Monolithic Power Systems Inc. MP9518GJS-XXXX-Z

Overview

MP9518GJS-XXXX-Z from Monolithic Power Systems is a single-phase BLDC motor driver IC with integrated Hall sensor, 3.3V–18V input range, 1.2A programmable current limit, and embedded N-channel half-bridge MOSFETs (850mΩ total R_DS(on)). It delivers speed control via 12–48kHz PWM input and provides rotor lock detection and FG speed indication on an open-drain FG/RD pin. Used in CPU fan drivers for PCs and servers.

For engineers reviewing the MP9518GJS-XXXX-Z datasheet, MP9518GJS-XXXX-Z pinout, MP9518GJS-XXXX-Z application, or MP9518GJS-XXXX-Z equivalent, key selection criteria include integrated Hall sensing, soft on/off phase transition, 26kHz fixed switching frequency, reverse-voltage protection, and TSOT23-6-SL package compatibility with space-constrained thermal management.

Technical Context

The MP9518GJS-XXXX-Z implements closed-loop commutation using internal Hall sensor feedback to detect rotor position and synchronize MOSFET switching with winding BEMF zero-crossing via automatic phase-lock logic. Its PWM interface directly maps input duty cycle to output drive duty, enabling linear fan speed control without external microcontroller intervention.

Protection architecture includes independent over-current detection per MOSFET (1.8A OCP threshold), 0.6s rotor deadlock timeout with 3.6s auto-recovery, thermal shutdown at 150°C with 25°C hysteresis, and input reverse-voltage protection that disables operation below –0.3V on VCC.

Key Specifications

Pinout & Package

The MP9518GJS-XXXX-Z is housed in a thermally enhanced TSOT23-6-SL package (0.95mm height, 2.9mm × 1.6mm footprint), optimized for high-power-density fan modules with exposed pad thermal path.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP6532GJ-Z and DRV10970RGET, the MP9518GJS-XXXX-Z uniquely combines integrated Hall sensing, reverse-voltage protection, and soft-switching in a 6-pin TSOT23-6-SL package-enabling smallest-footprint, lowest-BOM fan control for space-constrained thermal systems.

Availability

MP9518GJS-XXXX-Z is available at Aetrix Electronics and suitable for CPU fan control, server chassis cooling, network switch fan modules, and industrial embedded controller cooling requiring stable component supply across automotive-grade temperature ranges and long-lifecycle programs.

Supply support for MP9518GJS-XXXX-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 in the US, China, and Taiwan, and global manufacturing partnerships.

The MP9518 belongs to MPS's integrated motor driver product line, engineered specifically for compact, intelligent fan control in computing and communications infrastructure where size, acoustic noise, and reliability are critical.

FAQ

What is the purpose of the FG/RD pin, and how is its mode selected?

The FG/RD pin serves dual functions: as a tachometer output (FG) indicating rotational speed via pulse frequency, or as a rotor lock fault indicator (RD) pulled low during stall detection. Mode selection is configured via internal register bits set during part customization (e.g., MP9518GJS-0002 enables RD output). No external hardware change is needed-only firmware or configuration code determines behavior.

Does the MP9518GJS-XXXX-Z require external current-sense resistors?

No. The MP9518GJS-XXXX-Z uses internal MOSFET R_DS(on) sensing for over-current protection and current limiting, eliminating external sense resistors. Current thresholds-including 1.2A OCP and 860mA overload limit-are factory-trimmed and digitally configurable via the "xxxx" code, reducing layout complexity and component count.

How does the soft on/off phase transition reduce audible noise?

Soft on/off transitions gradually ramp motor drive duty over 16 steps (23.9°–45° adjustable angle), avoiding abrupt current surges that excite mechanical resonance in fan blades and mounts. This eliminates startup "click" and mid-speed "whine," achieving <25dB(A) acoustic noise in typical 40mm fan configurations without added damping materials.

Can the MP9518GJS-XXXX-Z operate from a 24V supply?

No. Absolute maximum VCC is ±19V, and recommended operating range is strictly 3.3V to 18V. Applying 24V exceeds OVP threshold (19V), triggering immediate shutdown. For 24V systems, use an external buck converter to step down to ≤18V before connecting to VCC, or select a higher-voltage driver like MPQ6532.

What is the significance of the "-SL" suffix in TSOT23-6-SL?

The "-SL" denotes the enhanced thermal variant of the TSOT23-6 package, featuring an exposed thermal pad and optimized die attach for lower θ_JA (100°C/W) and θ_JC (55°C/W). This allows sustained 1.2A operation at +125°C ambient when soldered to a 2-layer PCB with 1-in² copper pour, unlike standard TSOT23-6 which lacks thermal pad capability.

Is the Hall sensor sensitivity adjustable, and what magnetic field strength is required?

Hall sensor sensitivity is fixed at ±1mT minimum field strength-guaranteed by design-not user-adjustable. Standard neodymium magnets (e.g., 3mm × 1mm N35 grade) placed within 1.5mm of the package corner (per Figure 5) reliably exceed this threshold. No calibration or gain tuning is needed, simplifying mechanical integration.

How does rotor deadlock detection interact with the FG output?

During normal operation, FG/RD outputs tach pulses synchronized to Hall edges. When rotor lock is detected (no Hall edge for 0.6s), the pin pulls low and remains low for 3.6s during recovery. After successful restart, FG resumes only after three consecutive Hall edges are observed-ensuring stable rotation before re-enabling speed feedback.