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STMicroelectronics L99LD20Q6TR
- Part No.:
- L99LD20Q6TR
- Manufacturer:
- STMicroelectronics
- Category:
- LED Drivers
- Package:
- 40-TFQFN Exposed Pad
- Datasheet:
-
L99LD20Q6TR.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,847
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Product details
Overview
L99LD20Q6TR from STMicroelectronics is a dual-channel monolithic buck LED driver IC designed for automotive front lighting. It delivers up to 1.5 A average current per channel with up to 50 V LED forward voltage support, operates from 5.5–24 V battery input, integrates lossless current sensing and SPI-programmable peak current (0.179–1.695 A range), and features AEC-Q100 qualification for low-beam and turn-indicator applications.
For engineers reviewing the L99LD20Q6TR datasheet, L99LD20Q6TR pinout, L99LD20Q6TR application, or L99LD20Q6TR equivalent, this page provides verified technical context, SPI-configurable buck control architecture, real-time LED voltage feedback via VLED1/VLED2 pins, limp-home safety mode, and QFN40L 6×6 wettable-flank package thermal performance data.
Technical Context
The L99LD20Q6TR implements two independent constant off-time (COT) buck converters, each using integrated n-channel MOSFETs driven by bootstrap circuits. Peak current is set digitally via SPI DAC codes, enabling precise inductor current control without external shunt resistors.
Its functional safety architecture includes timeout watchdog, temperature warning at two thresholds, overtemperature shutdown, and direct-input (DIN) bypass mode. Diagnostics include digital LED voltage readback (VLED1/VLED2), open-load and short-circuit detection per channel, and status registers accessible via ST SPI v4.1 protocol.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Voltage | 5.5–24 V input supports wide automotive battery range including load dump transients. |
| LED Current Range | 0.179–1.695 A peak per channel, selectable via SPI to match inductor and LED string requirements. |
| LED Forward Voltage | Up to 50 V per channel enables multi-LED series strings in headlamp modules. |
| Switching Architecture | Constant VLED × TOFF control ensures stable current regulation across varying LED VF and input voltage. |
| Diagnostic Interface | ST SPI v4.1 with 10-bit PWM dimming, global status byte, and per-channel fault reporting. |
| Thermal Protection | Two-level temperature warning + overtemperature shutdown (TSD) with thermal foldback behavior. |
| Package | QFN40L 6×6 mm with exposed pad; RθJA = 30 °C/W on 4-layer PCB (100 cm² copper). |
Pinout & Package
QFN40L 6×6 mm package with wettable flanks and exposed thermal pad (pin 40). Designed for high-power automotive LED driving with optimized thermal dissipation and solder joint inspection capability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| V3V3 (Pin 1) | Internal LDO output | 3.3 V regulated supply for internal logic; requires 4.7 µF low-ESR capacitor. |
| CSN (Pin 3) | SPI chip select | Active-low enable for SPI communication; CMOS-compatible input. |
| PWMCLK (Pin 4) | PWM clock input | External clock source for 10-bit resolution internal PWM dimming generator. |
| DIN (Pin 10) | Direct drive input | Bypasses SPI control for emergency limp-home operation of both channels. |
| LX1F/LX2F (Pins 15/16) | Power switch source | High-current switching node connections for external freewheeling diodes. |
| VLED1/VLED2 (Pins 24/23) | LED anode sense | Digital readback of LED string forward voltage for diagnostics and open-load detection. |
| PGND (Pins 22,38) | Power ground | Dedicated low-impedance return path for buck power stages; separate from SGND. |
Key Features
| Feature | Design Value |
|---|---|
| Lossless current sensing | Integrated MOSFET RDS(on) sensing eliminates external shunt resistor, reducing BOM cost and thermal loss. |
| Programmable peak current | SPI-adjustable IL_PEAK in two ranges (low/high RDS_ON modes) enables flexible inductor selection. |
| Dual independent buck control | Each channel operates autonomously with dedicated VLED feedback, fault reporting, and protection logic. |
| Limp-home function | Hardware-enabled fallback mode via DIN pin ensures partial lighting functionality during MCU failure. |
| AEC-Q100 Grade 1 | Qualified for -40°C to +125°C ambient operation, meeting automotive front-lighting reliability standards. |
Applications
| Low Beam Headlamp | Turn Indicator Module |
|---|---|
Use Scenario: Primary illumination source in automotive headlamp assemblies requiring precise current regulation and thermal robustness. IC Role / Device Role / Timing Role: Dual-buck controller delivering synchronized 1.5 A average current per LED string with real-time VLED monitoring. Use Value: Enables adaptive beam shaping via SPI-programmable dimming and fault-aware operation under battery transients. | Use Scenario: Fast-response directional signaling system requiring rapid on/off cycling and fail-safe behavior. IC Role / Device Role / Timing Role: Independent channel control with 10-bit PWM dimming and hardware DIN-triggered limp-home activation. Use Value: Guarantees minimum visibility during microcontroller faults while maintaining E-mark compliance for flash timing. |
| Daytime Running Light (DRL) | Fog Light Assembly |
Use Scenario: Always-on exterior lighting operating continuously at partial brightness under variable ambient temperatures. IC Role / Device Role / Timing Role: Constant-current regulator with temperature warning thresholds and low standby current (<50 µA). Use Value: Prevents thermal derating through dual-threshold warning and maintains consistent luminance across vehicle life cycle. | Use Scenario: High-intensity auxiliary lighting deployed in low-visibility conditions with demanding thermal management. IC Role / Device Role / Timing Role: High-VF capable buck driver supporting up to 50 V LED strings and load-dump protected input stage. Use Value: Sustains full output during 12 V system surges (ISO 7637-2 Pulse 5a) without latch-off or reset. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel automotive LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AL8862Q-13 | Single-channel buck controller with external MOSFETs; no integrated power stage or VLED feedback. | Lacks dual-channel integration and diagnostic capability; requires additional components for two-string control. | Select when discrete layout flexibility and lower channel count justify added BOM complexity. |
| TLC6C5716-Q1 | 16-channel linear LED driver with PWM dimming; no buck conversion or high-VF support. | Optimized for low-voltage interior lighting; unsuitable for >20 V LED strings or front-lighting efficiency demands. | Prefer for dashboard or ambient lighting where thermal density and efficiency are secondary to channel count. |
Compared with AL8862Q-13 and TLC6C5716-Q1, the L99LD20Q6TR uniquely combines dual monolithic buck stages, integrated diagnostics, and AEC-Q100-compliant limp-home functionality-enabling compact, safety-aware front-lighting designs without external current sensing or redundant controllers.
