Application Note 1905 ISL85410EVAL1Z, ISL85418EVAL1Z Wide VIN 1A and 800mA Synchronous Buck Regulator Description Key Features The ISL85410EVAL1Z, ISL85418EVAL1Z kits are intended for use for point-of-load applications sourcing from 3V to 40V. The kits are used to demonstrate the performance of the ISL85410, ISL85418 Wide VIN Low Quiescent Current High Efficiency Synchronous Buck Regulators with 1A (ISL85410) and 800mA (ISL85418EVAL1Z) output current. • • • • • • The ISL85410, ISL85418 are offered in a 4mmx3mm 12 Ld DFN package with 1mm maximum height. The converter occupies 1.516cm2 area. 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 2A • Digital multimeters (DMMs) • 100MHz quad-trace oscilloscope • Signal generator • • • • Wide input voltage range 3V to 40V 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 1A (ISL85410) and 800mA (ISL85418) Internal or external soft-start Minimal external components required Power-good and enable functions available References • ISL85410 Datasheet • ISL85418 Datasheet Ordering Information FIGURE 1. FRONT OF EVALUATION BOARD ISL85410EVAL1Z March 13, 2015 AN1905.3 1 DESCRIPTION ISL85410EVAL1Z Evaluation Board (1A Output Current) ISL85418EVAL1Z Evaluation Board (800mA Output Current) ISL85410EVAL1Z ISL85410EVAL1Z PART NUMBER FIGURE 2. BACK OF EVALUATION BOARD ISL85410EVAL1Z 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 2013, 2014, 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. Application Note 1905 Quick Setup Guide Frequency Control 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 The ISL85410EVAL1Z, ISL85418EVAL1Z kit outputs are 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 datasheets ISL85410 and ISL85418 for further information. The ISL85410, ISL85418 have an 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 datasheets ISL85410 and ISL85418 for calculating the value of R10. Do not leave this pin floating. Disabling/Enabling Function The ISL85410, ISL85418 evaluation boards contain an 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 12 22 2x22 90.9 4.75 22 115 150 470 The ISL85410, ISL85418 evaluation boards have 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 preselected switching frequency set by R12 (see datasheets and previous section “Frequency Control” for details). If this pin is tied to GND the IC will operate in PFM mode. The S2 switch allows forced PFM or PWM modes. 5 22 47+22 90.9 12.4 27 DNP (Note 1) 100 470 Soft-start/COMP Control 3.3 22 47+22 90.9 20 27 DNP (Note 1) 100 470 2.5 22 47+22 90.9 28.7 27 DNP (Note 1) 100 470 1.8 12 47+22 90.9 45.5 27 DNP (Note 1) 70 470 Submit Document Feedback 2 Table 1 shows the component selection that should be used for the respective VOUT . TABLE 1. EXTERNAL COMPONENT SELECTION VOUT L1 C5 +C6 (V) (µH) (µF) R1 (kΩ) R2 (kΩ) C4 (pF) R12 (kΩ) R3 (kΩ) C7 (pF) R15 selects between internal (R15 = 0) and external soft-start. R11 