Application Note 1859 ISL85415EVAL1Z Wide VIN 500mA Synchronous Buck Regulator Description Quick Setup Guide The ISL85415EVAL1Z kit is intended for use for point-of-load applications sourcing from 3V to 36V. The kit is used to demonstrate the performance of the ISL85415 Wide VIN Low Quiescent Current High Efficiency Sync Buck Regulator with 500mA output current. The ISL85415 is offered in a 4mmx3mm 12 Ld DFN package with 1mm maximum height. The converter occupies 1.516 cm2 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 (P4) and the negative return to GND (P5). 3. Verify that the position is ON for S1. 4. Turn on the power supply. 5. Verify the output voltage is 3.3V for VOUT. Evaluating the Other Output Voltage Key Features • Wide input voltage range 3V to 36V • Synchronous operation for high efficiency • No compensation required • Integrated high-side and low-side NMOS devices • Selectable PFM or forced PWM mode at light loads • Internal fixed (500kHz) or adjustable switching frequency 300kHz to 2MHz • Continuous output current up to 500mA • Internal or external soft-start • Minimal external components required • Power-good and enable functions available The ISL85415VAL1Z kit output is preset to 3.3V; however, output voltages can be adjusted from 0.6V to 15V. The output voltage programming resistor, R2, will depend on the desired output voltage of the regulator and the value of the feedback resistor R1, as shown in Equation 1. 0.6 R 2 = R 1 --------------------------- V OUT – 0.6 (EQ. 1) If the output voltage desired is 0.6V, then R1 is shorted. Please note that if VOUT is less than 1.8V, the switching frequency and compensation must be changed for 300kHz operation due to minimum on-time limitation. Please refer to datasheet ISL85415 for further information. Table 1 on page 2 shows the component selection that should be used for the respective VOUTs. Recommended Equipment The following materials are recommended to perform testing: • 0V to 50V Power Supply with at least 2A source current capability • Electronic loads capable of sinking current up to 1.5A • Digital multimeters (DMMs) • 100MHz quad-trace oscilloscope • Signal generator FIGURE 1. FRONT OF EVALUATION BOARD ISL85415EVAL1Z May 16, 2014 AN1859.4 1 FIGURE 2. BACK OF EVALUATION BOARD ISL85415EVAL1Z CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. Copyright Intersil Americas LLC 2013, 2014. 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 1859 TABLE 1. EXTERNAL COMPONENT SELECTION VOUT (V) L1 (µH) COUT (µF) R1 (k) R2 (k) CFB (pF) RFS (k) RCOMP (k) CCOMP (pF) 12 45 10 90.9 4.75 22 115 100 470 5 22 2x22 90.9 12.4 100 120 100 470 3.3 22 2x22 90.9 20 100 120 100 470 2.5 22 2x22 90.9 28.7 100 120 100 470 1.8 22 22 100 50 22 120 50 470 Frequency Control The ISL85415 has a FS pin that controls the frequency of operation. Programmable frequency allows for optimization between efficiency and external component size. It also allows low frequency operation for low VOUTs when minimum on time would limit the operation otherwise. Default switching frequency is 500kHz when FS is tied to VCC (R10 = 0). By removing R10 the switching frequency could be changed from 300kHz (R12 = 340k) to 2MHz (R12 = 32.4k). Please refer to datasheet ISL85415 for