A8651 Low Input Voltage, Adjustable Frequency Dual Synchronous 2 A / 2 A Buck Regulator with Synchronization, 2 EN, and 2 NPOR FEATURES AND BENEFITS DESCRIPTION AEC-Q100 qualified The A8651 is an adjustable frequency, high output current, Operating voltage range: 2.5 to 5.5 V PWM regulator that integrates a high-side, P-channel MOSFET UVLO stop threshold: 2.25 V (max) and a low-side, N-channel MOSFET. The A8651 incorporates Dual outputs with up to 2 A output current per regulator current-mode control to provide simple compensation, excellent Adjustable output voltage as low as 0.8 V loop stability, and fast transient response. The A8651 uses Internal 80 m high-side switching MOSFET external compensation to accommodate a wide range of power Internal 55 m low-side switching MOSFET components to optimize transient response without sacrificing Adjustable oscillator frequency ( f ): 0.35 to 2.2 MHz stability. The A8651 regulates input voltages from 2.5 to 5.5 V, OSC Synchronizes to external clock: 1.2 to 1.5 f down to output voltages as low as 0.8 V and is able to supply OSC 180 phase shift between switching regulators up to 2 A of load current per regulator. Sleep mode supply current less than 5 A The A8651 features include an externally adjustable and Soft-start time externally set via the SS pin synchronizable switching frequency, an externally-set soft- Pre-biased startup capable start time to minimize inrush currents, independent EN inputs, Externally adjustable compensation and independent NPOR outputs with either 7.5 ms (A8651) or Stable with ceramic output capacitors 120 s (A8651-1) delay. The sleep mode current of the A8651 Independent enable inputs and NPOR output pins control circuitry is less than 5 A. Protection features include NPOR delay of 7.5 ms (A8651) or 120 s (A8651-1) VIN undervoltage lockout (UVLO), pulse-by-pulse overcurrent Adjustable current limiting (OCP) for each regulator protection (OCP), hiccup mode short-circuit protection (HIC), Hiccup mode short-circuit protection (HIC) overvoltage protection (OVP), and thermal shutdown (TSD). Overvoltage and overtemperature protection In addition, the A8651 provides open-circuit, adjacent pin Open-circuit and adjacent pin short-circuit tolerant short-circuit, and short-to-ground protection at every pin to Short-to-ground tolerant at every pin satisfy the most demanding automotive applications. Package: 20-pin TSSOP with exposed Continued on the next page thermal pad (suffix LP) APPLICATIONS: GPS/infotainment Automotive audio Home audio Not to scale Network and telecom 5 SYNCin FSET/SYNC L O1 V OUT1 1 C R SYNC FSET SW1 20 C V O1 VIN1 IN 16 R FB1 GND 18 C IN1 FB1 2 PGND1 A8651 R FB2 3 EN1 EN1 R PU1 17 COMP1 NPOR1 15 19 NPOR1 SS1 R Z1 C 4 SS1 ISET1 C L P1 O2 V OUT2 10 R SET1 C SW2 Z1 11 C VIN2 O2 R FB3 C IN2 14 9 FB2 PGND2 8 R EN2 EN2 FB4 13 R PU2 COMP2 NPOR2 12 6 SS2 R NPOR2 Z2 C 7 SS2 ISET2 C P2 R SET2 C Z2 Typical Application Diagram A8651-DS, Rev. 8 December 5, 2016Low Input Voltage, Adjustable Frequency Dual Synchronous A8651 2 A / 2 A Buck Regulator with Synchronization, 2 EN, and 2 NPOR DESCRIPTION (CONTINUED) The A8651 device is available in a 20-pin TSSOP package with exposed thermal pad for enhanced thermal dissipation (suffix LP). It is lead (Pb) free, with 100% matte-tin leadframe plating. Selection Guide Operating Ambient 1 Temperature Range Part Number Package Packing Leadframe Plating T , (C) A 2 A8651KLPTR-T 20-pin TSSOP with 4000 pieces per 40 to 125 exposed 100% matte tin 13-in. reel A8651KLPTR-T-1 thermal pad 1 Contact Allegro for additional packing options. 2 Part variant discontinued. Date of status change: September 1, 2016. Suggested replacement: A8651KLPTR-T-1. Table of Contents Specifications 2 Pre-Biased Startup 15 Absolute Maximum Ratings 3 Active Low Power-On Reset (NPORx) 16 Thermal Characteristics 3 Protection Features 16 Top-Level Functional Block Diagram 4 Undervoltage Lockout (UVLO) 16 Detailed Functional Block Diagram 5 Thermal Shutdown (TSD) 16 Pinout Diagram and Terminal List 6 Overvoltage Protection (OVP) 16 Electrical Characteristics 7 Pulse-by-Pulse Overcurrent Protection (OCP) 16 Characteristic Performance 10 Output Short Circuit (Hiccup Mode) Protection 17 Timing Diagram 12 Design and Component Selection 20 Functional Description 13 Setting the Output Voltage (V , R ) 20 OUT1 FBx Overview 13 PWM Switching Frequency (R ) 20 FSET Reference Voltage 13 Output Inductor (L ) 21 O Oscillator/Switching Frequency (R , f ) 13 FSET OSC Output Capacitors 22 Transconductance Error Amplifier 13 Input Capacitors 22 Slope Compensation 13 Soft-Start and Hiccup Mode Timing (C ) 23 SS1 ENx, VINx, and Sleep Mode 14 Compensation Components (RZ, CZ, CP) 24 Synchronization (FSET/SYNC) 14 A Generalized Tuning Procedure 26 Power MOSFETs 14 Power Dissipation and Thermal Calculations 28 Pulse Width Modulation (PWM) 14 PCB Component Placement and Routing 30 Current Sense Amplifier 14 Package Outline Diagram 33 Soft-Start (Startup) and Inrush Current Control 14 Allegro MicroSystems, LLC 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com