Texas Instruments LM2675N-3.3

Overview

LM2675N-3.3 from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering 3.3 V at up to 1 A output current, with ±1.5% output voltage tolerance, 260 kHz fixed-frequency operation, and 8 V to 40 V input range. It integrates a DMOS power MOSFET switch, internal frequency compensation, and thermal/current protection-designed for compact, high-efficiency power conversion in industrial and embedded systems.

For engineers reviewing the LM2675N-3.3 datasheet, LM2675N-3.3 pinout, LM2675N-3.3 application, or LM2675N-3.3 equivalent, key selection considerations include its fixed 3.3 V output, SOIC-8 package compatibility, 96% peak efficiency, TTL-compatible ON/OFF control, and minimal external component count (5 total).

Technical Context

The LM2675N-3.3 implements a synchronous-free buck topology using an integrated high-side DMOS FET with 0.3 Ω typical R_DS(ON), driven by a 260 kHz oscillator. Feedback regulation is achieved via direct connection of the FB pin to the output capacitor, eliminating external resistors-enabling precise 3.3 V setpoint maintenance across line (6.5–40 V) and load (20 mA–1 A) variations.

It operates in continuous conduction mode under full load, supports TTL-level shutdown (≤1.4 V disables, ≥1.4 V enables), and incorporates cycle-by-cycle current limiting (1.25–2.1 A), thermal shutdown, and frequency foldback during overcurrent faults-ensuring robust operation without external protection circuitry.

Key Specifications

Pinout & Package

LM2675N-3.3 is supplied in an 8-pin SOIC (D package), 4.9 mm × 6 mm body size, with exposed pad grounded for thermal performance. Pin functions are validated per TI SNVS129G Rev JUNE 2025.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2575H-3.3, LM2675N-3.3 delivers 20+ percentage points higher efficiency and half the solution size; versus TPS54331DR, it trades adjustability and current headroom for plug-and-play fixed-output deployment with fewer external parts.

Availability

LM2675N-3.3 is available at Aetrix Electronics and suitable for industrial automation, embedded computing, medical diagnostics, and automotive body electronics requiring stable component supply and long-term manufacturability.

Supply support for LM2675N-3.3 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 ICs, with decades of expertise in high-reliability power conversion solutions.

The LM2675 series belongs to TI's SIMPLE SWITCHER® family-designed specifically for engineers seeking easy-to-use, highly integrated DC-DC converters that minimize design time and external component count while delivering robust performance in harsh environments.

FAQ

What is the maximum input voltage rating for LM2675N-3.3?

The absolute maximum input voltage for LM2675N-3.3 is 45 V, but the recommended operating range is 6.5 V to 40 V per TI SNVS129G. Operation above 40 V risks permanent damage, while below 6.5 V prevents regulation. The 40 V upper limit accommodates automotive load-dump transients and industrial 24 V rail surges-making LM2675N-3.3 suitable for ruggedized applications where input stability cannot be guaranteed.

Does LM2675N-3.3 require external feedback resistors to set its output voltage?

No, LM2675N-3.3 does not require external feedback resistors. As a fixed 3.3 V version, its internal reference is hardwired to the FB pin-requiring only a direct connection from FB to the output capacitor. This eliminates resistor tolerance errors, temperature drift, and layout sensitivity associated with divider networks. The LM2675N-3.3 datasheet explicitly confirms this configuration in Figure 7-1 and Section 6.3.1, distinguishing it from the adjustable LM2675 versions that do require R1/R2 dividers.

What thermal management is needed for LM2675N-3.3 at full 1 A load?

At full 1 A load and 12 V input, LM2675N-3.3 dissipates approximately 0.5 W (based on 90% efficiency). TI specifies a junction-to-ambient thermal resistance (R_θJA) of 105°C/W for the SOIC-8 package on a standard 4-layer board with 1 in² copper. With that, temperature rise is ~53°C above ambient-well within the 125°C max junction limit. No heatsink is required; instead, ensure ≥1 in² of 2-oz copper connected to the GND pins and short, wide traces to C_IN/C_OUT. The exposed pad in PDIP variants further improves thermal performance.

Can LM2675N-3.3 be used in discontinuous conduction mode (DCM)?

Yes, LM2675N-3.3 operates naturally in discontinuous conduction mode (DCM) at light loads (<300 mA typical), as confirmed by Figure 5-16 in the datasheet. Its fixed-frequency PWM control adapts duty cycle downward until inductor current reaches zero each cycle. DCM reduces light-load quiescent current and improves efficiency below ~200 mA, but introduces higher output ripple. For applications requiring ultra-low ripple at all loads, pair LM2675N-3.3 with a post-regulating LDO or select a part with forced CCM mode.

Is LM2675N-3.3 RoHS compliant and lead-free?

Yes, LM2675N-3.3 is RoHS compliant and lead-free. Texas Instruments certifies all LM2675 variants manufactured after 2006-including the N-suffix SOIC-8 variant-as fully compliant with EU RoHS Directive 2011/65/EU and JEDEC JS-001 ESD standards. The "N" in LM2675N-3.3 denotes the green, lead-free SOIC package per TI's packaging nomenclature. Full compliance documentation, including substance declarations and test reports, is accessible via TI's Quality & Environmental page using the LM2675N-3.3 part number.