Application Note 1539 ISL8112EVAL1Z Evaluation Board Setup Procedure The ISL8112 is a dual-output Synchronous Buck controller with 2A integrated driver. It features high light load efficiency which is especially preferred in systems concerned with high efficiency in wide load range, like the battery powered system. ISL8112 includes two constant on-time PWM controllers. Both outputs can operate in an output fixed mode or an adjustable mode. In fixed mode, one output can be 5V or 3.3V and the other 1.5V or 1.05V. In adjustable mode, one output can range from 0.7V to 5.5V, and the other from 0V to 2.5V (sensing output voltage directly) or up to 5V (using resistor divider voltage for voltage sensing). This device also features a linear regulator providing 3.3V/5V, or adjustable from 0.7V to 4.5V via LDOREF. The linear regulator provides up to 100mA output current with automatic linear-regulator bootstrapping to the BYP input. When in switchover, the LDO output can source up to 200mA. ISL8112 includes on-board power-up sequencing, the power-good (PGOOD_) outputs, digital soft-start, and internal soft-stop output discharge that prevents negative voltages on shutdown. Recommended Equipment ISL8112 is implemented with constant on-time PWM control scheme which need no sense resistors and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic pulse-skipping mode maintains the switching frequency above 25kHz, eliminating undesired audible noises in low frequency operation at light load. Other features include pulse skipping which maximizes efficiency in light-load applications, and fixed-frequency PWM mode which reduces RF interference in sensitive applications. Evaluating the Other Output Voltage FIGURE 1. TOP VIEW February 22, 2010 AN1539.0 1 • 0V to 25V power supply with at least 20A source current capability, battery, or notebook AC adapter. • Two electronic loads capable of sinking current up to 15A. • Dummy loads for the LDO’s. • Digital multimeters (DMMs). • 100MHz quad-trace oscilloscope. • Signal generator. Quick Start 1. Ensure that the circuit is correctly connected to the supply and loads prior to applying any power. 2. Verify that position 2’s are ON for SW1, SW2, SW3, SW4, and SW5. Make sure that no other position of each switch is ON at the same time. 3. Turn on the input power supply. 4. Verify the output voltages are correct. 5. Verify the LDOs output voltages are correct. The ISL8112EVAL1Z board outputs are preset to 5V/7A, 3.3V/7A and 5V/200mA on LDO. The VOUT1 can also be adjusted between 0.7V to 5.5V by changing the value of R9 and R10 or R11 and R12 given by Equation 1: R 11 R 12 = --------------------------------------------( V OUT ⁄ V FB ) – 1 (EQ. 1) where VFB = 0.7V • The VOUT2 can track OUT2REF at 1:1 ratio with input voltage range from 0.7V to 2.5V. Likewise, the LDO output can also track LDOREF at 1:2 with voltage range from 0.35V to 2.25V. FIGURE 2. BOTTOM VIEW 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. 2010. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1539 ISL8112EVAL1Z Board Schematic P18 VOUT1 VCC R11 OPEN C3 1000PF R12 0 R16 200K C1 1UF 6 5 PH1 4 C16 10UF 2 D9 IRF7811AV Q4 1 7 6 4 5 D5 C17 1000PF 1 MODE P15 1 PGOOD1 P24 2 D1 1 C23 0.1UF 1 2 P23 4 5V 1 P17 VOUT2 61 5 VOUT1 4 3 1 PVCC R34 OPEN 1 EN_LDO P27 1 1 1 2 3 1 P8 D7 BAT54S C5 0.1UF 2 BYP P28 R6 25.5 D8 BAT54S NC PGOOD2 C30 C32 330UF 330UF C12 0.1UF SW4 1 2 3 P16 EN1 1 C28 DNP R26 DNP P7 VOUT1 8 3 C2 0.1UF SW3 1 2 3 1 2 3 P12 EN2 2 L1 4.7UH VCC 6 5 4 6 5 4 6 5 4 1 2 3 0 P11 1 2 P21 1 6 5 4 R4 200K R17 2 1 3 3 4 1 R23 OPEN R5 200K 4 P6 7 C6 0.1UF R14 OPEN SW5 3.3V 1 2 P22 1 VIN 8 2 FS 3 1 Q3 2 P30 SW2 C24 0.1UF 2 3 R8 1 VREF1 SW1 1 1 2 1 D2 IRF7807V 1 R2 OPEN FB1 R20 OPEN C8 1UF 1 VOUT1 C31 330UF 3 LDO R24 0 R19 OPEN R3 0 VCCIN PVCC 1 C29 330UF 1 R18 OPEN C27 DNP R25 DNP D4 D6 1 R27 OPEN P29 5 2 VIN 6 4 2 R7 OPEN 1 C15 1000PF 7 3 NC PVCC P5 1 1 P26 EP 