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Texas Instruments LP8543SQ
- Part No.:
- LP8543SQ
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LP8543SQ.pdf
- Description:
- IC LED DRV RGLTR PWM 60MA 24WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,071
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Product details
Overview
LP8543SQ from Texas Instruments is a SMBus/I²C-controlled white LED driver IC with integrated 38V 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, and phase-shift PWM dimming. It operates from 5.5V to 22V input and supports ambient light sensing via digital ALS interface for dynamic brightness regulation in portable displays.
For engineers reviewing the LP8543SQ datasheet, LP8543SQ pinout, LP8543SQ application, or LP8543SQ equivalent, this page provides verified technical context on adaptive boost efficiency, PSPWM thermal optimization, EEPROM-calibrated current matching across 7 strings, and dual-display group configuration (Display1/Display2) - all critical for backlight BOM consolidation and yield-sensitive LCD module design.
Technical Context
The LP8543SQ integrates a high-voltage DC/DC boost converter (38V max, 0.12 Ω RDS-ON) with adaptive output voltage control driven by real-time monitoring of OUT1–OUT7 saturation voltages. Its phase-shift PWM (PSPWM) dynamically disables LED strings to lower boost voltage under low-brightness or mismatched-VF conditions, reducing peak battery current and improving system efficiency by up to 15% versus fixed-frequency boost topologies.
It implements dual-mode serial control (SMBus v2.0 or I²C-compatible, selectable via IF_SEL), an internal 5.0 V ±0.5 V LDO (470 nF CVLDO required), and EEPROM-stored calibration for Display1/Display2 current values, ALS-to-backlight transfer curves, and thermal shutdown thresholds. Fault detection covers open/short LED strings, over-current, UVLO (configurable 2.7 V or 5.4 V threshold), and thermal regulation above user-programmed junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5 V to 22 V - supports 2× to 4× Li-ion battery stacks without external pre-regulation |
| Boost Output Voltage | Up to 38 V - enables driving up to 10 LEDs in series per string at typical forward voltage |
| LED Current Range | 0–60 mA per channel, 0.23 mA step - fine-grained binning compensation and panel-to-panel brightness matching |
| Current Matching (OUT1–OUT6) | ±0.5% to ±1.35% - ensures uniform luminance across multi-string backlights without external current mirrors |
| PWM Dimming Frequency | 229 Hz to 19.5 kHz - avoids audible noise while supporting high-speed camera flicker mitigation |
| Phase-Shift PWM (PSPWM) | Reduces average boost voltage by up to 4 V under 30% brightness - lowers power loss in switch and inductor |
| Ambient Light Interface | Digital light-to-frequency sensor input (ALSI) with programmable prescaler and response curve - eliminates external ADC and analog signal conditioning |
Pinout & Package
LP8543SQ is housed in a thermally enhanced WQFN-24 package (4.0 mm × 4.0 mm × 0.8 mm, 0.5 mm pitch) with exposed thermal pad. Pin 1 identifier marked on top surface; bottom-side thermal pad must be soldered to PCB ground plane for thermal regulation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND_SW | Boost converter ground reference | Separate ground return for high-current switch node - minimizes noise coupling into signal paths |
| PWM | External PWM dimming input | Accepts 0.1–25 kHz duty-cycle signals; enables stand-alone operation without MCU or serial bus |
| IF_SEL | Interface mode selection | Low = I²C mode; High = SMBus v2.0 mode - determines timing compliance and protocol-level error handling |
| EN | Enable control input | Active-high logic enable; ties to system power rail or PMIC sequencer for controlled startup/shutdown |
| ALSI | Ambient light sensor frequency input | Direct connection to light-to-frequency ALS ICs (e.g., TSL2561); no external RC filter required |
| ALSO | Ambient light sensor enable output | Open-drain active-high output to power external ALS - reduces standby current when ALS inactive |
| FAULT | Open-drain fault indicator | Asserts low on LED open/short, boost over-current, thermal shutdown, or UVLO - drives host interrupt line |
| VDDIO | Digital I/O reference voltage | 1.65–5.5 V supply for SDA/SCLK/ADR/IF_SEL - decouples logic voltage from VIN domain |
| SCLK / SDA | I²C/SMBus clock/data lines | Support 400 kHz I²C fast-mode or 100 kHz SMBus - compatible with standard microcontroller peripherals |
| OUT1–OUT7 | Current sink outputs | Seven independent 60 mA sinks; OUT1–OUT6 grouped as Display1, OUT7 configurable as Display2 or main backlight extension |
