STMicroelectronics LD39015M18R

Overview

LD39015M18R from STMicroelectronics is a 150 mA ultra-low-noise, low-quiescent-current LDO voltage regulator delivering fixed 1.8 V output with ±2.0% accuracy at 25 °C, 80 mV typical dropout at 100 mA, and 29 µVRMS output noise (1.1–100 kHz) without bypass capacitor. It operates from 1.5 V to 5.5 V input and features logic-controlled shutdown (EN pin), internal thermal/current protection, and stable operation with 1 µF ceramic output capacitor.

For engineers reviewing the LD39015M18R datasheet, LD39015M18R pinout, LD39015M18R application, or LD39015M18R equivalent, this page provides verified technical context for battery-powered portable electronics requiring high PSRR (65 dB @ 1 kHz), sub-µA shutdown current, and tight output tolerance across –40 °C to 125 °C.

Technical Context

The LD39015M18R implements a bandgap-referenced feedback loop with internal trimming resistors (R1/R2) to regulate 1.8 V output. Its enable-controlled NMOS pass transistor enables fast turn-on (30 µs) and <1 µA OFF-mode current. The architecture supports stability with low-ESR ceramic capacitors and includes dedicated thermal shutdown (160 °C trigger, 20 °C hysteresis) and constant-current short-circuit limiting (~350 mA).

Power supply rejection remains ≥62 dB up to 10 kHz, then rolls off; noise performance is optimized via internal compensation-no external bypass required for 29 µVRMS at 1.8 V output. Input UVLO thresholds (1.45 V turn-on, 1.30 V turn-off) ensure reliable start-up under weak-battery conditions.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.45 mm × 1.60 mm footprint, 0.95 mm pitch, 0.6 mm max height; RoHS-compliant ECOPACK®2 grade.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B182MR-G and RT9013-18GB, the LD39015M18R uniquely balances ultra-low noise (29 µVRMS), sub-µA shutdown, and 80 mV dropout in a 5-pin SOT23 package-making it optimal for space-constrained, battery-sensitive designs where both precision and efficiency are non-negotiable.

Availability

LD39015M18R is available at Aetrix Electronics and suitable for mobile phone power management, wearable sensor hub supply, and industrial wireless node applications requiring stable component supply, long-lifecycle support, and guaranteed parametric compliance per STMicroelectronics DocID14003 Rev 5.

Supply support for LD39015M18R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD39015 series belongs to ST's high-performance analog power management portfolio, engineered specifically for ultra-low-power, low-noise portable electronics where battery life, EMI robustness, and small form factor are critical design constraints.

FAQ

What is the minimum input voltage required for the LD39015M18R to maintain regulation?

The LD39015M18R requires a minimum input voltage of 1.88 V to sustain 1.8 V output at 100 mA load, based on its 80 mV typical dropout voltage. Below 1.88 V, output voltage drops linearly with input; the device remains functional down to 1.5 V input but cannot regulate 1.8 V below that threshold. UVLO circuitry disables regulation entirely below 1.30 V (turn-off threshold).

Can the LD39015M18R be used with a 0.47 µF output capacitor?

No-ST specifies a minimum 1 µF ceramic output capacitor (X5R/X7R) for stability, validated across temperature and load. Using 0.47 µF risks oscillation or poor transient response, as confirmed by Figure 7 (stability region) in the datasheet, which shows instability below ~0.8 µF at typical ESR values. Always adhere to the 1 µF minimum for production designs.

Does the EN pin require a pull-up resistor for default-on operation?

No external pull-up is required-the LD39015M18R has an internal pull-up on the EN pin. When left unconnected, EN floats to a logic-high state, enabling the regulator. However, for deterministic startup in noisy environments or when interfacing with open-drain GPIOs, a 100 kΩ external pull-up to VIN is recommended to ensure robust high-level assertion.

How does thermal shutdown behave during sustained overload?

When junction temperature reaches 160 °C, the LD39015M18R enters thermal shutdown, disabling the pass transistor and reducing output current to near zero. It remains latched off until temperature falls by ~20 °C (hysteresis), then automatically recovers. This cycle prevents permanent damage during continuous overloads or poor PCB heatsinking, as verified in Table 4 (thermal data) and Section 5 (electrical characteristics).