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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear + Switching

Texas Instruments TPS51275B-1RUKR

Name: TPS51275B-1RUKR
Brand: Texas Instruments
SKU: TPS51275B-1RUKR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TPS51275B-1RUKR

Manufacturer:: Texas Instruments

Category:: Voltage Regulators - Linear + Switching

Package:: 20-WFQFN Exposed Pad

Datasheet:: TPS51275B-1RUKR.pdf

Description:: IC REG QUAD BUCK/LNR SYNC 20WQFN

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Product details

Overview

TPS51275B-1RUKR from Texas Instruments is a dual synchronous buck controller with integrated 5-V/100-mA and 3.3-V/100-mA always-on LDOs, adaptive on-time D-CAP™ control, 300-kHz (CH1) and 355-kHz (CH2) switching frequencies, and 260-kHz VCLK output for external charge-pump gate drive - designed for notebook system power rails requiring tight regulation, fast transient response, and high light-load efficiency.

For engineers reviewing the TPS51275B-1RUKR datasheet, TPS51275B-1RUKR pinout, TPS51275B-1RUKR application, or TPS51275B-1RUKR equivalent, key selection considerations include its dual-channel independent enable (EN1/EN2), ±1% VFB reference accuracy, OOA light-load mode, low-side R_DS(on) current sensing, and 20-pin 3-mm × 3-mm WQFN (RUK) package with thermal pad.

Technical Context

The TPS51275B-1RUKR implements adaptive on-time D-CAP™ control without external compensation, using internal 2-V reference and valley-current sensing via CS1/CS2 pins to set overcurrent thresholds. Its two independent buck channels operate at fixed nominal frequencies (300 kHz CH1, 355 kHz CH2) with input voltage feed-forward to maintain stable on-time across 5–24 V VIN.

Light-load operation transitions smoothly into Out-of-Audio (OOA) mode-forcing minimum 40-µs switching intervals to avoid audible noise-while built-in soft-start (3.2 ms), output discharge, and combined PGOOD signaling support robust system sequencing in portable computing platforms.

Key Specifications

Parameter	Value and Actual Design Meaning
VIN Range	5 V to 24 V - supports wide-input notebook adapter and battery-supplied rails without pre-regulation.
Output Voltages	5 V ±10% (CH1) and 3.3 V ±10% (CH2) - adjustable via external resistor dividers on VFB1/VFB2.
Switching Frequencies	CH1: 300 kHz typ. (240–360 kHz), CH2: 355 kHz typ. (280–430 kHz) - enables optimized inductor sizing and EMI management.
VFB Reference Accuracy	±1% over –40°C to 85°C - ensures precise output regulation under thermal stress and load transients.
LDO Outputs	VREG5: 5 V / 100 mA; VREG3: 3.3 V / 100 mA - always-on, UVLO-protected supplies for gate drivers and analog circuitry.
VCLK Output	260 kHz square wave - drives external charge pump to generate high-side gate voltage without efficiency penalty.
OCP Sensing	Temperature-compensated R_DS(on) sensing via CS1/CS2 - eliminates sense resistors; 4500 ppm/°C I_CS slope matches MOSFET drift.
Protection Features	OVP (115% trip), UVP (60% trip), OTP (155°C shutdown), non-latch UVLO - ensures safe fault recovery in multi-rail systems.

Pinout & Package

TPS51275B-1RUKR is housed in a 20-pin, 3-mm × 3-mm WQFN package (RUK) with exposed thermal pad soldered to PCB ground plane for enhanced thermal performance (R_θJA = 94.1°C/W).

