Texas Instruments TPS78625DCQR

Overview

TPS78625DCQR 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 (50 µs). It features enable control, thermal shutdown, current limiting, and stable operation with a 1-µF ceramic output capacitor-designed for powering noise-sensitive RF analog circuitry such as VCOs and ADCs in portable wireless systems.

For engineers reviewing the TPS78625DCQR datasheet, TPS78625DCQR pinout, TPS78625DCQR application, or TPS78625DCQR equivalent, key selection criteria include dropout voltage at full load, output spectral noise density below 100 kHz, NR-capacitor-dependent noise filtering, and thermal performance in the SOT-223-6 package under 1.5-A continuous load.

Technical Context

The TPS78625DCQR uses a PMOS pass transistor architecture enabling low dropout (390 mV typical at 1.5 A) and reverse-current protection via an integrated back diode. Its internal 1.225-V bandgap reference feeds a precision error amplifier that regulates output against line/load transients with <7 mV load regulation and <12 %/V line regulation.

Operation is controlled by a logic-level enable input (1.7 V high threshold) and includes UVLO (2.25–2.65 V), thermal shutdown (~165 °C), and foldback current limiting (~2.8 A). Noise reduction is implemented via a dedicated NR pin with internal 250-kΩ resistor, requiring external bypass capacitance (0.001–0.1 µF) to filter reference noise before it modulates the output.

Key Specifications

Pinout & Package

The TPS78625DCQR is housed in a thermally enhanced 6-pin SOT-223 package (DCQ) with exposed thermal pad connected to GND; body size 6.50 mm × 3.50 mm, 1.8 mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79625DCQ and MCP1703T-2502E/MB, the TPS78625DCQR uniquely balances 1.5-A capability, 48 µV_RMS noise, and 49 dB PSRR in a thermally robust SOT-223-6 package - making it the only viable option for high-fidelity RF and precision analog power delivery at full load.

Availability

TPS78625DCQR is available at Aetrix Electronics and suitable for RF transceiver power, VCO biasing, precision ADC reference buffering, and portable audio codec applications requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for TPS78625DCQR 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 solutions for industrial, automotive, and communications markets.

The TPS786 family was engineered specifically for noise-critical RF and high-resolution analog signal chains - emphasizing ultralow output noise, high PSRR at 1–100 kHz, and fast transient response in compact thermally optimized packages.

FAQ

What is the minimum input voltage required for TPS78625DCQR to regulate 2.5 V at 1.5 A?

The TPS78625DCQR requires a minimum input voltage of 2.89 V to maintain regulation at 1.5 A, based on its typical dropout voltage of 390 mV. At higher junction temperatures or worst-case process corners, dropout may reach 580 mV, so design margin should target VIN ≥ 3.1 V for reliable operation across –40°C to +125°C.

How does the NR pin on TPS78625DCQR reduce output noise?

The NR pin on TPS78625DCQR connects internally to the voltage reference through a 250-kΩ resistor. Adding an external capacitor (0.001–0.1 µF) between NR and GND forms an RC low-pass filter that attenuates reference noise before it modulates the error amplifier. With 0.1 µF, TPS78625DCQR achieves 48 µV_RMS output noise; reducing capacitance increases noise but improves start-up time.

Can TPS78625DCQR operate without an external NR capacitor?

Yes, TPS78625DCQR functions without an NR capacitor, but output noise increases significantly - to ~50 µV_RMS with CNR = 0.001 µF and up to ~66 µV_RMS with no NR cap. The device remains stable and regulated, but the primary benefit of ultralow noise is forfeited. TI specifies CNR = 0.1 µF for optimal noise performance in RF applications.

What thermal considerations apply to TPS78625DCQR in SOT-223-6 (DCQ) package?

The TPS78625DCQR in DCQ package has R_θJA = 54.2°C/W and R_θJB = 8.9°C/W. To avoid thermal shutdown at 1.5 A with 2.89 V dropout (4.335 W dissipation), the PCB must provide ≥200 mm² copper area connected to the exposed tab via ≥6 thermal vias. Ambient temperature must stay ≤75°C for safe continuous operation.

Is TPS78625DCQR compatible with ceramic output capacitors smaller than 1 µF?

No - TI specifies a minimum 1-µF ceramic capacitor on the output for stability. Using smaller values risks oscillation due to insufficient phase margin in the control loop. The TPS78625DCQR is optimized for 1–10 µF X7R/X5R ceramics; tantalum or aluminum electrolytics are not recommended due to ESR sensitivity.