Monolithic Power Systems Inc. MP6505DM-LF

Overview

MP6505DM-LF from Monolithic Power Systems is a single-phase brushless-DC motor driver IC with integrated high-side (370mΩ) and low-side (230mΩ) MOSFETs, 4.5V–16V input range, 400mA continuous output current, and built-in Hall bias (1.2V), locked-rotor protection, and thermal shutdown - used in CPU fan control circuits for personal computers and servers.

For engineers reviewing the MP6505DM-LF datasheet, MP6505DM-LF pinout, MP6505DM-LF application, or MP6505DM-LF equivalent, key selection criteria include Hall-sensor interface compatibility, programmable minimum speed via RMI pin, FG/ RD open-collector status outputs, CT-based locked-rotor recovery timing, and TSSOP16 thermal performance under 400mA load.

Technical Context

The MP6505 operates in four distinct modes-minimum speed, variable speed, full-speed, and locked-rotor protection-determined by comparisons between VTH, RMI, and COSC oscillator voltage. Speed control is achieved either by analog DC voltage or PWM applied to VTH, while rotor position is sensed differentially across IN+ and IN− with ≥3mV sensitivity.

Internal circuitry includes a 1.2V Hall bias regulator (HB), 6V reference (VREF), dual-current-source CT timer for locked-rotor detection/recovery, and input over-voltage protection triggering at 20V with 1.7V hysteresis. The driver uses commutation feedback from Hall signals to dynamically set peak current limit via GC = 9 A/V gain.

Key Specifications

Pinout & Package

MP6505DM-LF is housed in a thermally enhanced 16-pin TSSOP package (5.0mm × 6.4mm) with exposed thermal pad connected to P-GND for improved heat dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-phase BLDC motor driver applications.

Compared with MP6504DJ-LF, MP6505DM-LF delivers higher current and integrated VREF for monitoring; versus TB6612FNG, it reduces system-level firmware burden through autonomous stall recovery and Hall bias - making it optimal for embedded thermal management where reliability and integration matter.

Availability

MP6505DM-LF is available at Aetrix Electronics and suitable for CPU fan control, server chassis cooling, and embedded industrial blower applications requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP6505DM-LF 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, LED drivers, motor drivers, and battery management solutions.

The MP6505 belongs to MPS's integrated BLDC motor driver product line, designed specifically for intelligent thermal management in computing and communications infrastructure where compact size, Hall-sensor integration, and autonomous fault handling are essential.

FAQ

What is the maximum allowable input voltage for MP6505DM-LF?

The absolute maximum input voltage (VCC) is 20V, but the recommended operating range is 4.5V to 16V. Exceeding 20V risks permanent damage. Input over-voltage protection activates at 20V (rising threshold) with 1.7V hysteresis, disabling high-side switches until voltage drops below 18.3V.

Can MP6505DM-LF drive motors without an external Hall sensor?

No - the MP6505DM-LF requires differential Hall sensor feedback on IN+ and IN− to determine rotor position and enable commutation. It does not support sensorless operation. The HB pin provides 1.2V bias to power the Hall sensor, and minimum detectable Hall signal amplitude is 3mV.

How is locked-rotor protection configured and reset?

Locked-rotor detection is enabled by connecting a capacitor to the CT pin. When Hall signals stop toggling, ICT1 charges the CT capacitor until VCTH (3.63V) is reached, triggering protection. ICT2 then discharges it to 0V before retry. No external reset is required - recovery is fully autonomous.

What is the function of the RMI pin, and what happens if left unconnected?

The RMI pin sets the minimum PWM duty cycle, defining the lowest motor speed. If left unconnected, it defaults to VTH potential via internal connection, causing the device to operate in full-speed mode - eliminating minimum speed control and potentially increasing acoustic noise at low loads.

Does MP6505DM-LF support PWM speed control, and what frequency range is acceptable?

Yes - VTH accepts PWM signals up to 6V amplitude and DC-coupled frequencies up to 10kHz. For stable operation, keep PWM frequency well below the internal oscillator frequency (26–36kHz). Typical implementation uses 100Hz–1kHz PWM for smooth speed transitions without interfering with commutation timing.

Is thermal pad connection mandatory for MP6505DM-LF in TSSOP16?

Yes - the exposed thermal pad (pin NC) must be soldered to a P-GND copper pour. Thermal resistance drops significantly (θJA improves from ~110°C/W to ~90°C/W) with proper pad connection. Failure to connect it risks thermal shutdown under sustained 400mA load, especially above 60°C ambient.

What is the purpose of the VREF pin, and can it be left floating?

VREF provides a stable 6V reference (±3%) for external monitoring or ADC calibration. It sources up to 5mA. Leaving it floating is electrically permissible but wastes its utility; connecting it to a voltage divider or ADC input enables real-time supply monitoring and improves system diagnostics fidelity.