Analog Devices Inc./Maxim Integrated MAX77857BEFE+T

Overview

MAX77857BEFE+T from Analog Devices is a high-efficiency, I²C-programmable buck-boost converter designed for USB PD OTG, Quick Charge, and dual-role power (DRP) ports. It operates across 2.5V–16V input, delivers up to 6A in buck mode and 4A in boost mode (boost ratio ≤1.3), features 7A switching current capability, and supports dynamic voltage scaling (DVS) from 4.5V to 15V using internal feedback resistors.

For engineers reviewing the MAX77857BEFE+T datasheet, MAX77857BEFE+T pinout, MAX77857BEFE+T application, or MAX77857BEFE+T equivalent, this device enables precise output voltage control, programmable slew rate, selectable switching frequency (1.1–2.27 MHz), configurable current limiting (0.99A–8.3A), and integrated protection including UVLO, OVP, OCP, and thermal shutdown - critical for compact, thermally constrained portable power designs.

Technical Context

The MAX77857BEFE+T implements a synchronous four-switch buck-boost topology with dual high-side/low-side MOSFETs (RDSON_HS = 20–35 mΩ, RDSON_LS = 22–43 mΩ) and integrated gate drivers. Its architecture supports seamless transition between buck and boost modes without discontinuity, enabled by real-time monitoring of VIN, VOUT, and load conditions.

It integrates an I²C interface (Fast Mode/Plus/High-Speed compatible) with priority over RSEL-configured settings, supporting dynamic DVS ramping (programmable slew rates from 1/6 to 4/3 mV/µs), FPWM mode forcing, and fault interrupt masking. The SEL pin decodes resistor values to set slave address, current limit threshold, and feedback configuration - enabling hardware-defined defaults before I²C initialization.

Key Specifications

Pinout & Package

MAX77857BEFE+T is packaged in a 3.5mm × 3.5mm, 16-lead Flip Chip QFN (FC2QFN) with 0.5mm pitch, optimized for high-density PCB layouts and thermal performance (θJA = 48.3°C/W on 4-layer board).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck-boost converter applications.

Compared with MP2965GQ-Z and TPS63900RSVR, the MAX77857BEFE+T uniquely combines wide 2.5V–16V input, 6A buck/4A boost capability, full I²C programmability, and USB PD-compliant features - making it the only option among the three suitable for next-generation mobile DRP and fast-charging applications requiring runtime adaptability.

Availability

MAX77857BEFE+T is available at Aetrix Electronics and suitable for USB PD OTG power banks, Qualcomm Quick Charge smartphone subsystems, and USB-C dual-role power (DRP) ports requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MAX77857BEFE+T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and consumer markets with precision power, sensing, and connectivity solutions.

The MAX77857 belongs to Analog Devices' high-density power management IC portfolio, engineered specifically for portable electronics requiring compact, efficient, and software-configurable buck-boost regulation - especially in USB-C, fast-charging, and dual-role power applications.

FAQ

What is the maximum output current capability of the MAX77857BEFE+T in buck and boost modes?

The MAX77857BEFE+T delivers up to 6A continuous output current in buck mode and up to 4A in boost mode when the boost ratio is ≤1.3. These ratings assume proper thermal management - junction temperature must remain ≤105°C for sustained 6A operation. The 7A typical switching current supports peak inductor current handling and transient response without saturation.

Does the MAX77857BEFE+T support dynamic voltage scaling (DVS) and how is it implemented?

Yes, the MAX77857BEFE+T supports full dynamic voltage scaling via its I²C interface. Output voltage is adjusted by programming the internal reference voltage (VREF) register (0x3D–0xCC, 0.299V–1.000V), which scales the feedback loop. With internal feedback resistors, DVS ranges from 4.5V to 15V in ~73.5mV steps; with external resistors, the range extends to 3V–15V, with step size determined by resistor ratio.

What package type and footprint does the MAX77857BEFE+T use, and what are its thermal characteristics?

The MAX77857BEFE+T uses a 3.5mm × 3.5mm, 16-lead Flip Chip QFN (FC2QFN) package (package code F163A3F+1). Its thermal resistance is θJA = 48.3°C/W on a standard 4-layer PCB per JEDEC JESD51-7. The exposed thermal pad must be soldered to a solid copper pour for optimal heat dissipation in high-current applications.

How does the SEL pin function on the MAX77857BEFE+T, and what parameters does it configure?

The SEL pin on the MAX77857BEFE+T accepts a single external resistor to AGND, decoding four distinct configurations. It sets the I²C slave address (four options), switching current limit threshold (four hardware-selectable levels), and feedback resistor selection (internal or external). This enables deterministic startup behavior before I²C communication begins.

Is the POKB/INTB pin available on the MAX77857BEFE+T, and what functionality does it provide?

Yes, the MAX77857BEFE+T is a MAX77857B variant and includes the POKB/INTB pin - an open-drain, active-low output that signals Power-OK status or fault interrupt conditions (OVP, OCP, thermal shutdown). It requires a 15kΩ pullup to VIO and is masked/enabled via I²C register control, allowing flexible system-level fault handling and sequencing.