Texas Instruments TLC5940NT

Overview

TLC5940NT from Texas Instruments is a 16-channel constant-current sink LED driver with 12-bit (4096-step) grayscale PWM control, 6-bit (64-step) dot correction stored in integrated EEPROM, and simultaneous LED open detection (LOD) and thermal error flag (TEF). It supports up to 120 mA per channel (VCC > 3.6 V), operates from 3 V to 5.5 V, and delivers precise current regulation for high-density LED signage and display backlighting.

For engineers reviewing the TLC5940NT datasheet, TLC5940NT pinout, TLC5940NT application, or TLC5940NT equivalent, key selection considerations include its serial 3-wire interface (SIN/SCLK/XLAT), GSCLK/BLANK timing constraints, IREF-based current programming, open-drain XERR error reporting, and HTSSOP-28 package thermal performance under sustained 16-channel drive.

Technical Context

The TLC5940NT implements dual-mode serial data loading: grayscale (GS) data (96 bits) and dot correction (DC) data (192 bits), selected via VPRG logic level. Its internal architecture separates GS counter (12-bit) and DC register (6-bit) paths, with XLAT latching data into either register based on VPRG state. GSCLK drives the PWM counter; BLANK forces all outputs OFF and resets the counter.

LED open detection monitors OUTn voltage during active sink operation (threshold ≤0.4 V); TEF triggers at junction temperature ≥170 °C (max). Both errors assert open-drain XERR low. Output delay increments by 20 ns per channel (0–300 ns total), reducing inrush current transients without external circuitry.

Key Specifications

Pinout & Package

Package: HTSSOP-28 (9.70 mm × 4.40 mm), thermally enhanced with exposed thermal pad (PWP suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC5940NT, TLC5941IPWPR trades EEPROM persistence for runtime current scaling flexibility, while MAX6966ATL+ sacrifices grayscale resolution and trimming capability for I²C simplicity and lower gate count-making TLC5940NT optimal for high-fidelity, maintenance-sensitive LED display systems.

Availability

TLC5940NT is available at Aetrix Electronics and suitable for LED signage, full-color video walls, and display backlighting requiring stable component supply, long-term manufacturability, and guaranteed thermal performance in HTSSOP packaging.

Supply support for TLC5940NT 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 TLC5940NT belongs to TI's high-performance LED driver product line, designed specifically for demanding visual applications requiring accurate grayscale rendering, robust fault detection, and seamless integration into large-scale LED arrays.

FAQ

What is the maximum output current per channel for the TLC5940NT?

The TLC5940NT supports up to 120 mA per channel when VCC exceeds 3.6 V. This maximum current is set by an external resistor connected to the IREF pin, where Imax ≈ 31.5 × V(IREF)/R(IREF) and V(IREF) is nominally 1.24 V. At VCC < 3.6 V, the limit drops to 60 mA per channel. The actual delivered current depends on R(IREF) value and operating temperature, with ±4% channel-to-channel matching specified.

How does the TLC5940NT implement dot correction, and where is the data stored?

The TLC5940NT implements 6-bit (64-step) dot correction per channel to compensate for LED forward-voltage variations and aging. Dot correction data is written to and retained in an integrated EEPROM. Programming requires VPRG = 20–23 V and DCPRG = HIGH. Once stored, the EEPROM retains values across power cycles, eliminating the need for host MCU initialization at startup-unlike volatile alternatives such as the TLC5941.

Can multiple TLC5940NT devices be connected together, and how is data routed?

Yes, multiple TLC5940NT devices can be daisy-chained using the SOUT-to-SIN connection. Data is shifted in MSB-first: 96 bits for grayscale or 192 bits for dot correction. The SOUT pin outputs status bits (LOD/TEF) after XLAT, enabling readback. Cascading preserves timing integrity-propagation delay from SOUT to next SIN is specified at 30 ns-and supports large LED matrices without address decoding or additional control lines.

What happens when the TLC5940NT detects an open LED or overtemperature condition?

Both LED open detection (LOD) and thermal error flag (TEF) assert the open-drain XERR pin low. LOD triggers when an enabled OUTn voltage falls below 0.4 V; TEF activates above 170 °C junction temperature. The XERR signal remains low until the fault clears and XLAT is pulsed to reset latched status. LOD can be masked by holding BLANK = HIGH, allowing independent thermal monitoring during display blanking periods.

What is the purpose of the graduated output delay feature in the TLC5940NT?

The TLC5940NT applies a fixed 20 ns delay increment between consecutive outputs (OUT0 = 0 ns, OUT1 = 20 ns, ..., OUT15 = 300 ns). This staggered turn-on/off reduces simultaneous switching current (di/dt), lowering peak input current demand and easing bypass capacitor sizing. It also minimizes conducted EMI and voltage droop on shared VCC/GND planes-critical in dense PCB layouts with many parallel TLC5940NT devices driving high-current LEDs.