selects between internal (R11 = 0) and external compensation. For applications where repetitive restarts of the IC are required, it is recommended to add a 350kΩ resistor in parallel to CSS in order to allow its fast discharge. Please refer to the pin description table of the ISL85410 and ISL85418 datasheets. NOTE: 1. Connect FS to VCC AN1905.3 March 13, 2015 Application Note 1905 ISL85410EVAL1Z Schematic U1 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 AN1905.3 March 13, 2015 Application Note 1905 Bill of Materials MANUFACTURER PART REFERENCE DESIGNATOR QTY UNITS ISL85400EVAL1ZREVAPCB 1 ea SEE LABEL-RENAME BOARD EEE-FK1H151P 1 ea 06035C104KAT2A 1 GRM188R61C105KA12D DESCRIPTION MANUFACTURER PWB-PCB, ISL85400EVAL1Z, REVA, ROHS INTERSIL C10 CAP, SMD, 10.3mm, 150µF, 50V, 20%, ROHS, ALUM.ELEC. PANASONIC ea C3 CAP, SMD, 0603, 0.1µF, 50V, 10%, X7R, ROHS AVX 1 ea C9 CAP, SMD, 0603, 1µF, 16V, 10%, X5R, MURATA ROHS C1608C0G1H270J 1 ea C4 CAP, SMD, 0603, 27pF, 50V, 5%, NP0, TDK ROHS C0603X7R160-333KNE 1 ea CSS CAP, SMD, 0603, 33000pF, 16V, 10%, VENKEL X7R, ROHS ECJ-1VC1H471J 1 ea C7 CAP, SMD, 0603, 470pF, 50V, 5%, NP0, ROHS 0 ea C8 CAP, SMD, 0603, DNP-PLACE HOLDER, ROHS 2 ea C1, C2 CAP, SMD, 1206, 10µF, 50V, 10%, X5R, ROHS TDK C5 CAP, SMD, 1206, 47µF, 6.3V, 20%, X5R, ROHS MURATA C3216X5R1H106K GRM31CR60J476ME19L PANASONIC ECJ-DV50J226M 2 ea C6 CAP, SMD, 1206, 22µF, 6.3V, 20%, X5R, ROHS PANASONIC DR73-220-R 1 ea L1 COIL-PWR INDUCTOR, SMD, 7.6mm, 22µH, 20%, 1.62A, ROHS COOPER/COILTRONICS 131-4353-00 2 ea J1, J2 CONN-SCOPE PROBE TEST PT, COMPACT, PCB MNT, ROHS TEKTRONIX 1514-2 4 ea P4, P5, P7, P9 CONN-TURRET, TERMINAL POST, TH, ROHS KEYSTONE 5002 5 ea P1, P2, P6, P8, P10 CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS KEYSTONE LTST-C190KGKT 1 ea D1 LED, SMD, 0603, GREEN CLEAR, 2V, 20mA, 571nm, 35mcd, ROHS LITEON/VISHAY ISL85410FRZ for ISL85410EVAL1Z, ISL85418FRZ for ISL85418EVAL1Z, 1 ea U1 IC-800mA BUCK REGULATOR, 12P, DFN, 3X4, ROHS INTERSIL 2N7002LT1G 1 ea Q1 TRANSISTOR-MOS, N-CHANNEL, SMD, ON SEMICONDUCTOR SOT23, 60V, 115mA, ROHS ERJ-3EKF20R0V 1 ea R4 RES, SMD, 0603, 20Ω, 1/10W, 1%, TF, ROHS PANASONIC CR0603-10W-000T 2 ea R10, R15 RES, SMD, 0603, 0Ω, 1/10W, TF, ROHS VENKEL CR0603-10W-1003FT 1 ea R3 RES, SMD, 0603, 100k, 1/10W, 1%, VENKEL TF, ROHS RK73H1JTTD2001F 1 ea R5 RES, SMD, 0603, 2k, 1/10W, 1%, TF, KOA ROHS CR0603-10W-2002FT 0 ea R2 RES, SMD, 0603, 20k, 1/10W, 1%, TF, VENKEL ROHS Submit Document Feedback 4 AN1905.3 March 13, 2015 Application Note 1905 Bill of Materials (Continued) QTY UNITS REFERENCE DESIGNATOR CR0603-10W-2003FT 2 ea R6, R7 ERJ-3EKF9092V 1 ea R1 0 ea GT11MSCBE 2 ea SW1, SW2 SWITCH-TOGGLE, SMD, 6PIN, SPDT, 2POS, ON-ON, ROHS DNP 0 ea P3 (3VH30/1JN5) DO NOT POPULATE OR PURCHASE MANUFACTURER PART Submit Document Feedback 5 DESCRIPTION MANUFACTURER RES, SMD, 0603, 200k, 1/10W, 1%, VENKEL TF, ROHS RES, SMD, 0603, 90.9k, 1/10W, 1%, PANASONIC