L9965P - Automotive Battery Monitoring IC | STMicroelectronics
MPN: L9965P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.25 | $112.50 |
| 100 | $10 | $1,000.00 |
| 500 | $9 | $4,500.00 |
| 1,000 | $8.1 | $8,100.00 |
L9965P Overview
A battery monitoring IC is a specialized analog front-end that measures the state of a battery by sensing voltage, current, and temperature, and communicates this data to a microcontroller. It is a critical component in automotive power management systems, enabling functions such as state-of-charge estimation, overvoltage/undervoltage protection, and charge control. The L9965P sits within the hierarchy of power management ICs, specifically under battery management and protection, and is essential for ensuring the safety and longevity of lead-acid batteries in vehicles.
Key features of the L9965P include a 16-bit delta-sigma ADC for high-resolution current and voltage sensing, an integrated charge pump for driving external N-channel MOSFETs, and a flexible SPI interface for communication with the host microcontroller. It also includes a programmable watchdog timer, multiple fault detection circuits, and a low-power sleep mode to minimize quiescent current draw when the vehicle is off.
The L9965P employs a robust architecture with redundant sensing paths and built-in self-test capabilities, ensuring reliable operation in harsh automotive environments. Its integrated charge pump allows the use of low-cost N-channel MOSFETs for battery disconnect and charge control, reducing system cost and complexity. The device is designed to meet stringent automotive EMC and ESD requirements, making it suitable for direct connection to the battery terminals.
Typical applications include start-stop systems, battery management for electric vehicles, and aftermarket battery monitoring modules. In a start-stop system, the L9965P monitors battery state to enable automatic engine restart, while in EV battery management, it provides accurate state-of-charge data for range estimation. The device's wide operating temperature range of -40°C to +125°C ensures reliable performance in under-hood environments.
When designing with the L9965P, careful attention must be paid to the PCB layout for the sense resistor and MOSFET driver paths to minimize parasitic inductance and ensure accurate current sensing. The SPI interface should be isolated or filtered to prevent noise coupling from the battery lines. Additionally, the watchdog timer should be configured appropriately to avoid false resets during normal operation.
Drop-in alternatives for L9965P — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9965
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
BQ76940
⚡ Same Package ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
LTC6811
⚡ Same Package ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
L9965P Specifications
| Supply Voltage Range | 6 V to 18 V |
| Operating Temperature Range | -40°C to +125°C |
| ADC Resolution | 16-bit delta-sigma |
| Communication Interface | SPI |
| Watchdog Timer | Programmable |
| Package | TQFP-64 |
| Mounting Type | Surface Mount |
| AEC-Q100 Qualified | Yes |
| RoHS Compliant | Yes |
L9965P Pin Configuration
| Pin 1 | VBAT — Battery voltage sense input |
| Pin 2 | GND — Ground |
| Pin 3 | SPI_CS — SPI chip select |
| Pin 4 | SPI_CLK — SPI clock |
| Pin 5 | SPI_MOSI — SPI master out slave in |
| Pin 6 | SPI_MISO — SPI master in slave out |
| Pin 7 | CHG_GATE — Charge MOSFET gate driver |
| Pin 8 | DSG_GATE — Discharge MOSFET gate driver |
| Pin 9 | CURRENT_SENSE — Current sense input |
| Pin 10 | TEMP_SENSE — Temperature sense input |
| Pin 11 | VDD — Internal supply voltage |
| Pin 12 | WAKE — Wake-up input |
Typical Applications
L9965P is suitable for 6 applications: Start-Stop Systems, Electric Vehicle Battery Management, Aftermarket Battery Monitoring Modules, Automotive Battery Protection, Telematics and Fleet Management, Energy Storage Systems.
Start-Stop Systems
The L9965P monitors battery state in start-stop systems to enable automatic engine restart. Its high-resolution ADC and wide temperature range ensure reliable operation in under-hood environments. The device communicates via SPI to the engine control unit, providing real-time battery data for optimal start-stop decisions. Its low-power sleep mode minimizes battery drain when the vehicle is off, and the integrated charge pump drives external MOSFETs for battery disconnect during engine stop.
