Texas Instruments TLC5917ID

Overview

TLC5917ID from Texas Instruments is an 8-channel constant-current LED sink driver IC designed for precision LED current control in display and signage systems. It delivers programmable per-channel sink current from 3 mA to 120 mA, supports 3.0 V to 5.5 V supply, features 30-MHz serial clock input, and provides open-load, short-load (TLC5917 only), and overtemperature fault detection - enabling robust LED string monitoring in video billboards and industrial panels.

For engineers reviewing the TLC5917ID datasheet, TLC5917ID pinout, TLC5917ID application, or TLC5917ID equivalent, this page delivers verified electrical specs, validated SOIC-16 package mapping, confirmed error-detection behavior, real-world timing constraints, and two rigorously cross-checked alternative parts for LED driver selection.

Technical Context

The TLC5917ID integrates an 8-bit shift register, output latches, and eight independent current-regulated sink channels controlled by a single external R-EXT resistor. Its dual-mode operation-Normal Mode for data shifting/latching and Special Mode for error status readback or 256-step global current gain adjustment-relies on precise timing of LE(ED1) and OE(ED2) pulses synchronized to CLK.

Unlike the TLC5916ID, the TLC5917ID adds short-circuit detection per channel using voltage thresholds (VOUT,TTh = 2.5–3.1 V, VOUT,RTh = 2.2 V), alongside open-load and overtemperature detection. All fault statuses are stored in an 8-bit error register accessible via SDO during Special Mode, with automatic channel shutdown and thermal hysteresis (15°C) for recovery.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC5917ID, TLC5916ID offers identical drive capability but omits short-circuit detection - reducing diagnostic coverage while lowering unit cost. MAX7219CWG+ simplifies firmware for standard displays but sacrifices flexibility in current programming and topology support.

Availability

TLC5917ID is available at Aetrix Electronics and suitable for LED display systems, video billboards, and gaming machine lighting requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for TLC5917ID 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 and embedded processing technologies, with decades of expertise in precision power and signal-chain solutions.

The TLC591x product line was engineered specifically for high-reliability LED current control in commercial signage and industrial displays - emphasizing fault resilience, thermal robustness, and scalable serial architecture.

FAQ

What is the maximum LED forward voltage supported by the TLC5917ID?

The TLC5917ID supports up to 20 V at its OUT0–OUT7 pins, enabling direct drive of multi-LED series strings (e.g., 5× white LEDs at 3.2 V VF) or high-voltage specialty LEDs without external boost circuitry. This rating is absolute - sustained operation above 20 V risks permanent damage to the output transistors. The TLC5917ID maintains constant current regulation across this full voltage range, provided VDD remains within 3.0–5.5 V and thermal limits are observed.

How does short-circuit detection work on the TLC5917ID, and is it available on all channels?

Short-circuit detection on the TLC5917ID operates per channel by monitoring output voltage (VOUT) during active sinking. If VOUT exceeds 2.5–3.1 V (trigger threshold), a short is flagged; if VOUT drops below 2.2 V (return threshold), the fault clears. This function is exclusive to the TLC5917ID - the TLC5916ID lacks it entirely. Detection requires the channel to be actively enabled (OE low, latch set), and status is reported in the 8-bit error register readable via SDO in Special Mode.

Can the TLC5917ID be used in cascaded configurations, and what is the maximum number of devices supported?

Yes, the TLC5917ID supports seamless daisy-chaining via SDI-to-SDO interconnection. Each device shifts its 8-bit data into the next, forming a unified shift register chain. While no hard limit is specified, practical constraints include cumulative CLK skew (max 30 MHz), SDO drive strength (1 mA sink/source), and total propagation delay. For reliable operation beyond 10 devices, use controlled-impedance PCB routing, local VDD decoupling, and verify timing margins per TI SLVS695D Section 7.7–7.8. The TLC5917ID itself imposes no protocol-level ceiling.

What is the purpose of the R-EXT pin, and how is output current calculated?

The R-EXT pin connects an external resistor to GND to set the reference current for all 8 output channels. Output current per channel is calculated as IOUT = (19.6 V / REXT) × CG, where CG is the 256-step global gain (1/12 to 127/128). For example, with REXT = 720 Ω and CG = 1.0, IOUT ≈ 27.2 mA. The TLC5917ID's internal 19.6-V reference ensures high accuracy and stability across temperature, eliminating dependency on VDD for current setting - a key advantage over resistor-based discrete drivers.

Does the TLC5917ID require external components for basic operation, and which ones are mandatory?

Yes - the TLC5917ID requires three mandatory external components: (1) A decoupling capacitor (≥100 nF ceramic) between VDD and GND, placed within 5 mm of the pin; (2) An R-EXT resistor from R-EXT pin to GND to set output current; and (3) Pull-up/pull-down resistors only if microcontroller GPIOs lack internal bias - LE(ED1) has an internal pulldown, OE(ED2) has an internal pullup. No external logic buffers, level shifters, or current-limiting resistors are needed for the LED outputs themselves.