A4403 Valley Current Mode Control Buck Converter Features and Benefits Description Extremely fast load-transient response with minimal The A4403 is a buck converter that uses valley current-mode output voltage delta control. This control scheme allows very short switch on-times Achieves high step-down ratios with on-times < 50 ns to be achieved, making it ideal for applications that require User-configurable on-time, achieving switching high switching frequencies combined with high input voltages frequencies up to 2 MHz and low output voltages. Minimal external components required Low cost is accomplished through high switching frequencies Optimized for low value filter capacitors and inductors of up to 2 MHz, allowing smaller and lower value inductors Wide input voltage range: 9 to 46 V and capacitors. In addition, minimal external components are Output Current: 3 A required through high levels of integration. Optimal drive Low standby current <100 A circuits are utilized to minimize switching losses. Supplied in thermally-enhanced QFN package The switching frequency is maintained constant, as the on-time Applications: is modulated by the input voltage. This feed-forward control ensures excellent line correction. The on-time is set by an Printers, scanners Set top box external resistor pulled-up to the input supply. Cable, DSL modems/routers High power LED supply Network and telecom Battery chargers When power is initially applied and the device is enabled, a Industrial control GPS / Infotainment user-configurable soft-start function occurs to minimize inrush Distributed power systems current and to prevent output overshoot. Internal housekeeping and bootstrap supplies are provided which only require the Package 16-contact QFN (suffix EU): addition of one small ceramic capacitor. A top-off charge pump is also provide to ensure correct operation at light loads. Internal diagnostics provide comprehensive protection against overcurrents, input undervoltages, and overtemperatures. The device package is a 16-contact, 4 mm 4 mm, 0.75 mm nominal overall height QFN, with exposed pad for enhanced 4 mm 4 mm 0.75 mm thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating. Typical Application Diagram V IN 9 to 46 V BOOT V OUT VIN C2 L1 5.0 V 22 nF C1 Efficiency versus Output Current 6.3 H 3 A R1 2.2 F LX V = 42 V 100 k 100 V IN A4403 90.00 D1 TON 5 V C4 C3 ISEN 10 F 10 F 85.00 6.3 V 6.3 V 3.3 V R3 R5 DIS 80.00 50 m 3.92 k 75.00 SGND SS 70.00 C5 47 nF FB 65.00 R6 GND 750 60.00 01 23 Output Current (A) All capacitors are X5R or X7R ceramic Resistors R3 and R4 should be surface mount, low inductance type, rated at 250 mW at 70C 4403-DS, Rev. 2 Efficiency (%)Valley Current Mode Control Buck Converter A4403 Selection Guide Part Number Packing Package A4403GEU-T 92 pieces per tube 16-contact 4 mm 4 mm QFN with exposed thermal pad A4403GEUTR-T 1500 pieces per 7-in. reel Absolute Maximum Ratings (reference to GND) Characteristic Symbol Notes Rating Units VIN Pin Supply Voltage V 0.3 to 50 V IN LX Pin Switching Node Voltage V 1 to 50 V LX ISEN Pin Current Sense Voltage V 1.0 to 0.5 V ISEN DIS Pin Disable Voltage V 0.3 to 7 V DIS TON Pin On-Time Voltage V 0.3 to 50 V TON Operating Ambient Temperature T Range G 40 to 105 C A Maximum Junction Temperature T (max) 150 C J Storage Temperature T 55 to 150 C stg Recommended Operating Conditions Characteristic Symbol Conditions Min. Typ. Max. Units Supply Voltage V 9 46 V IN Switching Node V 0.7 46 V LX Switching Frequency Range f Continuous conduction mode 0.45 2 MHz SW Operating Ambient Temperature T 40 105 C A Junction Temperature T 40 125 C J Thermal Characteristics may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions* Value Units Package Thermal Resistance, Junction to Ambient R On 4-layer PCB based on JEDEC standard 36 C/W JA Package Thermal Resistance, Junction to Pad R On 4-layer PCB based on JEDEC standard 2 C/W JP *Additional thermal information available on the Allegro website. Allegro MicroSystems, LLC 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com