Application Note 1630 Author: Tu Bu 6A Low Quiescent Current High Efficiency Synchronous Buck Regulator Description Quick Setup Guide The ISL8016CIR1EVAL1Z kit is intended for use by individuals with requirements for Point-of-Load applications sourcing from 2.7V to 5.8V. The ISL8016CIR1EVAL1Z simple smallest factor evaluation board is used for a quick and easy demonstration of the performance of the ISL8016 low quiescent high efficiency synchronous buck regulator. The ISL8016 is offered in a 3mmx4mm 20 Ld QFN package with 1mm maximum height. The complete converter occupies can be as small as 0.15in2 area. 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, the plus terminal to VIN, J1, and the negative return to PGND, J2. 3. Connect the output load to VOUT, the plus terminal to VOUT1, J3 and the negative return to PGND, J4. 4. Verify that the position is PWM for S1. 5. Verify the position is OPEN for S2 and S3. 6. Verify that the position is ON for S4 and S5. Key Features 7. Turn on the power supply. • High Efficiency Synchronous Buck Regulator with up to 97% Efficiency • 0.8% Reference Accuracy Over-Temperature/Load/Line • Fixed Output Voltage Option • ±10% Output Voltage Margining • Adjustable Current Limit • Current Sharing Capable • Start-up with Pre-Biased Output • Internal Soft-Start - 1ms or Adjustable • Soft-Stop Output Discharge During Disabled • Adjustable Frequency from 500kHz to 4MHz - Default at 1MHz • External Synchronization up to 4MHz - Master to Slave Phase Shifting Capability Recommended Equipment The following materials are recommended to perform testing: • 0V to 10V Power Supply with at least 10A source current capability or 5V battery • Electronic Loads capable of sinking current up to 7A • Digital Multimeters (DMMs) • 100MHz quad-trace oscilloscope • Signal generator 8. Verify the output voltage is 1.8V for VOUT1. Evaluating the Other Output Voltage The ISL8016CIR1EVAL1Z kit output is preset to 1.8V for VOUT1, however, output voltages can be adjusted from 0.6V to 5V. The output voltage programming resistor, R1, will depend on the desired output voltage of the regulator. The value for the feedback resistor is typically between 0Ω and 200kΩ, as shown in Equation 1. VFB R2 = R1 ⎛ ------------------------⎞ ⎝ VO – VFB⎠ (EQ. 1) If the output voltage desired is 0.6V, then R2 is left unpopulated and R1 is shorted. For faster response performance, add 10pF to 47pF in parallel to R1. Check bode plot to insure optimum performance. Frequency Control ISL8016 has an FS pin that controls the frequency of operation. Programmable frequency allows for optimization between efficiency and external component size. Default switching frequency is 1MHz when FS is tied to VIN (R6 = 0 and R5 is open). By connecting R5 to GND, the switching frequency could be changed from 