Texas Instruments TLC5917IDRG4

Overview

TLC5917IDRG4 from Texas Instruments is an 8-channel constant-current LED sink driver IC designed for precision LED current control in display and lighting systems. It delivers 3–120 mA per channel with ±3% inter-channel current matching, supports 3.0–5.5 V supply, and features open-load, short-load (TLC5917 only), and overtemperature detection - used in LED signage, video panels, and white goods backlighting.

For engineers reviewing the TLC5917IDRG4 datasheet, TLC5917IDRG4 pinout, TLC5917IDRG4 application, or TLC5917IDRG4 equivalent, key selection considerations include its 30-MHz serial interface, error-detection register readback via SDO, R-EXT–based current programming, and SOIC-16 package compatibility with cascaded LED driver architectures.

Technical Context

The TLC5917IDRG4 integrates an 8-bit shift register, output latches, and eight independent constant-current sinks with programmable global gain (256-step, 1/12 to 127/128). Its dual-mode operation-Normal Mode for data loading and Special Mode for error status readback or current gain configuration-relies on edge-triggered LE(ED1) and pulse-width–sensitive OE(ED2) control signals.

Unlike the TLC5916, the TLC5917IDRG4 includes short-to-VLED detection (trigger threshold 2.5–3.1 V, return threshold 2.2 V), enabled only when outputs are active. All channels share a single R-EXT resistor for current setting and feature thermal shutdown with hysteresis (15 °C) and automatic restart after cooling while preserving error status in the internal register.

Key Specifications

Pinout & Package

Package: SOIC-16 (9.90 mm × 3.91 mm), RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC5917IDRG4, TLC5916IDR omits short-circuit detection but retains identical thermal and open-load protection - suitable for cost-sensitive non-safety-critical LED arrays. MAX7219CWG+ trades per-channel current programmability for integrated display control, limiting use to predefined matrix topologies rather than arbitrary LED string configurations.

Availability

TLC5917IDRG4 is available at Aetrix Electronics and suitable for LED signage, video panels, and automotive interior lighting requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TLC5917IDRG4 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 TLC591x product line was engineered specifically for LED display and lighting systems demanding precise current regulation, fault resilience, and scalable serial control - targeting applications where brightness uniformity and diagnostic capability are critical.

FAQ

What is the maximum LED forward voltage supported by the TLC5917IDRG4?

The TLC5917IDRG4 supports up to 20 V at its OUT0–OUT7 pins, enabling direct drive of multi-LED series strings or high-forward-voltage LEDs like white or blue types without external boost circuitry. This rating is absolute maximum and applies regardless of output current level or ambient temperature within the specified operating range.

How does the TLC5917IDRG4 detect short-circuit conditions?

The TLC5917IDRG4 detects short-to-VLED faults by monitoring output voltage: if VOUT exceeds 2.5–3.1 V (trigger threshold) while the channel is active, it sets the corresponding bit in the error register. The condition clears only when VOUT drops below 2.2 V (return threshold). This functionality is exclusive to the TLC5917 family and absent in TLC5916.

Can the TLC5917IDRG4 be used in cascaded configurations?

Yes - the TLC5917IDRG4 supports daisy-chaining via its SDO (serial data out) and SDI (serial data in) pins. When multiple devices are cascaded, a single 8-bit data word shifts through all devices synchronously on CLK, enabling unified control of dozens of LED channels with minimal MCU GPIO usage and no additional logic.

What is the role of the R-EXT pin on the TLC5917IDRG4?

The R-EXT pin on the TLC5917IDRG4 connects to an external resistor tied to GND, establishing the reference current that scales all eight output channels proportionally. A 720 Ω resistor yields ~26 mA per channel at VDD = 3 V; changing R-EXT linearly adjusts full-scale current across the 3–120 mA range without altering digital control logic.

Does the TLC5917IDRG4 require external pull-up or pull-down resistors on control pins?

No - the TLC5917IDRG4 integrates internal 500 kΩ pulldown on LE(ED1) and internal 500 kΩ pullup on OE(ED2), eliminating need for external biasing. These ensure defined logic states during power-up and idle periods, supporting robust operation in noisy industrial environments without added passive components.