Texas Instruments LM2734YMKX

Overview

LM2734YMKX from Texas Instruments is a monolithic, current-mode PWM step-down DC-DC regulator in a Thin SOT-6 package, delivering 1-A output with internal 300-mΩ NMOS switch, 550-kHz fixed switching frequency, and 0.8-V to 18-V adjustable output voltage range. It enables compact point-of-load regulation in space-constrained battery-powered and USB-powered devices.

For engineers reviewing the LM2734YMKX datasheet, LM2734YMKX pinout, LM2734YMKX application, or LM2734YMKX equivalent, key selection criteria include input voltage range (3.0–20 V), shutdown current (30 nA), internal 0.8-V reference accuracy (±2%), soft-start timing (~200 µs), and thermal shutdown activation at 165°C.

Technical Context

The LM2734YMKX implements constant-frequency current-mode control with internal compensation, enabling stable regulation across wide input (3–20 V) and output (0.8–18 V) ranges without external loop components. Its 550-kHz oscillator supports ceramic inductors as small as 4.7 µH and chip capacitors under 10 µF.

It integrates undervoltage lockout (UVLO rising threshold 2.74 V, hysteresis 440 mV), cycle-by-cycle current limiting (1.7 A typical), overvoltage protection (10% above V_FB), and thermal shutdown (165°C trip, 150°C recovery). The BOOST pin requires ≥2.5 V above SW for optimal gate drive, with V_BOOST–V_SW limited to 5.5 V max.

Key Specifications

Pinout & Package

LM2734YMKX uses a 6-pin Thin SOT (DDC) package measuring 2.90 mm × 1.60 mm, optimized for high-density PCB layouts and thermal performance (R_θJA = 158.1°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2734ZMKX, the LM2734YMKX offers identical electrical performance but lacks automotive qualification; compared with TPS62231DRVR, it delivers higher output current and lower quiescent current at the cost of larger package and lower switching frequency - making LM2734YMKX optimal for cost-sensitive 1-A point-of-load designs requiring robust thermal behavior and proven reliability.

Availability

LM2734YMKX is available at Aetrix Electronics and suitable for local point-of-load regulation, USB-powered devices, and DSL modem power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM2734YMKX 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-reliability DC-DC conversion.

The LM2734YMKX belongs to TI's Thin SOT buck regulator product line, designed specifically for space-constrained, medium-current applications demanding high efficiency, minimal external components, and robust thermal performance in commercial and industrial environments.

FAQ

What is the maximum input voltage rating for the LM2734YMKX?

The LM2734YMKX has an absolute maximum input voltage rating of 24 V, but its recommended operating range is 3.0 V to 20 V. Exceeding 20 V may trigger undervoltage lockout hysteresis or reduce long-term reliability. For sustained operation, keep VIN ≤ 20 V per TI's recommended conditions; the 24-V absolute max is a stress limit, not a functional specification. Always verify layout thermal performance when operating near upper limits.

Does the LM2734YMKX require an external catch diode?

Yes, the LM2734YMKX requires an external Schottky catch diode (e.g., MBRM110L) connected between SW and VOUT. It does not integrate a synchronous rectifier; the diode provides the return path for inductor current during the switch-off phase. Diode selection must consider forward voltage (≤0.4 V typical), 1-A average current rating, and fast recovery to minimize losses. Omitting the diode will cause catastrophic failure due to unclamped inductive kickback at the SW pin.

How is the output voltage set on the LM2734YMKX?

The output voltage of the LM2734YMKX is set using a two-resistor feedback divider connected between VOUT, FB, and GND. With a precise 0.8-V internal reference, V_OUT = 0.8 V × (1 + R1/R2), where R1 connects to VOUT and R2 to GND. TI recommends 1% tolerance resistors (e.g., 8.87 kΩ and 10.2 kΩ for 3.3 V) and placing R2 adjacent to GND to minimize noise. The FB pin draws <250 nA, so divider current should be ≥10 µA for stability.

What is the purpose of the BOOST pin on the LM2734YMKX?

The BOOST pin on the LM2734YMKX supplies gate drive voltage to the internal 300-mΩ NMOS switch. It must be ≥2.5 V above the SW pin voltage during turn-on to ensure full R_DS(ON) performance and 1-A capability. A 0.01-µF X7R capacitor between BOOST and SW forms the bootstrap network. If V_BOOST–V_SW falls below 1.6 V, the switch cannot fully enhance, causing excessive conduction loss and potential thermal shutdown.

Can the LM2734YMKX operate without the EN pin connected?

No - the EN pin of the LM2734YMKX must not be left floating. An unconnected EN pin may float to an indeterminate voltage, causing erratic enable/disable behavior or preventing startup. TI specifies that EN must be pulled to VIN (for always-on) or to GND (for forced shutdown), or driven by a clean logic signal. A 100-kΩ pullup to VIN is acceptable for default-enable operation; never allow EN to be open-circuit in production designs.