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Texas Instruments LP8555YFQR
- Part No.:
- LP8555YFQR
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 36-WFBGA, DSBGA
- Datasheet:
-
LP8555YFQR.pdf
- Description:
- IC LED DRVR RGLTR PWM 36DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:2,969
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Product details
Overview
LP8555YFQR from Texas Instruments is a dual-boost, 12-channel LED backlight driver IC for tablet LCD displays. It integrates two asynchronous DC/DC boost converters (7–28 V output), 12 high-precision 50-mA current sinks with 12-bit brightness control, adaptive headroom-based output voltage regulation, and hybrid PWM/current dimming. It operates from 2.7 V to 20 V input and supports I²C and PWM control interfaces.
For engineers reviewing the LP8555YFQR datasheet, LP8555YFQR pinout, LP8555YFQR application, or LP8555YFQR equivalent, this page delivers verified technical context on dual-boost topology, adaptive VOUT control, phase-shifted PWM operation, thermal shutdown behavior, and LED string auto-detection - all critical for backlight power architecture selection and layout validation.
Technical Context
The LP8555YFQR implements two independent CPM-mode boost converters operating at 500 kHz or 1000 kHz (EPROM-configurable), with 180° phase shift between banks to reduce input ripple and EMI. Each bank features dedicated feedback (FB_A/FB_B), switch (SW_A/SW_B), and ground (GND_SW_A/GND_SW_B) terminals.
It uses adaptive output voltage control by continuously monitoring LED sink headroom voltages across both banks; boost voltage is dynamically adjusted to the minimum required level - e.g., 7 V minimum, up to 28 V maximum (VMAX = 11b) - minimizing power loss while maintaining regulation across varying LED forward voltage mismatches.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VDD Range | 2.7 V to 20 V - powers internal LDO and analog/digital blocks; supports wide-input battery-powered systems. |
| Boost Output Range | 7 V to 28 V - programmable max via EPROM (VMAX field); adapts dynamically to LED string headroom requirements. |
| LED Current Sinks | 12 × 50 mA - six per bank (LEDA1–LEDA6, LEDB1–LEDB6); ±4% output accuracy, 1% matching at 23 mA. |
| Switching Frequency | 500 kHz or 1000 kHz - EPROM-selectable; enables trade-off between efficiency, inductor size, and EMI performance. |
| I²C Interface | Standard-mode (400 kHz) - supports register access for brightness, fault status, and configuration; uses FSET/SDA and ISET/SCL pins. |
| Thermal Protection | 150 °C shutdown with 13 °C hysteresis - prevents permanent damage during sustained overload or poor PCB thermal design. |
| Efficiency | Up to 92% LED drive efficiency at 100% brightness (VIN = 3.7 V, 12×6 LEDs) - achieved via adaptive VOUT and phase-shifted PWM. |
Pinout & Package
LP8555YFQR is housed in a 36-bump DSBGA package (2.478 mm × 2.478 mm) with 0.4 mm pitch. The package supports fine-pitch routing and low-inductance grounding for high-frequency boost operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LEDA1–LEDA6, LEDB1–LEDB6 | LED current sink outputs | 12 individually controlled, high-precision sinks (50 mA max); each connects directly to cathode of one LED string. |
| FB_A / FB_B | Boost converter feedback inputs | Analog inputs monitoring boost output voltage; used by adaptive control loop to regulate VOUT_A/VOUT_B independently. |
| SW_A / SW_B | Boost switch node outputs | High-current switching nodes driving external inductors; require low-impedance routing and separate noisy GND_SW planes. |
| EN/VDDIO | Enable input & I/O supply | Active-high enable; also supplies 1.7–5.5 V to internal logic and I²C interface - must be low-impedance to avoid communication errors. |
| PWM/INT | Dual-function terminal | Configurable as PWM dimming input (BRTMODE ≠ 01) or open-drain interrupt output reporting faults (e.g., open LED, overvoltage). |
| FSET/SDA & ISET/SCL | I²C bus interface / frequency/current setting | When I²C active, function as SDA/SCL; when disabled (BRTMODE = 00), set boost frequency (FSET) and full-scale current (ISET) via external resistors. |
| VLDO & VDD | LDO output & main power input | VDD supplies 2.7–20 V to internal LDO; VLDO provides regulated output (2.7–5.5 V) for analog circuitry - requires 10 µF bypass capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-boost with 180° phase shift | Reduces input current ripple by ~70% and lowers EMI filter component count versus single-boost solutions. |
| Adaptive LED headroom control | Maintains only necessary boost voltage margin - cuts power loss up to 15% vs. fixed-output designs under partial-load conditions. |
| Hybrid PWM + current dimming | Enables >99% dimming range with minimal color shift and reduced thermal stress on LEDs compared to pure PWM. |
| LED string auto-detection | Automatically identifies 2–12 connected strings per bank - eliminates firmware calibration and supports flexible display configurations. |
| Comprehensive fault protection | Detects open/short LED, overvoltage (4 thresholds), overcurrent (3.1 A limit), UVLO, and thermal shutdown - latches or flags via INT pin. |
Applications
| Tablet LCD Backlight | Industrial Panel Display |
|---|---|
Use Scenario: Driving 12-string LED backlight in 10.1-inch tablet with variable battery voltage (3.0–4.2 V). IC Role / Device Role / Timing Role: Dual-boost LED driver with adaptive VOUT, hybrid dimming, and I²C configuration. Use Value: Maintains uniform brightness across temperature and battery discharge using real-time headroom feedback and 12-bit dimming resolution. |
Use Scenario: High-reliability backlight for medical diagnostic panel requiring fault logging and thermal robustness. IC Role / Device Role / Timing Role: Fault-aware LED controller with interrupt reporting, thermal shutdown, and open-LED detection. Use Value: Enables system-level safety compliance via automatic fault flagging and latchable shutdown - no external supervision needed. |
| Automotive Infotainment Display | POS Terminal LCD |
Use Scenario: 7-inch automotive display exposed to wide ambient temperature (−40°C to +85°C) and load dump transients. IC Role / Device Role / Timing Role: Wide-input LED driver with UVLO, overvoltage protection, and extended temp-grade operation. Use Value: Survives 22 V load dump events and maintains regulation down to −40°C using adaptive boost and matched current sinks. |
