L9918

The STMicroelectronics L9918 is a high-voltage, dual low-side driver designed for automotive and industrial applications requiring efficient switching of inductive and resistive loads. It integrates two independent low-side drivers with advanced protection features, offering reliable operation for solenoids, relays, DC motors, and resistive heating elements. The device operates over a wide supply voltage range and provides logic-level control inputs for microcontroller interfacing.

## Core Architecture

The L9918 employs a dual N-channel MOSFET output stage with integrated driver circuitry, allowing direct interfacing with logic-level control signals. The device includes current limiting, thermal shutdown, and undervoltage lockout to protect both the driver and connected loads. Internal clamp diodes handle inductive kickback, minimizing external component count and simplifying PCB design. The drivers are designed for fast switching and low on-resistance to reduce conduction losses and improve overall system efficiency.

## Electrical Specifications

* Supply Voltage (VCC): 5.5 V to 28 V, suitable for automotive and industrial power rails.
* Output Current (IOUT): 1.0 A continuous per channel with proper heatsinking, capable of driving moderate current loads.
* Peak Current (IPK): Up to 2 A for short duration transients.
* Output On-Resistance (RON): 0.35 Ω typical per channel at VCC = 14 V, minimizing conduction losses.
* Input Logic Threshold: 2.5 V typical, compatible with 3.3 V and 5 V logic levels.
* Propagation Delay: 300 ns typical, enabling responsive switching for fast PWM or control signals.
* Maximum Switching Frequency: Up to 20 kHz recommended for inductive loads to maintain thermal limits.

## Protection and Reliability Features

* Thermal Shutdown: Device disables outputs if junction temperature exceeds 150°C, automatically resumes operation after cooling.
* Overcurrent Protection: Limits current through the MOSFETs to prevent damage under short-circuit or stalled motor conditions.
* Undervoltage Lockout (UVLO): Prevents operation at VCC below 5.5 V, ensuring predictable driver behavior.
* Reverse Battery Protection: Prevents damage if supply polarity is inverted, critical for automotive applications.
* Load Dump and Transient Suppression: Integrated clamp diodes protect against voltage spikes from inductive loads and supply transients.
* ESD Protection: ±4 kV HBM and ±2 kV MM, enhancing robustness in handling and operational environments.

## Thermal and Environmental Characteristics

* Operating Temperature Range: -40°C to +150°C for automotive-grade applications.
* Storage Temperature Range: -55°C to +150°C.
* Thermal Resistance Junction-to-Ambient (RθJA): 60°C/W typical in free air; improved with PCB copper and heatsinking.
* Thermal Resistance Junction-to-Case (RθJC): 8°C/W typical, ensuring efficient heat dissipation for continuous operation.

## Mechanical and Package Details

* Package Type: SO-16N (Small Outline, 16 leads), optimized for space-constrained PCB layouts.
* Lead Finish: Matte tin over nickel, RoHS-compliant for reliable soldering.
* Dimensions: 10.0 mm × 6.0 mm typical, suitable for standard automotive and industrial PCB footprints.
* Weight: Approximately 1.2 g, compatible with surface-mount assembly processes.

## Applications

* Automotive low-side switching for lamps, solenoids, motors, and actuators.
* Industrial automation for driving valves, relays, and resistive heating elements.
* PWM-controlled loads requiring precise and robust low-side switching.
* Microcontroller or digital system interfacing where dual load channels are needed.
* Battery-powered or vehicle systems needing robust protection features against overcurrent, undervoltage, and thermal events.

## Development Support

STMicroelectronics provides support for the L9918 with:

* Application notes for optimal PCB layout and thermal management.
* Reference circuits for dual low-side switching of inductive and resistive loads.
* Design guidelines for PWM control, current limiting, and protection feature utilization.
* SPICE models and evaluation boards for system-level simulation and prototyping.

## Key Specifications

| Specification | Value |
| --------------------------- | --------------------------------------------------------------- |
| Supply Voltage (VCC) | 5.5 V – 28 V |
| Output Current (IOUT) | 1.0 A continuous per channel |
| Peak Current (IPK) | 2 A |
| Output On-Resistance (RON) | 0.35 Ω typical @ 14 V |
| Input Logic Threshold | 2.5 V typical |
| Propagation Delay | 300 ns typical |
| Maximum Switching Frequency | 20 kHz recommended |
| Thermal Shutdown | 150°C |
| Operating Temperature Range | -40°C to +150°C |
| Storage Temperature Range | -55°C to +150°C |
| Package Type | SO-16N |
| ESD Protection | ±4 kV HBM, ±2 kV MM |
| Protection Features | Overcurrent, UVLO, thermal shutdown, reverse battery protection |

The L9918 combines dual high-performance low-side MOSFET drivers with comprehensive protection features, low on-resistance, and fast switching capability, making it suitable for automotive, industrial, and general-purpose load-driving applications requiring reliability and efficiency.