Analog Devices Inc./Maxim Integrated MAX77857BEFE+

Overview

MAX77857BEFE+ 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 or 3V–15V with external resistors.

For engineers reviewing the MAX77857BEFE+ datasheet, MAX77857BEFE+ pinout, MAX77857BEFE+ application, or MAX77857BEFE+ equivalent, this device is selected for compact, thermally constrained systems requiring wide VIN range, programmable output voltage, adaptive current limiting, and integrated protection including UVLO, OCP, OVP, and thermal shutdown.

Technical Context

The MAX77857BEFE+ implements a synchronous four-switch buck-boost topology with dual LX nodes (LX1/LX2), integrated high-side and low-side MOSFETs (RDSON_HS = 20–35 mΩ, RDSON_LS = 22–43 mΩ), and automatic mode transition between buck, boost, and buck-boost regions based on VIN/VOUT ratio. Its control loop uses an error amplifier with internal compensation and supports both PWM and SKIP modes.

It integrates a 1.8V VL regulator powered from IN, a 1.08V–2.0V VIO supply domain for I²C logic, and a dedicated POK/INTB open-drain fault monitor (MAX77857B variant). Configuration is enabled via RSEL resistor selection (4 slave addresses, 4 current limits, internal/external FB choice) and prioritized I²C programming of output voltage, slew rate, switching frequency (1.1–2.27 MHz), and forced-PWM operation.

Key Specifications

Pinout & Package

MAX77857BEFE+ is packaged in a 3.5mm × 3.5mm, 16-lead Flip Chip QFN (FC2QFN) with 0.5mm pitch, optimized for thermal performance and high-current routing. The package supports JEDEC-standard reflow and does not require HDI PCB construction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ4282GL-AEC1-Z and TPS63802DLAR, MAX77857BEFE+ uniquely combines 16V input tolerance, 6A buck / 4A boost capability, and full I²C DVS within a thermally efficient 3.5mm × 3.5mm FC2QFN - making it the only option supporting USB PD 3.0 PPS negotiation and DRP port agility in space-constrained consumer electronics.

Availability

MAX77857BEFE+ is available at Aetrix Electronics and suitable for USB PD OTG power banks, Qualcomm Quick Charge smartphone subsystems, and notebook DRP port designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MAX77857BEFE+ 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 semiconductors, serving industrial, automotive, communications, and consumer markets with precision power, signal chain, and RF solutions.

The MAX77857 belongs to Analog Devices' power management IC portfolio targeting portable and USB-C ecosystem applications, specifically engineered to replace discrete buck + boost combinations in space- and thermally constrained USB PD, Quick Charge, and DRP implementations.

FAQ

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

The MAX77857BEFE+ delivers up to 6A continuous output current in buck mode and up to 4A in boost mode (with boost ratio ≤1.3). These values assume proper thermal management - junction temperature must remain ≤105°C for full 6A buck operation. The 7A typical switching current rating supports peak transient loads beyond steady-state ratings.

Does the MAX77857BEFE+ support dynamic voltage scaling (DVS) via I²C, and what is the voltage step resolution?

Yes, the MAX77857BEFE+ supports DVS over I²C. When using internal feedback resistors, output voltage is adjustable from 4.5V to 15V in precise 73.5mV steps. With external feedback, the range extends to 3V–15V, and step size depends on resistor divider ratio - enabling fine-grained USB PD Programmable Power Supply (PPS) compliance.

What package type and footprint does the MAX77857BEFE+ use, and is HDI PCB required?

The MAX77857BEFE+ uses a 3.5mm × 3.5mm, 16-lead Flip Chip QFN (FC2QFN) package with 0.5mm pitch. It does not require HDI PCB construction - standard 4-layer board design suffices, with thermal resistance θJA = 48.3°C/W measured on JEDEC JESD51-7 compliant test board.

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

The RSEL pin on the MAX77857BEFE+ accepts a single external resistor to AGND and decodes four distinct configurations: I²C slave address (0x48–0x4B), switching current limit threshold (0.99A–8.3A), and selection between internal or external feedback resistors. This enables hardware-only configuration without firmware or additional control lines.

What protection features are integrated into the MAX77857BEFE+, and how are faults reported?

The MAX77857BEFE+ integrates undervoltage lockout (UVLO), overcurrent protection (OCP), overvoltage protection (OVP), thermal shutdown (150°C), and output active discharge. Faults and Power-OK status are reported via the open-drain POKB/INTB pin (active-low), which can be pulled up to VIO with a 15kΩ resistor and monitored by host microcontroller interrupt.