STMicroelectronics LD2980CU18TR

Overview

LD2980CU18TR from STMicroelectronics is a 1.8 V fixed-output ultra-low-dropout linear voltage regulator in SOT23-5L package, designed for battery-powered and low-noise applications. It delivers up to 50 mA output current with 7 mV typical dropout at 1 mA load, 80 µA typical quiescent current in active mode, and <1 µA shutdown current. Its stable operation with low-ESR ceramic capacitors enables use in space-constrained portable electronics such as camera modules and PDA power rails.

For engineers reviewing the LD2980CU18TR datasheet, LD2980CU18TR pinout, LD2980CU18TR application, or LD2980CU18TR equivalent, key selection criteria include dropout voltage at light load, inhibit logic thresholds, output noise (160 µVRMS), thermal shutdown behavior (170 °C), and compatibility with 1 µF ceramic output capacitors - all critical for standby-sensitive embedded systems.

Technical Context

The LD2980CU18TR employs a PNP pass transistor architecture enabling ultra-low dropout voltage and minimal quiescent current across its full operating range. Its inhibit input (Pin 3) accepts TTL-compatible logic levels (VIH ≥ 1.3 V, VIL ≤ 0.18 V) and drives the regulator into sub-1 µA off-state without internal pull-up, requiring external biasing when unused.

Stability is ensured with low-ESR ceramic capacitors (≥1 µF for 1.8 V output), leveraging internal compensation optimized for ESR-dependent phase margin. The device integrates thermal shutdown (170 °C) and current limiting, with reverse-current protection achieved via absence of body diode in the pass element - limiting reverse conduction to ~160 µA through feedback resistors.

Key Specifications

Pinout & Package

SOT23-5L is a 5-pin, surface-mount plastic package measuring 2.95 × 1.60 × 1.30 mm (max height), optimized for high-density PCB layouts and automated assembly. Its exposed pad variant is not used; thermal resistance is R_thJA = 255 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-1802E/TT and XC6206P182MR-G, the LD2980CU18TR uniquely combines sub-10 mV dropout, <1 µA shutdown, 0.5% output accuracy, and integrated inhibit logic in SOT23-5 - making it optimal for battery-critical, noise-sensitive, and firmware-controlled power domains.

Availability

LD2980CU18TR is available at Aetrix Electronics and suitable for camera modules, portable audio devices, wireless sensor nodes, and PDA power management requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for LD2980CU18TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LD2980 series belongs to ST's ultra-low-quiescent-current LDO portfolio, engineered specifically for energy-harvesting systems, wearables, and battery-operated portable electronics demanding nanoscale standby power and millivolt-level regulation precision.

FAQ

What is the minimum input voltage required for regulation at 1.8 V output?

The LD2980CU18TR maintains regulation when input voltage exceeds output voltage by its dropout voltage. At 1 mA load, typical dropout is 7 mV, so minimum input is 1.807 V. At 50 mA, dropout rises to 150 mV typ., requiring ≥1.95 V input. Full-range operation assumes 2.5 V minimum per datasheet absolute rating.

Can the INHIBIT pin be left unconnected?

No. The INHIBIT pin has no internal pull-up or pull-down and must never be left floating. If shutdown control is unused, tie Pin 3 directly to VIN to ensure continuous operation. Floating causes undefined output state and potential instability due to noise coupling.

Is an input capacitor mandatory, and what type is recommended?

Yes - a minimum 1 µF ceramic capacitor is required at VIN, placed within 12.7 mm of the pin and returned to clean analog ground. X7R or NP0 dielectrics are preferred; tantalum or film types are acceptable but offer no advantage. Larger values improve transient response without stability risk.

Does the LD2980CU18TR support reverse-voltage protection?

It does not provide active reverse-voltage protection at VIN. However, its PNP pass transistor lacks a parasitic body diode, preventing reverse current flow from VOUT to VIN. When VOUT exceeds VIN, only ~160 µA flows through internal feedback resistors to GND - sufficient to avoid damage but not replace external protection in harsh environments.