onsemi MC78LC40NTR

Overview

MC78LC40NTR from onsemi is a fixed-output, micropower low-dropout linear voltage regulator delivering 4.0 V at up to 80 mA with ultra-low 1.1 µA typical quiescent current, housed in a Pb-free Thin SOT-23-5 package. It features ±2.5% output voltage accuracy over −40°C to +85°C, 30 mV typical dropout at 1 mA, and stable operation with ≥0.1 µF ceramic output capacitors. It is designed for battery-powered portable instrumentation requiring minimal standby power draw.

For engineers reviewing the MC78LC40NTR datasheet, pinout, applications, or equivalent options, key selection criteria include its 4.0 V fixed output, 1.1 µA quiescent current, 30 mV dropout voltage at 1 mA, SOT-23-5 package footprint, and compatibility with low-ESR ceramic capacitors without stability compensation.

Technical Context

The MC78LC40NTR employs a PMOS pass transistor architecture enabling low dropout performance and near-zero ground current increase under load. Its internal error amplifier compares the regulated output against a precision voltage reference, driving the PMOS gate to maintain regulation across line (1.0 V above V_OUT to 12 V) and load (1–80 mA) variations.

Designed for high PSRR and low noise (89 µV_RMS over 1–100 kHz), it operates without external compensation and supports input voltages up to 12 V while maintaining thermal shutdown protection and ESD robustness (2 kV HBM). The device achieves ±100 ppm/°C temperature coefficient and exhibits excellent load regulation (≤60 mV change from 1 to 10 mA).

Key Specifications

Pinout & Package

The MC78LC40NTR is packaged in a Pb-free Thin SOT-23-5 (Case 483) surface-mount package measuring 2.9 × 1.6 × 1.1 mm, with exposed pad not connected internally. Pin 1 is GND, Pin 2 is VIN, Pin 3 is VOUT, Pins 4 and 5 are no-connect terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP1700T-4002E/TT and TPS78040DRVR, the MC78LC40NTR offers the lowest dropout (30 mV) among the three-critical for single-cell systems-while maintaining ultra-low IQ and requiring no enable logic or external components, making it optimal for simple, space-constrained, long-life battery designs.

Availability

MC78LC40NTR is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered data loggers, handheld test instruments, and low-power industrial controllers requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MC78LC40NTR 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC78LC00 series was developed specifically for micropower, low-dropout regulation in space- and battery-constrained portable electronics-emphasizing ultra-low IQ, ceramic-capacitor stability, and industrial-grade reliability in miniature packages.

FAQ

What is the maximum input voltage rating for the MC78LC40NTR?

The MC78LC40NTR has a maximum input voltage rating of 12 V, as specified in the Absolute Maximum Ratings table. Operation above this level risks permanent damage. For reliable 4.0 V output regulation, the recommended minimum input is V_OUT + 1.0 V (i.e., 5.0 V), though the device maintains regulation down to a dropout of 30 mV (4.03 V input at 1 mA load). Thermal limits must also be observed at higher input-to-output differentials.

Does the MC78LC40NTR require an external output capacitor, and what value is recommended?

Yes, the MC78LC40NTR requires an external output capacitor for stability and transient response. The datasheet specifies a minimum value of 0.1 µF ceramic capacitor, placed as close as possible to the VOUT and GND pins. Larger values (e.g., 1–10 µF) improve load transient suppression and noise rejection but are not required for basic stability. The regulator is ESR-insensitive and does not require tantalum or electrolytic types.

What is the dropout voltage of the MC78LC40NTR at 80 mA output current?

The dropout voltage of the MC78LC40NTR at 80 mA is not explicitly listed in the datasheet, as electrical characteristics are specified only up to 10 mA for regulation parameters. However, Figure 6 shows dropout versus output current for the MC78LC30NTR (3.0 V version), and Figure 14 confirms dropout increases with output voltage. Extrapolating from the 4.0 V curve in Figure 14 and typical PMOS LDO behavior, dropout at 80 mA is approximately 350–400 mV. For design-critical applications, consult onsemi's application engineering or validate experimentally.

Is the MC78LC40NTR pin-compatible with other devices in the MC78LC00 series?

Yes, all MC78LC00 series variants with the NTR suffix-including MC78LC40NTR-are pin-compatible within the Thin SOT-23-5 package. Pin 1 is GND, Pin 2 is VIN, Pin 3 is VOUT, and Pins 4 and 5 are N/C across the entire NTR family. This allows drop-in replacement between 1.5 V, 1.8 V, 2.5 V, 2.7 V, 2.8 V, 3.0 V, 3.3 V, 4.0 V, and 5.0 V versions without PCB changes, provided input/output voltage margins and thermal constraints remain valid.

What is the thermal performance of the MC78LC40NTR in its SOT-23-5 package?

The MC78LC40NTR in the Thin SOT-23-5 (NTR) package has a junction-to-ambient thermal resistance (θ_JA) of 280 °C/W. At 85°C ambient temperature, its maximum power dissipation is limited to 140 mW. For example, at 4.0 V output and 80 mA load with 5.5 V input, power dissipation is (5.5 − 4.0) V × 80 mA = 120 mW - within safe limits. Adequate copper pour on the GND pad is essential to achieve rated θ_JA; insufficient layout may raise junction temperature beyond 125°C.