VNI4140K

The VNI4140K is a quad channel high-side intelligent power switch (IPS) from STMicroelectronics, built using the company’s VIPower (Vertical Intelligent Power) technology that integrates vertical power MOSFETs with bipolar and CMOS control circuits on a single monolithic die. This integration provides significant advantages in terms of compactness, reliability, and cost-effectiveness compared to discrete solutions.

Designed specifically for industrial applications, the VNI4140K drives four independent loads with one side connected to ground (high-side configuration). Each channel can supply up to 0.6A continuous current, with active current limiting at approximately 0.7A typical during short-circuit conditions, protecting both the load and the device itself.

A key architectural feature is the two-level thermal protection system. Each channel has its own junction temperature sensor that triggers thermal shutdown at approximately 170°C, with automatic restart when the junction cools below the reset threshold (~135°C). Additionally, a global case temperature sensor monitors the package temperature. If the case temperature reaches 130°C due to sustained overload on multiple channels, overloaded channels are shut down and restart non-simultaneously (staggered) to avoid high peak currents on the power supply. Non-overloaded channels continue operating normally.

The device includes comprehensive protection features: undervoltage lockout prevents operation below 10.5V, VCC clamping at 41V provides overvoltage protection, loss-of-ground protection ensures safe behavior if the ground connection is lost, and ESD protection up to ±25kV (IEC 61000-4-2) ensures robustness in industrial environments. The open-drain status pins provide per-channel diagnostic feedback for overtemperature/fault conditions, enabling intelligent monitoring by the system controller.

Packaged in PowerSSO-24 with an exposed thermal tab for efficient heat dissipation, the VNI4140K is fully specified for the industrial temperature range of -40°C to +125°C and is backed by ST’s 15-year product longevity commitment, ensuring long-term supply stability for industrial equipment manufacturers.

The VNI4140K quad high-side smart power switch operates through several integrated functional blocks:

1. Power Stage: Each of the four channels contains a vertical N-channel power MOSFET with RDS(on) of typically 80mΩ. The MOSFET is configured as a high-side switch, connecting the load to VCC when turned on. Multiple source-bonded pins (3 per channel) provide high current handling capability.

2. Charge Pump: Since the power MOSFETs are N-channel devices operating in high-side configuration, an internal charge pump generates a voltage above VCC to properly drive the MOSFET gates. The charge pump operates at approximately 1.45 MHz and requires no external components.

3. Input Logic and Level Shifter: The four INx pins accept 3.3V/5V CMOS/TTL logic levels. Input threshold levels are VIL = 0.8V max and VIH = 2.2V min. Level shifters translate the logic-level signals to the appropriate gate drive voltages referenced to VCC.

4. Current Limiting: Each channel has an active current limit circuit that senses the output current and reduces the gate drive if the current exceeds the limit threshold (typically 0.7A at 24V). This prevents the system power supply from collapsing during short-circuit conditions and protects the MOSFET from overcurrent damage.

5. Thermal Protection – Junction Level: Each channel has its own temperature sensor. If the junction temperature exceeds TTSD (typically 170°C), that channel is shut down. When the junction cools below TR (135°C), the channel automatically restarts. This creates thermal cycling during sustained overload conditions, protecting the device while maintaining partial functionality.

6. Thermal Protection – Case Level: A case temperature sensor monitors overall package temperature. If TCSD (typically 130°C) is reached, all overloaded channels are shut down. They restart non-simultaneously (staggered) when the case cools below TCR (110°C), preventing high peak inrush currents.

7. Undervoltage Lockout (UVLO): If VCC drops below the undervoltage threshold (10.5V max), all outputs are turned off to prevent undefined operation. Hysteresis (0.4-0.5V) prevents chattering at the threshold.

8. Status/Diagnostic Outputs: Four open-drain STATx pins provide per-channel fault indication. When a channel enters thermal shutdown due to overtemperature, its STAT pin goes low (sinking current). This allows the system controller to detect and diagnose fault conditions per channel.

9. Inductive Load Demagnetization: When turning off an inductive load, the output voltage is clamped to approximately VCC–41V, allowing the inductor current to circulate and decay rapidly. The PowerSSO package’s high thermal capacitance absorbs the energy pulse without external freewheeling diodes.

Package: PowerSSO-24 (also known as PowerSO-24). 24-lead surface-mount package with exposed bottom tab. Tab is at VCC potential. Each output channel has three parallel pins for high current carrying capacity.

• PLC Digital Output Modules: Four-channel isolated digital output cards for programmable logic controllers in factory automation, where the VNI4140K provides protected 24V outputs driving solenoids, relays, and indicator lamps with built-in fault diagnostics.
• Solenoid and Valve Drivers: Proportional and on/off solenoid valve control in pneumatic and hydraulic systems, leveraging the fast inductive load demagnetization feature to handle valve coil turn-off transients safely.
• Industrial Lamp and LED Drivers: Driving indicator lamps, stack lights, and LED arrays in industrial control panels, with the current limiting feature handling incandescent lamp inrush currents during turn-on.
• CNC Machine Tools: Auxiliary output control in CNC machine controllers, driving coolant pumps, tool changers, work holding solenoids, and other 24V DC loads in machining centers and robotic cells.
• Relay and Contactor Coil Drivers: Driving relay and contactor coils in motor control centers and power distribution panels, where the high-side configuration and integrated protection simplify design and improve reliability.
• Motor Control and Actuators: Small DC motor control, actuator drives, and stepper motor phase switching in industrial automation equipment requiring protected outputs with current limiting and thermal protection.
• Industrial PC Peripheral I/O: Add-on digital output cards for industrial PCs and embedded computers, providing isolated or non-isolated 24V outputs for machine vision systems, data acquisition, and test equipment.
• Building Automation: HVAC control systems, access control, and building management systems (BMS) requiring reliable 24V DC switching for dampers, locks, lighting relays, and other building loads.