Texas Instruments LM2679T-5.0/NOPB

Overview

LM2679T-5.0/NOPB from Texas Instruments is a monolithic 5-A step-down (buck) switching voltage regulator with fixed 5-V output, integrated 120-mΩ DMOS power switch, 260-kHz fixed-frequency oscillator, and resistor-programmable current limit (5.5–7.6 A at 25°C). It operates from 8 V to 40 V input and delivers ±2% output voltage tolerance over full line/load/temperature range, suited for industrial power supplies and battery charger pre-regulators.

For engineers reviewing the LM2679T-5.0/NOPB datasheet, LM2679T-5.0/NOPB pinout, LM2679T-5.0/NOPB application, or LM2679T-5.0/NOPB equivalent, key selection considerations include its TO-263-7 package thermal performance (R_θJA = 26°C/W with 7.4× paddle copper), soft-start timing capacitor interface, boot-strapped high-side gate drive, and feedback pin direct connection requirement for fixed-output operation.

Technical Context

The LM2679T-5.0/NOPB implements a voltage-mode PWM controller with internal 260-kHz oscillator driving a single high-side DMOS switch. Its feedback loop uses a two-stage high-gain amplifier referenced to an internal 1.21-V bandgap, requiring direct connection of FB (pin 6) to the output for fixed 5-V operation - no external divider needed.

Current limiting is implemented via a resistor (RADJ) from Current Adjust (pin 5) to GND, setting peak switch current per I_CL = 37,125 / R_ADJ (Ω). The CB (pin 3) boot capacitor enables full enhancement of the internal MOSFET gate, while SS (pin 7) controls soft-start ramp rate via external capacitor-to-ground.

Key Specifications

Pinout & Package

LM2679T-5.0/NOPB is packaged in TO-263-7 (KTW), a surface-mount thermally enhanced variant with exposed DAP connected to pin 9 (GND). Package dimensions are 10.10 mm × 8.89 mm, optimized for PCB copper area heat spreading.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2678-5.0/NOPB, LM2679T-5.0/NOPB provides 67% higher current capability with same footprint and control architecture; versus TPS54560DGQ, it offers simpler fixed-output implementation and proven thermal robustness in TO-263, but lacks synchronous rectification and input voltage headroom.

Availability

LM2679T-5.0/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, battery charger pre-regulators, and telecom line cards requiring stable component supply with long lifecycle support and traceable sourcing.

Supply support for LM2679T-5.0/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 company specializing in analog, embedded processing, and power management ICs, with leadership in high-reliability industrial and automotive power solutions.

The LM2679 series belongs to TI's SIMPLE SWITCHER® family - designed for ease-of-use in non-isolated DC-DC conversion, minimizing external component count while maintaining high efficiency and thermal robustness across 8–40 V input ranges.

FAQ

What is the maximum input voltage rating for LM2679T-5.0/NOPB?

The absolute maximum input voltage for LM2679T-5.0/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Operation above 40 V risks exceeding internal device stress limits and may trigger overvoltage protection or cause permanent damage. Designers should maintain input transient margins below 40 V under all conditions, including cold-cranking or load-dump scenarios in industrial systems.

Does LM2679T-5.0/NOPB require an external feedback resistor divider?

No, LM2679T-5.0/NOPB does not require an external feedback resistor divider. As a fixed 5-V output variant, it contains internal precision resistors that set the feedback reference to 1.21 V. Pin 6 (FB) must be connected directly to the output capacitor's positive terminal to close the regulation loop - adding external resistors would disrupt the factory-trimmed output accuracy.

How is the current limit configured on LM2679T-5.0/NOPB?

The current limit on LM2679T-5.0/NOPB is configured by connecting a resistor (RADJ) from pin 5 (Current Adjust) to GND. With RADJ = 5.6 kΩ, the typical peak switch current is 6.3 A at 25°C, calculated as I_CL = 37,125 / RADJ. This resistor allows precise fault-current setting without external sense elements, and the limit remains active during startup, overload, and short-circuit conditions.

What thermal performance can be expected from LM2679T-5.0/NOPB in TO-263-7 package?

In the TO-263-7 (KTW) package, LM2679T-5.0/NOPB achieves R_θJA = 26°C/W when mounted on 1.0064 in² (7.4× paddle area) of 1 oz. copper. At 5-A load and 12-V input, this yields ~1.75 W conduction loss (I²R), resulting in ~46°C junction rise above ambient - well within the –40°C to 125°C operating range. Thermal derating begins above 100°C junction temperature.

Can LM2679T-5.0/NOPB operate without a soft-start capacitor?

Yes, LM2679T-5.0/NOPB can operate without a soft-start capacitor: leaving pin 7 (SS) unconnected disables the soft-start function, causing immediate full-duty-cycle startup. However, omitting the capacitor increases input surge current and may induce voltage droop on shared rails or trip upstream current limiters. For reliable system-level power sequencing, a 1-nF capacitor from SS to GND is recommended to achieve ~10-ms VOUT ramp.