500kHz (R5 = 390k) to 4MHz (R5 = 40k) according to Equation 2: 200 ⋅ 10 3 R T [ kΩ ] = ------------------------------ – 10 f OSC [ kHz ] (EQ. 2) When using R5 to adjust the operational frequency, this also sets external compensation mode. Please refer to the ISL8016 datasheet (FN7616) for more details. May 17, 2011 AN1630.1 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. Copyright Intersil Americas Inc. 2011. All Rights Reserved. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. Application Note 1630 Soft-start Control Swtiches Control Short CSS1 to SGND for internal soft-start (approximately 1ms). Populate CSS1 to adjust the soft-start time. This capacitor, along with an internal 1.6mA current source, sets the soft-start interval of the converter, tSS. The ISL8016 evaluation board contains S1 thru S5 for various controls of the ISL8016 circuitries. Table 1 details this function. CSS1 [ μF ] = 3.33 ⋅ t SS [ s ] (EQ. 3) CSS must be less than 33nF to insure proper soft-start reset after fault condition. Synchronization Control The ISL8016 can be synchronized from 700kHz to 4MHz by an external signal applied to the SYNCIN pin. The rising edge on the SYNCIN triggers the rising edge of the PHASE pulse. Make sure that the minimum on-time of the PHASE node is greater than 140ns. SYNCOUT is a 250µA current pulse signal output triggered by the rising edge of the clock or the SYNCIN signal (whichever is greater in frequency) to drive the other ISL8016 and avoid the system’s beat frequencies effects. To implement time shifting between the master circuit to the slave, it is recommended to add a capacitor, C13 as shown in the schematic. The time delay from SYNCOUT_Master to SYNCIN_Slave is calculated in pF using the following: C 6 [ pF ] = 0.357 ⋅ t [ ns ] (EQ. 4) Where, t is the desired time shift between the master and the slave circuits in ns. Care must be taken to include PCB parasitic capacitance of ~3pF to 10pF. The maximum should be limited to 1/Fs-100ns to insure that SYNCOUT has enough time to discharge before the next cycle starts. 2 TABLE 1. SWITCH SETTINGS S1 MODE FUNCTION 1 PWM Fixed PWM frequency at light load 3 PFM Force continuous mode S2 ISET PROGRAM OUTUT CURRENT 1 LOW SET OUTPUT LOAD TO 2A. - OPEN SET OUTPUT LOAD TO 6A. 3 HIGH SET OUTPUT LOAD TO 4A. S3 VSET SET OUTPUT MARGIN 1 LOW SET OUTPUT VOLTAGE -10%. - OPEN NO OUTPUT VOLTAGE MARGIN 3 HIGH SET OUTPUT VOLTAGE +10%. S4 ENABLE 1 OFF DISABLE VOUT1 3 PFM ENABLE VOUT1 S5 ENABLE 1 OFF DISABLE VOUT2 3 PFM ENABLE VOUT2 FUNCTION FUNCTION AN1630.1 ISL8016CIR1EVAL1Z Schematic 3 31 31 C13 C11 330PF C26 2 1 VFB SYNCOUT2 16 A 1 2 R21 20 19 18 17 200K R22 100K R29 100K EN2 VIN SGND SYNCIN R19 0 VIN R20 16 1 21 SYNCOUT 15 2 3 3 15 4 4 14 5 5 13 10 SS 12 SYNCIN2 J5 C17 CSS2 DNP OPEN A A C19 C20 VOUT2 1 2 4 C14 A 47PF