| VIN | Main power input | 5.5–22 V input with internal UVLO; feeds both boost converter and internal LDO - no external bias required |
| SW | Boost switch node | Connects to external inductor (15 µH typical); requires low-ESR ceramic output capacitor (4.7 µF) |
| FB | Boost feedback input | Resistive divider sets regulated boost output voltage; supports dynamic adjustment via register write |
| VLDO | 5 V LDO output | Supplies 5 mA for external ALS or sensors; requires 470 nF ceramic capacitor - mandatory even if unused |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive Boost Voltage Control | Adjusts VBOOST in real time to minimum required level based on LED string VF - cuts power loss by up to 20% vs. fixed-output boost |
| Phase-Shift PWM (PSPWM) | Sequentially disables LED strings to reduce simultaneous conduction - lowers peak input current and improves battery runtime |
| EEPROM-Based Calibration | Stores factory-set current values, ALS response curves, and thermal thresholds - eliminates post-assembly trimming and enables one-time programming during module assembly |
| Dual-Display Grouping | Configurable assignment of OUT1–OUT6 to Display1 and OUT7 to Display2 - supports main + sub-display backlighting with independent current/PWM control |
| Integrated ALS Interface | Direct digital frequency input (ALSI) and programmable enable output (ALSO) - removes need for external ADC, op-amps, or discrete logic |
| Comprehensive Fault Detection | Reports open/short LED strings, boost over-current, UVLO, and thermal overload via FAULT pin and status register - enables automated production test and field diagnostics |
Applications
| Tablet LCD Backlight | Industrial HMI Display |
|---|---|
Use Scenario: 10.1-inch IPS LCD panel in battery-powered tablet requiring uniform edge-lit backlight with automatic ambient adaptation. IC Role / Device Role / Timing Role: LP8543SQ acts as primary WLED driver, managing 6 strings (Display1) with PSPWM dimming and ALS-driven brightness curve. Use Value: Adaptive boost reduces average input current by 18% at 50% brightness, extending battery life; EEPROM calibration ensures <±2% luminance variance across 10k-unit production run. |
Use Scenario: 12.1-inch ruggedized HMI display in factory automation panel operating continuously at 50°C ambient. IC Role / Device Role / Timing Role: LP8543SQ drives 7 LED strings (6 for main display, 1 for status indicator) with thermal regulation and fault reporting. Use Value: Programmable thermal shutdown threshold prevents LED degradation at elevated temperatures; FAULT pin triggers PLC alarm on open-circuit LED failure. |
| Medical Diagnostic Monitor | Automotive Infotainment Display |
Use Scenario: 15-inch diagnostic-grade monitor requiring precise grayscale tracking and zero flicker across clinical lighting environments. IC Role / Device Role / Timing Role: LP8543SQ provides 8-bit current control + 10-bit effective PWM resolution via piecewise-linear curve stored in EEPROM. Use Value: ±0.5% current matching between strings eliminates vertical banding; 19.5 kHz PWM frequency eliminates camera capture artifacts during image review. |
Use Scenario: 8-inch automotive center-stack display with 12 V battery input, needing robust UVLO, ESD protection, and ALS-based daylight/night mode switching. IC Role / Device Role / Timing Role: LP8543SQ serves as integrated backlight controller with 5.4 V UVLO threshold, 200 V machine-model ESD rating, and ALSI-driven auto-dimming. Use Value: Configurable UVLO prevents brown-out reset during cold-cranking; ALSO output powers TSL2572 sensor only when active - cuts parasitic drain. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar WLED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61165DRVR | Single-output 40 V boost LED driver; no integrated ALS interface, no EEPROM, no PSPWM; 1.2 MHz fixed-frequency switching | Requires external ALS circuitry and MCU-based dimming control; suitable for cost-sensitive single-string designs | Choose when only one LED string is needed and ALS integration is handled externally |
| MAX16832ATP+ | 6-channel current-sink driver with 40 V boost; supports analog/digital dimming but lacks adaptive boost, EEPROM, or ALS interface | No built-in ambient light compensation or factory calibration storage; relies on external microcontroller for curve mapping | Prefer for industrial lighting where thermal management is handled via heatsink, not IC regulation |
Compared with TPS61165DRVR and MAX16832ATP+, the LP8543SQ uniquely combines 7-channel current sinking, adaptive boost, on-chip ALS interface, and EEPROM-based calibration - enabling single-IC backlight solutions for medium-format LCDs with production-ready luminance consistency and reduced BOM count.
