Solid-State Power Switches Revolutionize Electrification with Compact Design and Intelligent Features

Designers are under growing pressure to replace bulky electromechanical relays with solid-state alternatives that are more robust and feature-laden. This trend has been especially apparent with Infineon, STMicroelectronics, and Power Integrations, releasing new power switches to the market in recent weeks.

Each of these companies has designed highly efficient switches that may provide precision current feedback, configurable protections, and robust operation in reduced package areas.

Power switches. Image used courtesy of All About Circuits

Infineon’s Power Profet

Infineon’s BTH50015-1LUA and BTH50030-1LUA smart high-side switches are part of the Power Profet family. Optimized for high-current automotive applications on 24-V and 48-V power nets, these devices integrate logic, protection, and diagnostic circuitry into an 8-pin TO-leadless surface-mount package.

The BTH50015-1LUA (datasheet linked) supports continuous load currents up to 35 A with a typical RDS(on) of 1.5 mΩ at 25°C, while the BTH50030-1LUA (datasheet linked) supports 25 A with a 3-mΩ RDS(on). Both devices maintain thermal stability up to 150°C and are load dump robust to 70 V.

Application diagram of the BTH50015-1LUA. Image used courtesy of Infineon

Their architecture incorporates ISO 26262-ready diagnostics and protection mechanisms, including accurate current sensing (±5% after calibration), over-temperature shutdown, overcurrent cutoff, and short-circuit detection with an IL threshold of 90 A for the BTH50015-1LUA and 55 A for the BTH50030-1LUA. Turn-on and turn-off times are under 225 µs for compatibility with low-frequency PWM control. 

Both devices can replace electromechanical relays and fuses and are engineered to endure over one million switching cycles. Integrated sense outputs provide analog feedback for load current monitoring and further condense PCB area.

ST’s Intelligent Power Switches

STMicroelectronics announced the IPS4140HQ and IPS4140HQ-1 quad high-side intelligent power switches. Integrated in an 8 mm × 6 mm QFN48L package, these devices support 10.5 V to 36 V operation with per-channel current limits of 0.7 A (IPS4140HQ) and 1.0 A (IPS4140HQ-1) and feature low RDS(on) values of 80 mΩ max at 25°C. 

Built using ST’s VIPower technology, the switches offer individual channel diagnostics and protection, including thermal shutdown, short-circuit protection, and output current limiting. For further protection, each channel includes an open-drain STATUS pin that flags overtemperature conditions. The design also supports resistive, inductive, and capacitive loads with rapid demagnetization via an integrated VCC clamp that limits turn-off transients to VCC -52 V.

Block diagram of the IPS4140HQ. Image used courtesy of STMicroelectronics

Switching characteristics include a typical turn-on delay of 16 µs and a charge pump switching frequency of 1.45 MHz to enhance EMC compliance. The ICs support up to 10-kHz input frequency and are compatible with 3.3 V and 5 V logic levels. Additional safety functions include loss-of-ground protection and undervoltage lockout with hysteresis. The devices meet IEC 61131-2 and IEC 61000-4-2/4/5 and are ESD rated to ±25 kV.

Power Integrations’ TinySwitch-5 ICs

Power Integrations' TinySwitch-5 family integrates a high-voltage, 725-V silicon MOSFET with a controller optimized for flyback converters in off-line switch-mode power supplies. To this end, the devices (datasheet linked) support both discontinuous conduction mode (DCM) and continuous conduction mode (CCM), modulating output via variable frequency and variable current control based on analog feedback. Operating at up to 150 kHz for a smaller transformer design, the device features a number of smart features for safety and performance.

For example, the controller embeds a 5-V regulator on the bypass pin, along with undervoltage and overvoltage detection, input line sensing, and a programmable current limit. Internal features include a frequency-jitter oscillator to reduce EMI, integrated soft-start circuitry to minimize startup stress, and lossless primary current sensing for efficiency optimization.

Application of the TinySwitch-5. Image used courtesy of Power Integrations

The device achieves up to 92% efficiency and supports up to 175 W output power in a compact footprint. At 230 VAC, no-load power consumption drops below 30 mW. The family's adjustable switching frequency and internal line undervoltage and overvoltage shutdown further enhance its design flexibility and robustness.

Power Density Meets System Intelligence

As electrification accelerates across industries, the ability to implement compact, software-friendly power stages will grow more valuable than raw switching speed alone. Each of the newly announced products is now available in quantity through standard distribution channels.