LM3480 Linear Regulator User Guide

The LM3480 is a compact, integrated low-dropout linear regulator designed for low-power and space-constrained applications. It is widely used in portable electronic devices, embedded systems, and industrial automation applications that require a compact size and efficient power regulation.

Overview of LM3480

The LM3480 is an integrated linear regulator that supports an input voltage up to 30V. With a full load of 100mA, the maximum voltage drop does not exceed 1.2V, demonstrating excellent low-dropout performance. The standard package of the LM3480 is a 3-pin SOT-23 small package, making it suitable for applications with high space requirements.
The LM3480 series offers multiple fixed output versions such as 5V, 12V, and 15V, serving as a compact alternative to the industry-standard LM78Lxx series and similar devices. Compared to the LM78Lxx series, which typically requires a 2V to 2.5V voltage drop, the LM3480 only needs about 1.2V, enabling it to handle more applications with low input-to-output voltage differences.

In addition, the LM3480 series also includes a 3.3V model. Combining the SOT-23 package of this series with its quasi-low dropout feature, the LM3480 can achieve an efficient and compact 3.3V/100mA bias power supply design, which can be directly regulated from a system 5V ±5% power supply.

LM3480 features

• Input Voltage Range:up to 30V
• 3.3-V, 5-V, 12-V, and 15-V Versions Available
• Packaged in the Tiny 3-Lead SOT-23 Package
• 30-V Maximum Input for Operation
• 1.2-V Ensured Maximum Dropout Over Full Load and Temperature Ranges
• 100-mA Ensured Minimum Load Current
• +5% Ensured Output Voltage Tolerance Over Full Load and Temperature Ranges
• -40 to +125°C Junction Temperature Range for Operation

LM3480 Pin Configuration and Functions

LM3480 absolute maximum ratings

LM3480 Functional Block Diagram

LM348 Application 

1. Miniature alternative solution for LM78Lxx series and similar devices
The LM3480 series is designed as a "miniature upgrade alternative" for traditional LM78Lxx linear regulators, especially suitable for scenarios with limited space and low dropout requirements. In traditional designs, if the input voltage is only slightly higher than the output (e.g., 7V → 5V), LM78L05 may not function properly, but the LM3480 can still provide a stable output. This makes it more advantageous in low headroom power systems.
2. 5V ±5% to 3.3V, 100 mA micro converter
The LM3480 (3.3V version) is very suitable as a simple linear converter for 5V to 3.3V conversion. Traditional LDOs (such as LM1117-3.3) usually require a voltage difference of about 1.2V to 1.3V, and at 4.75V input, it may already be close to the limit, but the LM3480 can still operate reliably. Without complex DC/DC, a low-cost and small-sized 3.3V power solution can be achieved.
3. Post-regulator for switching DC/DC converters
The LM3480 is often used as a post-regulator after a switching power supply (DC/DC) to improve power quality. This "DC/DC + LDO" combination is currently the mainstream power architecture in industrial design.
4. Bias power supply for analog circuits
The LM3480 is very suitable as an analog circuit bias power supply. Analog circuits are extremely sensitive to power noise, and the LM3480 can effectively provide a clean and stable reference power supply, avoiding signal distortion or drift.

LM3480 Alternative and Compatibility

The LM3480 can be used as an upgrade alternative for the following devices:

• LM78L05 / LM78L12 / LM78L15, etc.
• Other 100mA linear regulators

The advantages are:

• Lower voltage drop
• Smaller package
• More suitable for modern compact designs

Product Features of LM3480

• Low dropout design: Compared to traditional LM78Lxx (with a voltage drop of 2~2.5V), LM3480 has only about 1.2V
• Small package size: Suitable for high-density PCB layout
• Wide input range: Can be directly powered from high-voltage systems (such as 12V, 24V)
• High stability: Simple peripheral circuit, only requiring a small amount of capacitors

Common Problems and Solutions