24 23 22 21 20 19 0.1UF 2 C100B 1 10UF 10UF 2 C100A 1 TP103 3 0.1UF 3 2 C103 1 10K R102 10K 0 R101 R100 24 23 22 21 20 19 2 TP104 36 R3 2 2 C102 1 3 4 J7 3 U200 MLFP DNP 1 2 3 4 5 6 JP2 R207 24 23 22 21 20 19 1 1 25 1 2 TP209 24 23 22 21 20 19 2 1 1 2 3 4 5 6 7 8 9 10 11 12 2 7 8 9 10 11 12 1 R108 2 C207 1 0.01UF D200 47PF 1 0.1UF 174 2 C203 1 470PF 0 C106 2 C208 1 2 L100 10K 17.4K R110 4.7UH R202 C110 1 R209 2 C209 1 20K 1000PF 1 18 17 16 15 14 13 DNP R107 18 17 16 15 14 13 10K TP109 24 PIN PACKAGE R204 1 1 U100 MLFP DNP R201 R200 1 0.01UF 2 C107 1 25 EP 7 8 9 10 11 12 1 2 3 4 5 6 1 2 95.3K TP205 7 8 9 10 11 12 25 47PF 2 C108 1 TP105 1 2 3 4 5 6 5.49K 95.3K R109 2 C109 1 20K 1000PF TP110 R104 DNP R103 1 2 2 1 Q4 R111 1 JP3 2 75 R6 1 1 1 R2 2 TP112 TP100 5.49K D1 31 JP1 4.99K R203 OFF D100 TP211 1 2 1 1 Q6 TP204 1 TP111 1 2N7002 TP210 S1 1 R211 1 2 3 4 Q1 5.49K 1 ON D2 31 Q3 1 TP3 2 1 36 2N7002 P6 1 2 3 4 1 1 P1 1 AND 2 REG 1 REG 2 R5 R4 Q2 1 3 Q5 5.49K 1 1 J1 1 J2 2 OPEN 1 2 2 VOUT2 4 J10 Application Note 1277 1 2 3 3 2 75 R1 ISL8502EVAL1Z Schematic 2 VIN VOUT1 R105 AN1277.1 February 15, 2008 Application Note 1277 TABLE 2. COMPONENT LIST REF DES QTY VALUE TOL. VOLTAGE PACKAGE PART NUMBER C100A, C100B, C200A, C200B 4 10µF 20% 25V SM1206 - AVX, Samsung, TDK, Murata Multilayer Capacitor C102, C202 2 0.1µF 10% 16V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C103, C203 2 1µF 20% 6.3V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C104, C204 2 100µF 20% 35V RADIAL - SANYO C105, C205 2 22µF 20% 10V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C106, C206 2 OPEN - - SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C107, C207 2 0.1µF 10% 16V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C108, C208 2 47pF 5% 50V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C109, C209 2 1000pF 10% 50V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor C110, C210 2 470pF 10% 50V SM0402 - AVX, Samsung, TDK, Murata Multilayer Capacitor D1, D2 2 - - - - LTST-C170CKT LITEON AlGaAs on GaAs Red LED D100, D200 2 - - - - IN4148WS DIODES Fast Switching Diode J1, J2 2 - - - - 111-0701-001 JOHNSON-COMP Binding Post White J3-J6, P1, P6 6 - - - - PAD_150 GENERIC 0.150Pad with 0.110 Plated Thru Hole JP1-JP3 3 - - - - JUMPER2_100 GENERIC Two Pin Jumper L100, L200 2 4.7µH - 19mΩ 6_3X8_3 Q1, Q2, Q4, Q5 4 - - 30V SOT23 MMBT2222LT1 MOTOROLA NPN Transistor Q3, Q6 2 - - 60V SOT23 2N7002 FAIRCHILD N-Channel EMF Effect Transistor R1, R6 2 75 5% 100V SM0402 - Generic Thick Film Chip Resistor R100, R105, R205 3 0 1% 100V SM0402 - Generic Thick Film Chip Resistor R101, R102, R201,R202 4 10k 1% 100V SM0402 - Generic Thick Film Chip Resistor R103, R107, R200, R207 4 DNP 1% 100V SM0402 - Generic Thick Film Chip Resistor R104, R204 2 95.3k 1% 100V SM0402 - Generic Thick Film Chip Resistor R108, R208 2 17.4k 1% 100V SM0402 - Generic Thick Film Chip Resistor R109, R209 2 20k 1% 100V SM0402 - Generic Thick Film Chip Resistor R110, R210 2 174 1% 100V SM0402 - Generic Thick Film Chip Resistor R2, R4, R111, R211 4 5.49k 1% 100V SM0402 - Generic Thick Film Chip Resistor R203 1 4.99k 1% 100V SM0402 - Generic Thick Film Chip Resistor 4 MANUFACTURER CDRH8D28-4R7 SUMIDA DESCRIPTION Radial Elect. MV_AX Series Cap SMT Power Inductor AN1277.1 February 15, 2008 Application Note 1277 TABLE 2. COMPONENT LIST (Continued) REF DES QTY VALUE TOL. VOLTAGE PACKAGE PART NUMBER R3, R5 2 36 5% 100V SM0402 - S1 1 - - - - IKN0403000 TP3, TP100, TP103-TP105, TP109-TP112, TP200, TP203-TP205, TP209-TP212 17 - - - - U100, U200 2 - - - QFN 5 MANUFACTURER DESCRIPTION Generic Thick Film Chip Resistor APEM IK Series High Rel SPST SMT DIP Switch PAD_75 Generic 0.075 Pad with 0.036 Plated Thru Hole ISL8502 Intersil Synchronous Buck Regulator AN1277.1 February 15, 2008 Application Note 1277 ISL8502EVAL1Z Board Layout FIGURE 1. TOP COMPONENTS FIGURE 2. TOP LAYER ETCH 6 AN1277.1 February 15, 2008 Application Note 1277 ISL8502EVAL1Z Board Layout (Continued) FIGURE 3. 2ND LAYER ETCH FIGURE 4. 3RD LAYER ETCH 7 AN1277.1 February 15, 2008 Application Note 1277 ISL8502EVAL1Z Board Layout (Continued) FIGURE 5. BOTTOM LAYER COMPONENTS (MIRRORED) FIGURE 6. BOTTOM LAYER ETCH (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 8 AN1277.1 February 15, 2008