Monolithic Power Systems Inc. MPF42791DRT-0B-0000-Z

Overview

MPF42791DRT-0B-0000-Z from Monolithic Power Systems is a 2–16 series stacked-cell lithium-ion battery pack fuel gauge IC with integrated resistance detection, thermal modeling, and 5-level LED SOC indication. It estimates per-cell and pack state-of-charge (±2.5% accuracy with MP279x AFE), state-of-health, remaining runtime, charge time, and instantaneous available power. Used in light EVs and industrial energy storage systems requiring precise, long-term battery telemetry.

For engineers reviewing the MPF42791DRT-0B-0000-Z datasheet, MPF42791DRT-0B-0000-Z pinout, MPF42791DRT-0B-0000-Z application, or MPF42791DRT-0B-0000-Z equivalent, key selection criteria include its dual I²C interface (400 kHz with CRC), adaptive learning for SOH/ESR tracking, lifetime parameter logging, 6 µA disabled-mode current, and TQFN-32 (4 mm × 4 mm) package compatibility with BMS AFEs like MP2797DFP.

Technical Context

The MPF42791 operates as a host-controlled fuel gauge co-processor, relying on external AFEs (e.g., MP279x) to supply cell voltages, pack current, and temperature data via I²C. Its internal thermal model and impedance-based resistance detection enable dynamic SOC/SOH estimation across -40°C to +85°C.

It supports two independent I²C channels: primary (for MCU-driven configuration and telemetry) and secondary (for real-time monitoring or GUI access), with CHSL pin-selectable write capability. Execution is triggered by EXE_CMD, and results are retrieved via registers such as VRDG_CELLxx and FG_SOC_PACK.

Key Specifications

Pinout & Package

The MPF42791DRT-0B-0000-Z is housed in a thermally enhanced TQFN-32 (4 mm × 4 mm) package with exposed pad (Pin 33) requiring GND connection for optimal thermal performance and EMI suppression.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery fuel gauge applications.

Compared with BQ40Z50-R1 and MAX17853, the MPF42791DRT-0B-0000-Z delivers superior thermal-aware SOC accuracy with lower quiescent current (6 µA vs. 12 µA), simpler layout (TQFN-32 vs. 48-pin LQFP), and hardware-accelerated LED control-making it optimal for space-constrained, high-volume light EV and industrial battery packs.

Availability

MPF42791DRT-0B-0000-Z is available at Aetrix Electronics and suitable for light EVs, energy storage systems, and industrial mobility applications requiring stable component supply, long-lifecycle support, and production-ready fuel gauge integration.

Supply support for MPF42791DRT-0B-0000-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance power management ICs, including DC/DC converters, battery monitors, and fuel gauges for industrial, automotive, and consumer markets.

The MPF42791 belongs to MPS's Battery Management portfolio, designed specifically for high-accuracy, multi-cell lithium-ion fuel gauging in cost-sensitive, thermally demanding applications where adaptive learning and minimal host MCU overhead are critical.

FAQ

What is the minimum system requirement to operate the MPF42791DRT-0B-0000-Z?

The MPF42791 requires an external analog front-end (e.g., MP279x) to provide individual cell voltages, pack current, and temperature readings. It also needs a host MCU with I²C interface, interrupt capability, ≥48 KB Flash, and ≥4 KB RAM to manage register reads/writes, execute EXE_CMD, and process IRQ events.

How does the MPF42791 achieve ±2.5% SOC accuracy?

This accuracy is achieved only when paired with MPS's MP279x family of battery monitors under specified conditions: 10–50°C ambient, ≤1C charge/discharge rates, and proper configuration of the thermal model and resistance detection parameters. It is not guaranteed with third-party AFEs or outside these operating ranges.

Can the MPF42791 operate without the secondary I²C interface?

Yes. The secondary I²C (SCLMON/SDAMON) is optional. All core functionality-including SOC/SOH estimation, LED control, and primary telemetry-operates using only the primary SCL/SDA interface. CHSL can remain unconnected or tied low to disable secondary writes.

What is the role of the PB (pin 1) and how is it debounced?

Pin 1 (PB) is a push-button input that triggers immediate LED SOC display when LEDS_ON_BTN is enabled. Internal hardware debouncing eliminates need for external RC filters; the device samples PB at 100 Hz and requires ≥20 ms low assertion to register a valid press.

Does the MPF42791 support custom cell chemistry models?

No. It supports common lithium-ion chemistries (e.g., NMC, LCO, LFP) via pre-characterized models stored in on-chip ROM. Custom models cannot be loaded; however, adaptive learning refines SOH/ESR parameters within those fixed chemistry frameworks based on field usage data.

How is lifetime logging implemented and what data is retained?

Lifetime logging uses on-chip non-volatile memory to store cumulative cycle count, min/max cell voltage/temperature, total charge throughput (Ah), and SOH history. Data persists across power cycles and resets, with write endurance rated for >100,000 cycles per parameter group.

What thermal design considerations apply to the TQFN-32 package?

The exposed pad (Pin 33) must be soldered to a solid GND plane with ≥4 thermal vias (0.3 mm diameter) to achieve θJC = 4.5°C/W. PCB layout must maintain ≥0.5 mm clearance from adjacent copper pours to prevent thermal coupling and ensure accurate die temperature sensing.