1 VOUT2 2 1 P2 R31 0 C19 OPEN ISL8112 Q2 2 R1 1 8 1 2 P20 P4 3 C7 1UF 1 2 P3 1 4 3 LDO 5 1 1 4 PH2 P19 4 C14 10UF IRF7811AV BOOT2 LG2 PGND GND NC PVCC LG1 BOOT1 U1 0.1UF D3 BYP VSEN1 FB1 ILIM1 PGOOD1 EN1 UG1 PH1 VIN 1 P1 VREF1 FS VCC EN_LDO VREF2 VIN LDO LDOREF FS VCC EN_LDO P14 VREF2 BYP R30 0 6 1 C10 PVCC 3 C9 0.01UF 7 3 C26 0.1UF L2 OUT2REF ILIM2 VSEN2 MODE PGOOD2 EN2 UG2 PH2 C4 0.1UF VCC LDO C11 4.7UF 1 VREF1 R13 OPEN VIN 8 Q1 2 VCC 3 C18 OPEN PGOOD1 EN1 R10 0 1 R15 200K VOUT2 MODE PGOOD2 EN2 R9 OPEN VREF2 IRF7807V 2 R21 0 3 1 R22 OPEN R33 200K C13 R32 39.2K 0.1UF FIGURE 3. ISL8112EVAL1Z REV A BOARD SCHEMATIC TABLE 1. SW1 EN2 VOUT2 OUTPUT CONTROL 1 Connect to GND. VOUT2 output shutdown. 2 Connect to VCC. VOUT2 output active. 3 Connect to VREF1. VOUT2 sequence to VOUT1 output. NOTE: Only toggle one position at a time. TABLE 2. SW2 MODE OPERATING MODE 1 Connect to GND. Normal operation mode, allow automatic PWM/PFM switchover for pulse-skipping at light load. 2 Connect to VCC. Low noise, fixed-frequency PWM mode. 3 Connect to VREF1. Ultrasonic pulse-skipping mode (20kHz min.) NOTE: Only toggle one position at a time. 2 AN1539.0 February 22, 2010 Application Note 1539 TABLE 3. SW3 EN_LDO LDO CONTROL 1 Connect to GND. LDO output shutdown. 2 Connect to VCC. LDO output active. 3 N/C No Connect. NOTE: Only toggle one position at a time. TABLE 4. SW4 BYP OPERATING MODE 1 Connect to GND. Set BYP to 0V. No LDO switchover. 2 Connect to VOUT1. SET BYP to VOUT1. 3 Connect to VOUT2. SET BYP to VOUT2. NOTE: Only toggle one position at a time. TABLE 5. SW5 EN1 VOUT1 OUTPUT CONTROL 1 Connect to GND. VOUT1 output shutdown. 2 Connect to VCC. VOUT1 output active. 3 Connect to VREF1. VOUT1 sequence to VOUT2 output. NOTE: Only toggle one position at a time. Components List REF DES C1, C7, C8 C11 C14, C16 PART NUMBER QTY MANUFACTURER DESCRIPTION 08053D105KAT2A 3 AVX 1µF, 25V, X7R, 0805 H1065-00475-10V10 1 GENERIC 4.7µF, 10V X5R 1206 TMK432BJ106KM 2 TAIYO-YUDEN 10µF, 25V X5R 1210 GENERIC 0.1µF, 50V, X7R, 0805 C2, C4, C5, C6, C10, H1046-00104-50V10 C12, C13, C23, C24, C26 10 C27, C28 OPEN 0 - - C29, C30 6TPD330M 2 POSCAP SANYO 330µF, 6.3V, POS CAP 9mΩ, D size - - C3, C9, C15, C17, C18, C19 OPEN C31, C32 OPEN 0 POSCAP - D1, D4-D6 OPEN 0 DIODES-INC - D2, D3 OPEN 0 ON-SEMI - D7, D8 OPEN 0 DIODES - D9 OPEN 0 ON-SEMI 0.3A, 30V, Schottky SOT23 DR125-4R7-R 2 COOPER/COILTRONICS 4.7µH, 10.5mΩ, 12.5x12.5mm Shielded 1514-2 6 KEYSTONE Test Point Turret 0.150 Pad 0.100 Thole 131-4353-00 5 TEKTRONIX Scope Probe Test Point PCB Mount KEYSTONE Miniature Red Test Point 0.100 Pad 0.040 Thole KEYSTONE Miniature Black Test Point 0.100 Pad 0.040 Thole L1, L2 P1, P2, P5-P8 P19-P23 P3, P11, P12, P14-P18, P24, P26-P29 5000 P4, P30 5001 3 0 13 2 AN1539.0 February 22, 2010 Application Note 1539 Components List REF DES (Continued) PART NUMBER QTY MANUFACTURER DESCRIPTION Q1 IRF7821 1 IR 30V 13.6A HEXFET Power MOSFET Q2 IRF7832 1 IR 30V 20A HEXFET Power MOSFET Q3 IRF7807V 1 IR 30V 8.3A N-Channel Power MOSFET Q4 IRF7811AV 1 IR 30V 10.8A N-Channel Power MOSFET R1, R8 H2512-01R00-1/10W 2 GENERIC 1Ω, 1%, 0805 R15 H2512-01503-1/10W1 1 GENERIC 150kΩ, 1%, 0805 - - - - GENERIC 0Ω, 1%, 0805 R2, R7, R9, R11, R13, R14, R18, R19, R20, R22, R23, R27, R34 OPEN R25, R26 OPEN 0 0 R3, R10, R12, R17, R21, R24, R30, R31 H2512-00R00-1/10W R32 H2512-03922-1/10W1 1 GENERIC 39.2kΩ, 1%, 0805 R4, R5, R16, R33 H2512-02003-1/10W1 4 GENERIC 200kΩ, 1%, 0805 R6 H2512-025R5-1/10W1 1 GENERIC 25.5Ω, 1%, 0805 78B03S 5 GRAYHILL Dip Switch SPST (Raised Slide) ISL8112IRZ 1 INTERSIL High-Efficiency, Quad Output Controller SW1-SW5 U1 8 Layout FIGURE 4. TOP COMPONENTS 4 FIGURE 5. TOP ETCH AN1539.0 February 22, 2010 Application Note 1539 Layout (Continued) FIGURE 6. 2nd LAYER FIGURE 7. 3rd LAYER FIGURE 8. BOTTOM COMPONENTS (MIRRORED) FIGURE 9. BOTTOM ETCH 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 5 AN1539.0 February 22, 2010