Pin/Terminal	Circuit Role	Design Meaning
CS1, CS2	Overcurrent threshold setting inputs	Sink 10 µA current (temp-compensated); connect to GND via RCS to set valley OCL trip voltage (0.2–2 V range).
DRVH1, DRVH2	High-side gate drivers	Drive external N-channel MOSFET gates; bootstrap-supplied via VBST1/VBST2 capacitors tied to SW1/SW2.
DRVL1, DRVL2	Low-side gate drivers	Drive synchronous rectifier MOSFETs; sink/source capability supports zero-cross detection and DCM transition.
VFB1, VFB2	Feedback inputs	Monitor regulated outputs via resistor dividers; internal 2-V reference enables ±1% output accuracy.
EN1, EN2	Independent channel enables	Logic-level inputs (1.6 V ON, 0.3 V OFF); support staggered startup and dynamic rail sequencing.
VCLK	Charge-pump clock output	260-kHz open-drain signal referenced to VO1; active only when EN1 = high.
PGOOD	Combined power-good flag	Open-drain output pulled high externally; asserts high only when both CH1 and CH2 outputs are within 95–110% window.
VREG5, VREG3	Integrated LDO outputs	Always-on 5-V/100-mA and 3.3-V/100-mA supplies; power gate drivers (VREG5) and internal analog blocks (VREG3).
VO1	5-V switchover input	Enables VREG5 switchover: when CH1 PGOOD is high and VO1 > VREG5 − 1 V, internal MOSFET connects VO1 to VREG5.
Thermal Pad	Ground connection	Must be soldered to solid PCB ground plane to meet thermal specs and ensure reliable 85°C operation.

Key Features

Feature	Design Value
Adaptive On-Time D-CAP™ Control	Eliminates external compensation network; achieves fast transient response with minimal output capacitance in notebook applications.
Out-of-Audio (OOA) Light-Load Mode	Maintains switching above 20 kHz during light loads by forcing 40-µs min interval - prevents audible coil whine without increasing ripple.
Independent Dual-Channel Enable	EN1 and EN2 allow separate control of 5-V and 3.3-V rails - enabling flexible power sequencing, suspend/resume, and fault isolation.
Integrated Always-On LDOs	VREG5 (5 V/100 mA) powers gate drivers; VREG3 (3.3 V/100 mA) supplies internal analog circuits - both active beyond VIN UVLO (4.58 V).
Low-Side R_DS(on) Current Sensing	CS1/CS2 pins use temperature-compensated current source (4500 ppm/°C) to match MOSFET R_DS(on) drift - removes sense resistor and saves board space.
VCLK for External Charge Pump	260-kHz clock referenced to VO1 enables efficient bootstrap voltage generation - avoids dedicated charge-pump IC and improves converter efficiency.

Applications

Notebook CPU Core Power	Tablet System Rail Sequencing
Use Scenario: Supplies 5-V and 3.3-V rails for CPU I/O, chipset, and memory interface in ultrabook platforms with dynamic voltage scaling. IC Role / Device Role / Timing Role: Dual-channel synchronous buck controller with independent enable and combined PGOOD - manages rail ordering, soft-start timing (3.2 ms), and coordinated fault signaling. Use Value: Enables single-chip solution for dual-output system power with <1% output error, 260-kHz VCLK-driven gate drive, and OOA mode for silent operation during idle states.	Use Scenario: Powers application processor, display interface, and PMIC logic rails in 7–10 inch tablets with battery + adapter input flexibility. IC Role / Device Role / Timing Role: Dual-buck controller with always-on VREG3/VREG5 LDOs - provides stable bias for internal circuitry and external gate drivers before main rails ramp. Use Value: Reduces BOM count by integrating two LDOs and eliminating external compensation; VCLK output replaces discrete charge-pump IC for high-side drive.
Desktop Motherboard Standby Power	Embedded Industrial Controller PSU
Use Scenario: Generates 5-VSB and 3.3-VSB standby rails in ATX-compliant desktop motherboards with wake-on-LAN and USB charging support. IC Role / Device Role / Timing Role: Dual-channel controller with non-latch UVLO and separate EN1/EN2 - maintains LDO outputs during deep-sleep while disabling switchers to minimize quiescent current. Use Value: Achieves <180 µA VIN standby current with VREG3/VREG5 active; supports rapid wake-up via EN pin assertion and synchronized soft-start.	Use Scenario: Delivers tightly regulated 5-V and 3.3-V supplies for FPGA configuration, Ethernet PHY, and real-time MCU in fanless industrial controllers. IC Role / Device Role / Timing Role: Synchronous buck controller with OVP/UVP/OTP protection and thermal pad grounding - ensures reliability across –40°C to 85°C ambient with no airflow. Use Value: Provides ±1% output accuracy and 94.1°C/W thermal resistance in compact 3×3 mm WQFN - meets long-life, maintenance-free deployment requirements.

