48-channel constant-current sink for signage backplanes
The TLC5954RTQR is a 48-channel linear LED driver from Texas Instruments, built around a shift-register topology and designed for signage applications. Each of the 48 outputs sinks either 24.4 mA or 34.9 mA, selectable per channel, with a 10 V output compliance that gives headroom for series LED strings in large-format displays. Operating from a 3.0 V to 3.6 V supply rail, the driver accepts serial data and clocks it through the shift register, latching the output state on the rising edge of the latch signal. This makes it a direct fit for multiplexed or static-drive LED panels where the controller feeds pixel data over a few signal lines rather than one line per LED.
Output current selection and thermal budget
The two current settings — 24.4 mA and 34.9 mA — are set by an external resistor on the IREF pin. At 34.9 mA per channel, all 48 channels active simultaneously dissipate roughly 1.68 W in the driver (48 × 34.9 mA × 1.0 V dropout typical), which the 56-QFN exposed pad must conduct to the PCB copper plane. The -40°C to 85°C ambient range covers indoor signage and most outdoor cabinet environments, but the thermal pad solder joint and via array under the package determine the real junction temperature at full load. The 56-VFQFN package (8 mm × 8 mm) with exposed pad requires a thermal land pattern on the PCB — the datasheet's recommended footprint includes a 5.2 mm × 5.2 mm pad with a 3 × 3 via matrix to the ground plane. Without that thermal via cluster, the driver derates above 60°C ambient at full channel count.
Active production and sourcing posture
The TLC5954RTQR carries an active product status from Texas Instruments. It is ROHS3 compliant, which covers the EU RoHS exemption list through the latest revision. Sourced to order against BOM quantities through independent distribution channels.