STMicroelectronics VN31

Overview

VN31 from STMicroelectronics is a high-side smart power solid-state relay IC designed for automotive ISO-compliant load switching, featuring 31 A continuous output current at Tc = 85 °C, 60 V drain-source breakdown voltage, 0.03 Ω on-state resistance at 25 °C, 5 V logic-compatible input, and open-drain diagnostic output. It drives grounded resistive or inductive loads in engine control units, lighting modules, and body electronics.

For engineers reviewing the VN31 datasheet, VN31 pinout, VN31 application, or VN31 equivalent, key selection criteria include thermal shutdown behavior (140 °C trip, 125 °C reset), inductive demagnetization clamp (–18 V typical), ISO 7637-2 Pulse 5 level II surge immunity, and open-load detection timing (5–10 ms filtering).

Technical Context

The VN31 integrates a VIPower MOSFET with embedded protection logic and diagnostics. Its high-side architecture enables direct battery-switching of grounded loads, while internal thermal sensing triggers immediate shutdown at 140 °C junction temperature and automatic recovery at 125 °C. The device implements fast inductive demagnetization via active clamping to –18 V, reducing energy dissipation during turn-off.

Diagnostic functionality includes open-load detection in both ON and OFF states, overtemperature flagging, and short-to-VCC indication-all delivered through a single open-drain status output with configurable filtering (5–10 ms). Input hysteresis (0.5 V) and internal 6 V VIH clamp support robust noise immunity in harsh automotive environments.

Key Specifications

Pinout & Package

The VN31 is packaged in PENTAWATT (vertical, horizontal, or in-line) formats-thermally optimized for PCB mounting with exposed metal tab for heatsinking. All variants share identical pin numbering and functional assignment.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side automotive switch applications.

Compared with STSPIN32F0B and TPS4H160-Q1, the VN31 offers simpler integration for basic high-side switching with proven ISO qualification, minimal BOM count, and deterministic analog diagnostics-ideal for cost-sensitive, non-safety-critical automotive modules.

Availability

VN31 is available at Aetrix Electronics and suitable for engine control modules, body control units, headlamp drivers, and heated window controllers requiring stable component supply and long-term automotive-grade availability.

Supply support for VN31 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with vertical manufacturing capability.

The VN31 belongs to ST's VIPower M0-3 family of high-side drivers, engineered specifically for ISO 16750-compliant automotive load switching with integrated protection and diagnostics.

FAQ

What is the maximum inductive load energy the VN31 can safely demagnetize?

The VN31 achieves safe demagnetization using an internal –18 V clamp, limiting peak flyback voltage and reducing dissipated energy per cycle. For a 1 mH load at 11.5 A, the clamp reduces dissipation by ~65% versus a standard freewheeling diode. Actual safe inductance depends on switching frequency, ambient temperature, and heatsinking-designers should verify junction temperature using R_thj-case = 1.2 °C/W and P_dem = 0.5·L·I²·[(V_CC+V_demag)/V_demag]·f.

Can the VN31 be used with a 24 V truck battery system?

Yes-the VN31 supports V_CC up to 26 V and withstands ISO 7637-2 Pulse 5 Level III (46.5 V) when paired with a 150 Ω resistor and 1000 µF capacitor. Its 60 V V_DSS rating provides margin for load dump transients in 24 V commercial vehicle systems, though thermal design must account for higher conduction losses at elevated voltage.

How does the open-load detection work in both ON and OFF states?

The VN31 monitors output voltage relative to V_CC and GND. In OFF state, open load pulls OUT high; in ON state, open load causes abnormal V_DS rise. Both conditions trigger the STAT pin after 5–10 ms filtering. The truth table confirms STAT goes low for open load regardless of IN state, distinguishing it from short-to-V_CC (STAT low only when IN = H) and overtemperature (STAT low immediately, no delay).

Is external reverse-battery protection required?

A Schottky diode between Pin 1 (GND) and chassis ground is recommended for continuous –26 V reverse-battery protection. Without it, the device may latch or fail. Using a separate signal ground (as in Figure 11) avoids forward-voltage shift of input thresholds and allows use of a standard diode, simplifying layout while maintaining VIH/VIL integrity across temperature and supply variation.