Texas Instruments LM2736XMK/NOPB

Overview

LM2736XMK/NOPB from Texas Instruments is a monolithic, current-mode PWM step-down DC-DC regulator in a 6-pin Thin SOT-23 package. It delivers up to 750 mA output current with 1.6 MHz fixed switching frequency, 1.25 V internal reference (±2%), 350 mΩ NMOS switch R_DS(ON), and 30 nA shutdown current - enabling compact, high-efficiency local point-of-load regulation in space-constrained USB-powered devices.

For engineers reviewing the LM2736XMK/NOPB datasheet, LM2736XMK/NOPB pinout, LM2736XMK/NOPB application, or LM2736XMK/NOPB equivalent, key selection considerations include verified 1.6 MHz operation (not 550 kHz), bootstrap gate-drive architecture requiring external BOOST capacitor, thermal shutdown at 165°C, and compatibility with ceramic output capacitors for fast transient response in battery-powered systems.

Technical Context

The LM2736XMK/NOPB implements constant-frequency current-mode control with internal compensation, supporting duty cycles from 1% to 92% across its 3.0–18 V input range. Its 13 ns minimum on-time enables stable 1.25–16 V output regulation down to low VIN, while pulse-by-pulse current limiting (1.5 A typ) and overvoltage protection (FB > 1.375 V) ensure robust fault handling.

Operation relies on external bootstrap circuitry: BOOST pin voltage must exceed SW by 2.5–5.5 V to fully enhance the internal NMOS switch, with typical BOOST current of 2.2–3.3 mA at 50% duty cycle. Soft-start ramps the error amplifier reference over ~200 µs to limit inrush current during startup.

Key Specifications

Pinout & Package

LM2736XMK/NOPB uses a 6-pin Thin SOT-23 (DDC) package measuring 2.90 mm × 1.60 mm with exposed pad for thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2736YMK/NOPB, LM2736XMK/NOPB trades slightly lower efficiency at high duty cycles for significantly smaller magnetics and faster transient response; versus TPS62231DRVR, it supports wider input range and higher current but requires careful bootstrap design and occupies more layout area due to external components.

Availability

LM2736XMK/NOPB is available at Aetrix Electronics and suitable for USB-powered devices, battery-powered instruments, notebook subsystem rails, and DSL modem power management requiring stable component supply and long-term production continuity.

Supply support for LM2736XMK/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 specializing in analog and embedded processing technologies, with leadership in power management ICs for industrial, automotive, and consumer applications.

The LM2736 product line delivers high-frequency, integrated buck regulators targeting space-constrained point-of-load applications where minimal external components and fast transient response are critical design requirements.

FAQ

What is the switching frequency of the LM2736XMK/NOPB and how does it affect component selection?

The LM2736XMK/NOPB operates at a fixed 1.6 MHz switching frequency. This high frequency enables use of small 4.7 µH surface-mount inductors and 10 µF ceramic output capacitors, significantly reducing solution size compared to lower-frequency alternatives. It also improves transient response but requires attention to PCB layout for EMI control and proper BOOST capacitor placement to maintain gate drive integrity.

Does the LM2736XMK/NOPB require an external bootstrap capacitor, and what are the critical specifications?

Yes, the LM2736XMK/NOPB requires an external 0.01 µF (10 nF) X7R ceramic capacitor between BOOST and SW pins. This capacitor must withstand ≥16 V rating and be placed as close as possible to the pins to minimize loop inductance. Insufficient BOOST capacitance or poor placement causes inadequate gate drive, leading to increased R_DS(ON), thermal stress, and potential failure under 750 mA load.

How does the enable (EN) pin function on the LM2736XMK/NOPB, and what are its voltage thresholds?

The EN pin on the LM2736XMK/NOPB controls device operation: a logic-high voltage ≥1.8 V enables regulation, while a logic-low voltage ≤0.4 V places LM2736XMK/NOPB in shutdown mode drawing only 30 nA. The pin must never exceed VIN + 0.3 V, and floating is prohibited - tie to VIN through a pull-up or to GND through a pull-down resistor in production designs.

What protection features are integrated into the LM2736XMK/NOPB?

The LM2736XMK/NOPB integrates thermal shutdown (165°C trip, ~150°C recovery), output overvoltage protection (disables switch if FB > 1.375 V), undervoltage lockout with 440 mV hysteresis (2.74 V turn-on, 2.3 V turn-off), and cycle-by-cycle current limiting (1.5 A typical). These features operate autonomously without external components, enhancing system reliability in unattended or harsh environments.

Can the LM2736XMK/NOPB regulate output voltages below 1.25 V?

No, the LM2736XMK/NOPB cannot regulate below 1.25 V because it uses a fixed 1.25 V internal reference voltage for the feedback comparator. The minimum output is set by V_OUT = 1.25 V × (1 + R1/R2); with R2 = ∞ (open), V_OUT = 1.25 V. To achieve lower outputs, an external reference or different regulator architecture is required.