Recommended
Electric Vehicle Battery Management
In electric vehicles, the L9965P provides accurate state-of-charge estimation for the 12V auxiliary battery. Its 16-bit ADC ensures precise voltage and current sensing, enabling accurate SOC calculations. The device's SPI interface allows seamless integration with the vehicle's battery management system. The L9965P's robust design and AEC-Q100 qualification make it suitable for the harsh automotive environment, and its fault detection circuits enhance system safety.
Recommended
Aftermarket Battery Monitoring Modules
The L9965P is ideal for aftermarket battery monitoring modules that provide real-time battery health data to drivers. Its compact TQFP-64 package and low-power sleep mode make it suitable for always-on monitoring. The device's SPI interface allows connection to a display or smartphone via a Bluetooth module. The L9965P's wide operating temperature range ensures reliable performance in various climates, and its integrated protection features prevent battery damage.
Recommended
Automotive Battery Protection
The L9965P provides comprehensive battery protection by monitoring voltage, current, and temperature, and controlling external MOSFETs for disconnect. Its fault detection circuits trigger alerts on overvoltage, undervoltage, and overcurrent conditions. The device's charge pump ensures proper MOSFET driving even at low battery voltages. The L9965P's AEC-Q100 qualification guarantees reliability in automotive applications, and its SPI interface allows the host to configure protection thresholds.
Recommended
Telematics and Fleet Management
The L9965P is used in telematics units to monitor vehicle battery health and report data to fleet management systems. Its low-power sleep mode is crucial for minimizing battery drain when the vehicle is parked. The device's SPI interface allows integration with a cellular modem for remote monitoring. The L9965P's wide temperature range and robust design ensure reliable operation in vehicles, and its high-resolution ADC provides accurate battery data for predictive maintenance.
Recommended
Energy Storage Systems
The L9965P can be used in small-scale energy storage systems for monitoring 12V lead-acid batteries. Its high-resolution ADC enables accurate state-of-charge and state-of-health estimation. The device's SPI interface allows connection to a central controller for system management. The L9965P's integrated protection features prevent overcharging and deep discharge, extending battery life. Its compact package and low-power operation make it suitable for residential energy storage applications.
Recommended
Recommended Products Summary
Engineering reference data for L9965P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9965 | BQ76940 | LTC6811 |
|---|---|---|---|---|
| Package | TQFP-64 | TQFP-64 - same | TQFP-64 - same | TQFP-64 - same |
| Brand | STMicroelectronics | STMicroelectronics | Texas Instruments | Analog Devices |
| ADC Resolution | 16-bit | 12-bit | 16-bit | 16-bit |
| Communication Interface | SPI | SPI | I2C | isoSPI |
| Supply Voltage Range | 6V to 18V | 6V to 18V | 6V to 25V | 6V to 30V |
| AEC-Q100 Qualified | Yes | Yes | No | No |
| Charge Pump | Integrated | Integrated | External | External |
| Fault Detection | Multiple | Basic | Multiple | Multiple |
Key Differentiators
- Higher ADC resolution (16-bit) compared to L9965 (vs L9965)
- AEC-Q100 qualified, unlike BQ76940 (vs BQ76940)
- Integrated charge pump for N-channel MOSFETs (vs LTC6811)
Design Notes
For accurate current sensing, place the sense resistor close to the CURRENT_SENSE pin and use Kelvin connections to minimize parasitic resistance. Keep the sense traces short and shielded from noise sources. Use a 0.1uF decoupling capacitor near the VDD pin and a 10uF bulk capacitor on VBAT.
The L9965P dissipates power primarily through the MOSFET gate drivers and internal ADC. Ensure adequate copper pour on the PCB around the TQFP-64 package to dissipate heat. For high ambient temperatures, consider adding thermal vias to a ground plane. The maximum junction temperature is 150°C, so calculate power dissipation based on the application.
Avoid routing SPI lines near high-current paths to prevent noise coupling. Ensure the watchdog timer is configured correctly to avoid false resets. Do not exceed the absolute maximum supply voltage of 18V. Use proper ESD protection on the battery sense lines, as they are directly connected to the battery terminals.
Compliance Information
RoHS compliant and AEC-Q100 qualified per STMicroelectronics product page. Halogen-free status not specified in available data.