Availability
LP8543SQ is available at Aetrix Electronics and suitable for tablet LCD backlight, industrial HMI display, medical diagnostic monitor, and automotive infotainment display applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LP8543SQ 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 power management ICs, with decades of expertise in display power solutions and automotive-grade reliability.
The LP8543SQ belongs to TI's WLED backlight driver product line, engineered specifically for medium-format LCD panels (10–15 inches) where high efficiency, multi-string current matching, and ambient-aware dimming are essential for battery life and visual quality.
FAQ
What is the maximum number of LEDs the LP8543SQ can drive per string?
The LP8543SQ supports up to 10 LEDs in series per string, based on its 38 V maximum boost output voltage and typical white LED forward voltage of ~3.2 V. This allows full-string operation at 32 V (10 × 3.2 V) with sufficient headroom for regulation. The device's saturation voltage (VSAT) remains below 400 mV at 60 mA, ensuring stable current sinking across the full range. LP8543SQ achieves this without external components beyond the boost inductor and capacitors.
Does the LP8543SQ require external EEPROM for operation?
No, the LP8543SQ contains on-chip EEPROM that stores default LED current values, ALS response curves, thermal thresholds, and output configuration settings. This internal memory is programmed once during module manufacturing using standard SMBus/I²C commands - no external EEPROM or additional firmware infrastructure is needed. The LP8543SQ reads calibration data from its internal EEPROM at power-up and applies it automatically.
How does phase-shift PWM (PSPWM) improve efficiency in the LP8543SQ?
PSPWM in the LP8543SQ improves efficiency by sequentially disabling LED strings to lower the required boost output voltage. When strings with higher forward voltage are turned off, the boost regulator reduces its output to match the remaining active strings - cutting conduction and switching losses. At 30% brightness, this reduces average VBOOST by up to 4 V, lowering total power dissipation by ~15% compared to conventional fixed-frequency PWM. LP8543SQ implements this autonomously without MCU intervention.
Can the LP8543SQ drive two independent displays simultaneously?
Yes, the LP8543SQ supports dual-display operation via programmable grouping: OUT1–OUT6 are assigned to Display1 (main backlight), and OUT7 is independently configurable as Display2 (sub-display, status indicator, or keyboard backlight). Each group has dedicated 8-bit current and PWM registers, allowing separate brightness, dimming curve, and thermal regulation settings. This capability is stored in EEPROM and activated at startup - no runtime reconfiguration is needed. LP8543SQ enables true hardware-isolated dual-display control.
What ambient light sensors are compatible with the LP8543SQ ALS interface?
The LP8543SQ ALS interface is designed for digital light-to-frequency (LTF) sensors such as the TAOS TSL2561, AMS TSL2572, or Vishay VEML6030. These sensors output a square-wave signal whose frequency scales linearly with illuminance - directly accepted at the ALSI pin. The LP8543SQ measures this frequency, applies user-programmed compensation coefficients (stored in EEPROM), and maps it to backlight brightness. No external ADC, op-amp, or signal conditioning is required. LP8543SQ's ALSO pin provides synchronized 5 V power to the sensor.
LP8543SQ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 7
- Voltage - Supply (Min):
- 5.5V
- Voltage - Supply (Max):
- 22V
- Voltage - Output:
- 40V
- Current - Output / Channel:
- 60mA
- Frequency:
- 625kHz ~ 1.25MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-WQFN (4x4)
LP8543SQ FAQ
1.How can I place an order for LP8543SQ through Aetrix?
Please submit a Request for Quotation (RFQ) for LP8543SQ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LP8543SQ reliable?
The price and inventory of LP8543SQ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP8543SQ is usually 5 days.
3.What payment methods are accepted for LP8543SQ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP8543SQ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP8543SQ?
LP8543SQ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP8543SQ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LP8543SQ?
For technical support, including LP8543SQ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP8543SQ requirements.
6.How does Aetrix verify that LP8543SQ is sourced from the original manufacturer or authorized distributors?
All LP8543SQ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LP8543SQ meets industry standards.
7.What is the process for return or replacement of LP8543SQ?
All LP8543SQ units undergo pre-shipment inspection (PSI). If there is an issue with LP8543SQ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LP8543SQ part is unused and in its original packaging.
Return procedure for LP8543SQ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LP8543SQ Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
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BCR421UE6327HTSA1
Infineon Technologies
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LYT1604D-TL
Power Integrations
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HV9910CLG-G
Microchip Technology
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CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
Diodes Incorporated
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