ISL8107EVAL2Z ® Application Note June 9, 2009 AN1459.0 Introduction Circuit Setup The ISL8107 is a single-phase PWM controller that operates from 9V to 75V bias supply voltage. The PWM controller drives an external high-side N-Channel MOSFET in a non-synchronous buck converter topology. The ISL8107 features input voltage feed-forward compensation and overcurrent protection, etc. For a more detailed description of the ISL8107 functionality, refer to the ISL8107 Data Sheet http://www.intersil.com/data/fn/fn6605.pdf. The input supply of the power stage can be connected to the terminals P5 (VIN) and P6 (PGND). For single supply application, the ISL8107’s bias supply can be tied to VIN through J1 with shunt between pins 2 and 3. When using separate supplies, provide the ISL8107 bias voltage through P1 (VBIAS) with J1’s shunt between pins 1 and 2. The load can be connected to terminal P7 (VOUT) and P8 (PGND). TP3 and TP4 can be used for DMM to measure the output voltage. Enabling and disabling the controller can be done through the toggle switch, SW1. The ISL8107EVAL2Z Reference Design The ISL8107EVAL2Z evaluation board is designed to meet the output voltage and current specifications shown in Table 1. Schematic, bill of materials, and layout plots are included. TABLE 1. ISL8107EVAL2Z DESIGN PARAMETERS PARAMETER Input Voltage (VIN) MIN TYP MAX 18V 48V 75V Output Voltage (VOUT) 12V Output Voltage Ripple 30mV Continuous Load Current 5A Switching Frequency 200kHz Quick Start Evaluation Figure 1 shows a photograph of the ISL8107EVAL2Z board. ISL8107EVAL2Z Performance Start-Up Figure 2 shows the start-up waveforms of the ISL8107EVAL2Z. Upon the VCC and VFF exceeding their rising POR thresholds, the ISL8107 provides initially 2µA to charge the soft-start capacitor, CSS, connected to the ENSS pin. If the voltage at this pin is allowed to rise (the toggle switch, SW1, at ON position), the voltage on ENSS pin will ramp-up with at a slope determined by the 2µA current and the value of the soft-start capacitor. When the voltage at ENSS reaches 0.77V, the oscillator circuit is active, and generates sawtooth waveform. At the same time, the soft-start current is increased to 33µA; the ENSS voltage then ramps up at a faster rate. The UGATE starts switching when the ENSS voltage reaches 1.4V (Typ). PGOOD VOUT ENSS PHASE FIGURE 1. ISL8107EVAL2Z 1 FIGURE 2. START-UP WAVEFORMS 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. 2008. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1459 Output Voltage Ripple Figure 3 shows the ripple voltage on the output of the regulator at 5A load current. VOUT PHASE VOUT FIGURE 6. OUTPUT TRANSIENT FIGURE 3. OUTPUT VOLTAGE RIPPLE @ IOUT = 5A Figure 7 shows the response of the output when subjected to transient loading from 0.1A to 5A at 1A/µs (transition between continuous conduction mode and discontinuous conduction mode). Transient Responses Figures 4, 5, and 6 show the response of the output when subjected to transient loading from 1A to 5A at 1A/µs (within continuous conduction mode). VOUT VOUT FIGURE 7. OUTPUT TRANSIENT Efficiency and Line Regulation FIGURE 4. OUTPUT TRANSIENT The efficiency and the line regulation of the evaluation board with various input voltages are shown in Figures 8 and 9, respectively. 