Monolithic Power Systems Inc. MP6518GF-Z

Overview

MP6518GF-Z from Monolithic Power Systems is a bipolar stepper motor driver IC with integrated 8-N-channel MOSFETs, delivering up to 1.5A per phase across an 8V–35V supply range. It implements microstepping translation (full/half/quarter/eighth-step), features dual full-bridge PWM converters, and includes on-chip 3.3V regulator output for MCU interface power-enabling operation without external control rail. Used in precision motion control for security cameras and textile machinery.

For engineers reviewing the MP6518GF-Z datasheet, MP6518GF-Z pinout, MP6518GF-Z application, or MP6518GF-Z equivalent, key selection criteria include its TSSOP-28-EP package thermal performance, adjustable mixed-decay ratio via MDS pin, 300mΩ HS/LS R_ON, open-drain nFAULT/nHOME status reporting, and compatibility with 3.3V/5V logic interfaces.

Technical Context

The MP6518GF-Z integrates two independent full-bridge gate drivers with charge-pump high-side biasing, enabling 35V operation without external bootstrap components. Its translator core accepts STEP/DIR/MS1–MS3 inputs to generate precise current waveforms across 32 microsteps per electrical cycle, using DAC-controlled VREF scaling and external sense resistors for current regulation.

Current control employs programmable constant-off-time PWM with 2µs blanking time and configurable decay modes (slow/fast/mixed). Protection architecture includes independent over-current detection (2.5–5.5A trip), input OVP (36–40V), UVLO (6.5–7.7V), and thermal shutdown at 165°C-each asserting open-drain nFAULT.

Key Specifications

Pinout & Package

TSSOP-28-EP (9.7mm × 6.4mm) with exposed thermal pad; requires solder paste stencil optimization for GND pad thermal transfer and mechanical reliability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TB6600HG and DRV8825, the MP6518GF-Z uniquely combines single-supply operation (no external logic rail), nHOME for deterministic homing, and analog MDS-controlled decay tuning-making it optimal for compact, safety-critical industrial motion systems.

Availability

MP6518GF-Z is available at Aetrix Electronics and suitable for security camera pan/tilt mechanisms, textile machine actuators, and medical lab automation systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP6518GF-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 analog and power ICs, with design centers across Asia and North America.

The MP6518 belongs to MPS's stepper motor driver product line, engineered for industrial motion control applications demanding integrated power stages, microstepping precision, and robust fault protection in space-constrained designs.

FAQ

What is the maximum allowable motor supply voltage for MP6518GF-Z?

The absolute maximum VIN rating is 40V, but the recommended operating range is 8V to 35V. Exceeding 35V risks triggering the input over-voltage protection (OVP threshold 36–40V), which disables outputs and asserts nFAULT. Continuous operation above 35V voids reliability guarantees and may accelerate gate oxide stress in internal MOSFETs.

How does the MP6518GF-Z achieve microstepping without external controllers?

The MP6518GF-Z embeds a hardware translator that interprets STEP/DIR/MS1–MS3 logic inputs to generate precise phase current waveforms. It uses internal DACs to scale VREF and drive PWM comparators, producing sinusoidal current profiles across full/half/quarter/eighth-step modes-eliminating need for external microcontroller-based sequencing.

Can the 3.3V regulator output (3P3VOUT) power an external microcontroller?

Yes, 3P3VOUT delivers up to 10mA at 3.3V ±3%, sufficient for powering low-power MCUs (e.g., ARM Cortex-M0+) or sensor interfaces. It requires a 0.47µF ceramic capacitor to GND and must not be loaded beyond spec, as overcurrent causes dropout and destabilizes internal logic timing.

What is the purpose of the nRSET pin, and how does it differ from nHOME?

nRSET is an asynchronous reset that forces the translator to step #1 (home position) and clears all internal state; it is active-low with internal pull-down. nHOME is a status output that goes low only when the translator resides at step #1-it reflects position, not command. nRSET is used for initialization; nHOME enables closed-loop homing verification.

How does the MDS pin control decay mode, and why is this important?

MDS accepts 0–5V to set decay behavior: <2.5V enables adjustable mixed decay (fast-decay % proportional to voltage); >2.8V enables automatic decay (fast decay only when current decreases). This optimizes torque smoothness and heat generation-critical for maintaining holding torque during rapid direction reversals in precision motion systems.

Is thermal performance dependent on PCB layout, and what is required for full 1.5A operation?

Yes-θ_JA is 32°C/W on a 4-layer JEDEC board. To sustain 1.5A continuously at 35V, the exposed thermal pad must be fully soldered to a ≥2cm² internal GND plane with ≥6 thermal vias (0.3mm diameter). Without this, junction temperature exceeds 125°C, triggering thermal shutdown.

Does the MP6518GF-Z support stall detection, and if not, what alternatives exist?

No-stall detection requires current signature analysis beyond fixed-threshold OCP. However, designers can infer stall by monitoring nFAULT assertion frequency during STEP bursts or measuring VREF current deviation. For true stall detection, external current monitors (e.g., ACS712) paired with MCU firmware are recommended.