STMicroelectronics has introduced fast-starting intelligent power switches for safety-instrumented systems. They are designed to meet IEC 61131-2.

STM-IPS160HF high side switch

“With power-on delay time of less than 60µs, the IPS160HF and IPS161HF satisfy standardised requirements for interface types C and D in Safety Integrity Level (SIL) Class 3 applications,” according to the company. They will drive complex resistive, capacitive and inductive loads with one side connected to ground, such as valves, relays, and lamps”.

Input range is 8 – 60V, maximum switch resistance is 120mΩ, and rise and fall times are 10µs with 20µs propagation delay.

The series switch is an n-channel mosfet, driven by an on-board charge-pump. IPS160HF is rated at 2.5A output current, and IPS161HF for 0.7A. Both will withstand an applied supply voltage of up to 65, and integrate active-clamp circuitry for handling inductive loads.

Built-in safeguards include ground-disconnect and Vcc-disconnect, thermal shut-down, under-voltage lock-out and short-circuit cut-off – this cut-off acts after a delay time, programmed with an external capacitor.

A common diagnostic open drain output pin reports open load in off-state, over-load cut-off and thermal shut-down.

Open load protection, which can detect a broken wire between chip output and load circuit, is activated by connecting a resistor between the Vcc line and output pin – the data sheet has a detailed description in section 6.4.

As well as safety-related applications, use is also foreseen in factory automation: process control, PLCs (programmable logic controllers) and CNC (computer controlled) machines.

Packaging is a PowerSSO12 surface-mount.