calculating the value of R10. Do not leave this pin floating. Disabling/Enabling Function The ISL85415 evaluation board contains S1 switch that enables or disables the part, thus allowing low quiescent current state. Table 2 details this function. TABLE 2. SWITCH SETTINGS S1 ON/OFF CONTROL ON Enable VOUT OFF Disable VOUT SYNC Control The ISL85415 evaluation board has a SYNC pin that allows external synchronization frequency to be applied. Default board configuration has R6 = 200k to VCC, which defaults to PWM operation mode and also to the pre-selected switching frequency set by R12 (see ISL85415 datasheet and previous section “Frequency Control” for details). If this pin is tied to GND the IC will operate in PFM mode. S2 switch allows to force the PFM or PWM modes. Soft-Start /COMP Control R15 selects between internal (R15 = 0) and external soft-start. R11 selects between internal (R11 = 0) and external compensation. Please refer to Pin Description Table of the ISL85415 datasheet. Submit Document Feedback 2 AN1859.4 May 16, 2014 Application Note 1859 ISL85415EVAL1Z Schematic NOTE: The input electrolytic capacitor C10 is optional and it is used to prevent transient voltages when the input test leads have large parasitic inductance. It can be removed if the IC is used in a system application. Submit Document Feedback 3 AN1859.4 May 16, 2014 Application Note 1859 ISL85415 Bill of Materials PART NUMBER REFERENCE DESIGNATOR QTY UNITS ISL85400EVAL1ZREVAPCB 1 ea SEE LABEL-RENAME PWB-PCB, BOARD ISL85400EVAL1Z REVA, ROHS INTERSIL ISL85400EVAL1ZREVAPCB EEE-FK1H151P-T 1 ea C10 CAP, SMD, 10.3mm, 150µF, 50V, 20%, ROHS, ALUM. ELEC. PANASONIC EEE-FK1H151P H1045-00101-50V5-T 1 ea C4 CAP, SMD, 0603, 100pF, 50V, 5%, C0G, ROHS PANASONIC ECJ-1VC1H101J H1045-00104-50V10-T 1 ea C3 AVX CAP, SMD, 0603, 0.1µF, 50V, 10%, X7R, ROHS 06035C104KAT2A H1045-00105-16V10-T 1 ea C9 CAP, SMD, 0603, 1µF, 16V, 10%, X5R, ROHS MURATA GRM188R61C105KA12D H1045-00333-16V10-T 1 ea CSS CAP, SMD, 0603, 33000pF, 16V, 10%, X7R, ROHS VENKEL C0603X7R160-333KNE H1045-00471-50V5-T 1 ea C7 CAP, SMD, 0603, 470pF, 50V, 5%, NP0, ROHS PANASONIC ECJ-1VC1H471J H1045-DNP 0 ea C8 CAP, SMD, 0603, DNPPLACE HOLDER, ROHS H1065-00106-50V10-T 2 ea C1, C2 CAP, SMD, 1206, 10µF, TDK 50V, 10%, X5R, ROHS C3216X5R1H106K H1065-00226-6R3V20-T 2 ea C5, C6 CAP, SMD, 1206, 22µF, PANASONIC 6.3V, 20%, X5R, ROHS ECJ-DV50J226M DR73-220-R 1 ea L1 COIL-PWR INDUCTOR, SMD, 7.6mm, 22µH, 20%, 1.62A, ROHS COOPER/ COILTRONICS DR73-220-R 131-4353-00 2 ea J1, J2 CONN-SCOPE PROBE TEST PT, COMPACT, PCB MNT, ROHS TEKTRONIX 131-4353-00 1514-2 4 ea P4, P5, P7, P9 CONN-TURRET, TERMINAL POST, TH, ROHS KEYSTONE 1514-2 5002 5 ea P1, P2, P6, P8, P10 CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS KEYSTONE 5002 LTST-C190KGKT-T 1 ea D1 LITEON/VISHAY LED, SMD, 0603, GREEN CLEAR, 2V, 20mA, 571nm, 35mcd, ROHS LTST-C190KGKT ISL85415FRZ for ISL85415EVAL1Z 1 ea U1 INTERSIL IC-500mA BUCK REGULATOR, 12P, DFN, 3X4, ROHS ISL85415FRZ 2N7002LT1G-T 1 ea Q1 TRANSISTOR-MOS, NCHANNEL, SMD, SOT23, 60V, 115mA, ROHS H2511-00200-1/10W1-T 1 ea R4 RES, SMD, 0603, 20, PANASONIC 1/10W, 1%, TF, ROHS Submit Document Feedback 4 DESCRIPTION MANUFACTURER ON SEMICONDUCTOR MANUFACTURER PART 2N7002LT1G ERJ-3EKF20R0V AN1859.4 