Fast-starting intelligent power switches optimized for demanding safety applications

STMicroelectronics has added new fast-starting devices to its family of intelligent power switches for safety-instrumented systems. With power-on delay time of less than 60µs, the IPS160HF and IPS161HF satisfy standardized requirements for interface types C and D in Safety Integrity Level (SIL) Class 3 applications.

Featuring a wide input-voltage range of 8V-60V, maximum switch resistance (R_DS(on)) of 120mΩ, and10µs rise/fall time with 20µs propagation delay, these devices combine design flexibility, low power dissipation, and fast response. Extended diagnostics facilitate the design of safety-instrumented functions by indicating open load, over-current cut-off, and over-temperature shutdown.

The IPS160HF and IPS161HF safely drive complex resistive, capacitive, and inductive loads with one side connected to ground, such as valves, relays, and lamps. In addition to SIL-rated applications such as safety sensors, they can be used in general factory-automation and process-control equipment such as Programmable Logic Controllers (PLCs), I/O peripherals, and Computer Numerical Control (CNC) machines.

As intelligent power switches, the IPS160HF and IPS161HF integrate a logic interface, driving circuitry, various protection features, and an N-channel power-MOSFET output stage. The output stage is internally limited at 2.5A minimum output current for the IPS160HF and 0.7A for the IPS161HF. Both devices withstand an applied supply voltage of up to 65V and integrate active-clamp circuitry for handling inductive loads.

Built-in safeguards include ground-disconnect and VCC-disconnect protection, thermal shutdown, undervoltage lock-out, and short-circuit cut-off to protect the IC, the application, and the load against overstress. The cut-off acts after a delay time, which is programmed with an external capacitor, and provides non-dissipative protection that minimizes overheating.

The IPS160HF and IPS161HF are in production now and available in the thermally enhanced PowerSSO12 package from $1.49 for orders of 1,000 units.