LM3503SQ-25

LED Driver IC Overview

The LM3503SQ-25 is a dual-display constant current LED driver manufactured by National Semiconductor, now part of Texas Instruments. It features an integrated boost converter topology designed to drive two white LEDs from a single-cell lithium-ion or lithium-polymer battery source. The device operates within a supply voltage range of 2.5 V to 5.5 V and supports an output current of up to 400 mA. It utilizes a fixed switching frequency of 1 MHz and includes analog brightness control capabilities. The component is housed in a 16-pin LLP package and functions reliably across an operating temperature range of -40°C to +85°C.

LED Driver IC Feature Summary

• Integrates a high-efficiency step-up (boost) DC-DC converter for driving dual white LEDs from low-voltage sources.
• Provides precise constant current regulation with analog brightness control functionality via the control pin.
• Operates at a fixed 1 MHz switching frequency to minimize external component size and improve transient response.

LED Driver IC Applications

• Portable electronic devices requiring dual white LED illumination
• Battery-powered handheld instruments
• Mobile phone flash and keypad backlighting systems

LED Driver IC Procurement Notes

Verify the manufacturer designation carefully, as National Semiconductor was acquired by Texas Instruments. Ensure the specific suffix matches the required package and temperature grade. Confirm availability status, as older revisions may be discontinued or replaced by newer NOPB variants. Cross-reference datasheet revision dates to ensure compatibility with current design specifications.

LED Driver IC Selection Notes

Select this component when designing circuits that require driving two series-connected white LEDs from a single-cell battery. Consider the 400 mA maximum output current limit and the 1 MHz switching frequency constraints. Evaluate thermal performance within the LLP package for the intended enclosure. Verify input voltage ranges align with the battery chemistry used in the target application.

LED Driver IC Part Context

The LM3503 belongs to a family of dual-channel LED drivers designed for portable applications. It shares architectural similarities with other members like the LM3503SQ-16 and LM3503SQ-44, differing primarily in package options and specific electrical characteristics. These devices are commonly used in mobile communication equipment and consumer electronics where space efficiency and power management are critical.

LED Driver IC Replacement Considerations

Check for direct substitutes such as the LM3503SQ-16/NOPB or LM3503SQ-44/NOPB if package variations are acceptable. Verify functional equivalence with Texas Instruments' updated versions bearing the NOPB suffix. Ensure any replacement maintains the same boost topology and current regulation accuracy.