TF, ROHS R8, R9, R11, R12, R14 RES, SMD, 0603, DNP-PLACE HOLDER, ROHS ITT INDUSTRIES/C&K DIVISION AN1905.3 March 13, 2015 Application Note 1905 ISL85410EVAL1Z Board Layout FIGURE 3. SILK SCREEN TOP FIGURE 4. SILK SCREEN BOTTOM Submit Document Feedback 6 AN1905.3 March 13, 2015 Application Note 1905 ISL85410 Efficiency Curves fSW = 500kHz, TA = +25°C 100 100 95 95 90 VIN = 24V 85 VIN = 15V EFFICIENCY (%) EFFICIENCY (%) 90 80 VIN = 33V 75 70 65 75 70 55 55 0.1 0.2 0.3 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 50 1.0 VIN = 33V 65 60 0 0 FIGURE 5. EFFICIENCY vs LOAD, PFM, VOUT = 12V 100 90 85 85 VIN = 15V VIN = 24V 75 70 65 0.3 0.4 0.5 0.6 0.7 0.8 0.9 50 1.0 VIN = 15V 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 OUTPUT LOAD (A) FIGURE 8. EFFICIENCY vs LOAD, PWM, VOUT = 5V, L1 = 30µH FIGURE 7. EFFICIENCY vs LOAD, PFM, VOUT = 5V, L1 = 30µH 100 100 VIN = 5V 95 EFFICIENCY (%) VIN = 15V 75 70 VIN = 24V 65 VIN = 33V 85 80 65 60 55 0.2 0.3 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 FIGURE 9. EFFICIENCY vs LOAD, PFM, VOUT = 3.3V Submit Document Feedback 7 1.0 VIN = 33V 70 55 0.1 VIN = 15V 75 60 0 VIN = 5V 90 85 80 VIN = 12V 95 VIN = 12V 90 EFFICIENCY (%) VIN = 6V VIN = 24V OUTPUT LOAD (A) 50 1.0 65 55 0.2 0.9 70 60 0.1 0.8 75 55 0 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) VIN = 12V 80 60 50 0.3 95 VIN = 6V 90 80 0.2 FIGURE 6. EFFICIENCY vs LOAD, PWM, VOUT = 12V EFFICIENCY (%) EFFICIENCY (%) 95 0.1 100 VIN = 12V VIN = 15V 80 60 50 VIN = 24V 85 50 VIN = 24V 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 1.0 FIGURE 10. EFFICIENCY vs LOAD, PWM, VOUT = 3.3V AN1905.3 March 13, 2015 Application Note 1905 ISL85410 Efficiency Curves fSW = 500kHz, TA = +25°C (Continued) 100 100 95 VIN = 5V 90 85 EFFICIENCY (%) EFFICIENCY (%) 90 80 VIN = 15V 75 70 VIN = 33V 65 VIN = 24V 60 VIN = 12V 95 VIN = 12V VIN = 5V 85 80 75 70 VIN = 15V 65 60 VIN = 24V 55 55 50 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 50 1.0 0 0.1 0.2 0.3 5.004 0.6 0.7 0.8 0.9 1.0 5.030 5.003 5.025 VIN = 6V VIN = 12V 5.001 OUTPUT VOLTAGE (V) 5.002 OUTPUT VOLTAGE (V) 0.5 FIGURE 12. EFFICIENCY vs LOAD, PWM, VOUT = 1.8V FIGURE 11. EFFICIENCY vs LOAD, PFM, VOUT = 1.8V 5.000 4.999 4.998 4.997 VIN = 15V 4.996 VIN = 24V 4.995 4.993 0 0.1 0.2 0.3 VIN = 6V 5.020 VIN = 12V 5.015 5.010 5.005 VIN = 15V 5.000 4.995 4.994 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 4.990 1.0 VIN = 24V 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 OUTPUT LOAD (A) FIGURE 13. EFFICIENCY vs LOAD, PWM, VOUT = 5V, L1 = 30µH FIGURE 14. VOUT REGULATION vs LOAD, PFM, VOUT = 5V, L1 = 30µH 3.345 3.326 VIN = 5V VIN = 5V 3.325 3.340 3.324 OUTPUT VOLTAGE (V) VIN = 12V 3.323 3.322 3.321 VIN = 15V 3.320 3.319 VIN = 24V 3.318 3.317 3.316 0.4 OUTPUT LOAD (A) OUTPUT LOAD (A) OUTPUT VOLTAGE (V) VIN = 33V VIN = 12V 3.335 3.330 VIN = 33V 3.320 VIN = 33V 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 