Application Note 1360 ISL8012EVAL1Z: 2A Synchronous Buck Regulator with Integrated MOSFETs 2A Low Quiescent Current 1MHz High Efficiency Synchronous Buck Regulator ISL8012 is an integrated power controller rate for the 2A, 1MHz step-down regulator, which is ideal for any low power, low-voltage application. It is optimized for generating low output voltages down to 0.8V. The supply voltage range is from 2.7V to 5.5V, allowing for the use of a single Li+ cell, three NiMH cells or a regulated 5V input. It has a guaranteed minimum output current of 2A. 1MHz pulse-width modulation (PWM) switching frequency allows using small external components. It has flexible operation mode selection of forced PWM mode and PFM mode with as low as 35µA quiescent current for highest light load efficiency to maximize battery life. The ISL8012 includes a pair of low ON-resistance P-Channel and N-Channel internal MOSFETs to maximize efficiency and minimize external component count. 100% duty-cycle operation allows less than 400mV dropout voltage at 2A. Features • High Efficiency Synchronous Buck Regulator with up to 95% Efficiency • 1ms Reset Timer • Soft Discharge Output Cap During Enable • 2.7V to 5.5V Supply Voltage • 3% Output Accuracy Over-Temperature/Load/Line • 2A Guaranteed Output Current • 25µA Quiescent Supply Current in PFM Mode • Selectable Forced PWM Mode and PFM Mode • Less Than 1µA Logic Controlled Shutdown Current • 100% Maximum Duty Cycle for Lowest Dropout • Internal Current Mode Compensation • Internal Digital Soft-Start • Peak Current Limiting, Short Circuit Protection • Over-Temperature Protection • Enable • Small 10 Ld 3mmx3mm DFN The ISL8012 offers a 1ms Power-On-Reset (PG) timer at power-up. The timer output can be reset by RSI. When shutdown, ISL8012 discharges the output capacitor. Other features include internal digital soft-start, enable for power sequence, overcurrent protection and thermal shutdown. • Pb-Free (RoHS Compliant) The ISL8012 is offered in a 3mmx3mm 10 Ld DFN package with 1mm maximum height. The complete converter occupies less than 1cm2 area. • Plug-in DC/DC Modules for Routers and Switchers Ordering Information Pinout PART NUMBER PART (Notes 1, 2, 3) MARKING ISL8012IRZ 012Z TEMP. RANGE (°C) PACKAGE (Pb-Free) Applications • DC/DC POL Modules • µC/µP, FPGA and DSP Power • PGtable Instruments • Test and Measurement Systems ISL8012 (10 LD DFN) TOP VIEW PKG. DWG. # -40 to +85 10 Ld 3x3 DFN L10.3x3C NOTES: 1. Add “-T” or suffix for tape and reel. Please refer to TB347 for details on reel specifications. 2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020. VIN 1 10 LX VCC 2 9 PGND EN 3 8 SGND PG 4 7 VFB MODE 5 6 RSI 3. For Moisture Sensitivity Level (MSL), please see device information page for ISL8012. For more information on MSL please see techbrief TB363. November 4, 2009 AN1360.1 1 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. 2007, 2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Application Note 1360 What’s Inside Evaluating the Other Output Voltage The Evaluation Board Kit contains the following materials: • The ISL8012EVAL1Z REVC Board • The ISL8012 Data Sheet • This EVAL KIT Application Note Recommended Equipment The following materials are recommended to perform testing: • 0V to 10V power supply with at least 3A source current capability, battery and notebook AC adapter • Two electronic loads capable of sinking current up to 5A • Digital multimeters (DMMs) • 100MHz quad-trace oscilloscope • Signal generator Quick Setup Guide The ISL8012EVAL1Z kit output is preset to 1.8V; however, output voltages can be adjusted from 0.8V to 3.3V using