A8499 High Voltage Step-Down Regulator Features and Benefits Description 8 to 50 V input range The A8499 is a step down regulator that will handle a wide Integrated DMOS switch input operating voltage range. Adjustable fixed off-time The A8499 is supplied in a low-profile 8-lead SOIC with Highly efficient exposed pad (package LJ). Adjustable 1.2 to 24 V output Applications include: Printer power supplies Consumer equipment power supplies Package: 8-Lead SOIC with exposed thermal pad (suffix LJ) Approximate Scale 1:1 Typical Application +42 V Efficiency vs. Output Current CBOOT 90.0 0.01 F C3 C3 88.0 100 F 0.22 F 50 V 86.0 BOOT VIN 84.0 82.0 80.0 ENB LX L1 78.0 47 H VOUT A8499 3.3 V / 1.2 A V (V) OUT 76.0 TSET VBIAS 3.3 74.0 RTSET R1 5 72.0 121 k 17.8 k ESR 70.0 FB GND 0 200 400 600 800 1000 1200 1400 R2 COUT D1 10.2 k 220 F I (mA) OUT 10 V Circuit for 42 V step down to 3.3 V at 1.2 A. Efficiency data from circuit shown in left panel.Data is for reference only. A8499-DS, Rev. 5 Efficiency %+ A8499 High Voltage Step-Down Regulator Functional Block Diagram BOOT Boot Charge VIN V IN VOUT LX L1 D1 ESR COUT Switch PWM Switch C ENB Disable Clamp + TSET FB I Peak I Demand VBIAS is connected to VOUT COMP when V target is between OUT Bias Supply 3.3 and 5 V GND VBIAS UVLO Soft Start 1.2 V TSD Ramp Generation Ab so lute Max i mum Rat ings Package Thermal Characteristics* Supply Voltage, V .........................................................................50 V IN R JA VBIAS Input Voltage, V .................................................0.3 to 7 V Package PCB BIAS (C/W) Switch Voltage, V .........................................................................1 V LX LJ 35 4-layer ENB Input Voltage, V ......................................................0.3 to 7 V ENB * Additional information is available on the Allegro Web site Junction Temperature, T ....................................................... 150C J(max) Storage Temperature, T ............................................... 55C to 150C S Operating Ambient Temperature, T ............................... 20C to 85C A Ordering Information Use the following complete part numbers when ordering: a b Part Number Packing Description LJ package, SOIC surface mount with A8499SLJTR-T 13 in. reel, 3000 pieces/reel exposed thermal pad a Leadframe plating 100% matte tin. b Contact Allegro for additional packing options. Allegro MicroSystems, LLC 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com +