STMicroelectronics VN31-E

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-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, body electronics, and lighting modules.

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 clamping (–18 V typical), ISO 7637-2 Pulse 5 Level II immunity without external components, and open-load detection with 5 ms filtering in both ON/OFF states.

Technical Context

The VN31 integrates a VIPower MOSFET with embedded protection logic and diagnostics in a monolithic high-side switch architecture. Its thermal shutdown circuit responds within microseconds to localized die heating, and its diagnostic output encodes four fault conditions-open load (ON/OFF), short-to-VCC, and overtemperature-via voltage level and timing behavior.

Inductive load handling relies on active negative-voltage clamp generation (–14 to –24 V) during turn-off, enabling fast demagnetization while limiting dissipation per P_dem = 0.5·L·I²·[(V_CC+V_demag)/V_demag]·f. Protection against load dump (ISO 7637-2 Pulse 5 Level II) is achieved natively; Level III requires only a 150 Ω resistor and 1000 µF capacitor.

Key Specifications

Pinout & Package

PENTAWATT (vertical) package: 5-pin single-in-line power package with exposed metal tab for thermal conduction; pin 1 = GND, pin 2 = IN, pin 3 = V_CC, pin 4 = OUT, pin 5 = STATUS (open-drain).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STSPIN250 and TPS27081A, the VN31 uniquely delivers automotive-grade 31 A high-side switching with native ISO Pulse 5 immunity, –18 V inductive clamp, and multi-condition diagnostic output-making it irreplaceable for demanding engine, lighting, and body control applications.

Availability

VN31 is available at Aetrix Electronics and suitable for engine control units, automotive lighting modules, body control modules, and electric power steering auxiliary load switching requiring stable component supply across extended temperature and transient environments.

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 and application-focused design centers.

The VN31 belongs to ST's VIPower high-side driver product line, engineered specifically for ISO 16750/7637-compliant automotive load switching where reliability, integrated diagnostics, and transient robustness are mandatory.

FAQ

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

The VN31 supports fast demagnetization of inductive loads with a typical clamp voltage of –18 V. Using the formula P_dem = 0.5·L·I²·[(V_CC+V_demag)/V_demag]·f, safe operation depends on load inductance, current, switching frequency, and thermal environment. For example, at 13 V V_CC, 11.5 A, and 100 Hz, L must remain below ~1.2 mH to avoid thermal shutdown in a 1.2 °C/W heatsink setup.

Does the VN31 require an external flyback diode for inductive loads?

No. The VN31 integrates an active negative-voltage clamp that provides –14 to –24 V demagnetization voltage during turn-off, eliminating the need for an external freewheeling diode. This reduces board area, cost, and failure points while improving switching speed and efficiency compared to passive diode solutions.

How does the open-load detection behave during PWM operation?

The VN31 applies 5 ms filtering to open-load detection in both ON and OFF states. During PWM, if load disconnection occurs for <5 ms, the STATUS output remains unchanged. Only sustained disconnections ≥5 ms trigger a fault indication, preventing false alarms from transient interruptions caused by vibration or contact bounce.

Can the VN31 be used in 24 V commercial vehicle systems?

Yes-the VN31 supports V_CC up to 26 V and withstands ISO 7637-2 Pulse 5 Level II (46.5 V) natively. For Level III (69 V), add a 150 Ω resistor between pin 1 and ground plus a 1000 µF capacitor between pin 3 and ground when R_LOAD ≤ 20 Ω. Its –4 V reverse supply rating also accommodates polarity reversal events common in heavy-duty vehicle service.