Equations 1 and 2: R 1⎞ ⎛ VOUT = 0.8 ⎜ 1 + -------⎟ R 2⎠ ⎝ (EQ. 1) Let’s set R2 = 100kΩ VOUT R 1 = R 2 ⎛ ------------------ – 1⎞ ⎝ 0.8 ⎠ (EQ. 2) If the desired output is 0.8V, short R1 and open R2. Mode Control The ISL8012 has a MODE pin that controls the operation mode. When the MODE pin is driven to low or shorted to ground, the regulator operates in a forced PWM mode. The forced PWM mode remains the fixed PWM frequency at light load instead of entering the skip mode. TABLE 1. SWITCH SETTINGS SW2 SKIP FUNCTION PWM Fixed PWM Frequency at Light Load PFM Force Continuous Mode ENABLE ON/OFF CONTROL 4. Turn on the power supply. OFF Disable VOUT 5. Verify the output voltage is 1.8V for VOUT ON Enable VOUT 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 P4 (VIN) and the negative return to P5 (GND). 3. Verify that SW1 is in the ON position. 2 SW1 AN1360.1 November 4, 2009 ISL8012EVAL1Z Schematic 1 J1 2 5 4 3 1 P5 11 10 1 P7 1 P8 1 1 1 9 C5 10UF C4 R1 124K 220PF 6 C6 10UF 2 A 7 2 8 2 EN 3 PG 4 SKIP 5 LX PGND GND VFB RSI 2 2 C2 10UF 2 C1 10UF 1 1 3 VIN VCC EN POR SKIP EP 2 1 1 2 RSI A ISL8012IRZ Application Note 1360 A 2 VIN 1 P4 L1 L1 2.2UH 1.5UH A 5 4 3 U1 1 J2 R2 100K 1 A A RSI 1 P1 R3 100K A VIN 2N7002 1 P6 R9 OPEN 2 3 ON/EX SW1 1 OFF 1 R8 OPEN 1 AN1360.1 November 4, 2009 Q1 EN 1 31 1 PFM 2 P2 3 SW2 1 PWM 2 PG 2 2 D1 1 1 SKIP 21 2 R4 100K P3 1 R5 2K R7 100K 1 R6 100K 2 VIN 2 2 VIN A A A TABLE 2. BILL OF MATERIALS PART NUMBER QTY UNITS 4 ISL8012EVAL1ZREVCPCB 1 ea GRM31CR71A106KA01L-T 4 ea H1045-00221-50V5-T 1 DR73-2R2-R REFERENCE DESIGNATOR DESCRIPTION MANUFACTURER MANUFACTURER PART IMAGINEERING INC ISL8012EVAL1ZREVCPCB C1, C2, C5, C6 CAP, SMD, 1206, 10µF, 10V, 10%, X7R, ROHS, MONOLITHIC MURATA GRM31CR71A106KA01L ea C4 CAP, SMD, 0603, 220pF, 50V, 5%, C0G, ROHS VENKEL C0603COG500-221JNE 1 ea L1 COIL-PWR INDUCTOR, SMD, 7.6X6, 2.2uH, 20%, 4.15A, ROHS COOPER ELECTRONIC TECH. DR73-2R2-R 131-5031-00 2 ea J1, J2 CONN-SCOPE PROBE TEST PT, COMPACT, PCB MNT, ROHS TEKTRONIX 131-5031-00 1514-2 4 ea P4, P5, P7, P8 CONN-TURRET, TERMINAL POST, TH, ROHS KEYSTONE 1514-2 5002 4 ea P1-P3, P6 CONN-MINI TEST POINT, VERTICAL, WHITE, ROHS KEYSTONE 5002 LTST-C170CKT 1 ea D1 LED-GaAs RED, SMD, 2mmX1.25mm, 100mW, 40mA, LITEON/VISHAY 10mcd, ROHS LTST-C170CKT ISL8012IRZ 1 ea U1 IC-2A SYNCH. BUCK REGULATOR, 10P, DFN, 2X3, ROHS INTERSIL ISL8012IRZ 2N7002-7-F-T 1 ea Q1 TRANSISTOR, N-CHANNEL, 3LD, SOT-23, 60V, 115mA, ROHS DIODES, INC. 2N7002-7-F H2511-01003-1/10W1-T 5 ea R2-R4, R6, R7 RES, SMD, 0603, 100k, 1/10W, 1%, TF, ROHS H2511-01243-1/10W1-T 1 ea R1 RES, SMD, 0603, 124k, 1/10W, 1%, TF, ROHS YAGEO 9C06031A1243FKHFT H2511-02001-1/10W1-T 1 ea R5 RES,SMD,0603, 2k, 1/10W, 1%, TF, ROHS KOA RK73H1JTTD2001F H2511-DNP 0 ea R8, R9 RES, SMD, 0603, DNP-PLACE HOLDER, ROHS GT11MSCBE-T 2 ea SW1, SW2 SWITCH-TOGGLE, SMD, 6PIN, SPDT, 2POS, ON-ON, ROHS ITT INDUSTRIES/ C&K DIVISION GT11MSCBE 4-40X1/2-SCREW 4 ea Four corners. SCREW, 4-40X1/2in, PAN, NYLON, PHILLIPS, ROHS 4-40X3/4-STANDOFF 4 ea Four corners. STANDOFF, 4-40X3/4in, F/F, HEX, NYLON KEYSTONE 1902D 5X8-STATIC-BAG 1 ea Place assy in bag. BAG, STATIC, 5X8, ZIP LOC INTERSIL 212403-013 LABEL-SERIAL NUMBER 1 ea LABEL, FOR SERIAL NUMBER AND BOM REV # Application Note 1360 PWB-PCB, ISL8012EVAL1Z, REVC, ROHS AN1360.1 November 4, 2009 Application Note 1360 ISL8012EVAL1Z Board Layout FIGURE 1. TOP COMPONENTS FIGURE 2. TOP LAYER ETCH 5 AN1360.1 November 4, 2009 Application Note 1360 ISL8012EVAL1Z Board Layout (Continued) FIGURE 3. BOTTOM LAYER COMPONENTS (MIRRORED) FIGURE 4. BOTTOM LAYER ETCH (MIRRORED) 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 6 AN1360.1 November 4, 2009