User Guide 033 ISL8026xEVAL3Z Evaluation Board User Guide Description Key Features The ISL8026EVAL3Z and ISL8026AEVAL3Z are intended for use by customers with requirements for point-of-load applications sourcing from 2.5V to 5.5V. The ISL8026EVAL3Z and ISL8026AEVAL3Z are used to demonstrate the performance of the ISL8026 and ISL8026A, low quiescent high efficiency synchronous buck regulator. • High efficiency synchronous buck regulator with up to 95% efficiency • 1% reference accuracy over load/line/temperature (-40°C to +85°C) • Start-up with prebiased output • Internal soft-start - 1ms or adjustable The ISL8026 and ISL8026A are offered in a 3mmx3mm 16 Ld TQFN package with 1mm maximum height. The complete area that the converter occupies can be as small as 0.22in2. • Soft-stop output discharge during disabled • Adjustable frequency from 500kHz to 4MHz - default at 1MHz (2MHz for ISL8026A) Specifications PART NUMBER IOUT (MAX) (A) ISL8026 6 ISL8026A • External synchronization up to 4MHz fSW RANGE (MHz) Programmable 0.5 to 4MHz Programmable 1 to 4MHz VIN VOUT RANGE RANGE (V) (V) • Negative OC protection References PART SIZE (2mm) ISL8026, ISL8026A Datasheet 2.5 to 5.5 0.6 to 5.5 Ordering Information 3x3 PART NUMBER NOTES: 1. The Evaluation Boards’ default configuration are VOUT = 1.8V for ISL8026EVAL3Z (fSW = 1MHz) and ISL8026AEVAL3Z (fSW = 2MHz). DESCRIPTION ISL8026EVAL3Z Evaluation Board For ISL8026 ISL8026AEVAL3Z Evaluation Board For ISL8026A 2. VREF is 0.6V. ISL8026 GND PHASE VIN PHASE VIN PHASE VIN VOUT VIN GND PGND PGND EPAD PGND/ SGND PG COMP SS FB FS EN SYNC FIGURE 1. BLOCK DIAGRAM June 19, 2015 UG033.0 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2015. All Rights Reserved 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. User Guide 033 FIGURE 2. ISL8026EVAL3Z Recommended Equipment FIGURE 3. ISL8026AEVAL3Z The following materials are recommended to perform testing: 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. • 0V to 10V power supply with at least 10A source current capability or 5V battery VFB R 2 = R 1 --------------------------- VO – VFB • Electronic loads capable of sinking current up to 7A 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 the Bode plot to insure optimum performance. • Digital Multimeters (DMMs) • 100MHz quad-trace oscilloscope • Signal generator Quick Setup Guide 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, P4 and the negative return to PGND, P5. 3. Connect the output load to VOUT, the plus terminal to VOUT, P3 and the negative return to PGND, P7. 4. Verify that the position is set to PWM for SW2. 5. Verify that the position is set to ON for SW1. 6. Turn on the power supply. 7. Verify that the output voltage is 1.8V for VOUT. Operating Range (EQ. 1) Frequency Control The ISL8026 and ISL8026A have 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 for ISL8026EVAL3Z and 2MHz for ISL8026AEVAL3Z when FS is tied to VIN (R11 = 0 and R12 is open). By changing the value of R12 , the switching frequency can be changed from 500kHz to 4MHz according to Equation 2: 220 10 3 R T k = ------------------------------ – 14 f OSC kHz (EQ. 2) When using R12 