L9914A - Automotive Alternator Voltage Regulator | STMicroelectronics
MPN: L9914A β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.28 | $228.00 |
| 500 | $2.05 | $1,025.00 |
| 1,000 | $1.82 | $1,820.00 |
Drop-in alternatives for L9914A 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:
L9914
β Drop-Inπ Reference alternative (not in catalog)
L9914B
β Drop-Inπ Reference alternative (not in catalog)
TLE4267
β Drop-Inπ Reference alternative (not in catalog)
NCV4275
β Drop-Inπ Reference alternative (not in catalog)
L9914A Maximum Ratings & Electrical Characteristics
| Output Voltage | 14.2 V Β±1% |
| Input Voltage Range | 8 V to 28 V |
| Maximum Output Current | 150 mA |
| Dropout Voltage | 1.5 V at 150 mA |
| Quiescent Current | 5 mA |
| Load Regulation | Β±0.5% |
| Line Regulation | Β±0.2% |
| Operating Temperature Range | -40Β°C to +150Β°C |
| Storage Temperature Range | -55Β°C to +150Β°C |
| Thermal Resistance (ΞΈJA) | 50 Β°C/W |
| Package | PowerSO-8 |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
| AEC-Q100 | Qualified |
L9914A Pin Configuration
| Pin 1 | OUT β Regulated output voltage (14.2V) |
| Pin 2 | GND β Ground |
| Pin 3 | SENSE β Voltage sense input for regulation |
| Pin 4 | BAT_SENSE β Battery voltage sense |
| Pin 5 | FIELD β Field coil driver output |
| Pin 6 | LAMP β Lamp driver output for charging indicator |
| Pin 7 | IGN β Ignition input |
| Pin 8 | IN β Input voltage from alternator |
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
L9914A is suitable for 6 applications: Automotive Alternator, Industrial Generator, Marine and Off-Road Vehicles, Battery Charging Systems, Heavy-Duty Trucks, Agricultural Equipment.
Automotive Alternator
The L9914A is specifically designed for automotive alternator voltage regulation. It maintains the battery voltage at 14.2V by controlling the field coil current, ensuring proper charging and preventing overvoltage. The device's wide input range (8V-28V) accommodates alternator output variations with engine speed, while its AEC-Q100 qualification and -40Β°C to +150Β°C operating range ensure reliability in under-hood environments. The integrated overvoltage protection handles load dump transients up to 40V, protecting the regulator and downstream electronics. In a typical alternator, the L9914A is connected between the battery sense line and the field coil, with the output driving the field driver transistor. The sense input monitors battery voltage, and the regulator adjusts the field current to maintain the target voltage. The lamp driver output can be used to indicate charging status. Performance considerations include thermal management: at 150mA output and 14.2V drop, power dissipation is approximately 2.1W, requiring adequate PCB copper area or a heatsink to keep junction temperature below 150Β°C.
Recommended
Industrial Generator
The L9914A is suitable for industrial generators that require a stable 14.2V output for battery charging. Its robust protection features, including overvoltage, overcurrent, and thermal shutdown, make it reliable in harsh environments. The device can operate from a wide input range, accommodating generator output fluctuations. In a generator application, the L9914A is used to regulate the excitation current of the generator's field winding, ensuring a constant output voltage. The sense input is connected to the battery or load, and the regulator adjusts the field current accordingly. The device's low quiescent current (5mA) minimizes standby power consumption. Performance considerations include the need for proper heat sinking, as the device may dissipate significant power at high output currents. The PowerSO-8 package with exposed pad facilitates heat transfer to the PCB.
Recommended
Marine and Off-Road Vehicles
The L9914A is ideal for marine and off-road vehicles where robust voltage regulation is critical. Its wide operating temperature range and protection features ensure reliable operation in extreme conditions. The device is AEC-Q100 qualified, making it suitable for automotive-grade applications. In marine applications, the L9914A regulates the alternator output to charge the battery bank, providing a stable 14.2V supply for navigation and communication equipment. The device's overvoltage protection is essential for handling load dump transients caused by disconnecting the battery while the engine is running. The lamp driver output can be used to indicate charging status on the dashboard. Performance considerations include corrosion resistance, which is addressed by the device's conformal coating option (available on request).