Use Scenario: Compact retail POS terminal with space-constrained PCB and cost-sensitive BOM. IC Role / Device Role / Timing Role: Integrated dual-boost solution eliminating discrete controllers, MOSFETs, and external current regulators. Use Value: Reduces component count by ≥12 parts and footprint by >35% versus discrete boost + linear sink implementations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED backlight driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61165DRVR | Single-boost, 6-channel, 30-mA sinks; no adaptive VOUT or I²C; fixed 1-MHz switching. | Limited to ≤6 strings; lacks auto-detection, phase-shift, and hybrid dimming - suitable only for simpler, lower-cost displays. | Choose when board space allows larger inductor and system requires only basic PWM dimming without diagnostics. |
| LM3409QMYX/NOPB | External-FET LED controller (no integrated switches); supports >1 A per channel; no I²C or built-in current sinks. | Requires external MOSFETs, sense resistors, and DACs for dimming - higher BOM cost and layout complexity. | Prefer for high-power (>1000 mA) or multi-color RGB backlight systems where flexibility outweighs integration benefits. |
Compared with TPS61165DRVR and LM3409QMYX/NOPB, the LP8555YFQR delivers superior integration (dual boost + 12 sinks + I²C), adaptive efficiency optimization, and comprehensive fault coverage - making it optimal for compact, high-performance tablet and industrial displays where reliability and power savings are prioritized.
Availability
LP8555YFQR is available at Aetrix Electronics and suitable for tablet backlighting, industrial HMI panels, and automotive infotainment displays requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LP8555YFQR 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 technologies with over 50 years of innovation in precision analog ICs.
The LP8555YFQR belongs to TI's high-efficiency LED backlight driver product line, designed specifically for thin, battery-powered tablet PCs requiring adaptive voltage control, low audible noise, and robust fault handling.
FAQ
What is the maximum LED string voltage supported by the LP8555YFQR?
The LP8555YFQR supports a maximum boost output voltage of 28 V, configurable via EPROM (VMAX = 11b). This allows driving up to 8 white LEDs in series (assuming typical VF ≈ 3.5 V) per string while maintaining sufficient headroom for regulation. The adaptive control loop ensures the output never exceeds this limit unless an open-LED fault occurs - in which case VMAX caps the voltage to protect external components.
Does the LP8555YFQR require external MOSFETs for boost operation?
No, the LP8555YFQR integrates two high-current NMOS power switches (SW_A and SW_B) with 0.16 Ω typical RDS(on). Each switch supports up to 3.1 A peak current and eliminates the need for external MOSFETs, gate drivers, or bootstrap circuits - simplifying layout and reducing BOM count. External components required are only inductors, input/output capacitors, and optional current-setting resistors.
How does the LP8555YFQR achieve reduced audible noise in LED dimming?
The LP8555YFQR reduces audible noise through phase-shifted PWM dimming: LED banks A and B are driven with 180° out-of-phase PWM signals. This cancels mechanical vibration in the inductors and minimizes acoustic resonance in the display assembly. Combined with programmable slew-rate control and spread-spectrum switching, it achieves near-silent operation even at low brightness levels - critical for premium tablet user experience.
Can the LP8555YFQR operate without I²C communication?
Yes, the LP8555YFQR supports standalone operation using only PWM input and external resistors. When BRTMODE = 00, FSET/SDA and ISET/SCL pins configure boost frequency and full-scale LED current respectively. EN/VDDIO enables the device, and PWM/INT serves as dimming input - enabling full functionality without microcontroller firmware or I²C bus overhead.
What thermal management considerations apply to the LP8555YFQR in high-power designs?
The LP8555YFQR has a junction-to-board thermal resistance (θJB) of 16.3 °C/W in its DSBGA package. For designs delivering >200 mA total LED current, thermal vias under the GND and GND_SW pads are essential. Layout must separate noisy switch grounds (GND_SW_A/B) from quiet analog/digital grounds (GND), and maintain ≥10 mm² copper area under the die for effective heat spreading - especially when operating near 20 V input or 28 V output.
LP8555YFQR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 36-WFBGA, DSBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 12
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 20V
- Voltage - Output:
- 7V ~ 28V
- Current - Output / Channel:
- 180mA
- Frequency:
- 500kHz, 1MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-DSBGA
LP8555YFQR FAQ
1.How can I place an order for LP8555YFQR through Aetrix?
Please submit a Request for Quotation (RFQ) for LP8555YFQR 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 LP8555YFQR reliable?
The price and inventory of LP8555YFQR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP8555YFQR is usually 5 days.
3.What payment methods are accepted for LP8555YFQR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP8555YFQR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP8555YFQR?
LP8555YFQR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP8555YFQR 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 LP8555YFQR?
For technical support, including LP8555YFQR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP8555YFQR requirements.
6.How does Aetrix verify that LP8555YFQR is sourced from the original manufacturer or authorized distributors?
All LP8555YFQR 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 LP8555YFQR meets industry standards.
7.What is the process for return or replacement of LP8555YFQR?
All LP8555YFQR units undergo pre-shipment inspection (PSI). If there is an issue with LP8555YFQR, 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 LP8555YFQR part is unused and in its original packaging.
Return procedure for LP8555YFQR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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