DATASHEET ISL85003, ISL85003A FN7968 Rev.2.00 Highly Efficient 3A Synchronous Buck Regulator Jan 15, 2016 The ISL85003 and ISL85003A are synchronous buck regulators Features with integrated high-side and low-side FETs. The regulator can Input voltage range 4.5V to 18V operate from an input voltage range of 4.5V to 18V while delivering a very efficient continuous 3A current. This is all Output voltage adjustable from 0.8V, 1% delivered in a very compact 3mmx4mm DFN package. Efficiency up to 95% The ISL85003 is designed on Intersils proprietary fab process Integrated boot diode with undervoltage detection that is designed to deliver very low r FETs with an DS(ON) Current mode control optimized current mode controller wrapped around it. The high-side NFET is designed to have an r of 65m while - DCM/CCM DS(ON) the low-side NFET is designed to have an r of 45m . DS(ON) - Internal or external compensation options With these two FETs, the device delivers very high efficiency - 500kHz switching frequency option power to the load. - External synchronization up to 2MHz on ISL85003 The ISL85003 can automatically switch between DCM and Adjustable soft-start time on the ISL85003A CCM for light-load efficiency in DCM. The switching frequency Open-drain PG window comparator in CCM is internally set to 500kHz. -Built-in protection The device provides a maximum static regulation tolerance of - Positive and negative overcurrent protection 1% over wide line, load and temperature ranges. The output - Overvoltage and thermal protection is user adjustable, with external resistors, down to 0.8V. Pulling EN above 0.6V enables the controller. The regulator supports - Input overvoltage protection prebiased output. Small 12 Ld 3mmx4mm Dual Flat No-Lead (DFN) package Fault protection is provided by internal current limiting during positive or negative overcurrent conditions, output and input Applications under and overvoltage detection and an over-temperature Network and communication equipment monitoring circuit. Industrial process control Related Literature Multifunction printers AN1935, ISL85003DEMO1Z, ISL85003ADEMO1Z Point-of-load regulators Evaluation Board User Guide Standard 12V rail supplies AN1930, ISL85003EVAL2Z, ISL85003AEVAL2Z Evaluation Embedded computing Board User Guide AN1965, Effectively Using the Intersil Small Form Factor Power Management Evaluation Boards OPTIONAL CAP NO CAP: t = 2ms SS U1 ISL85003A t = 2ms, FIXED U1 ISL85003 SS For t >2ms, ADD CAP: SS C nF = 4.1 * t ms -1.6nF C SS 2 SS C C 3 0.1F 3 0.1F 22nF L = 0.5V H = 1.20V POS EDGE 1 1 12 12 SYNC BOOT SYNC SYNC BOOT L = DE H = FPWM C 1F C 4 4 1F 11 11 2 2 PG PG VDD PG PG VDD OPEN DRAIN, ADD PULL-UP +5V OPEN DRAIN, ADD PULL-UP +5V 4.5 TO 18V 3 10 3 10 4.5 TO 18V EN EN VIN VIN EN VIN VIN EN THRESHOLD 1V, HYST 100mV THRESHOLD 1V, HYST 100mV C C C 5 5 C 6 6 +0.8V 8mV +0.8V 8mV 4 9 10F 10F GND 10F 10F GND 4 9 AGND AGND FB VIN FB VIN R R R R 1 2 1 2 301k 57.1k 5 8 301k 57.1k 5 8 C C 1 1 COMP PHASE COMP PHASE 1% 1% 1% 1% 4.7pF 4.7pF +5V +5V L L 1 1 6 7 MAX 3A 7 6 MAX 3A AGND PHASE VOUT AGND PHASE VOUT f = 500kHz 4.7H f = 500kHz 4.7H SW C C ,22F SW C ,22F 9 C 8 8 9 GND 47F GND 47F DEVICE MUST BE DEVICE MUST BE CONNECTED TO GND CONNECTED TO GND PLANE WITH 8 VIAs. PLANE WITH 8 VIAs. +5V FIGURE 1A. ISL85003 V RANGE FROM 4.5V TO 18V, V = 5V AND FIGURE 1B. ISL85003A V RANGE FROM 4.5V TO 18V, V = 5V IN OUT IN OUT AND INTERNAL COMPENSATION WITH EXTERNAL INTERNAL COMPENSATION WITH EXTERNAL SOFT-START FREQUENCY SYNC FIGURE 1. TYPICAL APPLICATION SCHEMATICS FN7968 Rev.2.00 Page 1 of 23 Jan 15, 2016 13 PGND 13 PGNDISL85003, ISL85003A Table of Contents Functional Block Diagram 3 Pin Configurations . 4 Pin Descriptions . 4 Ordering Information 5 Absolute Maximum Ratings . 6 Thermal Information . 6 Recommended Operating Conditions 6 Electrical Specifications . 6 Typical Performance Curves 8 Detailed Description 15 Operation Initialization 15 CCM Control Scheme . 15 Light-Load Operation . 15 Synchronization Control 16 Enable, Soft-Start and Disable . 16 Output Voltage Selection . 16 Protection Features . 16 Switching Regulator Overcurrent Protection . 16 Negative Current Protection . 17 Output Overvoltage Protection . 17 Input Overvoltage Protection 17 Thermal Overload Protection 17 Power Derating Characteristics 17 Application Guidelines 17 BOOT Undervoltage Detection . 17 Switching Regulator Output Capacitor Selection 17 Output Inductor Selection . 18 Input Capacitor Selection . 19 Loop Compensation Design . 19 Compensator Design Goal . 20 High DC Gain . 20 Layout Considerations 21 Revision History 22 About Intersil 22 Package Outline Drawing 23 FN7968 Rev.2.00 Page 2 of 23 Jan 15, 2016