Texas Instruments LM2734ZSDX

Overview

LM2734ZSDX from Texas Instruments (formerly National Semiconductor) is a monolithic 3 MHz PWM step-down DC-DC regulator in a 6-lead LLP (3 mm × 3 mm) package, featuring an internal 300 mΩ NMOS switch, 1 A output current capability, 0.8 V ±2% reference, and 30 nA shutdown current. It delivers point-of-load regulation for space-constrained battery- and USB-powered systems.

For engineers reviewing the LM2734ZSDX datasheet, LM2734ZSDX pinout, LM2734ZSDX application, or LM2734ZSDX equivalent, key selection criteria include its fixed 3 MHz switching frequency, internal current-mode control with no external compensation, 3 V to 20 V input range, and thermal/overvoltage/current-limit protection - all critical for compact, high-efficiency 1 A buck designs.

Technical Context

The LM2734ZSDX employs constant-frequency current-mode PWM control with internal compensation, enabling stable regulation across 3 V–20 V input and 0.8 V–18 V output without external loop components. Its 13 ns minimum on-time supports high duty-cycle operation down to 0.8 V output even at 20 V input.

It integrates a 300 mΩ NMOS power switch (TSOT-6) or 340 mΩ (LLP), 0.8 V 2% internal reference, pulse-by-pulse current limit (1.7 A typ), thermal shutdown (165°C), and output overvoltage protection (10% above V_FB). The BOOST pin requires external bootstrap capacitor and diode for gate drive.

Key Specifications

Pinout & Package

The LM2734ZSDX is packaged in a 6-lead LLP (3 mm × 3 mm, NS Package Number SDE06A) with exposed thermal pad (DAP) internally connected to GND. This thermally enhanced package supports higher power density than TSOT-6 in space-limited layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2734ZSDX, TPS62130ARGTR eliminates the BOOST circuit and improves light-load efficiency, while MP2307DN-LF-Z offers higher current and input voltage at the cost of added design complexity and larger footprint.

Availability

LM2734ZSDX is available at Aetrix Electronics and suitable for DSL modems, USB-powered devices, and battery-powered instrumentation requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for LM2734ZSDX 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 acquired National Semiconductor in 2011 and maintains its analog power portfolio with rigorous qualification and long-term support.

The LM2734Z series belongs to TI's high-frequency monolithic buck regulator product line, designed specifically for space-constrained, medium-current point-of-load applications where simplicity, small solution size, and fast transient response are prioritized over ultra-low quiescent current or synchronous rectification.

FAQ

What is the package type and thermal pad configuration of the LM2734ZSDX?

The LM2734ZSDX uses a 6-lead LLP package (3 mm × 3 mm, NS Package Number SDE06A) with an exposed die attach pad (DAP) internally connected to GND. This pad must be soldered to a dedicated thermal land on the PCB with ≥4 thermal vias to a solid internal GND plane to maintain junction temperature within −40°C to +125°C operating range. The DAP is not electrically isolated and serves solely for heat dissipation.

Does the LM2734ZSDX require an external Schottky diode, and why?

Yes, the LM2734ZSDX requires an external Schottky catch diode (e.g., BAT54, SS14) connected between SW and GND. Because it is a nonsynchronous buck converter, the internal NMOS switch turns off during the off-time, and the inductor current must be recirculated through this external diode. A low-forward-voltage Schottky minimizes conduction loss - typical diode loss accounts for ~150 mW at 1 A - directly impacting overall efficiency and thermal performance of the LM2734ZSDX.

What is the minimum recommended output capacitance for stable operation of the LM2734ZSDX?

The LM2734ZSDX requires a minimum of 10 µF ceramic output capacitance (X5R or X7R dielectric) placed close to the IC. This value ensures loop stability, adequate transient response, and acceptable output voltage ripple - especially critical given its 3 MHz switching frequency and internal compensation. Using less than 10 µF risks instability or excessive overshoot during load steps; increasing capacitance beyond 10 µF is permissible and improves transient margin without compromising stability of the LM2734ZSDX.

How does the BOOST pin function, and what external components are mandatory?

The BOOST pin supplies gate drive voltage to the internal NMOS switch via a bootstrap circuit. A 0.01 µF X7R ceramic capacitor must be placed between BOOST and SW pins, and a Schottky or small-signal diode (e.g., BAT54) must connect VIN (or VOUT) to BOOST. This arrangement generates a voltage ~1.6–5.5 V above SW to fully enhance the NMOS. Omitting or misrouting these components will cause the LM2734ZSDX to fail to regulate or exhibit intermittent dropout under load.

Can the LM2734ZSDX operate with an input voltage below 3 V, and what happens if VIN drops during operation?

No, the LM2734ZSDX cannot operate below 3 V input - its absolute minimum operating VIN is 3 V per datasheet specifications. If VIN falls below 2.74 V (UVLO rising threshold), the LM2734ZSDX disables switching and enters undervoltage lockout. With ~440 mV hysteresis, it remains disabled until VIN rises above ~2.3 V, preventing oscillation during marginal input conditions. Attempting to operate below 3 V risks unregulated output, excessive junction heating, or failure to start up reliably.