Texas Instruments TPS78628KTTT

Overview

TPS78628KTTT from Texas Instruments is a fixed-output 2.8-V, 1.5-A low-dropout linear regulator in TO-263-5 package, featuring 410 mV typical dropout at full load, 49 dB PSRR at 10 kHz, and ultralow 48 µV_RMS output noise with 0.1 µF NR capacitor-designed for powering noise-sensitive RF VCOs and ADCs in portable wireless systems.

For engineers reviewing the TPS78628KTTT datasheet, TPS78628KTTT pinout, TPS78628KTTT application, or TPS78628KTTT equivalent, key selection criteria include dropout voltage under 1.5-A load, PSRR performance above 1 kHz, noise spectral density below 100 Hz–100 kHz bandwidth, thermal resistance (R_θJA = 40.7°C/W), and compatibility with 1-µF ceramic output capacitors.

Technical Context

The TPS78628KTTT uses a PMOS pass transistor architecture enabling low dropout and reverse-current protection via integrated back diode. Its internal 1.225-V bandgap reference feeds a precision error amplifier driving the pass element, with dedicated NR pin filtering reference noise through an internal 250-kΩ resistor and external bypass capacitor.

Operation includes enable-controlled startup (EN logic-high >1.7 V), UVLO activation at 2.25 V, and thermal shutdown at ~165°C with automatic recovery at ~140°C. Quiescent current is 265 µA typical in active mode and <1 µA in shutdown-supporting battery-powered applications requiring fast wake-up and ultra-low standby power.

Key Specifications

Pinout & Package

TPS78628KTTT is housed in a TO-263-5 (KTT) thermally enhanced package with exposed tab electrically connected to GND, measuring 10.16 mm × 8.42 mm. The tab must be soldered to a PCB ground plane with 5×4 thermal vias for optimal thermal performance (R_θJB = 21.5°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79628DRBR, TPS78628KTTT offers higher thermal margin in high-power RF sections but larger footprint; versus LP5907TMX-2.8/NOPB, it delivers 6× the output current at modest noise penalty-making it the sole viable choice for 1.5-A, noise-sensitive analog rails.

Availability

TPS78628KTTT is available at Aetrix Electronics and suitable for RF front-end modules, high-speed data acquisition systems, portable wireless transceivers, and industrial sensor nodes requiring stable component supply across extended production lifecycles.

Supply support for TPS78628KTTT 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 ICs, embedded processors, and power management solutions for industrial, automotive, and communications markets.

The TPS786 family was engineered specifically for noise-critical RF and precision analog applications-delivering ultralow noise, high PSRR, and fast transient response in thermally robust packages for portable and battery-powered systems.

FAQ

What is the minimum input voltage required for TPS78628KTTT to regulate 2.8 V at 1.5 A?

The TPS78628KTTT requires a minimum input voltage of 3.21 V to maintain regulation at 1.5 A, based on its typical 410 mV dropout voltage (2.8 V + 0.41 V). At lower input voltages, the device enters dropout and output voltage drops linearly with VIN. The absolute minimum specified VIN is 2.7 V, but regulation is not guaranteed below 3.21 V under full load.

How does the NR pin affect noise performance in TPS78628KTTT?

The NR pin in TPS78628KTTT connects to the internal voltage reference through a 250-kΩ resistor; adding an external 0.1 µF ceramic capacitor forms a low-pass filter that reduces reference noise, lowering total output noise to 48 µV_RMS. Larger NR capacitors increase startup time due to RC delay and may degrade stability if leakage current exceeds 1 nA.

Can TPS78628KTTT be used with a 1-µF output capacitor?

Yes, TPS78628KTTT is explicitly designed to be stable with a minimum 1-µF ceramic output capacitor, unlike many legacy LDOs requiring ≥10 µF. This reduces solution size and cost while maintaining phase margin >60° across temperature and load. For best noise performance, TI recommends ≥2.2 µF.

What thermal considerations apply to TPS78628KTTT in TO-263-5 package?

TPS78628KTTT in TO-263-5 has R_θJA = 40.7°C/W and R_θJB = 21.5°C/W. To avoid thermal shutdown at 1.5 A with 5.5 V input, the PCB must provide ≥4.5 cm² copper area under the tab with 5×4 thermal vias. Junction temperature must stay ≤125°C for continuous operation per datasheet limits.

Does TPS78628KTTT support reverse current protection?

Yes, TPS78628KTTT incorporates a PMOS pass transistor with an intrinsic body diode that conducts reverse current from OUT to IN when VIN falls below VOUT (e.g., during power-down). This feature prevents output bus collapse but does not limit reverse current-external circuitry is recommended if sustained reverse conduction could damage upstream sources.