L99LD21 - Automotive LED Driver | STMicroelectronics
MPN: L99LD21 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.5 | $3.50 |
| 10 | $3.15 | $31.50 |
| 100 | $2.8 | $280.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.1 | $2,100.00 |
Drop-in alternatives for L99LD21 β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
L99LD20
β Drop-Inπ Reference alternative (not in catalog)
L99LD21-Q1
β Drop-Inπ Reference alternative (not in catalog)
L99LD21-TR
β Drop-Inπ Reference alternative (not in catalog)
LT3756
β Drop-Inπ Reference alternative (not in catalog)
TPS92691
β Drop-Inπ Reference alternative (not in catalog)
L99LD21 Maximum Ratings & Electrical Characteristics
| Input Voltage Range | 5.5 V to 28 V |
| Output Current | 1.5 A |
| Output Voltage | Up to 60 V |
| Switching Frequency | 100 kHz to 1 MHz |
| Dimming Control | PWM |
| Efficiency | Up to 95% |
| Quiescent Current | 2 mA |
| Operating Temperature | -40C to +150C |
| Package | PowerSSO-36 |
| Mounting Type | Surface Mount |
| Protection Features | Over-temperature, Over-voltage, Over-current |
| Fault Output | Yes |
| Automotive Grade | AEC-Q100 |
| RoHS Status | Compliant |
| MSL Level | 3 |
L99LD21 Pin Configuration
| Pin 1 | VIN β Input supply voltage |
| Pin 2 | GND β Ground |
| Pin 3 | SW β Switch node |
| Pin 4 | BOOT β Bootstrap capacitor |
| Pin 5 | LED+ β LED anode connection |
| Pin 6 | LED- β LED cathode connection |
| Pin 7 | PWM β PWM dimming input |
| Pin 8 | FAULT β Fault output |
| Pin 9 | EN β Enable input |
| Pin 10 | COMP β Compensation pin |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
L99LD21 is suitable for 6 applications: Automotive Headlamps, Daytime Running Lights, Fog Lamps, Interior Ambient Lighting, Adaptive Front Lighting Systems, Commercial Vehicle Lighting.
Automotive Headlamps
The L99LD21 is ideal for automotive headlamp applications, providing high output current and precise current regulation for high-brightness LEDs. Its wide input voltage range and AEC-Q100 qualification ensure reliable operation in harsh automotive environments. The device's boost converter topology efficiently steps up the battery voltage to the level required by the LED string, while the integrated high-side current source maintains consistent brightness. PWM dimming allows for adaptive lighting features, and the fault output enables diagnostic functions in the lighting control unit.
Recommended
Daytime Running Lights
The L99LD21 is well-suited for daytime running lights (DRLs), which require high efficiency and reliable operation. The device's high efficiency reduces power dissipation, which is critical in thermally constrained automotive environments. Its PWM dimming capability allows for brightness adjustment to meet regulatory requirements. The wide input voltage range ensures compatibility with both 12V and 24V electrical systems. The compact PowerSSO-36 package simplifies PCB layout in space-constrained modules.
Recommended
Fog Lamps
The L99LD21 is suitable for fog lamp applications, providing robust current regulation for high-brightness LEDs. The device's integrated protection features, including over-temperature and over-voltage protection, ensure reliable operation in demanding conditions. The boost converter topology efficiently drives LED strings with high forward voltages. The fault output allows for system monitoring and diagnostics. The device's wide operating temperature range of -40C to +150C ensures reliable performance in extreme weather conditions.
Recommended
Interior Ambient Lighting
The L99LD21 is ideal for interior ambient lighting applications, offering precise current control and PWM dimming for customizable lighting effects. The device's high efficiency minimizes power dissipation, which is important in enclosed spaces. The compact PowerSSO-36 package allows for integration into small lighting modules. The wide input voltage range ensures compatibility with the vehicle's electrical system. The device's AEC-Q100 qualification guarantees reliability for automotive interior applications.
Recommended
Adaptive Front Lighting Systems
The L99LD21 is well-suited for adaptive front lighting systems (AFS), which require dynamic brightness control and high reliability. The device's PWM dimming capability enables smooth transitions between lighting modes. The high output current supports multiple LED strings, and the wide input voltage range accommodates varying battery conditions. The integrated fault output allows for real-time diagnostics, enhancing system safety. The device's AEC-Q100 qualification ensures compliance with automotive standards.
Recommended
Commercial Vehicle Lighting
The L99LD21 is suitable for commercial vehicle lighting applications, such as trucks and buses, which require robust and reliable LED drivers. The device's wide input voltage range supports 24V electrical systems commonly found in commercial vehicles. The high output current and high efficiency make it ideal for driving high-brightness LEDs in headlamps and signal lights. The device's protection features ensure reliable operation in demanding environments. The AEC-Q100 qualification guarantees long-term reliability.
Recommended
Recommended Products Summary
Engineering reference data for L99LD21 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L99LD20 | L99LD21-Q1 | LT3756 |
|---|---|---|---|---|
| Package | PowerSSO-36 | PowerSSO-36 - same | PowerSSO-36 - same | PowerSSO-36 - same |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Analog Devices |
| Output Current | 1.5 A | 1 A | 1.5 A | 1 A |
| Input Voltage Range | 5.5V to 28V | 5.5V to 28V | 5.5V to 28V | 4.5V to 40V |
| Switching Frequency | 100kHz to 1MHz | 100kHz to 1MHz | 100kHz to 1MHz | 100kHz to 1MHz |
| Dimming Control | PWM | PWM | PWM | PWM |
| Efficiency | Up to 95% | Up to 95% | Up to 95% | Up to 94% |
| Automotive Grade | AEC-Q100 | AEC-Q100 | AEC-Q100 | No |
Key Differentiators
- Higher output current of 1.5A (vs L99LD20)
- Automotive grade AEC-Q100 qualification (vs LT3756)
- Wide input voltage range of 5.5V to 28V (vs TPS92691)
Design Notes
The L99LD21 can dissipate significant power at high output currents. Ensure adequate thermal management by using a large copper pour on the PCB and providing proper airflow. The PowerSSO-36 package has an exposed pad that should be soldered to a thermal relief pattern to improve heat dissipation.
Place the input and output capacitors as close to the L99LD21 pins as possible to minimize parasitic inductance. Use a 10uF ceramic capacitor on the input and a 10uF ceramic capacitor on the output. Add a 0.1uF ceramic capacitor for high-frequency noise bypass. The bootstrap capacitor should be placed close to the BOOT pin.
Do not exceed the maximum input voltage of 28V. Ensure the PWM dimming signal is properly level-shifted if the microcontroller operates at a different voltage. The fault output is open-drain and requires a pull-up resistor. Verify the compensation network values to ensure loop stability.
Compliance Information
RoHS compliant per STMicroelectronics product page. AEC-Q100 qualified for automotive applications.
