Texas Instruments TPS78618KTTRG3

Overview

TPS78618KTTRG3 from Texas Instruments is a fixed-output 1.8-V, 1.5-A low-dropout linear regulator with enable input, ultralow noise (48 µV_RMS at 100 Hz–100 kHz), high PSRR (49 dB at 10 kHz), and fast start-up (≤110 µs with 0.01 µF NR capacitor). It delivers stable power to noise-sensitive RF circuitry such as VCOs and ADCs in portable wireless systems.

For engineers reviewing the TPS78618KTTRG3 datasheet, TPS78618KTTRG3 pinout, TPS78618KTTRG3 application, or TPS78618KTTRG3 equivalent, key selection criteria include dropout voltage at full load (not specified for TPS78618 per datasheet), NR-capacitor-dependent noise performance, thermal derating in TO-263-5 package, and compatibility with 1-µF ceramic output capacitors.

Technical Context

The TPS78618KTTRG3 uses a PMOS pass transistor architecture enabling low dropout operation without reverse-current protection diode limitations. Its internal 1.225-V bandgap reference feeds a precision error amplifier that regulates output via feedback from the NR pin network-where an external bypass capacitor forms a low-pass filter to suppress reference noise.

Enable functionality is implemented with TTL-compatible logic thresholds (EN ≥1.7 V for ON, ≤0.7 V for shutdown), reducing quiescent current to <1 µA in standby. Thermal shutdown activates at ~165°C and recovers at ~140°C, while overcurrent limiting engages at ~2.8 A with foldback behavior.

Key Specifications

Pinout & Package

TPS78618KTTRG3 is housed in a TO-263-5 (KTT) thermally enhanced package with exposed tab electrically connected to GND. The 10.16 mm × 8.42 mm body supports high-power dissipation via PCB copper area and thermal vias.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS78618KTTRG3, TPS79618DRBR offers superior noise and PSRR at reduced current capability, while LP5907MFX-1.8/NOPB trades output current for extreme low-power operation and miniature footprint-neither is pin-compatible, and both require layout revision.

Availability

TPS78618KTTRG3 is available at Aetrix Electronics and suitable for RF front-end power, precision ADC biasing, portable audio subsystems, and industrial sensor nodes requiring stable component supply across extended temperature ranges.

Supply support for TPS78618KTTRG3 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 since the 1980s.

The TPS786 family was engineered for noise-critical RF and audio applications demanding simultaneous low dropout, high PSRR, and ultralow output noise in thermally robust packages.

FAQ

What is the maximum input voltage rating for TPS78618KTTRG3?

The absolute maximum input voltage for TPS78618KTTRG3 is 6 V. However, the recommended operating range is 2.7 V to 5.5 V. Exceeding 6 V risks permanent damage. Operation above 5.5 V violates recommended conditions and may degrade long-term reliability even if within absolute max limits. Always ensure VIN stays within 2.7–5.5 V during normal use of TPS78618KTTRG3.

Does TPS78618KTTRG3 require an external feedback resistor network?

No, TPS78618KTTRG3 is a fixed-output 1.8-V regulator and does not require external feedback resistors. It uses an internal resistor divider tied to the NR pin for noise filtering-not for voltage setting. The FB pin is not present on fixed versions like TPS78618KTTRG3; only adjustable variants (e.g., TPS78601) use external R1/R2 networks. TPS78618KTTRG3 connects NR to an external capacitor only.

What is the thermal resistance (RθJA) of TPS78618KTTRG3 in its TO-263-5 package?

The junction-to-ambient thermal resistance (RθJA) for TPS78618KTTRG3 in the KTT (TO-263-5) package is 40.7°C/W under JEDEC-standard high-K board conditions. This value assumes a 5×4 thermal via array connecting the exposed tab to the PCB ground plane. Actual RθJA will improve with larger copper areas and additional vias, and worsen in compact layouts with limited copper.

Can TPS78618KTTRG3 operate with a 1-µF output capacitor?

Yes, TPS78618KTTRG3 is explicitly characterized as stable with a minimum 1-µF ceramic output capacitor, per TI's datasheet Section 6.5 and Figure 20. Unlike many LDOs requiring 10–22 µF tantalum or aluminum electrolytic capacitors, TPS78618KTTRG3 achieves phase margin and transient stability using only 1 µF or larger X5R/X7R ceramics-reducing board area and cost.

What is the purpose of the NR pin on TPS78618KTTRG3?

On TPS78618KTTRG3, the NR (Noise Reduction) pin connects internally to the 1.225-V bandgap reference through a 250-kΩ resistor. An external capacitor (0.001–0.1 µF) placed between NR and GND forms an RC low-pass filter that attenuates reference noise, directly lowering output spectral noise density. For TPS78618KTTRG3, a 0.1-µF NR capacitor yields 48 µV_RMS integrated noise.