Texas Instruments TLC5947DAP

Overview

TLC5947DAP from Texas Instruments is a 24-channel, 12-bit PWM constant-current LED sink driver with integrated 4-MHz oscillator, ±2% channel-to-channel current accuracy, 30-mA per channel capability, and thermal shutdown protection. It operates from 3.0 V to 5.5 V and supports LED power supply up to 30 V, enabling high-fidelity grayscale control in static LED signage and message boards.

For engineers reviewing the TLC5947DAP datasheet, TLC5947DAP pinout, TLC5947DAP application, or TLC5947DAP equivalent, key selection considerations include its 288-bit serial interface timing (30 MHz standalone), grouped 4×6-channel soft-start for EMI reduction, BLANK/XLAT control sequence, and DAP (HTSSOP-32) thermal performance with PowerPAD™.

Technical Context

The TLC5947DAP implements a fully autonomous grayscale PWM engine: internal 4-MHz oscillator drives a 12-bit counter that compares against latched 12-bit GS data per channel, generating precise on-time durations from 0% to 99.98%. Grayscale data are loaded via 288-bit shift register (24 × 12 bits), then transferred to latch on XLAT rising edge.

Output drivers are grouped into four 6-channel sets (e.g., OUT0/4/8/12/16/20) with staggered turn-on/turn-off timing to suppress inrush current and EMI. Thermal shutdown activates at 162°C (typical) junction temperature and auto-restarts when temperature falls below threshold minus 10°C hysteresis.

Key Specifications

Pinout & Package

Package: HTSSOP-32 (DAP) with exposed thermal pad (11.00 mm × 6.20 mm); PowerPAD™ soldering required for rated thermal performance (RθJA = 32.8°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC5947DAP, TLC5940IPW demands external clock generation and lacks thermal shutdown hysteresis, while MAX6966ATL+ trades channel count and daisy-chain capability for I²C ease-of-use and smaller footprint-neither matches the integrated oscillator + 24-channel + PowerPAD™ thermal solution of TLC5947DAP.

Availability

TLC5947DAP is available at Aetrix Electronics and suitable for static LED signage, message boards, and amusement illumination requiring stable component supply, long-term industrial availability, and consistent thermal performance across temperature extremes.

Supply support for TLC5947DAP 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 connectivity technologies, with decades of expertise in precision power and signal chain solutions.

The TLC5947 belongs to TI's high-accuracy LED driver product line, engineered specifically for demanding visual applications requiring uniform grayscale fidelity, thermal resilience, and simplified system-level timing.

FAQ

What is the function of the IREF pin on the TLC5947DAP?

The IREF pin on the TLC5947DAP serves as the reference node for setting the full-scale constant-current output. Connecting an external resistor between IREF and GND establishes the sink current for all 24 channels via the formula IOUT ≈ 41 × VREF / RIREF, where VREF is internally regulated to 1.20 V (typ). For example, a 1.6 kΩ resistor yields ~30.75 mA per channel. This single-point calibration ensures matched current across channels without per-channel trimming.

How does the TLC5947DAP handle thermal overload conditions?

The TLC5947DAP incorporates an integrated thermal shutdown (TSD) circuit that disables all 24 output drivers when the junction temperature exceeds 162°C (typical). Outputs remain off until the junction cools below (162°C – THYS), where THYS is 10°C (typical) hysteresis. This automatic recovery prevents permanent damage during sustained overloads or poor heatsinking, and requires no external intervention-critical for unattended signage or lighting systems.

Can the TLC5947DAP operate without an external clock source?

Yes, the TLC5947DAP can operate without an external clock source because it integrates a factory-trimmed 4-MHz internal oscillator. This oscillator directly drives the 12-bit grayscale counter and PWM timing engine, enabling autonomous display repetition while BLANK is low. External SCLK is only required for serial data loading-making the TLC5947DAP ideal for systems where clock resource sharing or board space is constrained.

What is the purpose of the SOUT pin on the TLC5947DAP?

The SOUT pin on the TLC5947DAP outputs the most significant bit (MSB) of the grayscale shift register on the falling edge of SCLK, enabling seamless daisy-chaining of multiple TLC5947DAP devices. When cascading, SOUT of one IC connects to SIN of the next, allowing a single 288×N-bit data stream to configure N devices. This eliminates parallel bus routing and reduces MCU pin count-essential for large LED arrays requiring dozens of channels.

How does the TLC5947DAP reduce electromagnetic interference (EMI) during LED switching?

The TLC5947DAP reduces EMI by dividing its 24 output channels into four groups of six (e.g., OUT0/4/8/12/16/20), with sequential turn-on and turn-off timing staggered by ~15–33 ns between groups. This grouped delay prevents simultaneous current surges that cause voltage droop and radiated noise. Combined with CMOS-level I/O and internal slew-rate control, this architecture meets stringent EMI requirements in commercial signage and indoor lighting without added filtering components.