Texas Instruments LM2736XMK

Overview

LM2736XMK from Texas Instruments is a monolithic, current-mode PWM step-down DC-DC regulator in a 6-pin Thin SOT-6 package (2.90 mm × 1.60 mm), delivering up to 750 mA output current with 1.6 MHz fixed switching frequency, 1.25 V internal reference (±2%), and 350 mΩ NMOS switch R_DS(ON). It enables compact point-of-load regulation in battery-powered devices, USB-powered systems, and space-constrained HDD core supplies.

For engineers reviewing the LM2736XMK datasheet, LM2736XMK pinout, LM2736XMK application, or LM2736XMK equivalent, key selection considerations include its 1.6 MHz operation enabling ultra-small external inductors (e.g., 4.7 µH), 30 nA shutdown current for low-power standby, internal soft-start (200 µs ramp), and integrated overvoltage protection triggered at FB = 1.375 V.

Technical Context

The LM2736XMK uses constant-frequency current-mode control with internal compensation, supporting stable regulation across 3.0 V–18 V input and 1.25 V–16 V adjustable output via resistor divider on FB. Its 13 ns minimum on-time enables high duty-cycle operation down to 1.25 V output even at 18 V input.

It integrates undervoltage lockout (UVLO rising threshold 2.74 V, hysteresis 440 mV), cycle-by-cycle current limit (1.5 A typical), thermal shutdown (165 °C trip), and output overvoltage protection (10% above 1.25 V reference). The BOOST pin requires ≥2.5 V above SW for optimal gate drive, with recommended V_BOOST–V_SW between 2.5 V and 5.5 V.

Key Specifications

Pinout & Package

LM2736XMK is housed in a 6-pin Thin SOT-6 (DDC) package measuring 2.90 mm × 1.60 mm × 0.95 mm, optimized for thermal performance on 2-layer PCBs (θ_JA = 204 °C/W) and high-density layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2736YMK, LM2736XMK delivers superior power density and low-VOUT capability due to its 1.6 MHz frequency and 13 ns on-time; versus TPS62231DRVR, it trades higher maximum input voltage (18 V vs. 6.5 V) and output current (750 mA vs. 600 mA) for slightly larger footprint and lower switching frequency.

Availability

LM2736XMK is available at Aetrix Electronics and suitable for USB-powered devices, battery-powered portable electronics, and HDD core power applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM2736XMK 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 logic ICs for industrial, automotive, and personal electronics markets.

The LM2736XMK belongs to TI's high-frequency, thin-package DC-DC regulator product line, engineered specifically for space-constrained, battery-aware applications demanding high efficiency, fast transient response, and minimal external components.

FAQ

What is the recommended input capacitor for LM2736XMK in a 5 V input, 3.3 V/750 mA application?

For LM2736XMK operating from 5 V input, a 10 µF, 6.3 V, X5R ceramic capacitor (e.g., TDK C3216X5ROJ106M) placed within 2 mm of VIN and GND pins is recommended. This value ensures sufficient RMS current handling (IRMS-IN ≈ 350 mA at D=0.66) and low ESL to suppress high-frequency switching noise. Larger values (e.g., 22 µF) may improve hold-up time but offer diminishing returns in ripple suppression.

Does LM2736XMK require an external bootstrap diode?

Yes, LM2736XMK requires an external Schottky diode (e.g., 1N4148W or equivalent) between VIN and BOOST to charge the bootstrap capacitor during SW low phase. The diode must support ≥50 mA peak current and exhibit ≤1 V forward drop at 10 mA to ensure reliable gate drive. Placing the diode close to the BOOST pin minimizes parasitic inductance that could degrade startup reliability.

Can LM2736XMK regulate output voltages below 1.25 V?

No, LM2736XMK cannot regulate below 1.25 V because its internal feedback reference is fixed at 1.25 V ±2%. The output voltage is set by VOUT = 1.25 V × (1 + R1/R2), so the lowest achievable output is 1.25 V (when R1 = 0 Ω). For sub-1.25 V rails, a different regulator with adjustable reference or external error amplifier is required.

How does the current limit function in LM2736XMK during overload conditions?

LM2736XMK implements cycle-by-cycle current limiting: each switching cycle measures switch current via internal sense FET and comparator. If sensed current exceeds 1.5 A (typical), the switch turns off immediately and remains off until the next oscillator cycle begins. This prevents thermal runaway during short-circuit or heavy overload while maintaining regulation under normal loads up to 750 mA.

What is the purpose of the BOOST capacitor in LM2736XMK, and what value is recommended?

The BOOST capacitor (e.g., 0.01 µF, 16 V, X7R ceramic like TDK C1005X7R1C103K) provides gate drive voltage for the internal NMOS switch. It is charged via the external BOOST diode during SW low time and supplies charge to the gate during high-side conduction. A 0.01 µF value ensures adequate charge storage for 1.6 MHz operation while minimizing board area and ESR-related losses.