OUTPUT LOAD (A) FIGURE 15. VOUT REGULATION vs LOAD, PWM, VOUT = 3.3V Submit Document Feedback 8 VIN = 15V 3.325 1.0 3.315 VIN = 24V 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 1.0 FIGURE 16. VOUT REGULATION vs LOAD, PFM, VOUT = 3.3V AN1905.3 March 13, 2015 Application Note 1905 ISL85410 Efficiency Curves 1.810 1.816 OUTPUT VOLTAGE (V) VIN = 12V 1.808 OUTPUT VOLTAGE (V) 1.818 VIN = 5V VIN = 15V 1.809 fSW = 500kHz, TA = +25°C (Continued) 1.807 1.806 1.805 1.804 VIN = 33V 1.803 VIN = 24V 1.802 1.812 VIN = 12V 1.810 VIN = 15V 1.808 1.806 1.804 VIN = 33V 1.802 1.801 1.800 VIN = 5V 1.814 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 1.0 FIGURE 17. VOUT REGULATION vs LOAD, PWM, VOUT = 1.8V ISL85410 Typical Performance Curves 1.800 0 0.1 0.2 0.3 VIN = 24V 0.4 0.5 0.6 0.7 OUTPUT LOAD (A) 0.8 0.9 1.0 FIGURE 18. VOUT REGULATION vs LOAD, PFM, VOUT = 1.8V fSW = 500kHz, VIN = 24V, VOUT = 3.3V, 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 19. START-UP AT NO LOAD, PFM FIGURE 20. START-UP AT 1A, PWM LX 20V/DIV LX 5V/DIV VOUT 2V/DIV IL 500mA/DIV PG 2V/DIV 200µs/DIV 5ns/DIV FIGURE 21. SHUTDOWN AT 1A, PWM FIGURE 22. JITTER AT 1A LOAD, PWM Submit Document Feedback 9 AN1905.3 March 13, 2015 Application Note 1905 ISL85410 Typical Performance Curves fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C (Continued) LX 20V/DIV LX 20V/DIV VOUT 20mV/DIV VOUT 20mV/DIV IL 20mA/DIV IL 20mA/DIV 10ms/DIV 1µs/DIV FIGURE 23. STEADY STATE AT NO LOAD, PFM FIGURE 24. STEADY STATE AT NO LOAD, PWM LX 20V/DIV LX 20V/DIV VOUT 20mV/DIV VOUT 50mV/DIV IL 1A/DIV IL 200mA/DIV 1µs/DIV 10µs/DIV FIGURE 25. STEADY STATE AT 1A, PWM FIGURE 26. LIGHT LOAD OPERATION AT 20mA, PFM VOUT 100mV/DIV VOUT 100mV/DIV IL 1A/DIV IL 1A/DIV 200µs/DIV 200µs/DIV FIGURE 27. LOAD TRANSIENT, PFM FIGURE 28. LOAD TRANSIENT, PWM Submit Document Feedback 10 AN1905.3 March 13, 2015 Application Note 1905 ISL85410 Typical Performance Curves fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C (Continued) LX 20V/DIV VOUT 20mV/DIV IL 1A/DIV 10µs/DIV FIGURE 29. PFM TO PWM TRANSITION LX 20V/DIV LX 20V/DIV VOUT 2V/DIV VOUT 2V/DIV IL 1A/DIV IL 1A/DIV PG 2V/DIV PG 2V/DIV 10ms/DIV 50µs/DIV FIGURE 30. OVERCURRENT PROTECTION, PWM FIGURE 31. OVERCURRENT PROTECTION HICCUP, PWM LX 20V/DIV LX 20V/DIV VOUT 5V/DIV SYNC 2V/DIV IL 1A/DIV PG 2V/DIV 200ns/DIV 20µs/DIV FIGURE 32. SYNC AT 1A LOAD, PWM FIGURE 33. NEGATIVE CURRENT LIMIT, PWM Submit Document Feedback 11 AN1905.3 March 13, 2015 Application Note 1905 ISL85410 Typical Performance Curves fSW = 500kHz, VIN = 24V, VOUT = 3.3V, TA = +25°C (Continued) LX 20V/DIV VOUT 5V/DIV VOUT 2V/DIV IL 500mA/DIV PG 2V/DIV PG 2V/DIV 200µs/DIV FIGURE 34. NEGATIVE CURRENT LIMIT RECOVERY, PWM 500µs/DIV FIGURE 35. 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 Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com Submit Document Feedback 12 AN1905.3 March 13, 2015