100 VOUT EFFIECIENCY (%) 95 PHASE 90 VIN = 24V 85 VIN = 36V VIN = 48V 80 VIN = 60V 75 70 FIGURE 5. OUTPUT TRANSIENT 2 VIN = 18V 0 1 2 3 4 LOAD CURRENT (A) 5 6 FIGURE 8. CONVERTER EFFICIENCY (VOUT = 12V) AN1459.0 June 9, 2009 Application Note 1459 12.100 OUTPUT VOLTAGE (V) 12.090 VIN = 24V 12.080 VIN = 18V 12.070 12.060 12.050 12.040 VIN = 60V VIN = 48V VIN = 36V 12.030 12.020 12.010 12.000 0 1 2 3 4 LOAD CURRENT (A) 5 6 FIGURE 9. LINE REGULATION FOR VOUT = 12V 3 AN1459.0 June 9, 2009 ISL8107EVAL2Z Schematic J1 P1 1 3 2 1 VBias R19 DNP P2 R8 0 P5 VIN 1 1 1 P6 2 2 C17 100uF 100V 1 1 2 C15 1uF 1 4 C8 100pF 1 C7 1uF SYNC 2 C14 1uF C9 1uF P4 1 C16 100uF 100V 2 2 R9 0 1 Vin GND GND 1 2 GND R6 3.16k 1 R17 2 2 D3 MMBD1204/SOT VFF OCSET VBIAS SYNC 1k 1 2 1 1 1 1 2 1 R20 1k 2 1 C26 1uF 1 2 1 C24 1uF C22 150uF C20 DNP Vout C25 1uF C23 1uF 1 PGND ENSS DNP 1 I aefgaeg 2 C21 150uF 2 2 P7 L1 22uH VOUT 2 D2 D1 V10P10 C12 1uF C13 0.01uF 2 1 C19 DNP ENSS 12 C11 PGOOD COMP TP3 TP1 R7 10 2 COMP Q2 DNP 2 8 ISL8107 C29 DNP 1 13 PHASE FB 2 PHASE 7 C18 DNP Q1 HAT2175H 1 14 TGATE U1 1 TGATE C10 0.1uF 1 15 BOOT C30 DNP 2 BOOT FB C28 DNP 2 1 SGND 17 1 2 VFF 6 TP4 2 R12 DNP P8 1 1 2 SGND DNP C6 DNP OCSET 16 PVCC 2 C2 82pF 3 PVCC EP 1 RTCT PGND 11 2 5 PGOOD 10 1 R2 20k RT/CT VBG C1 8.2nF VBIAS 4 SYNC 2 C5 1000pF VBG 9 1 R16 0 1 GND TP2 R11 PVCC D4 2 C3 6.8nF R4 1.24k 1 1 SW1 1 Q3 BSS123LT1 R10 1 PGOOD 0 C27 1000pF 1 GND PGND 0 PVCC 3 R15 0 C4 0.22uF 2 2 R1 11.3k P3 R13 R18 10K 2 1 R3 442 2 Vreg Vreg 10K Application Note 1459 R14 0 R5 40.2k AN1459.0 June 9, 2009 Application Note 1459 Bill of Materials REFERENCE QTY PART NUMBER DESCRIPTION PACKAGE VENDOR U1 1 ISL8107IRZ Single PWM Controller 16 Ld QFN Q1 1 HAT2175 100V N-Channel MOSFET LFPAK Renesas Q3 1 BSS123LT1G N-Channel MOSFET, 0.17A SOT-23 On Semi. D1 1 V10P10 100V Schottky Diode Rectifier TO-277A Vishay D3 1 MMBD1204 100V Ultrafast Diode SOT-23 Fairchild DIALIGHT Intersil D4 1 597-3311 LED Green SMD1206 L1 1 HC9-220-R 22µH Power Inductor SMD 12.9x13.2 Coiltronics Q2, D2 0 DNP CAPACITORS C1 1 8200pF, 50V, X7R, 10%, Ceramic Capacitor 0603 Various C2 1 82pF, 50V, COG, 10%, Ceramic Capacitor 0603 Various C3 1 6800pF, 50V, X7R, 10%, Ceramic Capacitor 0603 Various C4 1 0.22µF, 16V, X7R, 10%, Ceramic Capacitor 0603 Various C5 1 0805 Murata C7, C9, C14, C15 4 1µF, 100V, X7R, 10%, Ceramic Capacitor 1210 Various C8 1 100pF, 50V, COG, 10%, Ceramic Capacitor 0603 Various C10 1 0.1µF, 50V, X7R, 10%, Ceramic Capacitor 0603 Various C12, C23, C24, C25, C26 5 1µF, 25V, X5R, 10%, Ceramic Capacitor 0805 Various C13 1 0.01µF, 50V, X7R, 10%, Ceramic Capacitor 0603 Various C16, C17 2 100ME100PX 100µF, 100V, Aluminum Electrolytic Capacitor RAD 12.5x20 Sanyo C21, C22 2 20SEQP150M 150µF, 20V, OSCON Capacitor RAD 10x13 Sanyo 1000pF, 50V, X7R, 10%, Ceramic Capacitor 0603 Various C27 1 C6, C11, C18, C19, C20, C28, C29, C30 0 GRM2195C2A102JA01D 1000pF, 100V, COG, 5%, Ceramic Capacitor DNP RESISTORS R1 1 Resistor, 11.3kΩ, 1%, 1/10W 0603 Various R2 1 Resistor, 20kΩ, 1%, 1/10W 0603 Various R3 1 Resistor, 442Ω, 1%, 1/10W 0603 Various R4 1 Resistor, 1.24kΩ, 1%, 1/10W 0603 Various R5 1 Resistor, 40.2kΩ, 1%, 1/10W 0603 Various R6 1 Resistor, 3.16kΩ, 1%, 1/10W 0603 Various R7 1 Resistor, 10Ω, 1%, 1/10W 0603 Various R8, R9, R10, R11, R14, R15, R16 7 0Ω Resistor, 1/10W 0603 Various R13, R18 2 Resistor, 10kΩ, 5%, 1/10W 0603 Various R17 1 Resistor, 1kΩ, 1%, 1/10W 0603 Various R20 1 Resistor, 1kΩ, 1%, 1W 2512 Various R12, R19 0 DNP OTHERS J1 1 68000-236-1X3 Connector Header BERG/FCI SW1 1 GT11MSCKE SMD Toggle Switch C&K P1 through P8 8 1514-2 Turret Post Keystone 5 AN1459.0 June 9, 2009 Application Note 1459 ISL8107EVAL2Z Layout FIGURE 10. TOP SILK SCREEN FIGURE 11. TOP ASSEMBLY 6 AN1459.0 June 9, 2009 Application Note 1459 ISL8107EVAL2Z Layout (Continued) FIGURE 12. TOP LAYER FIGURE 13. LAYER 2 7 AN1459.0 June 9, 2009 Application Note 1459 ISL8107EVAL2Z Layout (Continued) FIGURE 14. LAYER 3 FIGURE 15. BOTTOM LAYER 8 AN1459.0 June 9, 2009 Application Note 1459 ISL8107EVAL2Z Layout (Continued) FIGURE 16. BOTTOM SILK SCREEN 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 9 AN1459.0 June 9, 2009