Linear Regulator (LDO): Dropout Voltage 100-300 mV typical

Component Specifications

Definition

A Low-Dropout Linear Regulator (LDO) is a DC linear voltage regulator that can regulate the output voltage even when the supply voltage is very close to the output voltage. It maintains a stable output voltage by using a pass transistor controlled by an error amplifier, with feedback from the output to adjust the transistor's conductivity. LDOs are characterized by their low dropout voltage (typically 100-300mV), low noise, and simple implementation, making them ideal for applications requiring clean, stable power from batteries or noisy sources.

Working Principle

The LDO operates by comparing a fraction of the output voltage (via a feedback resistor network) to a stable reference voltage using an error amplifier. The amplifier adjusts the gate/base of a pass transistor (usually a PNP bipolar or PMOS FET) to control current flow from input to output, maintaining a constant output voltage despite variations in input voltage or load current. The dropout voltage is the minimum input-output differential required for regulation, determined by the saturation characteristics of the pass transistor.

Materials

Semiconductor silicon substrate with integrated circuits; package materials include plastic (e.g., epoxy molding compound) or ceramic; lead frames of copper alloy; bonding wires of gold or aluminum.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Package Types	SOT-23, SOT-223, DFN, QFN
Output Current	Up to 3A (depending on package)
Dropout Voltage	100-300 mV typical
Line Regulation	0.1% typical
Load Regulation	0.2% typical
Quiescent Current	10-150 µA
Output Voltage Range	1.2V to 5V adjustable/fixed
Operating Temperature	-40°C to +125°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 9001, JEDEC JESD22, IEC 60747

Parent Products

This component is used in the following industrial products

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Engineering Analysis

Risks & Mitigation

Thermal overload from excessive power dissipation
Instability with certain output capacitors
Input voltage transients exceeding maximum ratings
Electrostatic discharge (ESD) damage during handling

FMEA Triads

Trigger: Excessive load current or high input-output differential
Failure: Thermal shutdown or permanent damage due to overheating
Mitigation: Implement current limiting, use thermal protection circuits, ensure adequate heat sinking, and derate specifications for high temperatures.

Trigger: Insufficient or improper output capacitance
Failure: Output oscillation or instability
Mitigation: Follow manufacturer recommendations for capacitor type (e.g., low-ESR ceramic) and value; include stability analysis in design.

Trigger: Input voltage spikes or reverse polarity
Failure: Internal component breakdown
Mitigation: Add input protection diodes, transient voltage suppressors, and ensure proper polarity connection in circuit design.

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Output voltage tolerance typically ±1% to ±3% over temperature and load variations

Test Method

Testing per JEDEC standards for electrical characteristics (e.g., JESD22), including line/load regulation, dropout voltage, and thermal performance; environmental testing per IEC 60068 for temperature and humidity.

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Linear Regulator (LDO)

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Frequently Asked Questions

What is the main advantage of an LDO over a switching regulator?

LDOs provide lower noise and simpler design with no switching artifacts, making them suitable for noise-sensitive analog/RF circuits, though they are less efficient due to dissipative regulation.

How do I select an LDO for my application?

Consider dropout voltage, output current, input voltage range, quiescent current (for battery life), noise performance, and package size. Ensure the input voltage always exceeds the output voltage by at least the dropout voltage under all conditions.

Can LDOs be used in high-current applications?

Yes, but thermal management is critical due to power dissipation (P_loss = (V_in - V_out) * I_out). Use heat sinks or select packages with low thermal resistance for currents above 500mA.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Linear Regulator (LDO)