May 16, 2014 Application Note 1859 ISL85415 Bill of Materials (Continued) PART NUMBER REFERENCE DESIGNATOR QTY UNITS H2511-00R00-1/10W-T 1 ea R15 RES, SMD, 0603, 0, 1/10W, TF, ROHS VENKEL CR0603-10W-000T H2511-01003-1/10W1-T 1 ea R3 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS VENKEL CR0603-10W-1003FT H2511-01203-1/10W1-T 1 ea R12 RES, SMD, 0603, 120k, 1/10W, 1%, TF, ROHS VISHAY/DALE CRCW0603120KFKEA H2511-02001-1/10W1-T 1 ea R5 RES, SMD, 0603, 2k, 1/10W, 1%, TF, ROHS KOA RK73H1JTTD2001F H2511-02002-1/10W1-T 1 ea R2 RES, SMD, 0603, 20k, VENKEL 1/10W, 1%, TF, ROHS CR0603-10W-2002FT H2511-02003-1/10W1-T 2 ea R6, R7 RES, SMD, 0603, 200k, 1/10W, 1%, TF, ROHS VENKEL CR0603-10W-2003FT H2511-09092-1/10W1-T 1 ea R1 PANASONIC RES, SMD, 0603, 90.9k, 1/10W, 1%, TF, ROHS H2511-DNP 0 ea R8-R11, R14 RES, SMD, 0603, DNPPLACE HOLDER, ROHS GT11MSCBE-T 2 ea SW1, SW2 SWITCH-TOGGLE, SMD, ITT 6PIN, SPDT, 2POS, ON- INDUSTRIES/C&K DIVISION ON, ROHS 5X8-STATIC-BAG 1 ea PLACE ASSY IN BAG BAG, STATIC, 5X8, ZIPLOC, ROHS DNP 0 ea P3 (3VH30/1JN5) LABEL-DATE CODE 1 ea LABEL-RENAME BOARD 1 ea Submit Document Feedback 5 RENAME PCB TO: ISL85415EVAL1Z DESCRIPTION MANUFACTURER INTERSIL MANUFACTURER PART ERJ-3EKF9092V GT11MSCBE 212403-013 DO NOT POPULATE OR PURCHASE INTERSIL LABEL-DATE CODE_BOM REV#_SERIAL# LABEL ON ZIL & QUEL LABEL-DATE CODE LABEL, TO RENAME BOARD LABEL-RENAME BOARD INTERSIL AN1859.4 May 16, 2014 Application Note 1859 ISL85415EVAL1Z Board Layout FIGURE 3. SILK SCREEN TOP Submit Document Feedback 6 AN1859.4 May 16, 2014 Application Note 1859 ISL85415EVAL1Z Board Layout (Continued) FIGURE 4. SILKSCREEN BOTTOM Efficiency Curves 100 100 VIN = 15V VIN = 12V VIN = 6V 90 90 85 85 80 75 70 VIN = 33V VIN = 24V 65 V V V V V 7 VIN = 15V 65 55 Submit Document Feedback VIN = 33V 70 55 FIGURE 5. EFFICIENCY vs LOAD, PFM, VOUT = 5V VIN = 24V 75 60 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) VIN = 12V 80 60 50 0 VIN = 6V 95 EFFICIENCY (%) EFFICIENCY (%) 95 FSW = 800kHz, TA = +25°C 50 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) FIGURE 6. EFFICIENCY vs LOAD, PWM, VOUT = 5V AN1859.4 May 16, 2014 Application Note 1859 Efficiency Curves FSW = 800kHz, TA = +25°C (Continued) 100 100 90 90 85 85 80 75 70 VIN = 33V VIN = 24V 65 75 70 60 55 50 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) OUTPUT LOAD (A) FIGURE 7. EFFICIENCY vs LOAD, PFM, VOUT = 3.3V FIGURE 8. EFFICIENCY vs LOAD, PWM, VOUT = 3.3V 100 100 95 VIN = 15V VIN = 12V 80 75 70 VIN = 33V VIN = 24V 75 70 65 55 55 50 0.30 0.35 0.40 0.45 0.50 VIN = 24V 0 VIN = 33V 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) OUTPUT LOAD (A) FIGURE 10. EFFICIENCY vs LOAD, PWM, VOUT = 1.8V FIGURE 9. EFFICIENCY vs LOAD, PFM, VOUT = 1.8V 5.020 5.018 VIN = 6V 5.012 5.010 VIN = 24V 5.006 OUTPUT VOLTAGE (V) VIN = 12V 5.014 5.008 VIN = 6V 5.015 VIN = 15V 5.016 OUTPUT VOLTAGE (V) VIN = 5V 80 60 0.05 0.10 0.15 0.20 0.25 VIN = 12V 85 60 50 0 VIN = 15V 90 EFFICIENCY (%) EFFICIENCY (%) 85 65 95 VIN = 5V 90 5.004 VIN = 33V VIN = 24V 65 55 0 VIN = 5V 80 60 50 VIN = 12V VIN = 15V 95 EFFICIENCY (%) EFFICIENCY (%) VIN = 5V VIN = 12V VIN = 15V 95 5.010 VIN = 33V 5.005 VIN = 24V 5.000 VIN = 12V 4.995 VIN = 15V 4.990 4.985 4.980 VIN = 33V 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) FIGURE 