Texas Instruments LM2651MTC-2.5/NOPB

Overview

LM2651MTC-2.5/NOPB from Texas Instruments is a 1.5-A synchronous step-down DC-DC switching regulator with fixed 2.5-V output, 4–14-V input range, 300-kHz fixed-frequency PWM operation, and patented current-mode control. It integrates high- and low-side MOSFETs (R_DS(on) = 75 mΩ), achieves up to 97% efficiency, and supports ultralow 7-µA shutdown current - ideal for battery-powered PDA and handheld scanner power rails.

For engineers reviewing the LM2651MTC-2.5/NOPB datasheet, LM2651MTC-2.5/NOPB pinout, LM2651MTC-2.5/NOPB application, or LM2651MTC-2.5/NOPB equivalent, key selection criteria include its 2.5-V ±2.8% output accuracy over temperature, sleep-mode hysteresis of 48 mV, 2-A cycle-by-cycle current limit, thermal shutdown at 165°C, and TSSOP-16 package compatibility with space-constrained portable designs.

Technical Context

The LM2651MTC-2.5/NOPB operates in constant-frequency (300 kHz) current-mode PWM under moderate-to-heavy loads and automatically transitions to hysteretic mode below 100-mA load to sustain >80% efficiency at 15 mA. Its patented internal current sensing eliminates external sense resistors, improving noise immunity and reducing BOM count.

It features integrated high- and low-side MOSFETs with 75-mΩ R_DS(on), bootstrap-driven high-side gate (6.7-V regulated V_BOOT), programmable soft-start via external capacitor on SD(SS), and undervoltage lockout with 3.85-V rising threshold and 210-mV hysteresis - enabling robust start-up and brownout protection in variable-input industrial and portable systems.

Key Specifications

Pinout & Package

LM2651MTC-2.5/NOPB is housed in a 16-pin TSSOP package (5.00 mm × 4.40 mm body size) with exposed thermal pad (PGND-connected) for enhanced power dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck regulator applications.

Compared with TPS5430DDAR and LM2678-2.5/NOPB, the LM2651MTC-2.5/NOPB offers the smallest solution size for 1.5-A 2.5-V applications, lowest shutdown current (7 µA), and automatic light-load mode - making it optimal for space- and battery-limited portable systems where fixed output is acceptable.

Availability

LM2651MTC-2.5/NOPB is available at Aetrix Electronics and suitable for personal digital assistants, handheld scanners, and battery-powered medical devices requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LM2651MTC-2.5/NOPB 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 and industrial-grade reliability.

The LM2651 product line was designed specifically for battery-powered portable electronics requiring high efficiency across wide load ranges, minimal external components, and robust protection - targeting PDA, scanner, and handheld instrumentation markets.

FAQ

What is the output voltage tolerance of the LM2651MTC-2.5/NOPB over temperature?

The LM2651MTC-2.5/NOPB delivers a fixed 2.5-V output with ±2.8% tolerance over the full −40°C to +125°C junction temperature range, as specified in the Electrical Characteristics table for the LM2651-2.5 variant. This corresponds to 2.43 V minimum and 2.574 V maximum at 25°C, tightening to 2.388 V–2.575 V across temperature extremes - ensuring reliable operation for 2.5-V logic and analog circuits without external trimming.

Does the LM2651MTC-2.5/NOPB require external feedback resistors?

No, the LM2651MTC-2.5/NOPB does not require external feedback resistors because it is a fixed-output variant with the 2.5-V reference internally connected to the FB pin. Unlike the adjustable LM2651-ADJ version, this part eliminates the R1/R2 divider, reducing component count, PCB area, and potential drift sources - simplifying design for dedicated 2.5-V rail applications.

What is the purpose of the VCB pin on the LM2651MTC-2.5/NOPB?

VCB is the bootstrap capacitor terminal for the high-side MOSFET gate driver. A 0.1-µF ceramic capacitor must be placed between VCB and the SW pin to generate the ~6.7-V gate drive voltage required to fully enhance the internal high-side FET. This bootstrap configuration enables efficient synchronous operation without a floating high-voltage supply, and improper VCB capacitor placement causes erratic switching or failure to start.

How does the LM2651MTC-2.5/NOPB manage efficiency at light loads?

The LM2651MTC-2.5/NOPB maintains high efficiency down to 15-mA load by automatically entering a low-power hysteretic mode when output current falls below 100 mA. In this mode, both internal MOSFETs turn off until output voltage drops to the lower hysteresis threshold (2.5 V − 48 mV), then resumes brief PWM bursts - achieving >80% efficiency at 15 mA without external control circuitry or mode-select pins.

Is the LM2651MTC-2.5/NOPB pin-compatible with other LM2651 variants?

Yes, all LM2651 variants - including LM2651MTC-1.8/NOPB, LM2651MTC-2.5/NOPB, LM2651MTC-3.3/NOPB, and LM2651MTC-ADJ/NOPB - share identical 16-pin TSSOP (PW) packaging and pinout. The only functional difference is the internal feedback reference; therefore, swapping variants requires no PCB changes, though output capacitor and inductor selection should be verified for the new voltage/current profile.