Analog Devices Inc. DC949A-A

Overview

DC949A-A from Analog Devices (formerly Linear Technology) is an evaluation board for the LT3478-1 high-power LED driver IC. It implements a 6-LED white Luxeon III boost configuration delivering 700mA constant current at up to 15W output, with True Color PWM dimming up to 3000:1 and programmable thermal derating. Designed for automotive TFT LCD backlight validation.

For engineers reviewing the DC949A-A datasheet, DC949A-A pinout, DC949A-A application, or DC949A-A equivalent, this board enables rapid prototyping of high-brightness LED drivers requiring wide input range (8V–16V), precise current regulation, open-LED protection, and automotive-grade thermal management.

Technical Context

The DC949A-A implements the LT3478-1 in fixed-frequency boost topology with 500kHz switching, using a 10µH inductor, 0.1Ω internal sense resistor, and 45.3k/54.9k/69.8k/130k resistor network for OVP, CTRL1, CTRL2, and RT programming. It supports true-color PWM dimming via external MOSFET control on the PWM pin.

Board-level features include inrush current protection, programmable soft-start (via 10nF SS capacitor), separate VS supply routing, and exposed-pad thermal management aligned with the 16-pin TSSOP package's PGND pad (Pin 17). All protections - UVLO, OVP, overtemperature latch - are fully enabled and validated per LT3478-1 spec.

Key Specifications

Availability

DC949A-A is available at Aetrix Electronics and suitable for automotive display backlighting, industrial HMI lighting, and heads-up display (HUD) development requiring stable component supply, full-function evaluation, and production-representative thermal performance.

Supply support for DC949A-A 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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The DC949A-A belongs to Linear's legacy evaluation board portfolio for LED driver ICs, specifically engineered to accelerate design-in of high-current, automotive-qualified boost controllers with True Color PWM capability.

FAQ

What is the primary function of the DC949A-A evaluation board?

The DC949A-A evaluation board is a fully assembled and tested platform for the LT3478-1 LED driver IC. It demonstrates a 6-LED white Luxeon III boost configuration delivering 700mA constant current at up to 15W, with validated True Color PWM dimming, thermal derating, and all protection features enabled. It is not a standalone IC but a reference design for rapid system validation.

Does the DC949A-A support input voltages outside the 8V–16V range shown in the schematic?

No - the DC949A-A is optimized and tested for 8V to 16V input per its bill of materials and layout. While the underlying LT3478-1 IC supports 2.8V–36V, the board's passive components (inductor saturation, capacitor voltage ratings, diode reverse voltage) are selected for the 8V–16V automotive use case. Operation outside this range requires redesign and revalidation of the DC949A-A circuit.

Can the DC949A-A be used to evaluate the LT3478 (non-"-1") variant?

No - the DC949A-A is specifically designed for the LT3478-1, which integrates the 0.1Ω LED current sense resistor. The LT3478 requires an external sense resistor and different CTRL1 scaling (10mV/mA vs. 100mV/A), making the DC949A-A's resistor network, feedback path, and calibration invalid for the base LT3478. Use DC949A (non-"-A") for LT3478 evaluation.

How is True Color PWM dimming implemented on the DC949A-A?

The DC949A-A implements True Color PWM dimming by routing the LT3478-1's PWM pin to an external N-channel MOSFET placed in series with the LED string ground path. This preserves constant peak LED current during each PWM on-cycle, maintaining chromaticity across the full 3000:1 dimming range. The board includes test points and jumper options to interface with external PWM signal sources.

Is thermal performance data available for the DC949A-A under full-load conditions?

Yes - the DC949A-A datasheet provides measured thermal data: at 15W output (700mA × ~21.4V LED string), with 200 LFM airflow and standard 2-layer 2oz copper PCB, the LT3478-1 junction temperature stabilizes at ≤115°C. The board's exposed-pad soldering to a continuous ground plane and thermal vias under Pin 17 are critical to achieving this result, as confirmed in Linear's DC949A-A design files.