Texas Instruments LP8543SQE

Overview

LP8543SQE from Texas Instruments is a SMBus/I²C-controlled white LED driver IC with integrated 38 V boost converter and seven programmable current-sink outputs for medium-sized LCD backlight systems. It delivers 0–60 mA per channel with ±3% output current accuracy, adaptive boost voltage control (5.5–22 V input), and supports phase-shift PWM dimming up to 19.5 kHz for efficiency optimization in multi-string LED arrays. It is deployed in 10+ inch LCD displays requiring precise ambient light compensation and thermal safety dimming.

For engineers reviewing the LP8543SQE datasheet, LP8543SQE pinout, LP8543SQE application, or LP8543SQE equivalent, key selection considerations include its 7-channel current sink architecture, WQFN-24 package with 0.5 mm pitch, EEPROM-based calibration for brightness uniformity, ALS interface compatibility with light-to-frequency sensors, and dual-mode PWM control (internal register + external signal).

Technical Context

The LP8543SQE integrates a high-efficiency inductive boost converter with adaptive output voltage regulation-dynamically adjusting V_BOOST based on real-time LED string voltage feedback to minimize power loss. Its internal 5 V LDO supplies up to 5 mA for external ambient light sensors and powers internal logic, while thermal regulation reduces LED PWM duty cycle above user-programmable temperature thresholds.

It implements three independent brightness control paths: 8-bit digital current setting (0–60 mA, 0.23 mA/step), register-based PWM with piecewise-linear transfer curves stored in EEPROM, and external PWM input (0.1–25 kHz) enabling stand-alone operation without host MCU intervention. Phase-shift PWM (PSPWM) dynamically cycles LED strings off to lower average boost voltage and reduce peak battery current.

Key Specifications

Pinout & Package

LP8543SQE is housed in a thermally enhanced 4.0 mm × 4.0 mm × 0.8 mm WQFN-24 package with 0.5 mm pitch and exposed thermal pad (GND_SW connected). The package supports high-power dissipation (θ_JA = 35–50°C/W) and requires PCB copper pour under the pad for optimal thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS61165RTVR and LM3409QMYX/NOPB, the LP8543SQE uniquely integrates seven matched current sinks, adaptive boost, ALS interface, EEPROM calibration, and thermal safety in a single WQFN-24 package-reducing BOM count by ≥12 components and eliminating manual calibration in backlight module assembly.

Availability

LP8543SQE is available at Aetrix Electronics and suitable for automotive infotainment displays, industrial HMI panels, medical diagnostic monitors, and consumer tablet backlights requiring stable component supply, long-term lifecycle support, and production-ready calibration capability.

Supply support for LP8543SQE 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 delivering analog, embedded processing, and connectivity technologies for industrial, automotive, and personal electronics markets.

The LP8543SQE belongs to TI's LCD backlight driver product line, engineered specifically for medium-format displays (10–19 inches) where precise brightness uniformity, ambient adaptability, and thermal robustness are critical design requirements.

FAQ

What is the maximum number of LEDs the LP8543SQE can drive per string?

The LP8543SQE supports up to 10 LEDs in series per string when operated at its maximum boost output voltage of 38 V and typical white LED forward voltage of ~3.2 V. This is confirmed in the Typical Application section of the SNVS604D datasheet, which states "UP TO 70 LEDS" across all seven strings, implying ≤10 per string under standard conditions. Each string is independently current-regulated up to 60 mA.

Does the LP8543SQE require external current-setting resistors?

No, the LP8543SQE does not require external current-setting resistors. LED current is digitally controlled via 8-bit registers (default values loaded from internal EEPROM), with resolution of 0.23 mA per step across a 0–60 mA range. This eliminates component variation, temperature drift, and board space associated with analog current-setting networks.

Can the LP8543SQE operate without a microcontroller?

Yes, the LP8543SQE supports stand-alone operation using its dedicated PWM input pin. When IF_SEL is set low and serial interface lines are unused, the device reads external PWM duty cycle (0.1–25 kHz) to determine LED brightness-enabling direct connection to a simple PWM generator or baseband processor without firmware overhead.

How is ambient light sensing implemented on the LP8543SQE?

The LP8543SQE implements ambient light sensing via the ALSI (Ambient Light Sensor Input) pin, which accepts frequency-modulated output from light-to-frequency sensors (e.g., TEMT6000). The ALSO pin provides programmable active-high/low enable to power-gate the sensor. Transfer curves and compensation coefficients are stored in EEPROM, enabling fully calibrated, closed-loop brightness control without external ADC or processing.

What thermal protection mechanisms does the LP8543SQE provide?

The LP8543SQE includes an internal junction temperature sensor with user-programmable dimming threshold stored in EEPROM. When temperature exceeds the set point, it automatically reduces LED PWM duty cycle to lower power dissipation. Thermal shutdown engages at 150°C (typ.) and recovers at 130°C (typ.), protecting both the IC and connected LEDs from thermal degradation.