Texas Instruments LP2985A-18DBVRE4

Overview

LP2985A-18DBVRE4 from Texas Instruments is a fixed-output 1.8 V, 150-mA low-dropout linear regulator in SOT-23-5 package with ±1% output tolerance (A-grade), 280 mV typical dropout at full load, and ultra-low 30 μV_RMS output noise when used with a 10-nF bypass capacitor. It delivers stable power to noise-sensitive analog circuitry in space-constrained portable systems.

For engineers reviewing the LP2985A-18DBVRE4 datasheet, LP2985A-18DBVRE4 pinout, LP2985A-18DBVRE4 application, or LP2985A-18DBVRE4 equivalent, key selection criteria include dropout voltage under 150 mA load, shutdown current ≤0.01 μA, thermal performance in SOT-23, stability with ceramic output capacitors ≥2.2 μF, and low-noise operation enabled by the dedicated BYPASS pin.

Technical Context

The LP2985A-18DBVRE4 uses a PNP pass transistor architecture enabling ultra-low dropout-7 mV at 1 mA and 280 mV at 150 mA-while maintaining tight regulation across –40°C to +125°C. Its internal bandgap reference feeds a high-gain error amplifier that drives the pass element, with feedback taken directly from the VOUT pin.

Shutdown is implemented via an active-low ON/OFF pin with logic thresholds of ≤0.15 V (OFF) and ≥1.6 V (ON); the device draws only 0.01 μA in shutdown. The BYPASS pin connects to the reference node, allowing external 10-nF capacitor filtering to reduce output noise to 30 μV_RMS (300 Hz–50 kHz).

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm footprint, surface-mount, lead-free (RoHS-compliant), moisture sensitivity level 1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout regulator applications.

Compared with MCP1700T-1802E/TT and TLC7701QDCKR, the LP2985A-18DBVRE4 uniquely combines 150 mA capability, 280 mV dropout, and 30 μV_RMS noise via the BYPASS pin-making it optimal for noise-critical 1.8-V analog rails where both current and spectral purity matter.

Availability

LP2985A-18DBVRE4 is available at Aetrix Electronics and suitable for portable medical sensors, digital camera image sensors, wearable health monitors, and industrial IoT edge nodes requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LP2985A-18DBVRE4 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 delivering analog and embedded processing solutions, with leadership in power management ICs, signal chain components, and high-reliability industrial products.

The LP2985 family was designed specifically for cost-sensitive, space-constrained portable electronics requiring low-noise, low-dropout regulation with minimal external components-targeting battery-powered cameras, audio devices, and medical sensors.

FAQ

What is the maximum input voltage rating for the LP2985A-18DBVRE4?

The LP2985A-18DBVRE4 has an absolute maximum input voltage rating of 16 V, with recommended operating range from 2.2 V to 16 V. Operation above 16 V risks permanent damage due to internal junction breakdown; sustained operation near 16 V requires thermal derating per the 206°C/W θ_JA specification.

Does the LP2985A-18DBVRE4 require an external bypass capacitor to achieve its specified 30 μV_RMS noise performance?

Yes-the LP2985A-18DBVRE4 achieves 30 μV_RMS output noise only when a 10-nF ceramic capacitor is connected between the BYPASS pin and GND. Without this capacitor, output noise rises to approximately 65 μV_RMS; the BYPASS pin must not be left floating or tied directly to VOUT or GND.

Can the LP2985A-18DBVRE4 operate stably with a 1-μF ceramic output capacitor?

No-the LP2985A-18DBVRE4 requires a minimum 2.2 μF output capacitor for stability, as confirmed in Section 8.1.3.2 of the datasheet. Using a 1-μF ceramic capacitor violates the minimum capacitance requirement and may cause oscillation or poor transient response, especially across temperature extremes.

What is the purpose of the ON/OFF pin on the LP2985A-18DBVRE4, and how should it be handled if not used?

The ON/OFF pin is an active-low enable input: pulling it ≤0.15 V disables the regulator (I_Q = 0.01 μA), while ≥1.6 V enables it. If unused, TI specifies that ON/OFF must be tied directly to VIN-not left floating-to guarantee reliable turn-on; unconnected pins risk erratic behavior or increased noise susceptibility.

How does the dropout voltage of the LP2985A-18DBVRE4 vary with load current and temperature?

The LP2985A-18DBVRE4 dropout voltage increases with load: 7 mV at 1 mA, 120 mV at 50 mA, and 280 mV at 150 mA (typical, 25°C). Over temperature (–40°C to +125°C), dropout rises to 575 mV max at 150 mA, as shown in Figure 3 of the datasheet-designers must ensure sufficient input headroom across the full operating range.