to adjust the operational frequency, this also sets the external compensation mode. Please refer to the ISL8026, ISL8026A datasheet for more details. By default, the ISL8026EVAL3Z is configured for the operating conditions shown in the “Quick Setup Guide”. The board can also support a wider operating range. Modifying the operating conditions will change the performance results. The ISL8026EVAL3Z and ISL8026AEVAL3Z outputs are preset to 1.8V for VOUT, however, output voltages can be adjusted from 0.6V to 5V. The output voltage programming resistor, R1, will Submit Document Feedback 2 UG033.0 June 19, 2015 User Guide 033 PCB Layout Recommendation Soft-start Control Short CSS to SGND for internal soft-start (approximately 1ms). Populate CSS to adjust the soft-start time. This capacitor, along with an internal 1.6µA current source, sets the soft-start interval of the converter, tSS. CSS F = 3.33 t SS s (EQ. 3) CSS must be less than 33nF to insure proper soft-start reset after fault condition. Switches Control The ISL8026EVAL3Z and ISL8026AEVAL3Z boards contain SW1 and SW2 for various controls of the ISL8026, ISL8026A circuitries. Table 1 details this function. TABLE 1. SWITCH SETTINGS SW1 ENABLE 1 OFF DISABLE VO 3 ON ENABLE VO SW2 MODE 1 PWM Fixed PWM frequency at light load 3 PFM Force continuous mode Submit Document Feedback FUNCTION The PCB layout is a very important converter design step to make sure the designed converter works well. For ISL8026, ISL8026A, the power loop is composed of the output inductor L’s, the output capacitor (COUT), the PHASE pins and the PGND pin. It is necessary to make the power loop as small as possible and the connecting traces among them should be direct, short and wide. The switching node of the converter, the PHASE pins and the traces connected to the node are very noisy, so keep the voltage feedback trace away from these noisy traces. The input capacitor should be placed as close as possible to the VIN pin. The ground of input and output capacitors should be connected as close as possible. The heat of the IC is mainly dissipated through the thermal pad. Maximizing the copper area connected to the thermal pad is preferable. In addition, a solid ground plane is helpful for better EMI performance. It is recommended to add at least 5 vias ground connection within the pad for the best thermal relief. FUNCTION 3 UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Schematic - - / 3 $ 9,1 8+ 3+$6( 92 3 & 8) 8) & 9,1 9,1 3* 6<1& 3*1' 3*1' 3*1'6*1' )% 8 & 8) 5 $ 5 . 3 & 3) $ ,6/,57$-= 8) (3 6<1& 3* 5 (1 )6 66 &203 & 3+$6( 3+$6( 3+$6( 9,1 & 8) &+ 3 . (1 $ $ 66 & 3) 5 5 &66 . 5 8) . 9,1 '13 & 23(1 $ $ $ 9,1 9,1 9,1 5 . 5 21 6<1& 3 3* 5 . (1 ' . 