Texas Instruments TPS78625DCQ

Overview

TPS78625DCQ from Texas Instruments is a fixed-output 2.5-V, 1.5-A low-dropout linear regulator with ultralow noise (48 µV_RMS), high PSRR (49 dB at 10 kHz), and fast start-up (110 µs with 0.01 µF NR capacitor). It features enable control, thermal shutdown, current limiting, and stable operation with only a 1-µF ceramic output capacitor - deployed in RF power supply rails for VCOs and ADCs.

For engineers reviewing the TPS78625DCQ datasheet, TPS78625DCQ pinout, TPS78625DCQ application, or TPS78625DCQ equivalent, key selection criteria include dropout voltage at full load (not specified for TPS78625 per datasheet), noise performance under 1.5-A load, PSRR above 1 kHz, NR capacitor dependency, and SOT-223-6 thermal design constraints.

Technical Context

The TPS78625DCQ uses a PMOS pass transistor architecture enabling low dropout and reverse-current protection via an integrated back diode. Its internal 1.225-V bandgap reference feeds a precision error amplifier, with noise reduction achieved through a dedicated NR pin tied to a 250-kΩ internal resistor and external bypass capacitor.

Operation is controlled by a logic-level enable input (EN) that transitions the device between active mode (265 µA quiescent current) and shutdown (<1 µA). Protection includes foldback current limiting (~2.8 A peak), thermal shutdown at ~165°C, and UVLO activation at 2.25–2.65 V with 100-mV hysteresis.

Key Specifications

Pinout & Package

The TPS78625DCQ is housed in a 6-pin SOT-223 package (body size 6.50 mm × 3.50 mm) with exposed thermal pad connected to GND. The tab is electrically grounded and must be soldered to PCB copper for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79625DCQ and LP5907MFX-2.5/NOPB, the TPS78625DCQ uniquely balances 1.5-A delivery, 48-µV_RMS noise, and SOT-223 thermal performance - making it optimal for mid-power RF and precision analog where both current and noise matter.

Availability

TPS78625DCQ is available at Aetrix Electronics and suitable for RF front-end power rails, high-resolution data acquisition systems, portable audio codecs, and Bluetooth baseband subsystems requiring stable component supply across industrial and consumer production cycles.

Supply support for TPS78625DCQ 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 designing analog ICs, embedded processors, and system-on-chip solutions for industrial, automotive, and communications markets.

The TPS786 family was engineered specifically for noise-sensitive analog and RF applications demanding high PSRR, ultralow output noise, and fast transient response in compact packages - targeting cellular infrastructure, portable medical devices, and high-fidelity audio.

FAQ

What is the dropout voltage specification for TPS78625DCQ?

The TPS78625DCQ datasheet explicitly states that dropout voltage is "not measured" for TPS78618 and TPS78625 because the minimum input voltage is defined as 2.7 V - meaning the device is guaranteed to regulate at VIN ≥ 2.7 V regardless of VDO magnitude. Designers must ensure VIN remains ≥ 2.7 V under all operating conditions, including worst-case line and load transients. The TPS78625DCQ does not publish a numerical VDO value like other members of the family (e.g., TPS78630's 390 mV at 1.5 A).

Does TPS78625DCQ require an external feedback resistor network?

No, the TPS78625DCQ is a fixed-output variant and does not use the FB pin. Its output is internally set to 2.5 V, and Pin 5 is designated as NR (Noise Reduction), not FB. An external capacitor (0.001–0.1 µF) must be connected from NR to GND to achieve specified noise performance. Using resistors on the NR pin or attempting to configure feedback will prevent proper operation and violate the device's fixed-output design.

Can TPS78625DCQ operate with a 1-µF output capacitor?

Yes, the TPS78625DCQ is explicitly characterized and guaranteed stable with a minimum 1-µF ceramic output capacitor - a key advantage over legacy LDOs requiring ≥10 µF tantalum. This enables smaller PCB footprints and lower cost. However, using ≥2.2 µF improves load transient response and PSRR, especially at higher frequencies. The 1-µF minimum applies only to ceramic capacitors with low ESR; polymer or tantalum types are not recommended unless validated per TI's stability guidelines.

What is the maximum allowable input voltage for TPS78625DCQ?

The absolute maximum input voltage for TPS78625DCQ is 6 V, but the recommended operating range is strictly 2.7 V to 5.5 V per the datasheet's Recommended Operating Conditions table. Exceeding 5.5 V risks violating safe operating area limits and may trigger overvoltage stress even if below the 6-V absolute max. Applications powered from 5-V rails (e.g., USB or DC/DC outputs) must ensure worst-case tolerance (e.g., 5.5 V + 5%) stays within spec - derating or input clamping may be required in high-reliability designs.

How does the NR capacitor affect start-up time in TPS78625DCQ?

The NR capacitor directly sets the TPS78625DCQ start-up time via the RC time constant formed with the internal 250-kΩ resistor. With 0.01 µF, start-up is 110 µs; with 0.1 µF, it increases to ~480 µs. Larger NR capacitors improve noise filtering but delay regulation onset - critical in systems requiring fast power sequencing (e.g., Bluetooth LE connection windows). TI specifies 0.001–0.1 µF as the valid range; values outside this range risk incomplete charging or excessive delay, degrading system responsiveness without additional noise benefit.