Texas Instruments LM2831YMFX

Overview

LM2831YMFX from Texas Instruments is a monolithic, high-frequency PWM step-down DC-DC regulator in SOT-23-5 package, delivering 1.5A output current with internal 130 mΩ PMOS switch, fixed 550 kHz switching frequency, and 0.6 V ±2% feedback reference voltage. It operates from 3.0 V to 5.5 V input and supports adjustable output down to 0.6 V, targeting space-constrained local power conversion in USB-powered devices and HDD core supplies.

For engineers reviewing the LM2831YMFX datasheet, LM2831YMFX pinout, LM2831YMFX application, or LM2831YMFX equivalent, key selection considerations include its 550 kHz fixed-frequency operation, SOT-23-5 thermal performance (θ_JA = 118 °C/W), 30 nA shutdown current, current-mode control architecture, and compatibility with ceramic output capacitors for fast transient response.

Technical Context

The LM2831YMFX employs current-mode PWM control with internal compensation, enabling stable regulation across load and line variations without external loop components. Its 550 kHz switching frequency-internally fixed per variant-supports compact magnetics while maintaining >93% peak efficiency at 1.5 A output.

It integrates pulse-by-pulse current limiting (typ. 2.5 A), thermal shutdown (165 °C), output overvoltage protection (15% above V_FB), and internal soft-start (≈600 µs ramp). The 0.6 V reference and 2% tolerance enable precise output setting via external resistor divider, with FB bias current <100 nA ensuring minimal divider error.

Key Specifications

Pinout & Package

SOT-23-5 package (NSC drawing MF05A, top mark SKZB), thermally enhanced with exposed pad not present - requires standard SOT-23 footprint and reflow profile.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Compared with LM2831YMFX, TPS62231DRVR offers higher switching frequency and lower active IQ but adds complexity with external FET drive; MP2101DQ-LF-Z provides wider input range and same R_DS(ON), yet omits integrated OVP and thermal shutdown - making LM2831YMFX preferable where robustness and simplicity are prioritized.

Availability

LM2831YMFX is available at Aetrix Electronics and suitable for USB-powered devices, HDD core power supplies, and DSL modem subsystems requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for LM2831YMFX 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-efficiency DC-DC conversion.

The LM2831YMFX belongs to TI's monolithic buck regulator product line, designed specifically for compact, high-current point-of-load applications in portable and space-constrained electronics where integration, thermal efficiency, and ease of use are critical.

FAQ

What is the switching frequency of the LM2831YMFX?

The LM2831YMFX has a fixed internal switching frequency of 550 kHz. This value is factory-set and cannot be adjusted externally. It is optimized to balance inductor size, efficiency, and transient response for 1.5 A loads in SOT-23-5 packaging. The 550 kHz frequency enables use of standard 4.7 µH shielded inductors and avoids audible noise while maintaining >93% peak efficiency at 5 V input to 3.3 V output.

Does the LM2831YMFX require external compensation components?

No, the LM2831YMFX uses internally compensated current-mode control, eliminating the need for external compensation networks. This simplifies design and reduces BOM count - only five external components (inductor, Schottky catch diode, input capacitor, output capacitor, and feedback resistor divider) are required for full operation. The internal compensation ensures stability across the full 0.6 V–4.5 V output range and 3.0 V–5.5 V input range with standard ceramic capacitors.

What is the maximum output current capability of the LM2831YMFX?

The LM2831YMFX delivers up to 1.5 A continuous output current under typical conditions (T_A = 25 °C, 5 V input, 3.3 V output, proper PCB thermal design). Its 130 mΩ internal PMOS switch and thermal shutdown (165 °C) protect against overload. Peak current limit is typ. 2.5 A, and minimum guaranteed limit is 1.8 A across temperature and input voltage - sufficient to handle transient loads in HDD and USB applications without derating.

Can the LM2831YMFX operate with a 3.3 V input supply?

Yes, the LM2831YMFX supports input voltages from 3.0 V to 5.5 V, making it fully compatible with 3.3 V rails. At 3.3 V input, it can regulate down to 0.6 V output with duty cycle up to ~96%, provided the output current remains within thermal limits. Efficiency remains >85% at 1.5 A load (3.3 V → 1.2 V), and the 550 kHz frequency ensures stable operation without requiring special layout adjustments beyond standard high-frequency buck practices.

What protection features are integrated into the LM2831YMFX?

The LM2831YMFX integrates pulse-by-pulse current limiting (typ. 2.5 A), thermal shutdown (165 °C), output overvoltage protection (triggered at 15% above 0.6 V reference), undervoltage lockout (2.73 V rising threshold), and internal soft-start (≈600 µs). These features eliminate the need for external protection circuitry in most applications, reducing design risk and component count while ensuring reliable startup, fault recovery, and safe operation under abnormal conditions.