Texas Instruments TLC5947RHBT

Overview

TLC5947RHBT from Texas Instruments is a 24-channel, constant-current sink LED driver IC with 12-bit (4096-step) PWM grayscale control, 30-mA per channel output capability, integrated 4-MHz internal oscillator, and thermal shutdown protection. It operates from 3.0 V to 5.5 V supply and supports LED power up to 30 V - used in high-fidelity static LED displays requiring precise brightness uniformity.

For engineers reviewing the TLC5947RHBT datasheet, TLC5947RHBT pinout, TLC5947RHBT application, or TLC5947RHBT equivalent, key selection considerations include channel-to-channel current accuracy (±2% typ), cascaded data transfer rate (15 MHz), grouped 4-channel delay for EMI reduction, and HTSSOP-32 package thermal performance with PowerPAD™.

Technical Context

The TLC5947RHBT implements a fully autonomous PWM timing engine driven by its internal 4-MHz oscillator, eliminating external clock dependency. Grayscale data (288 bits) are serially loaded via SIN/SCLK, latched on XLAT rising edge, and applied to 24 independent constant-current sinks.

Its noise-reduction architecture staggers turn-on/off across four 6-channel groups (e.g., OUT0/4/8/12/16/20 → OUT1/5/9/13/17/21 → OUT2/6/10/14/18/22 → OUT3/7/11/15/19/23), limiting inrush current and EMI. Thermal shutdown activates at 162°C (typ) with 10°C hysteresis, ensuring safe operation under sustained load.

Key Specifications

Pinout & Package

Package: HTSSOP-32 (32-pin, 11.00 mm × 6.20 mm) with exposed thermal pad (PowerPAD™) for enhanced heat dissipation. Requires soldering to PCB copper area for rated 5318 mW power handling at TA < 25°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC5947RHBT, TLC5946RHBR offers pin-compatible scaling down to 16 channels in smaller HTSSOP-28, while TPS61196RGTT trades cascading capability for integrated DC-DC conversion - making TLC5947RHBT optimal for fixed-rail, high-channel-count, thermally demanding LED arrays.

Availability

TLC5947RHBT is available at Aetrix Electronics and suitable for static LED displays, message boards, amusement illumination, and TV backlighting requiring stable component supply, long-term industrial availability, and traceable sourcing.

Supply support for TLC5947RHBT 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 leader specializing in analog, embedded processing, and high-reliability components for industrial, automotive, and consumer applications.

The TLC5947RHBT belongs to TI's precision LED driver product line, engineered for high-brightness, high-uniformity LED systems where accurate current matching, thermal resilience, and simplified timing control are critical.

FAQ

What is the maximum LED forward voltage supported by the TLC5947RHBT?

The TLC5947RHBT supports LED anode voltages up to 30 V at its OUT0–OUT23 pins. This allows direct connection to high-VF LED strings (e.g., 6–10 white LEDs in series) without external voltage translation. The device maintains constant-current regulation across this range as long as VCC remains within 3.0–5.5 V and thermal limits are observed. The TLC5947RHBT output stage is rated for 33 V absolute maximum, providing 3-V margin for transients.

How does the TLC5947RHBT achieve thermal shutdown and recovery?

The TLC5947RHBT integrates a thermal sensor that disables all 24 output drivers when junction temperature exceeds +162°C (typical). Outputs remain off until temperature falls below +152°C (10°C hysteresis), then automatically resume operation at the next internal oscillator clock edge. This behavior is fully autonomous - no external circuitry or host intervention is required. The TLC5947RHBT's HTSSOP-32 PowerPAD™ package enhances heat transfer to the PCB, delaying TSD activation under sustained load.

Can the TLC5947RHBT operate without an external microcontroller after initialization?

Yes - once grayscale data are loaded and latched via XLAT, the TLC5947RHBT runs autonomously using its internal 4-MHz oscillator. The auto-display-repeat function continuously cycles through the programmed PWM sequence without further host commands. BLANK and XLAT can be held static (e.g., BLANK = low, XLAT = low after initial latch) for uninterrupted operation. The TLC5947RHBT only requires MCU interaction for dynamic brightness updates or display changes.

What is the purpose of the 4-channel grouping feature in the TLC5947RHBT?

The TLC5947RHBT divides its 24 outputs into four staggered groups (e.g., OUT0/4/8/12/16/20 → OUT1/5/9/13/17/21 → etc.) to suppress inrush current and EMI. Each group activates ~15–33 ns after the prior one, spreading the total 720-mA peak (24 × 30 mA) over time. This reduces instantaneous supply demand and radiated noise - critical in sensitive audio or RF environments. The TLC5947RHBT's datasheet specifies tD2–tD4 propagation delays to quantify this sequencing.

How is output current calibrated on the TLC5947RHBT?

Output current on the TLC5947RHBT is set by an external resistor (RIREF) connected between IREF and GND. The relationship is IOUT = 41.0 / RIREF (mA, with RIREF in kΩ); e.g., 1.6 kΩ yields ~25.6 mA, and 1.2 kΩ yields ~34.2 mA. Current accuracy is ±2% channel-to-channel and ±2% device-to-device (typical), verified across temperature and voltage. The TLC5947RHBT's VIREF pin outputs a stable 1.20 V reference, enabling precision resistor selection and validation.