Monolithic Power Systems Inc. MP6501AGF

Overview

MP6501AGF from Monolithic Power Systems is a bipolar stepper motor driver IC with integrated dual full-bridge N-channel MOSFETs, supporting 8V–35V supply, 2.5A peak output current per bridge, eighth-step microstepping, and on-chip 3.3V regulator for controller-free operation. It delivers precise current control via external sense resistors and programmable constant off-time PWM in printers, CNC stages, and automated lab equipment.

For engineers reviewing the MP6501AGF datasheet, MP6501AGF pinout, MP6501AGF application, or MP6501AGF equivalent, key selection criteria include its TSSOP-28 EP package thermal performance, dual-bridge R_DS(on) of 220 mΩ (HS/LS), adjustable mixed decay ratio, fault reporting via open-drain nFAULT, and compatibility with 3.3V/5V logic interfaces without auxiliary supply.

Technical Context

The MP6501AGF implements a translator-based microstepping architecture with MS1–MS3 inputs selecting full/half/quarter/eighth-step modes, generating 32 discrete current steps per electrical cycle. Its DAC-driven current regulation uses VREF and external R_SENSE to set trip thresholds with ±5% accuracy at 100% scale.

It employs a charge pump (CPA/CPB/VCP) to drive high-side gates, supports automatic and mixed decay modes controlled by MDS voltage, and integrates independent over-current protection (OCP), input over-voltage protection (OVP), UVLO, and thermal shutdown - all signaled via nFAULT.

Key Specifications

Pinout & Package

TSSOP-28 EP (9.7mm × 6.4mm) with exposed thermal pad soldered to PCB ground plane for enhanced thermal dissipation (θ_JA = 32°C/W, θ_JC = 6°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bipolar stepper motor driver applications.

Compared with TB6600HG and DRV8825, MP6501AGF uniquely combines integrated 3.3V regulation, eighth-step resolution, OVP, nHOME, and TSSOP-28 thermal efficiency - making it optimal for space-constrained, self-contained stepper systems needing robust fault signaling and supply flexibility.

Availability

MP6501AGF is available at Aetrix Electronics and suitable for printer motion control, CNC axis actuation, automated lab instrumentation, and 3D printer extruder positioning requiring stable component supply across production lifecycles.

Supply support for MP6501AGF 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 analog and power ICs, with design centers in the US, China, and Taiwan.

The MP6501AGF belongs to MPS's stepper motor driver product line, engineered for compact, thermally efficient motion control in industrial automation and precision equipment where integrated MOSFETs and self-contained logic supply reduce system-level complexity.

FAQ

What is the maximum allowable voltage on the VREF pin?

The VREF pin accepts 0V to 3.3V. Exceeding 3.3V risks damaging the internal DAC and current comparator. It is typically tied to the 3P3VOUT pin or an external precision reference. The full-scale current limit is calculated as I_LIM = 5 × V_REF / R_SENSE, so accurate VREF voltage directly determines motor current accuracy.

How does the nSLEEP function interact with the 3.3V regulator?

When nSLEEP is driven low, the internal charge pump and 3P3VOUT regulator halt immediately, dropping the 3.3V output. All logic and gate drivers disable, and quiescent current falls to 1µA. After waking (nSLEEP high), allow ≥1ms for regulator stabilization before issuing STEP commands to ensure reliable translator operation.

Can MP6501AGF drive unipolar stepper motors?

No. MP6501AGF is designed exclusively for bipolar stepper motors with center-tapped or dual-winding configurations. Its dual full-bridge topology requires four-terminal connections (AOUT1/AOUT2/BOUT1/BOUT2) and cannot interface with the five- or six-wire unipolar motor wiring scheme or its single-coil activation method.

What is the purpose of the blanking time (t_BLANK)?

t_BLANK = 2µs is a fixed internal delay after each bridge switching event that disables the current sense comparator. This prevents false OCP triggering caused by reverse-recovery spikes in MOSFET body diodes or parasitic LC ringing, ensuring stable PWM regulation even with fast-switching or high-inductance windings.

How is thermal performance affected by the exposed pad connection?

The exposed thermal pad on the TSSOP-28 EP package must be soldered to a dedicated PCB copper pour tied to GND. Without this connection, θ_JA degrades from 32°C/W to >60°C/W, risking thermal shutdown at ≤1.5A continuous load. Proper pad layout with ≥4 thermal vias to inner ground planes is essential for sustained 2.5A operation.

Does MP6501AGF support stall detection?

No. Stall detection requires real-time back-EMF or current signature analysis beyond MP6501AGF's capabilities. It provides only over-current, over-voltage, UVLO, and thermal fault flags via nFAULT. For stall detection, external current monitoring with MCU firmware or dedicated stall-detect ICs (e.g., TMC2130) are required.

What happens during automatic decay mode when current demand decreases?

In automatic decay mode (MDS > 2.8V), if the new DAC-set current level is lower than the previous step, the device enters mixed decay with 30% fast-decay ratio for the entire off-time. This rapidly reduces winding current to match the lower target, minimizing settling time and improving step response fidelity.