Texas Instruments TPS79942DDCT

Overview

TPS79942DDCT from Texas Instruments is a 200-mA, low-quiescent-current (40 μA), ultralow-noise (10.5 × V_OUT μV_RMS), high-PSRR (66 dB at 1 kHz) low-dropout linear regulator in a 5-pin SOT-23-THIN package. It delivers a fixed 4.2 V output with ±2% accuracy over load, line, and temperature (–40°C to +125°C), and features a 100-mV typical dropout at 200 mA - optimized for RF power supply filtering in portable wireless systems.

For engineers reviewing the TPS79942DDCT datasheet, TPS79942DDCT pinout, TPS79942DDCT application, or TPS79942DDCT equivalent, this page provides verified technical context, validated pin functions, confirmed noise/PSRR performance under real operating conditions (C_NR = 0.01 μF, I_OUT = 100 mA), and two rigorously cross-checked alternative parts for RF-sensitive LDO selection.

Technical Context

The TPS79942DDCT employs a PMOS pass element with an advanced BiCMOS process to achieve 100-mV dropout at full 200-mA load while maintaining 66 dB PSRR at 1 kHz and 51 dB at 10 kHz. Its precision 1.193-V internal reference and feedback loop ensure ±2% total output accuracy across –40°C to +125°C, with inrush current protection activated on EN toggle.

It integrates overshoot detection (5% threshold) and active pulldown (350-Ω equivalent) for fast load transient recovery, and uses a dedicated NR pin to bypass bandgap noise - enabling 10.5 × V_OUT μV_RMS output noise when C_NR = 0.01 μF. Stability is guaranteed with ≥2.2-μF ceramic output capacitance (X5R/X7R, ESR < 1.0 Ω).

Key Specifications

Pinout & Package

The TPS79942DDCT is housed in a 5-pin SOT-23-THIN package (2.90 mm × 1.60 mm, 0.95-mm height), optimized for space-constrained RF modules and handheld devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS79942DDCT, TPL720F42PDBVR offers higher current capacity but sacrifices noise performance and PSRR above 1 kHz due to missing NR pin; LP5907MFX-4.2/NOPB delivers superior low-frequency PSRR but cannot match the 44.1 μV_RMS noise floor achievable with TPS79942DDCT's NR-capacitor configuration.

Availability

TPS79942DDCT is available at Aetrix Electronics and suitable for RF power management, wearable electronics, and wireless communication modules requiring stable component supply, long-term lifecycle support, and traceable sourcing for production programs.

Supply support for TPS79942DDCT 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 leader specializing in analog and embedded processing technologies, with decades of LDO innovation for high-performance power management.

The TPS799 product line was engineered specifically for RF and precision analog applications demanding ultralow noise, high PSRR, and minimal quiescent current - targeting wireless infrastructure, mobile handsets, and high-fidelity sensor interfaces.

FAQ

What is the maximum input voltage rating for the TPS79942DDCT?

The TPS79942DDCT has an absolute maximum input voltage of 7.0 V. However, its recommended operating input range is 2.7 V to 6.5 V. Operation above 6.5 V risks exceeding safe junction temperature or violating thermal limits, especially at high ambient temperatures or full 200-mA load. The device's UVLO circuit activates below 1.90 V and releases above 2.20 V, ensuring reliable startup only within its specified input window.

Does the TPS79942DDCT require an external noise-reduction capacitor to achieve its specified output noise?

Yes - the TPS79942DDCT achieves its 10.5 × V_OUT μV_RMS (≈44.1 μV_RMS) output noise specification only when a 0.01-μF capacitor is connected to the NR pin. Without this capacitor, output noise rises to 94 × V_OUT μV_RMS (≈395 μV_RMS). The NR pin is high-impedance, so low-leakage ceramic capacitors (e.g., X7R, C0G) are required; aluminum or tantalum types are unsuitable.

Can the TPS79942DDCT be used without an enable signal?

Yes - the TPS79942DDCT can operate without an external enable signal by connecting the EN pin directly to the IN pin. This configures the device for always-on operation. When EN is tied to IN, the regulator powers up as soon as VIN reaches the UVLO release threshold (~2.20 V). No additional pull-up resistor is needed, and the EN pin draws only 0.03–1 μA when enabled, minimizing impact on source impedance.

What output capacitor value and type does the TPS79942DDCT require for stability?

The TPS79942DDCT requires a minimum 2.2-μF ceramic output capacitor with ESR < 1.0 Ω for guaranteed stability across –40°C to +125°C. X5R and X7R dielectrics are recommended for minimal capacitance drift over temperature and voltage. Larger values (e.g., 10 μF) improve transient response but do not affect stability. Tantalum or electrolytic capacitors are not recommended due to higher ESR and aging effects.

How does the TPS79942DDCT handle load transients in RF applications?

The TPS79942DDCT handles load transients using an active pulldown circuit that engages when output voltage overshoots by ≥5%. This circuit behaves like a 350-Ω resistor to ground, rapidly correcting overshoot and reducing settling time. Combined with excellent line/load transient response and 2.2-μF ceramic output capacitance, it maintains <±10 mV deviation during 100-mA step changes - critical for preserving RF signal integrity during burst-mode transmission.