Notebook CPU Core Power

Tablet System Rail Sequencing

Use Scenario: Supplies 5-V and 3.3-V rails for CPU I/O, chipset, and memory interface in ultrabook platforms with dynamic voltage scaling.

IC Role / Device Role / Timing Role: Dual-channel synchronous buck controller with independent enable and combined PGOOD - manages rail ordering, soft-start timing (3.2 ms), and coordinated fault signaling.

Use Value: Enables single-chip solution for dual-output system power with <1% output error, 260-kHz VCLK-driven gate drive, and OOA mode for silent operation during idle states.

Use Scenario: Powers application processor, display interface, and PMIC logic rails in 7–10 inch tablets with battery + adapter input flexibility.

IC Role / Device Role / Timing Role: Dual-buck controller with always-on VREG3/VREG5 LDOs - provides stable bias for internal circuitry and external gate drivers before main rails ramp.

Use Value: Reduces BOM count by integrating two LDOs and eliminating external compensation; VCLK output replaces discrete charge-pump IC for high-side drive.

Desktop Motherboard Standby Power

Embedded Industrial Controller PSU

Use Scenario: Generates 5-VSB and 3.3-VSB standby rails in ATX-compliant desktop motherboards with wake-on-LAN and USB charging support.

IC Role / Device Role / Timing Role: Dual-channel controller with non-latch UVLO and separate EN1/EN2 - maintains LDO outputs during deep-sleep while disabling switchers to minimize quiescent current.

Use Value: Achieves <180 µA VIN standby current with VREG3/VREG5 active; supports rapid wake-up via EN pin assertion and synchronized soft-start.

Use Scenario: Delivers tightly regulated 5-V and 3.3-V supplies for FPGA configuration, Ethernet PHY, and real-time MCU in fanless industrial controllers.

IC Role / Device Role / Timing Role: Synchronous buck controller with OVP/UVP/OTP protection and thermal pad grounding - ensures reliability across –40°C to 85°C ambient with no airflow.

Use Value: Provides ±1% output accuracy and 94.1°C/W thermal resistance in compact 3×3 mm WQFN - meets long-life, maintenance-free deployment requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TPS51275RUKR	Non-B version; lacks OOA light-load mode and uses standard D-CAP (not D-CAP™ B) with different frequency mapping.	Higher light-load ripple and potential audible noise; suitable where acoustic performance is not critical.	Select TPS51275RUKR only if OOA mode and tighter light-load regulation are unnecessary.
ISL95831IRZ	Single-channel 5-V buck controller with integrated 3.3-V LDO; no second buck channel or VCLK output.	Requires external 3.3-V regulator or second controller for dual-rail systems; no charge-pump clock support.	Choose ISL95831IRZ only for cost-sensitive single-rail designs where 3.3-V is derived separately.

Compared with TPS51275RUKR and ISL95831IRZ, the TPS51275B-1RUKR uniquely delivers dual independent buck channels, OOA light-load operation, and VCLK for charge-pump drive - making it the only option that fully integrates notebook-class dual-rail power with silent, efficient, and sequenced delivery.

Availability

TPS51275B-1RUKR is available at Aetrix Electronics and suitable for notebook computers, tablet computers, and desktop motherboards requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for TPS51275B-1RUKR 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 power conversion IC design.

The TPS51275B-1RUKR belongs to TI's D-CAP™ synchronous buck controller product line, engineered specifically for high-efficiency, low-component-count system power supplies in portable and embedded computing platforms.

