Texas Instruments LM2677S-5.0/NOPB

Overview

LM2677S-5.0/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC voltage regulator with integrated 100-mΩ DMOS power switch, delivering up to 5 A output current at a fixed 5 V output. It operates from 8 V to 40 V input, achieves up to 92% efficiency, and supports internal 260-kHz or external 280–400-kHz synchronization - used in battery chargers, communications equipment, and industrial power supplies.

For engineers reviewing the LM2677S-5.0/NOPB datasheet, LM2677S-5.0/NOPB pinout, LM2677S-5.0/NOPB application, or LM2677S-5.0/NOPB equivalent, key selection considerations include its ±2% output tolerance over line/load/temperature, 50-μA standby current in shutdown mode, thermal shutdown and current-limit protection, and TO-263-7 (KTW) package with exposed thermal pad for high-power dissipation.

Technical Context

The LM2677S-5.0/NOPB implements a fixed-frequency PWM buck controller with internal 260-kHz oscillator and optional external sync input (pin 5), enabling precise ripple frequency control for EMI-sensitive radio and comms systems. Its high-side DMOS switch features 0.14 Ω typical R_DS(ON) at 25°C, supporting continuous 5-A output with thermal shutdown and cycle-by-cycle current limiting.

Feedback is internally trimmed for 5-V fixed output - pin 6 (FB) connects directly to output capacitor - eliminating external resistor dividers. The ON/OFF pin (pin 7) provides logic-level enable/disable with 1.4-V threshold and 50-μA quiescent draw in shutdown, while the CB pin (pin 3) requires a 0.01-μF bootstrap capacitor to drive the high-side gate above VIN.

Key Specifications

Pinout & Package

LM2677S-5.0/NOPB is packaged in a 7-pin TO-263 (KTW) surface-mount package with an exposed thermal pad (DAP) for enhanced heat dissipation. Dimensions: 10.16 mm × 8.69 mm × 4.83 mm. The DAP must be soldered to a PCB ground plane per AN-1187 guidelines.

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, LM2677S-5.0/NOPB delivers 67% higher current capacity and superior thermal performance in TO-263; versus TPS54560BQPWPRQ1, it offers simpler external component count and lower cost but lacks synchronous rectification and automotive qualification.

Availability

LM2677S-5.0/NOPB is available at Aetrix Electronics and suitable for battery charging systems, industrial power preregulation, communications equipment, and ruggedized embedded systems requiring stable component supply and long-term manufacturability.

Supply support for LM2677S-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 headquartered in Dallas, Texas, designing and manufacturing analog, embedded processing, and digital signal processing technologies since 1930.

The LM2677S-5.0/NOPB belongs to TI's SIMPLE SWITCHER® family - engineered for ease of use in high-current DC-DC conversion, minimizing external components while maintaining robust thermal and electrical performance across industrial and communications applications.

FAQ

What is the maximum input voltage rating for LM2677S-5.0/NOPB?

The absolute maximum input voltage for LM2677S-5.0/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Operation beyond 40 V risks exceeding safe operating area limits and may trigger overvoltage protection or cause permanent damage. Designers should maintain at least 5-V margin below 45 V for reliability across temperature and transient conditions. LM2677S-5.0/NOPB includes internal clamping to protect against brief overvoltage events within datasheet limits.

Does LM2677S-5.0/NOPB require an external feedback resistor divider?

No, LM2677S-5.0/NOPB does not require an external feedback resistor divider. As a fixed 5-V output variant, its internal reference and gain network are factory-trimmed - pin 6 (FB) must be connected directly to the output capacitor. Adding external resistors would disrupt regulation and cause output deviation. This simplifies layout and improves accuracy versus adjustable versions like LM2677-ADJ. LM2677S-5.0/NOPB relies solely on this direct FB-to-VOUT connection for stable 5-V operation.

Can LM2677S-5.0/NOPB synchronize to an external clock, and what are the requirements?

Yes, LM2677S-5.0/NOPB supports external synchronization via pin 5 (SYNC). The external clock must be TTL- or CMOS-compatible (0 V to >3 V), have 50% duty cycle, and operate between 280 kHz and 400 kHz. TI recommends AC-coupling through a 100-pF capacitor and pulling pin 5 to ground with a 1-kΩ resistor. Using SYNC disables current-limit foldback, so short-circuit protection remains active but frequency-dependent. LM2677S-5.0/NOPB defaults to 260-kHz internal operation if SYNC is left open.

What thermal management guidance applies to LM2677S-5.0/NOPB in TO-263 package?

LM2677S-5.0/NOPB in TO-263 (KTW) package requires soldering the exposed thermal pad (DAP) to a minimum 0.136 in² copper area for R_θJA ≈ 56°C/W; increasing copper to 0.4896 in² reduces it to 35°C/W. Thermal vias under the DAP improve heat transfer to inner layers. Layout must minimize trace inductance on VIN/GND paths and avoid routing sensitive signals near VSW. LM2677S-5.0/NOPB includes thermal shutdown at ~165°C with hysteresis - sustained operation above 125°C junction temperature degrades reliability.

How does the ON/OFF pin function on LM2677S-5.0/NOPB, and what voltage thresholds apply?

The ON/OFF pin (pin 7) enables or disables LM2677S-5.0/NOPB. A voltage ≥1.4 V (typical) turns the regulator ON; <0.8 V (min) forces shutdown with 50-μA quiescent current. The pin has an internal 20-μA pullup and 7-V Zener clamp. Driving it externally requires staying within 0–6 V absolute max. Leaving it floating enables the device. This pin supports power sequencing, remote control, and low-power sleep modes - critical for battery-operated systems using LM2677S-5.0/NOPB as main supply.