Analog Devices Inc. DC905A

Overview

DC905A from Analog Devices (formerly Linear Technology) is a demonstration board for the LT3491 fixed-frequency step-up current-mode DC/DC LED driver in SC70 package. It implements two independent LED drive circuits - "Small Size" (15mA, 20.3V output) and "High Efficiency" (20mA, 20.6V output) - sharing six LEDs with jumper-selectable operation. Designed for evaluation of high-side current sensing, internal Schottky integration, and open-circuit protection in portable backlighting applications.

For engineers reviewing the DC905A datasheet, DC905A pinout, DC905A application, or DC905A equivalent, this board enables rapid validation of LT3491 performance under 3V–5V input, PWM/DC dimming control, efficiency vs. size trade-offs, and high-frequency (1.8–2.8MHz) switching behavior in space-constrained LED systems.

Technical Context

Demonstration circuit DC905A hosts the LT3491 IC, which integrates a 2.3MHz nominal switching frequency, internal Schottky diode, and high-side current sense amplifier enabling ground-referenced LED cathodes. Its open-circuit protection triggers at 26–28V on the CAP pin, and quiescent current is 4mA active / 10µA shutdown.

The board supports dual operating modes via JP1–JP4 jumpers: "Small Size" mode delivers 15mA at ≥73.6% efficiency; "High Efficiency" mode delivers 20mA at ≥75.5% efficiency. Input voltage is constrained to 3–5V by external capacitors, though the LT3491 IC itself supports up to 12V absolute maximum.

Key Specifications

Availability

DC905A is available at Aetrix Electronics and suitable for LED backlight evaluation, portable display power design, and high-frequency boost converter prototyping requiring stable component supply and documented reference performance.

Supply support for DC905A 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

Analog Devices acquired Linear Technology in 2017; LT and LTC are registered trademarks. The company designs precision analog, power management, and signal conditioning ICs for industrial, automotive, and communications systems.

DC905A belongs to Linear's demonstration circuit series for DC/DC LED drivers. It was developed to showcase the LT3491's high-side current sensing, integrated Schottky, and compact solution size in battery-powered lighting applications.

FAQ

What is the primary function of the DC905A demonstration board?

The DC905A demonstration board is designed exclusively to evaluate the LT3491 step-up LED driver IC. It provides two fully assembled, jumper-selectable circuits - "Small Size" (15mA) and "High Efficiency" (20mA) - each driving six shared LEDs. DC905A enables hands-on validation of switching frequency, dimming methods, efficiency, and protection features without custom PCB design. No other IC or function is implemented on DC905A.

Can DC905A operate with input voltages above 5V?

No - DC905A is rated for 3V to 5V input only due to its onboard input capacitor voltage rating. Although the LT3491 IC itself supports up to 12V absolute maximum input, the DC905A board's passive components (especially CIN) are selected for 5V operation. Exceeding 5V risks capacitor failure and invalidates all published performance data for DC905A.

How do I switch between the "Small Size" and "High Efficiency" modes on DC905A?

Use jumpers JP1–JP4: for "Small Size" mode, set JP1=ON, JP2=OFF, JP3=ON, JP4=OFF; for "High Efficiency" mode, set JP1=OFF, JP2=ON, JP3=OFF, JP4=ON. These configurations route feedback and enable signals to match the respective circuit's component values and optimize either footprint (Small Size) or efficiency (High Efficiency). Both modes share the same six LEDs and VOUT node.

Does DC905A support PWM dimming, and how is it implemented?

Yes - DC905A supports three dimming methods: filtered PWM (via CTRL1), direct DC dimming (via CTRL2), and direct PWM (per LT3491 datasheet Section 9). To use CTRL1 or CTRL2, remove JP1 or JP2 respectively and apply the control signal. The board includes RC filtering on CTRL1 but not on CTRL2, enabling both analog and digital brightness control without modifying the LT3491's internal current regulation loop.

Is the LT3491 IC on DC905A replaceable with another part?

No - DC905A is a fixed-function demonstration board built specifically for the LT3491 in SC70-6 package. The layout, compensation network, and jumper configuration are optimized for that single IC. Substituting any other device - including pin-compatible alternatives - would require redesign of feedback, timing, and protection circuitry. DC905A does not support IC replacement or socketed upgrades.