5 . (1 3:0 3)0 6: 2)) 3 6<1& 6: 4 5 5 23(1 23(1 3 $ $ $ FIGURE 4. SCHEMATIC Submit Document Feedback 4 UG033.0 June 19, 2015 User Guide 033 Bill Of Materials MANUFACTURER PART QTY UNIT ISL8026REVAPCB 1 ea. C0603C0G500-220JNE 1 ea. GRM188R71H221KA01D 1 ea. C0603X7R160-333KNE 1 C0603X7R160-104KNE REFERENCE DESIGNATOR DESCRIPTION MANUFACTURER PWB-PCB, ISL8026, REVA, ROHS IMAGINEERING INC C4 CAP, SMD, 0603, 22pF, 50V, 5%, C0G, ROHS VENKEL C7 CAP, SMD, 0603, 220pF, 50V, 10%, X7R, ROHS MURATA ea. CSS CAP, SMD, 0603, 33000pF, 16V, 10%, X7R, ROHS VENKEL 1 ea. C3 CAP, SMD, 0603, 0.1µF, 16V, 10%, X7R, ROHS VENKEL 0 ea. C8 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS GRM31CR60J226KE19L 4 ea. C1, C2, C5, C6 CAP, SMD, 1206, 22µF, 6.3V, 10%, X5R, ROHS MURATA ETQP3W1R0WFN 1 ea. L1 (ISL8026) 1µH, 6.9mΩ, 8.1A, ROHS, SHIELDED PANASONIC ETQP3WR68WFN 1 ea. L1 (ISL8026A) 0.68µH, 4.9mΩ, 9.6A, ROHS, SHIELDED PANASONIC 131-4353-00 2 ea. J1, J2 1514-2 4 ea. P4, P5, P7, P8 CONN-TURRET, TERMINAL POST, TH, ROHS KEYSTONE 5002 3 ea. P1, P2, P6 CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS KEYSTONE LTST-C170CKT 1 ea. D1 LED-GaAs RED, SMD, 2x1.25mm, 100mW, 40mA, 10mcd, ROHS LITEON/VISHAY ISL8026 1 ea. U1 IC-5A BUCK REGULATOR, 16P, QFN, 3x3, ROHS INTERSIL 2N7002-7-F 1 ea. Q1 TRANSISTOR, N-CHANNEL, 3 LD, SOT-23, 60V, 115mA, ROHS DIODES, INC. 0 ea R11 (ISL8026) 1 ea. CONN-SCOPE PROBE TEST PT, COMPACT, PCB MNT, ROHS TEKTRONIX RES, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER R11 (ISL8026A) RES, SMD, 0603, 0Ω, 1/16W, 1%, TF, ROHS GENERIC ERJ-3EKF20R0V 1 ea. R3 RES, SMD, 0603, 20Ω, 1/10W, 1%, TF, ROHS PANASONIC CR0603-10W-1003FT 1 ea. R2, R14 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS VENKEL CR-0603-10W-1913FT 1 ea. R12 (ISL8026) RES, SMD, 0603, 191k, 1/10W, 1%. TF, ROHS VENKEL 1 ea. R12 (ISL8026A) RES, SMD, 0603, 0.1%, MF, DNP-PLACE HOLDER 4 ea. R1, R4, R6, R7 RES, SMD, 0603, 200k, 1/10W, 1%, TF, ROHS 0 ea. R5, R8, R9 RES, SMD, 0603, DNP-PLACE HOLDER, ROHS GT11MSCBE 2 ea. SW1, SW2 Submit Document Feedback 5 CR0603-10W-2003FT VENKEL SWITCH-TOGGLE, SMD, 6 PIN, SPDT, 2POS, ON-ON, ROHS ITT INDUSTRIES/ C&K DIVISION UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Board Layout ISL8026 FIGURE 5. TOP LAYER COMPONENTS Submit Document Feedback 6 UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Board Layout (Continued) FIGURE 6. TOP LAYER ETCH Submit Document Feedback 7 UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Board Layout (Continued) FIGURE 7. SECOND LAYER ETCH Submit Document Feedback 8 UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Board Layout (Continued) FIGURE 8. THIRD LAYER ETCH Submit Document Feedback 9 UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Board Layout (Continued) FIGURE 9. BOTTOM LAYER ETCH Submit Document Feedback 10 UG033.0 June 19, 2015 User Guide 033 ISL8026xEVAL3Z Board Layout (Continued) FIGURE 10. BOTTOM LAYER COMPONENTS Submit Document Feedback 11 UG033.0 June 19, 2015 User Guide 033 Typical Performance Curves 100 PHASE 5V/DIV 3.3 V 90 -PFM OUT EFFICIENCY (%) 3.3 V 80 -PWM OUT VOUT RIPPLE 20mV/DIV 70 60 50 40 0.0 IL 2A/DIV 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 OUTPUT LOAD (A) 500ns/DIV FIGURE 11. EFFICIENCY vs LOAD (1MHz 5VIN) FIGURE 12. STEADY STATE AT 5A PWM VOUT RIPPLE 100mV/DIV VOUT RIPPLE 100mV/DIV IL 2A/DIV IL 2A/DIV 200µs/DIV FIGURE 13. LOAD TRANSIENT (PWM) 200µs/DIV FIGURE 14. LOAD TRANSIENT (PFM) 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 document is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com Submit Document Feedback 12 UG033.0 June 19, 2015