High Efficiency Synchronous Buck Regulator

® ISL8011 Data Sheet July 11, 2006 FN9254.0 1.2A Integrated FETs, High Efficiency Synchronous Buck Regulator ISL8011 is an integrated FET, 1.2A synchronous buck regulator for general purpose point-of load applications. It is optimized for generating low output voltages down to 0.8V. The supply voltage range is from 2.7V to 5.5V allowing the use from common 3.3V or 5V supply rails and Lithium ion battery inputs. It has guaranteed minimum output current of 1.2A. 1.5MHz pulse-width modulation (PWM) switching frequency allowing the use of small external components. The ISL8011 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 200mV dropout voltage at 1.2A. The ISL8011 offers a 200ms Power-On-Reset (POR) timer at power-up. When shutdown, the ISL8011 discharges the output capacitor. Other features include internal digital softstart, enable for power sequence, overcurrent protection, and thermal shutdown. The ISL8011 is offered in a 10 Ld 3x3mm DFN package with 1mm maximum height. The complete converter occupies less than 1cm2 area. Features • High Efficiency Synchronous Buck Regulator with Up to 95% Efficiency • 2.7V to 5.5V Supply Voltage • 1.2A Guaranteed Output Current • 100% Maximum Duty Cycle • Peak Current Limiting, Short Circuit Protection • 200ms Power-On Reset • 3% Output Accuracy Over Temperature/Load/Line • Less than 1µA Logic Controlled Shutdown Current • Internal Loop Compensation • Internal Digital Soft-Start • Over-Temperature Protection • Enable • Small 10 Ld 3x3mm DFN • Pb-Free Plus Anneal Available (RoHS Compliant) Applications • DC/DC POL Modules • µC/µP, FPGA & DSP Power Ordering Information TEMP. RANGE PART NUMBER PART (°C) (NOTE) MARKING ISL8011IRZ ISL8011IRZ-T 011Z 011Z PACKAGE (Pb-Free) PKG. DWG. # • Plug-in DC/DC Modules for Routers and Switchers • Portable Instruments • Test and Measurement Systems -40 to 85 10 Ld 3x3 DFN L10.3x3 -40 to 85 10 Ld 3x3 DFN L10.3x3 NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are 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. Pinout ISL8011 (10 LD 3x3 DFN) TOP VIEW PVIN VCC EN POR GND 1 2 3 4 5 10 PHASE 9 PGND 8 SGND 7 FB 6 N/C 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. 2006. All Rights Reserved All other trademarks mentioned are the property of their respective owners. ISL8011 Absolute Maximum Ratings (Reference to SGND) Supply Voltage (PVIN, VCC) . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V EN, MODE, PHASE, POR . . . . . . . . . . . . . . . . . . -0.3V to VCC+0.3V FB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V PGND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 0.3V Thermal Information Thermal Resistance (Notes 1, 2) θJA (°C/W) θJC (°C/W) 3x3 DFN Package . . . . . . . . . . . . . . . . 46 4 Junction Temperature Range. . . . . . . . . . . . . . . . . . . -55°C to 150°C Storage Temperature Range . . . . . . . . . . . . . . . . . . . -65°C to 150°C Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C Recommended Operating Conditions PVIN Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.5V Load Current Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 1.2A Ambient Temperature Range . . . . . . . . . . . . . . . . . . . .-40°C to 85°C CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTES: 1. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech Brief TB379. 2. θJC, “case temperature” location is at the center of the exposed metal pad on the package underside. See Tech Brief TB379. Electrical Specifications Unless otherwise noted, all parameter limits are guaranteed over the recommended operating conditions and the typical specification are measured at the following conditions: TA = 25°C, VPVIN = VVCC = 3.6V, EN = VCC, L = 1.8µH, C1 = 10µF, C2 = 10µF, IOUT = 0A (see the Typical Application Circuit). SYMBOL TEST CONDITIONS MIN TYP MAX UNITS PARAMETER SUPPLY VCC Undervoltage Lockout Threshold VUVLO Rising Falling 2.2 - 2.5 2.4 5 0.1 2.7 8 2 V V mA µA Quiescent Supply Current Shut Down Supply Current OUTPUT REGULATION FB Regulation Voltage IPVIN ISD No load at the output VCC = PVIN = 5.5V, EN = low VFB TA = 0°C to 85°C TA = -40°C to 85°C 0.784 0.78 -3 1.2 0.8 0.8 0.1 0.2 - 0.816 0.82 3 - V V µA % %/V A FB Bias Current Output Voltage Accuracy Line Regulation Maximum Output Current COMPENSATION Error Amplifier