Monolithic Power Systems Inc. MP6508AGQ-Z

Overview

MP6508AGQ-Z from Monolithic Power Systems is a bipolar stepper motor driver IC integrating two N-channel full-bridge power stages, operating from 2.7V to 18V input voltage and delivering up to 1.2A per channel. It features internal charge pump, 250mΩ high-side R_DS(ON), 1.6mA quiescent current, and fault reporting via open-drain FAULT pin - used in compact POS printers and battery-powered camera pan/tilt mechanisms.

For engineers reviewing the MP6508AGQ-Z datasheet, MP6508AGQ-Z pinout, MP6508AGQ-Z application, or MP6508AGQ-Z equivalent, key selection criteria include its QFN-16 (3mm×3mm) thermally enhanced package, dual full-bridge gate logic control (AIN1/AIN2/BIN1/BIN2), internal constant off-time PWM current regulation, and integrated OCP/UVLO/thermal shutdown protections.

Technical Context

The MP6508AGQ-Z implements two independent full-bridge drivers with internal N-channel MOSFETs, each featuring matched 250mΩ (typ.) high-side and 235mΩ (typ.) low-side R_DS(ON) at 9V and 25°C. Its internal charge pump enables high-side gate drive without external bootstrap components.

Current regulation operates in either external PWM mode (via AIN1/AIN2/BIN1/BIN2 logic inputs) or internal constant off-time mode using external sense resistors (SENA/SENB) and a 204mV (typ.) V_REF threshold. Fault detection includes cycle-by-cycle over-current protection independent of sense resistance, thermal shutdown at 165°C, and UVLO with 2.5V rising threshold and 75mV hysteresis.

Key Specifications

Pinout & Package

The MP6508AGQ-Z is housed in a thermally enhanced QFN-16 (3mm × 3mm) package with an exposed thermal pad soldered to GND on the PCB for efficient heat dissipation. The package complies with JEDEC MO-220 VEED-4 and has MSL Level 1 rating.

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, the MP6508AGQ-Z delivers optimal balance of compact size, integrated charge pump, independent bridge fault handling, and ultra-low sleep current - making it uniquely suited for portable, battery-sensitive, and space-constrained stepper applications.

Availability

MP6508AGQ-Z is available at Aetrix Electronics and suitable for point-of-sale printers, video security cameras, digital still camera focus modules, and battery-powered educational robotics requiring stable component supply and long-lifecycle support.

Supply support for MP6508AGQ-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-efficiency power management ICs, including DC/DC converters, LED drivers, motor drivers, and battery management solutions.

The MP6508A belongs to MPS's integrated stepper motor driver product line, designed specifically for compact, low-power, and thermally constrained motion control applications in consumer and industrial edge devices.

FAQ

What is the maximum allowable motor supply voltage for MP6508AGQ-Z?

The absolute maximum VIN rating is +20V, but the recommended operating range is 2.7V to 18V. Exceeding 18V risks violating the 1V headroom limit for AOUTx/BOUTx pins relative to VIN and may trigger UVLO or damage internal structures. For 18V nominal systems, ensure transient spikes remain below 20V with proper input filtering.

How does the internal current regulation work without external PWM signals?

In internal PWM mode, the MP6508AGQ-Z uses external sense resistors (R_SENA/R_SENB) to monitor winding current. When the voltage across either resistor reaches 204mV (typ.), the high-side FET turns off. After a fixed 26µs off-time, it re-enables - creating constant-frequency, variable-duty-cycle current control independent of MCU timing resources.

Can MP6508AGQ-Z drive two independent DC motors instead of a stepper?

Yes - the dual full-bridge architecture supports independent bidirectional control of two brushed DC motors. Each bridge (A and B) accepts separate logic inputs (AIN1/AIN2 and BIN1/BIN2), enabling forward/reverse/brake functionality per motor without shared timing constraints or current sensing dependencies.

What thermal design practices are essential for 1.2A continuous operation?

To sustain 1.2A per channel, solder the exposed thermal pad directly to a solid GND plane, use ≥4 thermal vias (0.3mm diameter) under the pad connected to inner GND layers, and maintain ≥200mm² copper area on top/bottom layers. With this layout, θ_JA drops from 50°C/W to ~35°C/W, limiting junction rise to <50°C at 25°C ambient.

Is the FAULT pin compatible with 3.3V microcontrollers?

Yes - the FAULT pin is open-drain with 1µA leakage and 200mV max VOL at 1mA sink. A 10kΩ pull-up to 3.3V yields ~3.1V logic-high and <0.3V logic-low, meeting standard CMOS input thresholds. No level-shifting is required for direct interfacing with 3.3V MCUs such as STM32 or ESP32.

Does MP6508AGQ-Z support microstepping?

No - the MP6508AGQ-Z supports only full-step and half-step excitation modes via discrete logic inputs (AIN1/AIN2/BIN1/BIN2). It lacks internal indexer, clock divider, or analog current DAC required for true microstepping. For 1/4 or finer resolution, pair it with an external step/dir controller or use DRV8825/STSPIN220 instead.

What is the wake-up time from nSLEEP mode?

The typical wake-up time from nSLEEP assertion to full bridge readiness is 0.75ms, with a maximum of 0.9ms. During this interval, the internal charge pump stabilizes, VDD regulator settles, and gate drivers initialize - no additional software delay is needed before issuing first step command.