Texas Instruments TPS78633KTTRG3

Overview

TPS78633KTTRG3 from Texas Instruments is a fixed-output 3.3-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 uses a PMOS pass device, supports 2.7–5.5 V input, and delivers stable regulation for RF power supplies in cellular transceivers and precision analog front-ends.

For engineers reviewing the TPS78633KTTRG3 datasheet, TPS78633KTTRG3 pinout, TPS78633KTTRG3 application, or TPS78633KTTRG3 equivalent, key selection criteria include dropout voltage at full load (340–510 mV), noise-reduction capacitor dependency, thermal performance in TO-263-5 package, and enable-input logic thresholds (1.7 V high, 0.7 V low).

Technical Context

The TPS78633KTTRG3 implements a PMOS-based LDO architecture with internal 1.225-V bandgap reference and integrated noise-reduction filter (250 kΩ resistor + external NR capacitor). Its control loop is optimized for stability with ≥1 µF ceramic output capacitance and exhibits excellent line/load transient response due to fast error amplifier dynamics and low output impedance.

Functional modes are controlled via the EN pin: active regulation above 1.7 V, shutdown below 0.7 V (I_Q < 1 µA). Protection includes current limiting (~2.8 A), thermal shutdown (~165°C), and UVLO (2.25–2.65 V with 100 mV hysteresis), all implemented without external components.

Key Specifications

Pinout & Package

TPS78633KTTRG3 is packaged in TO-263-5 (KTT), a thermally enhanced surface-mount package with exposed tab connected to GND. Dimensions: 10.16 mm × 8.42 mm × 4.57 mm. The tab must be soldered to a PCB ground plane with ≥5×4 thermal vias for R_θJC(bot) = 2.1°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79633DRBR and LP38798SD-3.3/NOPB, the TPS78633KTTRG3 uniquely balances 1.5-A capability, 48-µV_RMS noise, and 340-mV dropout in a thermally efficient TO-263 package-making it optimal for RF and portable medical systems requiring both current and spectral purity.

Availability

TPS78633KTTRG3 is available at Aetrix Electronics and suitable for cellular transceiver power supplies, VCO biasing circuits, portable medical sensor front-ends, and industrial PLC analog input modules requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for TPS78633KTTRG3 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 and high-reliability signal-chain solutions.

The TPS786 family was designed specifically for noise-sensitive RF and precision analog applications, emphasizing ultralow output noise, high PSRR, and fast transient response in compact thermally enhanced packages.

FAQ

What is the minimum input voltage required for TPS78633KTTRG3 to maintain 3.3 V output at 1.5 A?

The TPS78633KTTRG3 requires a minimum input voltage of 3.64 V at 1.5 A load, based on its maximum dropout voltage of 510 mV. At typical conditions (340 mV dropout), VIN ≥ 3.64 V ensures regulation. Below 2.7 V, UVLO disables the device regardless of EN state.

How does the NR pin function in TPS78633KTTRG3, and what capacitor value is recommended?

The NR pin connects internally to the voltage reference through a 250-kΩ resistor. Adding an external capacitor (0.001–0.1 µF) forms a low-pass filter that reduces reference noise, lowering output noise to 48 µV_RMS. TI recommends 0.1 µF for lowest noise; larger values slow start-up due to RC time constant.

Can TPS78633KTTRG3 operate with a 1-µF output capacitor, and is it stable with ceramic types?

Yes, the TPS78633KTTRG3 is specified stable with ≥1 µF ceramic output capacitors (X5R/X7R). Unlike many LDOs, it does not require ESR tuning-its internal compensation works with zero-ESR ceramics, simplifying layout and improving transient response without series resistors.

What thermal derating applies to TPS78633KTTRG3 in TO-263-5 package at 70°C ambient?

With R_θJC(bot) = 2.1°C/W and R_θJA = 40.7°C/W, the TPS78633KTTRG3 can deliver 1.5 A continuously at 70°C ambient if the PCB provides adequate copper area and thermal vias. Derating begins above 110°C junction; thermal shutdown activates at ~165°C with auto-recovery at ~140°C.

Does TPS78633KTTRG3 support reverse current protection, and how does it behave during input brownout?

The TPS78633KTTRG3 uses a PMOS pass transistor with an intrinsic back diode. During input brownout (VIN < VOUT), reverse current flows from OUT to IN uncontrolled. External reverse-blocking diodes or ideal diode controllers are required if reverse conduction must be prevented in system-level fault conditions.