Texas Instruments LP5900SDX-2.8/NOPB

Overview

LP5900SDX-2.8/NOPB from Texas Instruments is a 150-mA ultra-low-noise LDO regulator designed for RF and analog circuits, delivering 2.8 V output with ±2% tolerance, 6.5 μV_RMS output noise, 75 dB PSRR at 1 kHz, and 80 mV typical dropout voltage. It operates across 2.5 V–5.5 V input range and supports stable regulation with only 0.47-μF ceramic input/output capacitors-no noise bypass capacitor required.

For engineers reviewing the LP5900SDX-2.8/NOPB datasheet, LP5900SDX-2.8/NOPB pinout, LP5900SDX-2.8/NOPB application, or LP5900SDX-2.8/NOPB equivalent, key selection criteria include low-noise power delivery to sensitive RF front-ends, minimal external component count in space-constrained portable designs, thermal performance under 150-mA load, and enable-controlled power sequencing in battery-powered systems.

Technical Context

The LP5900SDX-2.8/NOPB employs an innovative internal RC-filtered reference architecture that suppresses internal noise before reaching the output buffer-enabling 6.5 μV_RMS noise without external bypass capacitance. Its enable pin features a 1-MΩ internal pull-down resistor and logic-level thresholds (V_IL ≤ 0.4 V, V_IH ≥ 1.2 V), supporting direct interfacing with standard CMOS I/O.

Stability is guaranteed with 0.47-μF X7R/X5R ceramic capacitors on both input and output, with ESR between 5 mΩ and 500 mΩ. The device maintains regulation down to zero load current and includes thermal shutdown (160°C trip, 20°C hysteresis) and short-circuit protection (300 mA limit).

Key Specifications

Pinout & Package

LP5900SDX-2.8/NOPB is packaged in a 6-pin WSON (NGF) with exposed thermal pad (2.50 mm × 2.20 mm nominal body size). The thermal pad must be connected to PCB ground plane via thermal vias for reliable thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL720F12-DBVR and TPS7A2028PDQNR, LP5900SDX-2.8/NOPB uniquely balances 2.8 V output, 150 mA capability, best-in-class 6.5 μV_RMS noise, and 75 dB PSRR-making it the optimal choice for noise-sensitive RF/analog bias where fixed 2.8 V is required and board space is constrained.

Availability

LP5900SDX-2.8/NOPB is available at Aetrix Electronics and suitable for cellular handset power management, portable WLAN transceiver biasing, and high-precision analog sensor conditioning requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for LP5900SDX-2.8/NOPB 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, embedded processing, and connectivity technologies, with over 90 years of innovation in power management ICs.

LP5900SDX-2.8/NOPB belongs to TI's ultra-low-noise LDO family engineered specifically for RF and high-fidelity analog signal chains in battery-powered portable electronics-prioritizing noise suppression, minimal external components, and thermal robustness.

FAQ

What is the minimum input voltage required for LP5900SDX-2.8/NOPB to regulate 2.8 V output?

The LP5900SDX-2.8/NOPB requires a minimum input voltage of 2.88 V (2.8 V + 80 mV typical dropout) to maintain regulation at full 150 mA load. Under light loads, regulation begins at VIN ≥ 2.5 V per recommended operating conditions, but stable 2.8 V output at rated current demands VIN ≥ VOUT + VDO. Always verify margin using worst-case 150 mV dropout at temperature.

Can LP5900SDX-2.8/NOPB operate without an output capacitor?

No. LP5900SDX-2.8/NOPB requires a minimum 0.47-μF ceramic output capacitor with ESR between 5 mΩ and 500 mΩ for stability and transient response. Operation without C_OUT causes oscillation and loss of regulation. The "no bypass capacitor" claim refers only to elimination of the traditional 10-nF noise-filtering cap-not removal of the essential output stabilization capacitor.

Is the thermal pad of LP5900SDX-2.8/NOPB required to be grounded?

Yes. The exposed thermal pad on the LP5900SDX-2.8/NOPB WSON package must be soldered to the PCB ground plane. TI specifies connecting it to the same ground potential as pin 3 (GND); floating or connecting to other potentials risks thermal failure and violates absolute maximum ratings. At least four 0.3-mm thermal vias are recommended to achieve R_θJB = 20.4°C/W.

Does LP5900SDX-2.8/NOPB support zero-load operation?

Yes. LP5900SDX-2.8/NOPB remains stable and delivers regulated 2.8 V output with 0 mA load current, as confirmed in Electrical Characteristics (I_LOAD = 0 mA test condition) and Feature Description ("No-Load Stability"). This enables use in high-impedance bias networks and always-on monitoring circuits without risk of instability.

What is the enable pin behavior when left unconnected on LP5900SDX-2.8/NOPB?

When the EN pin of LP5900SDX-2.8/NOPB is left unconnected, its internal 1-MΩ pull-down resistor holds it below 0.4 V, ensuring the device remains fully disabled with <1 μA quiescent current. This fail-safe behavior prevents unintended power-up and is explicitly documented in Pin Functions and Device Functional Modes sections of the datasheet.