STMicroelectronics LD3980PU18R

Overview

LD3980PU18R from STMicroelectronics is a low-dropout linear regulator delivering 1.8 V at up to 300 mA with 130 mV typical dropout (at 300 mA), 110 µA typical quiescent current (no load), ±1.0% output voltage accuracy at 25°C, and stable operation with 1 µF ceramic output capacitor. It serves as a local power rail regulator in battery-powered portable electronics requiring ultra-low quiescent current and logic-controlled shutdown.

For engineers reviewing the LD3980PU18R datasheet, LD3980PU18R pinout, LD3980PU18R application, or LD3980PU18R equivalent, key selection criteria include dropout performance at light-to-full load, shutdown leakage (<0.5 µA), thermal protection behavior (140°C trip, 15°C hysteresis), and compatibility with minimal 1 µF ceramic CO.

Technical Context

The LD3980PU18R employs a P-channel MOSFET pass transistor with internal 0.7 V bandgap reference and error amplifier feedback loop, enabling regulation down to 1.7 V input while maintaining high PSRR (60 dB @ 1 kHz) even near dropout. Its shutdown function is active-low on SHDN pin, reducing supply current to ≤0.5 µA by disabling all internal biasing and the pass element.

It integrates three protection mechanisms: constant-current limiting (~650 mA short-circuit current), thermal overload shutdown (140°C junction trip with 15°C hysteresis), and internal power dissipation control governed by R_thJA = 55°C/W. Output stability is guaranteed with 1–10 µF ceramic capacitors having ESR between 10–5000 mΩ.

Key Specifications

Pinout & Package

LD3980PU18R is housed in a thermally enhanced DFN6 (3 mm × 3 mm, 0.75 mm height) package with exposed thermal pad. Pin 1 is OUT; Pins 2 and 3 are NC; Pin 4 is GND; Pin 5 is SHDN (active-low enable); Pin 6 is IN. The exposed pad must be soldered to a PCB thermal plane for optimal power dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6206P182MR and AP7361-18SG-7, LD3980PU18R uniquely combines 300 mA capability, 130 mV dropout, and 60 dB PSRR in a DFN6 package - making it optimal for space-constrained, noise-critical, high-current portable applications.

Availability

LD3980PU18R is available at Aetrix Electronics and suitable for mobile phone baseband power, wireless headset audio codec supply, and PDA application processor core applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LD3980PU18R 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 microcontrollers, power management ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The LD3980 belongs to ST's low-power linear regulator product line, engineered specifically for battery-operated portable equipment demanding ultra-low IQ, logic-controlled shutdown, and ceramic-capacitor stability.

FAQ

What is the minimum input voltage required for LD3980PU18R to maintain 1.8 V output at 300 mA?

The minimum input voltage is calculated as V_OUT + V_DROP = 1.8 V + 0.13 V = 1.93 V. At 300 mA load and −40°C to +85°C, the maximum dropout is 150 mV, so 1.95 V input guarantees regulation. Below this, output collapses linearly with input.

Can LD3980PU18R operate with a 0.47 µF ceramic output capacitor?

No. The datasheet specifies a minimum of 1 µF ceramic capacitor for stability. Using 0.47 µF risks oscillation or poor transient response, as confirmed by Figure 8 and Section 6.5, which define 1–10 µF as the validated range.

Is the exposed thermal pad on the DFN6 package electrically connected internally?

No. The exposed pad is a thermal slug only - not connected to any internal circuit node. It must be soldered to a PCB copper pour tied to GND for heat dissipation, but no electrical connection is required or recommended.

Does LD3980PU18R require an input capacitor, and if so, what value and type?

Yes. A minimum 1 µF ceramic capacitor is required at the IN pin, placed within 3 mm of the package. This stabilizes input impedance, limits ripple from upstream sources, and improves load transient response - per Figure 2 and Section 6.5 recommendations.