Trans-conductance PHASE P-Channel MOSFET On Resistance IFB FB = 0.75V PVIN = VO + 0.5V to 5.5V, IO = 0 to 1.2A, TA = -40°C to 85°C PVIN = VO + 0.5V to 5.5V (minimal 2.7V) Adjustable version, design info only - 20 - µA/V PVIN = 3.6V, Io = 200mA PVIN = 2.7V, Io = 200mA 1.5 - 0.12 0.16 0.11 0.15 2.1 100 1.6 1.1 0.22 0.27 0.22 0.27 2.6 1.75 140 - Ω Ω Ω Ω A % MHz ns ms N-Channel MOSFET On Resistance PVIN = 3.6V, Io = 200mA PVIN = 2.7V, Io = 200mA P-Channel MOSFET Peak Current Limit PHASE Maximum Duty Cycle PWM Switching Frequency PHASE Minimum On Time Soft Start-Up Time IPK fS TA = -40°C to 85°C 1.35 - 2 FN9254.0 July 11, 2006 ISL8011 Electrical Specifications Unless otherwise noted, all parameter limits are guaranteed over the recommended operating conditions and the typical specification are measured at the following conditions: TA = 25°C, VPVIN = VVCC = 3.6V, EN = VCC, L = 1.8µH, C1 = 10µF, C2 = 10µF, IOUT = 0A (see the Typical Application Circuit). (Continued) SYMBOL TEST CONDITIONS MIN TYP MAX UNITS PARAMETER POR Output Low Voltage Delay Time POR Pin Leakage Current Minimum Supply Voltage for Valid POR Signal Internal PGOOD Low Rising Threshold Internal PGOOD Low Falling Threshold Internal PGOOD High Rising Threshold Internal PGOOD High Falling Threshold Internal PGOOD Delay Time EN Logic Input Low Logic Input High Logic Input Leakage Current Thermal Shutdown Thermal Shutdown Hysteresis Sinking 1mA, FB = 0.7V 150 200 0.01 92 88 108 105 50 0.3 275 0.1 94.5 91 110.5 108 - V ms µA V % % % % µs POR = VCC = 3.6V 1.2 Percentage of Nominal Regulation Voltage Percentage of Nominal Regulation Voltage Percentage of Nominal Regulation Voltage Percentage of Nominal Regulation Voltage 89.5 85 105.5 102 - 1.4 Pulled up to 5.5V - 0.1 150 25 0.4 1 - V V µA °C °C Typical Operating Performance 100 VOUT = 3.3V 2.60 90 EFFICIENCY (%) VOUT = 2.5V VOUT (V) VOUT = 1.8V 80 2.55 2.50 70 2.45 60 50 200 350 500 650 800 950 1100 LOAD CURRENT (mA) 2.40 50 250 450 650 850 1050 LOAD CURRENT (mA) FIGURE 1. EFFICIENCY vs LOAD CURRENT (VIN = 5.0V) FIGURE 2. VOUT vs LOAD CURRENT (VIN = 5V) 3 FN9254.0 July 11, 2006 ISL8011 Typical Operating Performance 7 SWITCHING FREQUENCY (MHz) VO = 2.8V 6 INPUT CURRENT (mA) 5 4 3 2 1 0 2.9 (Continued) 1.605 1.6 1.595 1.59 1.585 1.58 1.575 1.57 3.4 3.9 4.4 4.9 5.4 2.7 3.2 3.7 4.2 VIN (V) 4.7 5.2 VIN VOLTAGE RANGE (2.9V-5.5V) FIGURE 3. IQ vs VIN FIGURE 4. SWITCHING FREQUENCY vs VIN 1.61 1.61 1.608 1.605 1.606 VO (V) VO (V) 2.7 3.7 VIN (V) 4.7 1.6 1.604 1.602 1.595 1.6 5.7 1.59 0 200 400 IO (mA) 600 800 1000 FIGURE 5. LINE REGULATION (IO = 1A) FIGURE 6. LOAD REGULATION (VIN = 3.6V) FIGURE 7. SOFT-START FIGURE 8. STEADY-STATE (VIN = 3.6V; VO = 1.6V; IO = 1A) 4 FN9254.0 July 11, 2006 ISL8011 Typical Operating Performance (Continued) FIGURE 9. LOAD TRANSIENT (VIN = 3.6V; VO = 1.6V; IO = 0A~1A) Pin Descriptions PVIN Input supply voltage. Connect a 10µF ceramic capacitor to power ground. FB Buck regulator output feedback. Connect to the output through a resistor divider for adjustable the output voltage. Exposed Pad The exposed pad must be connected to the PGND pin for proper electrical performance and optimal thermal performance. VCC Supply voltage for internal analog and digital control circuits, delivered from PVIN. Bypass with 0.1µF ceramic capacitor to signal ground. EN Regulator enable pin. Force this pin above 1.4V enable the chip. Force this pin below 0.4V shutdown the chip and discharge output capacitor when driven to low. Do not leave this pin floating. POR 200ms timer output. At power-up or EN HI, this output is a 200ms delayed Power-Good signal for the output voltage. GND Ground. PHASE Switching node connection. Connect to one terminal of inductor. PGND Power ground. Connect all power grounds to this pin. SGND Analog ground. SGND and PGND should only have one point connection. 5 FN9254.0 July 11, 2006 ISL8011 Typical Applications ISL8011 VIN 2.7V to 5.5V C1 10µF C3 0.1µF L PVIN PHASE 1.8µH C2 10µF R2 61.9kO VOUT 1.3V, 1.2V VCC PGND SGND EN R1 100kO R3 100kO FB POR GND FIGURE 10. TYPICAL APPLICATION FOR ADJUSTABLE VERSION Block Diagram VCC Shutdown Soft-Start Shutdown 400kO 25pF 0.8pF 5O PVIN Oscillator EA EN Bandgap 0.8V COMP PWM Control and Drivers PGND PHASE Slope Compensation CSA1 FB OCP 0.864V 0.85V 0.736V POR 200ms Delay SCP 0.2V SGND GND FIGURE 11. FUNCTIONAL BLOCK DIAGRAM