A J6 FB2 FB2 PGND A COMP2 COMP2 DRAWN BY: SS2 C18 22UF 22UF OPEN OPEN PGND COMP SS COMP ISET FS VSET EN 11 A ISET 17 C27 47PF VOUT2 NOTE: PLEASE KEEP COMP PIN TRACES SHORT PLEASE KEEP FB1, FB2 PINS TRACES SHORT A PGND SLAVE ISL8016IRZ PG FS VFB 18 200K 9 VIN EN SYNCIN SYNCIN3 19 8 VSET SGND 20 7 PG2 R25 6 6 21 PGND 22UF 22UF OPEN OPEN PGND SYNCOUT C24 PGND LX ISL8016IRZ PG C23 A PGND U3 C22 LX LX 9 10 VIN C21 LX LX 8 VOUT2 2 EP VIN EP VIN 7 0.68UH LX 1 VIN 0 COMP2 47K L2 VIN L3 R3 A 1.0UH VIN A VIN 100K 22UF A 22UF R7 A R14 A A C12 R4 C6 OPEN SS2 200K VIN EN211 FS2 12 VSET13 ISET14 C25 22UF 0 R5 DNP 3 A J4 PGND COMP1 220PF OPEN R6 1 2 4 2 A 200K 47PF DATE: ENGINEER: RELEASED BY: DATE: TITLE: UPDATED BY: DATE: SS2 JUN XIAO 06/11/09 TESTER MASK# JUN XIAO DATE: ISL8016 EVALUATION BOARD SCHEMATIC HRDWR ID ISL8016 REV. A Application Note 1630 LX2 JC111_07XX A C5 CSS1 Q2 PG2 2 2N7002 100K FB1 17 VFB C4 R1 R2 18 SGND A A 0 19 PGND 4 VOUT1 3 2 2 1 1 2 C10 22UF 22UF OPEN OPEN R13 20 PGND SS DNP C9 C8 COMP PG1 PG2 Q1 A R9 D2 PGND 1 2K 20 A SYNCIN ISET 2N7002 SYNCIN1 SYNCOUT1 0 J3 C7 FB2 SYNCOUT FS PG1 9 VOUT1 L1 R24 ISL8016IRZ PG VOUT2 1.0UH MASTER VIN VSET OFF R26 100K D1 A 8 EN 100K PG1 10 VIN LX 3 R27 7 PGND EN1 2K R16 C2 22UF J2 R17 R11 C1 22UF JC111_07XX R28 100K VSET OFF DNP A ON/EX VIN A R18 3 ON/EX LX A VIN S3 1 S4 1 EP EN1 OFF EN2 A 3 2 S5 1 3 3 2 EN2 22UF OPEN A VIN LX PFM JC111_07XX J1 VIN S1 1 OPEN A R12 100K VIN PWM C3 SYNCIN1 2 R15 4 LX1 16 2 S2 1 OFF 3 4 R23 100K ON/EX 5 SYNCIN1 6 R8 100K 3 ON/EX VSET 1 2 EN1 11 FS1 12 VSET13 ISET14 SS1 15 ISET ISET VIN 21 R10 100K 2 VIN 3 VIN JC111_07XX VIN AN1630.1 Application Note 1630 TABLE 2. BILL OF MATERIALS PART NUMBER REFERENCE DESIGNATOR QTY UNITS DESCRIPTION MANUFACTURER PART # MANUFACTURER ISL8016CIR1EVAL1ZREVAPCB 1 ea SEE LABEL-RENAME BOARD PWB-PCB, ISL8016CIR1EVAL1Z, REVA, ROHS TBD ISL8016CIR1EVAL1ZREVAPCB H1045-00150-50V5-T 1 ea C4 CAP, SMD, 0603, 15pF, 50V, 5%, NPO, ROHS MURATA GRM39COG150J050AD H1045-00221-50V5-T 1 ea C5 CAP, SMD, 0603, 220pF, 50V, VENKEL 5%, C0G, ROHS C0603COG500-221JNE H1045-00333-50V5-T 1 ea CSS1 CAP, SMD, 0603, 33000pF, 25V, 5%, X7R, ROHS 06035C333JAT2A H1045-DNP 0 ea C3, C6, CSS2 CAP, SMD, 0603, DNP-PLACE MURATA HOLDER, ROHS H1065-00226-6R3V20-T 5 ea C1, C2, C7, C8, C10 CAP, SMD, 1206, 22µF, 6.3V, 20%, X5R, ROHS H1065-00476-6R3V20-T 1 ea C9 CAP, SMD, 1206, 47µF, 6.3V, MURATA 20%, X5R, ROHS H1065-DNP 0 ea C19, C20, C23, C24 CAP, SMD, 1206, DNP-PLACE HOLDER, ROHS IHLP-5050CE-01-1R0M 1 ea L1 COIL-PWR INDUCTOR, SMD, 13mm, 1.0µH, 20%, 24A, ROHS VISHAY IHLP-5050CE-01-1R0M 111-0702-001 2 ea J1, J3 CONN-GEN, BIND.POST, INSUL-RED, THMBNUT-GND JOHNSON COMPONENTS 111-0702-001 111-0703-001 2 ea J2, J4 CONN-GEN, BIND.POST, INSUL-BLK, THMBNUT-GND JOHNSON COMPONENTS 111-0703-001 131-4353-00 2 ea LX1, VOUT1 