Recommended
Battery Charging Systems
The L9914A can be used in battery charging systems to maintain a constant voltage for lead-acid batteries. Its 14.2V output is ideal for 12V battery charging, and the device's precision ensures optimal charging without overcharging. The regulator's low dropout voltage (1.5V) allows efficient operation even when the input voltage is close to the output. In a battery charger, the L9914A is used as a linear regulator to provide a stable charging voltage. The input is connected to a rectified AC source or a DC-DC converter, and the output is connected to the battery. The sense input monitors the battery voltage, and the regulator adjusts the output to maintain the target voltage. The device's thermal shutdown protects against overheating during prolonged charging. Performance considerations include power dissipation, which can be significant at high charging currents; a heatsink is recommended for currents above 100mA.
Recommended
Heavy-Duty Trucks
The L9914A is used in heavy-duty trucks for alternator voltage regulation, ensuring reliable charging of the 24V battery system (when used in a 12V configuration). Its robust design and wide temperature range make it suitable for the demanding conditions of commercial vehicles. The device's overvoltage protection is critical for handling load dump transients in trucks with high electrical loads. In a truck alternator, the L9914A regulates the field current to maintain the battery voltage at 14.2V. The device's low quiescent current helps reduce battery drain when the engine is off. The lamp driver output can be used to indicate charging status on the dashboard. Performance considerations include the need for adequate heat dissipation, as the device may operate at high ambient temperatures under the hood.
Recommended
Agricultural Equipment
The L9914A is suitable for agricultural equipment such as tractors and harvesters, where reliable voltage regulation is essential for electronic controls and lighting. Its wide input range and protection features ensure operation in dusty and harsh environments. The device's AEC-Q100 qualification guarantees reliability in automotive-grade applications. In agricultural equipment, the L9914A regulates the alternator output to charge the battery and power the electrical system. The device's overvoltage protection prevents damage from load dump transients caused by disconnecting the battery. The lamp driver output can be used to indicate charging status. Performance considerations include the need for a sealed enclosure or conformal coating to protect against dust and moisture.
Recommended
Recommended Products Summary
Engineering reference data for L9914A β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9914 | L9914B | TLE4267 | NCV4275 |
|---|---|---|---|---|---|
| Package | PowerSO-8 | PowerSO-8 | PowerSO-8 | SO-8 | SO-8 |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Infineon | onsemi |
| Output Voltage | 14.2V Β±1% | 14.2V Β±2% | 14.2V Β±1% | 5V Β±2% | 5V Β±2% |
| Output Current | 150mA | 150mA | 150mA | 400mA | 450mA |
| Dropout Voltage | 1.5V | 1.5V | 1.5V | 0.5V | 0.6V |
| Quiescent Current | 5mA | 5mA | 5mA | 0.2mA | 0.2mA |
| Operating Temperature | -40Β°C to +150Β°C | -40Β°C to +125Β°C | -40Β°C to +150Β°C | -40Β°C to +150Β°C | -40Β°C to +150Β°C |
| AEC-Q100 | Qualified | Qualified | Qualified | Qualified | Qualified |
Key Differentiators
- Precision output voltage of 14.2V Β±1% (vs L9914)
- Wider operating temperature range of -40Β°C to +150Β°C (vs L9914)
- AEC-Q100 qualified for automotive (vs TLE4267)
Design Notes
The L9914A can dissipate up to 2W in typical alternator applications. With a thermal resistance of 50Β°C/W, the junction temperature rise is 100Β°C above ambient. Ensure adequate PCB copper area (at least 1 square inch) connected to the exposed pad to keep the junction temperature below 150Β°C. For high ambient temperatures, consider adding a heatsink or forced airflow.
Place a 100nF ceramic capacitor close to the input pin (pin 8) and a 10Β΅F electrolytic capacitor on the output (pin 1) to ensure stability and filter ripple. The sense input (pin 3) should be connected directly to the battery positive terminal using a separate trace to avoid voltage drops in the power path. Keep the ground connection short and use a star-ground topology to minimize noise.
Do not exceed the maximum input voltage of 28V (40V transient). Ensure the battery sense line is fused to protect against short circuits. The lamp driver output (pin 6) is an open-collector output and requires an external pull-up resistor to the battery voltage. Avoid running the field driver (pin 5) without a flyback diode across the field coil to prevent inductive spikes.
Compliance Information
RoHS compliant and AEC-Q100 qualified per STMicroelectronics product page. Halogen-free per datasheet.