FAQ

What is the primary function of the TPS51275B-1RUKR in a notebook power system?

The TPS51275B-1RUKR serves as a dual-channel synchronous buck controller that generates regulated 5-V and 3.3-V system rails. It integrates two always-on LDOs (VREG5 and VREG3), adaptive on-time D-CAP™ control, and a 260-kHz VCLK output for external charge-pump gate drive - enabling high-efficiency, low-noise, and compact power delivery in notebook platforms without external compensation components.

How does the TPS51275B-1RUKR achieve light-load efficiency without audible noise?

The TPS51275B-1RUKR uses Out-of-Audio (OOA) mode to prevent switching frequencies from falling into the audible range (20–20 kHz). When load decreases, it forces a minimum 40-µs interval between switching events - maintaining operation above 25 kHz while preserving high efficiency and low output ripple. This behavior is intrinsic to the TPS51275B-1RUKR's control architecture and requires no external configuration.

Can the TPS51275B-1RUKR operate with only one channel enabled?

Yes, the TPS51275B-1RUKR supports independent channel control via EN1 and EN2 pins. Either channel can be disabled while the other remains active - for example, EN1 = high and EN2 = low enables only the 5-V output, with VREG3 and VREG5 still powered. The TPS51275B-1RUKR maintains LDO functionality and PGOOD assertion only for enabled channels per Table 1 in the datasheet.

What is the role of the VCLK pin on the TPS51275B-1RUKR?

The VCLK pin on the TPS51275B-1RUKR outputs a 260-kHz square wave referenced to VO1, used to drive an external charge-pump circuit that generates high-side gate drive voltage. This eliminates the need for a dedicated charge-pump IC and improves overall converter efficiency. VCLK activates only when EN1 is asserted high and remains inactive otherwise - a feature unique to the TPS51275B-1RUKR among its family variants.

Does the TPS51275B-1RUKR require external compensation components?

No, the TPS51275B-1RUKR uses adaptive on-time D-CAP™ control architecture, which eliminates the need for external compensation networks such as RC filters or type-II/III compensators. This simplifies design, reduces BOM count, and improves transient response - a core advantage confirmed in the TPS51275B-1RUKR datasheet Section 8.3.1 and Functional Block Diagram.

TPS51275B-1RUKR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: D-CAP™

Package/Case:: 20-WFQFN Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Active

Topology:: Step-Down (Buck) Synchronous (2), Linear (LDO) (2)

Number of Outputs:: 4

Frequency - Switching:: 300kHz, 355kHz

Voltage/Current - Output 1:: Controller

Voltage/Current - Output 2:: Controller

Voltage/Current - Output 3:: 3V, 100mA

w/LED Driver:: No

w/Supervisor:: No

w/Sequencer:: No

Voltage - Supply:: 5.5V ~ 24V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-WQFN (3x3)

TPS51275B-1RUKR FAQ

1.How can I place an order for TPS51275B-1RUKR through Aetrix?

Please submit a Request for Quotation (RFQ) for TPS51275B-1RUKR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for TPS51275B-1RUKR reliable?

The price and inventory of TPS51275B-1RUKR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TPS51275B-1RUKR is usually 5 days.

3.What payment methods are accepted for TPS51275B-1RUKR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TPS51275B-1RUKR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TPS51275B-1RUKR?

TPS51275B-1RUKR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TPS51275B-1RUKR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for TPS51275B-1RUKR?

For technical support, including TPS51275B-1RUKR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TPS51275B-1RUKR requirements.

6.How does Aetrix verify that TPS51275B-1RUKR is sourced from the original manufacturer or authorized distributors?

All TPS51275B-1RUKR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that TPS51275B-1RUKR meets industry standards.

7.What is the process for return or replacement of TPS51275B-1RUKR?

All TPS51275B-1RUKR units undergo pre-shipment inspection (PSI). If there is an issue with TPS51275B-1RUKR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The TPS51275B-1RUKR part is unused and in its original packaging.

Return procedure for TPS51275B-1RUKR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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