CONN-SCOPE PROBE TEST PT, COMPACT, PCB MNT, ROHS TEKTRONIX 131-4353-00 1514-2 2 ea J5, J6 CONN-TURRET, TERMINAL POST, TH, ROHS KEYSTONE 1514-2 5000 14 ea EN1, EN2, FB2, PG1, CONN-MINI TEST PT, PG2, SS2, ISET, VSET, VERTICAL, RED, ROHS COMP2, SYNCIN1SYNCIN3, SYNCOUT1, SYNCOUT2 KEYSTONE 5000 LTST-C170CKT 2 ea D1, D2 LITEON/VISHAY LED-GaAs RED, SMD, 2X1.25mm, 100mW, 40mA, 10mcd, ROHS LTST-C170CKT B340B-13-F-T 2 ea D1, D2 DIODE-SCHOTTKY, SMD, SMB, 2P, 40V, 3A, ROHS DIODES INC. B340B-13-F ISL8016IRZ 1 ea MASTER IC-ADJ. 6A BUCK REGULATOR, 20P, QFN, 3X4, ROHS INTERSIL ISL8016IRZ 2N7002-7-F-T 2 ea Q1, Q2 TRANSISTOR, N-CHANNEL, 3 DIODES, INC. LD, SOT23, 60V, 115mA, ROHS H2505-DNP 0 ea R6, R9 ,R20, R28 RESISTOR,SMD,0603,0.1%, MF,DNP-PLACE HOLDER H2510-DNP 0 ea R4, R7, R13, R14, R19, R21, R22, R25, R29 RES,SMD,0402, DNP, DNP, DNP,TF,ROHS 4 AVX GRM36COG680J050AQ GRM31CR60J476ME19L 2N7002-7-F AN1630.1 Application Note 1630 TABLE 2. BILL OF MATERIALS (Continued) PART NUMBER REFERENCE DESIGNATOR QTY UNITS DESCRIPTION MANUFACTURER H2511-00200-1/10W1-T 1 ea R24 RES,SMD,0603,20ohm,1/1 0W,1%,TF,ROHS H2511-00R00-1/10W-T 1 ea R18 RES, SMD, 0603, 0Ω, 1/10W, VENKEL TF, ROHS CR0603-10W-000T H2511-01003-1/10W1-T 9 ea R2, R3, R8, R10-R12, R16, R23, R26 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS VENKEL ERJ-3EKF1003V ROHM CR0603-10W-1003FT YAGEO MCR03EZPFX1003 VISHAY/DALE ERJ-3EKF1004V PANASONIC ERJ-3EKF2003V VENKEL CR0603-10W-2003FT ROHM MCR03EZPFX2003 KOA RK73H1JTTD2003F VISHAY/DALE CRCW06031M00FKEA H2511-02003-1/10W1-T 2 ea R1, R5 RES, SMD, 0603, 200k, 1/10W, 1%, TF, ROHS PANASONIC MANUFACTURER PART # ERJ-3EKF20R0V H2511-DNP 0 ea R17, R27 RES, SMD, 0603, DNP-PLACE HOLDER, ROHS H2514-DNP 0 ea R15 RES,SMD, 1210, DNP, DNP, DNP, TF, ROHS GT11MSCBE-T 3 ea S1, S4, S5 SWITCH-TOGGLE, SMD, 6PIN, ITT INDUSTRIES/C&K SPDT, 2POS, ON-ON, ROHS DIVISION GT11MSCBE GT13MSCBE 2 ea S2, S3 SWITCH-TOGGLE, SMD, 6PIN, ITT INDUSTRIES/C&K DIVISION SPDT, 3POS, ON-OFF-ON, ROHS GT13MSCBE DNP 0 ea C11-C14, C17, C18, C21, C22, C25-C27 DO NOT POPULATE OR PURCHASE DNP 0 ea L2, L3, LX2, VOUT2, U3, DO NOT POPULATE OR SLAVE PURCHASE 5 AN1630.1 Application Note 1630 ISL8016CIR1EVAL1Z Board Layout ISL8016CIR1EVAL1Z FIGURE 1. TOP LAYER COMPONENTS 6 AN1630.1 Application Note 1630 ISL8016CIR1EVAL1Z Board Layout (Continued) FIGURE 2. TOP LAYER ETCH 7 AN1630.1 Application Note 1630 ISL8016CIR1EVAL1Z Board Layout (Continued) FIGURE 3. SECOND LAYER ETCH 8 AN1630.1 Application Note 1630 ISL8016CIR1EVAL1Z Board Layout (Continued) FIGURE 4. THIRD LAYER ETCH 9 AN1630.1 Application Note 1630 ISL8016CIR1EVAL1Z Board Layout (Continued) FIGURE 5. BOTTOM LAYER ETCH 10 AN1630.1 Application Note 1630 ISL8016CIR1EVAL1Z Board Layout (Continued) FIGURE 6. BOTTOM LAYER COMPONENTS 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 11 AN1630.1