Availability
L99LD20Q6TR is available at Aetrix Electronics and suitable for automotive front lighting, adaptive driving beam systems, and exterior signal lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for L99LD20Q6TR 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
STMicroelectronics is a global semiconductor leader specializing in automotive, industrial, and power management solutions, with broad analog and mixed-signal portfolio.
The L99LD20 belongs to ST's automotive LED driver product line, engineered specifically for functional-safety-critical front lighting applications requiring programmability, diagnostics, and robust transient protection.
FAQ
What is the maximum allowable LED string voltage per channel?
The L99LD20Q6TR supports up to 50 V forward voltage per LED string, verified under continuous conduction mode with VBUCKIN ≥ 12 V and junction temperature ≤ 125 °C. This enables configurations with 12–15 white LEDs in series, assuming typical 3.2–3.8 V VF per diode. The device uses constant VLED × TOFF architecture to maintain regulation across this range without external compensation.
How does the limp-home function operate without MCU involvement?
The limp-home mode activates when the DIN pin is pulled high, forcing both buck channels into fixed 50% duty-cycle operation independent of SPI registers. This hardware-based fallback ensures minimum light output during MCU failure or firmware crash. The mode remains active until DIN returns low, and it coexists with temperature warning and overtemperature shutdown protections.
Can the L99LD20Q6TR drive LED strings with different forward voltages simultaneously?
Yes-each buck channel operates independently with dedicated VLED1/VLED2 sense inputs and separate peak current programming. Channel 1 can regulate a 36 V DRL string while Channel 2 drives a 48 V low-beam string, provided input voltage exceeds the higher VLED plus dropout margin. The constant off-time architecture inherently accommodates mismatched VF without cross-regulation.
What thermal derating applies above 105 °C junction temperature?
Above 105 °C, the L99LD20Q6TR initiates temperature warning (flagged in Status Register 2), reducing LED current by 0.5%/°C until 125 °C, where overtemperature shutdown latches off both channels. Recovery requires thermal cooldown below 115 °C and either SPI reset command or power cycle. This staged response prevents thermal runaway while preserving diagnostic visibility.
L99LD20Q6TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 40-TFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Buck
- Internal Switch(s):
- Yes
- Number of Outputs:
- 2
- Voltage - Supply (Min):
- 5.5V
- Voltage - Supply (Max):
- 24V
- Voltage - Output:
- 50V
- Current - Output / Channel:
- 1.5A
- Frequency:
- -
- Dimming:
- PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (6x6)
L99LD20Q6TR FAQ
1.How can I place an order for L99LD20Q6TR through Aetrix?
Please submit a Request for Quotation (RFQ) for L99LD20Q6TR 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 L99LD20Q6TR reliable?
The price and inventory of L99LD20Q6TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L99LD20Q6TR is usually 5 days.
3.What payment methods are accepted for L99LD20Q6TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L99LD20Q6TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L99LD20Q6TR?
L99LD20Q6TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L99LD20Q6TR 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 L99LD20Q6TR?
For technical support, including L99LD20Q6TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L99LD20Q6TR requirements.
6.How does Aetrix verify that L99LD20Q6TR is sourced from the original manufacturer or authorized distributors?
All L99LD20Q6TR 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 L99LD20Q6TR meets industry standards.
7.What is the process for return or replacement of L99LD20Q6TR?
All L99LD20Q6TR units undergo pre-shipment inspection (PSI). If there is an issue with L99LD20Q6TR, 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 L99LD20Q6TR part is unused and in its original packaging.
Return procedure for L99LD20Q6TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
L99LD20Q6TR Tags
-
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
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
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