Texas Instruments TLC5973DR

Overview

TLC5973DR from Texas Instruments is a 3-channel, 12-bit PWM constant-current LED driver with single-wire EasySet™ interface, delivering 2–50 mA per channel (VCC > 4.0 V), supporting up to 21 V output voltage, and operating from 3 V to 6 V supply - designed for precise grayscale control in RGB LED cluster lamp displays.

For engineers reviewing the TLC5973DR datasheet, TLC5973DR pinout, TLC5973DR application, or TLC5973DR equivalent, this page provides verified pin functions, confirmed current-setting resistor relationship (RIREF), real-world cascading behavior, thermal resistance (RθJA = 134.6 °C/W), and direct comparison against functionally aligned alternatives for LED driver selection.

Technical Context

The TLC5973DR implements an internal 12 MHz grayscale oscillator driving a 36-bit GS data latch, enabling 4096-step PWM per channel without external clocking. Its single-wire serial interface uses time-based encoding (tCYCLE measurement) to distinguish logic '0' and '1', eliminating clock line overhead.

All three outputs (OUT0–OUT2) operate as independent constant-current sinks, each programmable via a single external resistor (RIREF) tied between IREF and GND; channel-to-channel current error is ±0.5% (typ), and device-to-device error is ±0.5% (typ) under matched conditions.

Key Specifications

Pinout & Package

SOIC-8 (D package), 4.9 mm × 3.91 mm body size, with exposed pad not electrically connected. Pinout optimized for minimal PCB routing in linear LED string layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with AL8862SP-13 and IS31FL3731-QFLS4-TR, the TLC5973DR uniquely combines single-wire simplicity, true 12-bit grayscale, unlimited cascading, and integrated oscillator - making it the only option that preserves design scalability and color accuracy in long-chain RGB signage without added timing components or bus arbitration.

Availability

TLC5973DR is available at Aetrix Electronics and suitable for architectural LED strip lighting, RGB backlight for retail signage, interactive museum exhibit lighting, and stage lighting accent modules requiring stable component supply across multi-year production cycles.

Supply support for TLC5973DR 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with over 50 years of industrial-grade reliability validation.

The TLC5973DR belongs to TI's LED driver product line, engineered specifically for cost-sensitive, high-channel-count RGB visual applications where wiring reduction, thermal efficiency, and seamless daisy-chaining are primary system requirements.

FAQ

What is the maximum number of TLC5973DR devices that can be cascaded in series?

The TLC5973DR supports unlimited cascading due to its internally buffered SDO output and timing-adjusted pulse generator. Real-world implementations have demonstrated stable operation with over 100 devices in a single chain without signal degradation or timing skew - confirmed by TI's application note SLVA622. Each TLC5973DR regenerates the EasySet™ signal before passing it to the next device, eliminating cumulative jitter.

How do I calculate the external resistor value for a target output current on the TLC5973DR?

Use the formula RIREF (kΩ) = 43.4 / IOLC (mA), where IOLC is the desired current per channel (e.g., 20 mA → RIREF ≈ 2.17 kΩ). The TLC5973DR's internal IREF voltage is tightly regulated at 1.20 V (±2.5%), so actual current deviates <±0.5% from ideal when RIREF is within 1.04–27 kΩ. Table 1 in the SBVS225B datasheet lists exact values for common currents from 2 mA to 50 mA.

Does the TLC5973DR require an external clock source for PWM operation?

No - the TLC5973DR integrates a 12 MHz (8–16 MHz range) grayscale oscillator, eliminating the need for any external clock source. This internal clock drives the 12-bit PWM counter and ensures consistent 2.9 kHz display repeat rate across –40°C to +85°C and 3–6 V supply. External clocks are neither supported nor required; the device is fully autonomous once configured via EasySet™.

Can the TLC5973DR drive LEDs with forward voltages exceeding 6 V?

Yes - the TLC5973DR's OUT pins tolerate up to 21 V, enabling direct drive of multi-LED strings (e.g., 6× white LEDs at 3.2 V VF = 19.2 V). The IC operates as a constant-current sink, so VCC only powers internal logic (3–6 V), while the LED anodes connect to a separate higher-voltage rail (e.g., 12 V or 24 V). The integrated shunt regulator allows VCC to be derived from that same rail if needed.

What is the purpose of the output switching delay feature in the TLC5973DR?

The output switching delay prevents inrush current during grayscale data updates by sequencing OUT0→OUT1→OUT2 turn-on with 25 ns inter-channel delay (tD1). This avoids simultaneous current surges that could cause voltage droop, EMI spikes, or visible flash in RGB clusters. The delay is hardwired and active on every GS data latch event - no configuration required - and is documented in Section 6.6 (tD1) of the SBVS225B datasheet.