Texas Instruments TPS51275RUKR

Overview

TPS51275RUKR from Texas Instruments is a dual synchronous step-down controller with integrated 5-V and 3.3-V LDOs, designed for notebook and tablet power supplies. It operates from 5 V to 24 V input, delivers regulated 5 V and 3.3 V outputs (±10% adjustability), features adaptive on-time D-CAP™ control, and includes a 260-kHz VCLK output for external charge-pump gate drive.

For engineers reviewing the TPS51275RUKR datasheet, TPS51275RUKR pinout, TPS51275RUKR application, or TPS51275RUKR equivalent, key selection considerations include its auto-skip light-load operation, separate EN1/EN2 control, ±1% reference accuracy, built-in output discharge, and 20-pin 3 mm × 3 mm QFN (RUK) package with thermal pad.

Technical Context

The TPS51275RUKR implements adaptive on-time D-CAP™ control without external compensation, using internal 2.0-V reference and low-side R_DS(on) current sensing. Its two independent buck channels operate at 300 kHz (CH1, 5 V) and 355 kHz (CH2, 3.3 V) in CCM, with minimum off-time of 200–500 ns and on-time extension up to 4× (CH1) or 3× (CH2) for high-duty-cycle support.

It integrates two 100-mA LDOs: VREG3 is always-on; VREG5 is enabled by EN1 or EN2 and supports switchover to VO1 when conditions are met. Protection includes OVP (112.5–117.5%), UVP (55–65%), non-latch UVLO (VIN = 4.58 V), OTP (155 °C), and cycle-by-cycle OCP via temperature-compensated CS current sensing.

Key Specifications

Pinout & Package

TPS51275RUKR is housed in a 20-pin, 3 mm × 3 mm QFN package (RUK) with exposed thermal pad soldered to PCB ground plane for thermal management.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-buck controller applications.

Compared with TPS51275BRUKR and TPS51275CRUKR, the TPS51275RUKR offers the baseline auto-skip functionality with standard OC configuration, making it optimal for cost-sensitive notebook designs where VREG5 enable sequencing and simple OCP tuning are sufficient.

Availability

TPS51275RUKR is available at Aetrix Electronics and suitable for notebook computers, tablet computers, embedded controller power, and industrial HMI display supply requiring stable component supply and long-term production continuity.

Supply support for TPS51275RUKR 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 computing and portable electronics.

The TPS51275 family was designed specifically for high-density, cost-optimized dual-rail power solutions in thin-and-light notebooks and tablets, integrating controller, gate drivers, LDOs, and protection in a single QFN package.

FAQ

What is the primary function of the TPS51275RUKR in a power supply design?

The TPS51275RUKR serves as a dual synchronous step-down controller that generates regulated 5-V and 3.3-V outputs from a 5–24-V input. It integrates gate drivers, 100-mA LDOs (VREG3 always-on, VREG5 EN-controlled), VCLK clock output, and comprehensive protection - eliminating discrete components needed for notebook and tablet power rails. Its D-CAP™ control enables stable operation with minimal external parts.

Does the TPS51275RUKR support independent enable control for its two output channels?

Yes, the TPS51275RUKR provides separate EN1 and EN2 inputs to independently enable or disable the 5-V (CH1) and 3.3-V (CH2) buck channels. This allows precise power sequencing - for example, enabling VREG3 first, then CH2 for I/O, then CH1 for core logic - meeting Intel VR and ACPI specifications. EN thresholds are 1.6 V (ON) and 0.3 V (OFF) with ±1-µA input current.

How does the TPS51275RUKR handle light-load efficiency optimization?

The TPS51275RUKR uses auto-skip mode to reduce switching frequency during light loads, maintaining high efficiency without increasing output voltage ripple. Unlike fixed-frequency operation, auto-skip extends off-time while preserving on-time, allowing seamless transition into discontinuous conduction mode. This avoids audible noise and improves efficiency below ~10% load - critical for battery-powered notebook idle states.

What is the role of the VCLK pin on the TPS51275RUKR, and how is it used?

The VCLK pin on the TPS51275RUKR outputs a 260-kHz square wave referenced to VO1, intended to drive an external charge-pump circuit. When EN1 is asserted, VCLK activates and provides timing for generating boosted gate-drive voltage (e.g., 10–12 V) for high-side N-MOSFETs - reducing reliance on bootstrap capacitors and improving high-duty-cycle performance. If unused, the pin may be left floating.

Can the TPS51275RUKR's VREG5 LDO be powered from the 5-V output rail instead of VIN?

Yes, the TPS51275RUKR supports VREG5 switchover: when CH1 PGOOD is high, CH1 is not in overcurrent, and VO1 exceeds VREG5 − 1 V, the internal switchover MOSFET connects VREG5 to VO1 and disables the internal 5-V LDO regulator. This improves system efficiency by eliminating LDO dropout loss. VREG3 input also switches from VIN to VO1 in this state, reducing overall quiescent current.