A4491 Triple Output Step-Down Switching Regulator Features and Benefits Description Three buck converters in a single package Designed to provide the power supply requirements of printers, 4.5 to 23 V input voltage range office automation, industrial, and portable equipment, the 550 kHz fixed frequency A4491 provides three high current, high performance, switching Multiphase switching for smaller components and regulator outputs in a single package, saving space, cost and lower EMI component count. Independent control of each converter for sequencing and shutdown control High frequency switching allows selection of inexpensive Power-on-reset flag with adjustable delay inductors and small ceramic output capacitors. The turn-on Internal compensation to minimize components and cycles of the regulators are interleaved to minimize stresses on simply design the input capacitors and to reduce EMI. Independent Enable 4 4 mm QFN Package, small PCB footprint pins simplify power sequencing and shutdown capabilities, and a power-on-reset (POR) circuit with user configurable delay indicates when enabled regulators are in specification. Continued on the next page Package: 20-contact QFN (suffix ES) Applications: Photo, inkjet, and portable printers Set-top boxes Tablet computing Other Consumer Electronics applications Point-of-sale applications Security systems Approximate size Gaming machines Other Industrial applications Typical Application V BB VDD CP1 CP2 VCP VBB1 PORZ LX1 CPOR V REG1 FB1 Microcontroller or A4491 Controller Logic VBB2 ENB1 ENB2 LX2 V ENB3 REG2 FB2 VBB3 PGND LX3 GND V REG3 FB3 4491-DS, Rev. 1A4491 Triple Output Step-Down Switching Regulator Description (continued) The POR flag also indicates when the input voltage drops below Output current capability is 4.5A total for all 3 outputs, depending specification, giving the system controller advance warning while on the combinations of V and each V level. IN OUT the switchers continue to operate down to the shutdown level. The A4491 is provided in a 20-contact, 4 mm 4 mm, 0.75 mm Internal diagnostics provide comprehensive protection against nominal overall height QFN, with exposed pad for enhanced overloads, input undervoltages, and overtemperatures. thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating. Selection Guide Operating Temperature Range Part Number Packing (C) A4491EESTR-T 1500 pieces per 7-in. reel 40 to 85 Absolute Maximum Ratings (reference to GND) Characteristic Symbol Notes Rating Units Load Supply Voltage V 24 V BB LX1, LX2, and LX3 Pins V 1 to 24 V LXn PORZ and VDD Pins V 0.3 to 7 V IN ENBx Pin Input Current I Driven by a current-limited voltage source 1 mA ENBx Operating Ambient Temperature T Range E 40 to 85 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 To operate at V < 6 V, connect V BB DD Load Supply Voltage V supply to the V supply. See Powering 4.5 23 V BB BB Configurations section. LX1, LX2, and LX3 Pins V 0.7 23 V LXn Operating Ambient Temperature T 40 85 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 R On 4-layer PCB based on JEDEC standard 37 C/W JA *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