11. VOUT REGULATION vs LOAD, PWM, VOUT = 5V Submit Document Feedback 8 4.975 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) FIGURE 12. VOUT REGULATION vs LOAD, PFM, VOUT = 5V AN1859.4 May 16, 2014 Application Note 1859 Efficiency Curves FSW = 800kHz, TA = +25°C (Continued) 3.345 3.336 VIN = 15V 3.332 VIN = 12V VIN = 5V 3.330 3.328 3.326 VIN = 24V VIN = 33V 3.335 VIN = 24V 3.325 3.320 VIN = 33V 0 3.310 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0 OUTPUT LOAD (A) FIGURE 13. VOUT REGULATION vs LOAD, PWM, VOUT = 3.3V 1.785 1.776 1.780 VIN = 15V 1.775 1.774 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) FIGURE 14. VOUT REGULATION vs LOAD, PFM, VOUT = 3.3V 1.777 VIN = 12V 1.773 1.772 VIN = 5V 1.771 VIN = 5V VIN = 15V 1.775 1.770 VIN = 12V VIN = 24V 1.765 VIN = 33V 1.760 1.770 1.769 VIN = 15V 3.330 3.315 3.324 3.322 VIN = 5V 3.340 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 3.334 VIN = 12V 0 VIN = 33V VIN = 24V 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) FIGURE 15. VOUT REGULATION vs LOAD, PWM, VOUT = 1.8V Typical Performance Curves 1.755 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 OUTPUT LOAD (A) FIGURE 16. VOUT REGULATION vs LOAD, PFM, VOUT = 1.8V VIN = 24V, VOUT = 3.3V, FSW = 800kHz, TA = +25°C. LX 20V/DIV LX 20V/DIV VOUT 2V/DIV VOUT 2V/DIV IL 500mA/DIV EN 20V/DIV PG 2V/DIV PG 2V/DIV 5ms/DIV 5ms/DIV FIGURE 17. START-UP AT NO LOAD, PFM FIGURE 18. START-UP AT 500mA, PWM Submit Document Feedback 9 AN1859.4 May 16, 2014 Application Note 1859 Typical Performance Curves VIN = 24V, VOUT = 3.3V, FSW = 800kHz, TA = +25°C. (Continued) LX 20V/DIV VOUT 2V/DIV LX 5V/DIV IL 500mA/DIV PG 2V/DIV 50µs/DIV 50ns/DIV FIGURE 19. SHUTDOWN AT 500mA, PWM FIGURE 20. JITTER AT 500mA, PWM LX 20V/DIV LX 20V/DIV VOUT 10mV/DIV VOUT 10mV/DIV IL 100mA/DIV IL 200mA/DIV 5ms/DIV 500ns/DIV FIGURE 21. STEADY STATE AT NO LOAD, PFM FIGURE 22. STEADY STATE AT NO LOAD, PWM LX 20V/DIV LX 20V/DIV VOUT 50mV/DIV VOUT 10mV/DIV IL 500mA/DIV IL 200mA/DIV 1µs/DIV 10µs/DIV FIGURE 23. STEADY STATE AT 500mA LOAD, PWM FIGURE 24. LIGHT LOAD OPERATION AT 20mA, PFM Submit Document Feedback 10 AN1859.4 May 16, 2014 Application Note 1859 Typical Performance Curves VIN = 24V, VOUT = 3.3V, FSW = 800kHz, TA = +25°C. (Continued) VOUT 50mV/DIV VOUT 100mV/DIV IL 500mA/DIV IL 500mA/DIV 200µs/DIV 200µs/DIV FIGURE 25. LOAD TRANSIENT, PFM FIGURE 26. LOAD TRANSIENT, PWM LX 20V/DIV LX 20V/DIV VOUT 2V/DIV VOUT 2V/DIV IL 1A/DIV IL 500mA/DIV PG 2V/DIV 2µs/DIV 20µs/DIV FIGURE 28. OVERCURRENT PROTECTION, PWM FIGURE 27. PFM TO PWM TRANSITION LX 20V/DIV LX 20V/DIV VOUT 2V/DIV SYNC 2V/DIV IL 1A/DIV PG 2V/DIV 50ms/DIV FIGURE 29. OVERCURRENT PROTECTION HICCUP, PWM Submit Document Feedback 11 200ns/DIV FIGURE 30. SYNC AT 500mA LOAD, PWM AN1859.4 May 16, 2014 Application Note 1859 Typical Performance Curves VIN = 24V, VOUT = 3.3V, FSW = 800kHz, TA = +25°C. (Continued) LX 20V/DIV LX 20V/DIV VOUT 5V/DIV VOUT 5V/DIV IL 0.5A/DIV IL 0.5A/DIV PG 2V/DIV PG 2V/DIV 10µs/DIV 200µs/DIV FIGURE 31. NEGATIVE CURRENT LIMIT, PWM FIGURE 32. NEGATIVE CURRENT LIMIT RECOVERY, PWM VOUT 2V/DIV PG 2V/DIV 500µs/DIV FIGURE 33. OVER-TEMPERATURE PROTECTION, PWM 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 AN1859.4 May 16, 2014