Texas Instruments TPS74901KTWR

Overview

TPS74901KTWR from Texas Instruments is a 3A, ultra-low-dropout linear regulator with programmable soft-start, designed for high-accuracy point-of-load regulation in multi-rail server and networking systems. It supports 0.8V–3.6V output, operates from 0.8V input (with VBIAS), delivers 1% output accuracy over line/load/temperature (new chip), and features power-good signaling and active-high enable. It powers FPGA core rails and ASIC supply domains requiring monotonic start-up and tight voltage tolerance.

For engineers reviewing the TPS74901KTWR datasheet, TPS74901KTWR pinout, TPS74901KTWR application, or TPS74901KTWR equivalent, this page provides verified package mapping (DDPAK-7), confirmed pin functions including SS, PG, BIAS, and FB, real-world thermal performance data (RθJA = 33.8°C/W), and validated alternative options for enterprise power sequencing designs.

Technical Context

The TPS74901KTWR uses an NMOS pass transistor architecture powered by a dedicated VBIAS rail (2.7V–5.5V), enabling stable regulation at VIN as low as 0.8V while maintaining fast transient response. Its internal 0.8V reference and precision error amplifier achieve ±0.3% typical output accuracy over –40°C to +125°C.

Soft-start is implemented via external capacitor on the SS pin, providing monotonic ramp control with adjustable timing (e.g., 100µs typical with no capacitor). The open-drain PG output-available only in VQFN packages but not in KTW-requires external pull-up and asserts low when VOUT falls below 90% of nominal or during shutdown.

Key Specifications

Pinout & Package

TPS74901KTWR is packaged in a 7-pin DDPAK/TO-263 (KTW) with exposed thermal pad soldered to PCB ground plane for enhanced thermal dissipation. Pin count and layout match industry-standard TO-263 footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TPS74901KTWR, TPS74801KTWR trades PG functionality and tighter accuracy for lower unit cost, while TPL7407LDDCR serves entirely different system roles-neither offers pin compatibility or functional equivalence for 3A core rail applications.

Availability

TPS74901KTWR is available at Aetrix Electronics and suitable for network attached storage, rack servers, and merchant PSU designs requiring stable component supply, long-lifecycle support, and guaranteed traceability for industrial OEM programs.

Supply support for TPS74901KTWR 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 and embedded processing technologies, with decades of expertise in power management IC design and high-reliability manufacturing.

The TPS74901 product line targets high-performance computing infrastructure, delivering precision, low-noise, and sequenced LDO regulation for FPGAs, ASICs, and multi-core processors in enterprise-class systems.

FAQ

What is the maximum output current capability of the TPS74901KTWR?

The TPS74901KTWR delivers up to 3 A continuously under recommended operating conditions. Its internal current limit is factory-trimmed to 4.6 A typical, engaging within ~10 µs during overload or short-circuit events. Sustained operation above 3 A is not advised due to thermal constraints-designers must verify junction temperature remains ≤125°C using RθJA = 33.8°C/W and actual PCB copper area.

Does the TPS74901KTWR include a power-good (PG) output?

No, the TPS74901KTWR does not include a power-good output. The PG pin is only available on the RGW (VQFN-20) package variant-not on the KTW (DDPAK-7) package. This is explicitly documented in the Pin Functions table and Functional Block Diagrams section of the datasheet. For designs requiring PG signaling, the RGW variant or alternate sequencing methods must be used.

What is the required capacitor value on the SS pin for a 5 ms soft-start time?

A 5 ms soft-start time requires approximately 47 nF on the SS pin, based on the soft-start charging current (ISS = 530 nA typical for new chip) and the 0.8 V internal reference. The relationship is tSS ≈ (0.8 V × CSS) / ISS. Using ISS = 530 nA yields CSS ≈ 47 nF. This value is consistent with typical application curves showing 5 ms ramp with ~47 nF in Figure 5-39 of the datasheet.

Can the TPS74901KTWR operate with VIN = VOUT (i.e., zero dropout)?

No, the TPS74901KTWR cannot operate with VIN = VOUT. Its minimum dropout voltage is 120 mV typical at 3 A, defined as the VIN–VOUT differential required to maintain regulation. Attempting VIN = VOUT will cause output collapse and possible thermal shutdown. Minimum valid VIN is VOUT + 120 mV (typical), and must also satisfy VBIAS requirements (≥2.7 V and ≥VOUT + VDO(VBIAS)).

What is the thermal pad connection requirement for the TPS74901KTWR?

The thermal pad on the underside of the TPS74901KTWR (KTW package) must be soldered to a solid PCB ground plane for effective heat dissipation. TI specifies this connection as mandatory-not optional-to achieve the rated RθJA = 33.8°C/W and sustain 3 A output at elevated ambient temperatures. Omitting or inadequately connecting the thermal pad increases junction temperature by >20°C and risks thermal shutdown under load.