STMicroelectronics ACS108-5SA-AP

Overview

ACS108-5SA-AP from STMicroelectronics is an AC line switch designed for static on/off control of low-power inductive and resistive loads in home appliances. It features 500 V blocking voltage (VDRM/VRRM), 0.8 A RMS on-state current (IT(RMS)), <10 mA gate trigger current (IGT), integrated clamping structure (VCL = 600 V), and TO-92 package with common (COM) pin connected to the lead frame for thermal and reference integrity. It drives solenoids, valves, relays, and micro-motors in washing machines and dishwashers.

For engineers reviewing the ACS108-5SA-AP datasheet, ACS108-5SA-AP pinout, ACS108-5SA-AP application, or ACS108-5SA-AP equivalent, this device offers direct microcontroller interface without external protection, IEC61000-4-5 compliance, simplified PCB layout via COM-referenced drive, and validated turn-off ruggedness for 230 V AC systems with inductive loads up to 0.2 A.

Technical Context

The ACS108-5SA-AP implements a monolithic AC switch with integrated avalanche clamping and gate-level shifter driver. Its negative-gate-triggering architecture requires gate current sourced *from* the controller (i.e., current flows out of the G pin), enabling direct MCU connection without level-shifting circuitry.

It operates in full-cycle AC conduction mode with junction temperature range –30 °C to +125 °C and supports surge currents up to 7.3 A (50 Hz) without failure. Thermal resistance Rth(j-a) is 150 °C/W (TO-92), and the COM pin serves as both power return and thermal path reference.

Key Specifications

Pinout & Package

ACS108-5SA-AP uses the TO-92 plastic package with lead frame exposed as the COM terminal. The tab is electrically connected to pin 2 (COM), providing both thermal conduction path and circuit reference point.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar AC line switching applications.

Compared with ACS108-5SA-AP, the -5SN offers superior thermal dissipation for dense layouts but requires rework of footprint and assembly process, while the -5SA-TR delivers identical performance in automated production-making the AP variant optimal for prototyping and low-volume through-hole builds.

Availability

ACS108-5SA-AP is available at Aetrix Electronics and suitable for washing machine control modules, dishwasher valve actuation circuits, and refrigerator defrost heater drivers requiring stable component supply and long-lifecycle support for white goods OEMs.

Supply support for ACS108-5SA-AP 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, designing and manufacturing analog, mixed-signal, power, and microcontroller solutions for automotive, industrial, and consumer markets.

The ACS™ AC Switch family was developed specifically for solid-state replacement of electromechanical relays in 230 V AC appliance control, emphasizing surge immunity, thermal integration, and direct microcontroller compatibility.

FAQ

What is the maximum allowable ambient temperature for continuous 0.8 A operation?

The ACS108-5SA-AP supports 0.8 A RMS only at Tlead = 75 °C (lead temperature), not ambient. In TO-92 configuration, its maximum ambient temperature for 0.8 A is approximately 35 °C with no airflow, per Figure 6. Derating is required above that-e.g., 0.4 A at 60 °C ambient-due to Rth(j-a) = 150 °C/W and Tj(max) = 125 °C.

Can ACS108-5SA-AP drive a 230 V AC relay coil rated at 0.35 A?

Yes-it supports up to 0.8 A RMS on resistive loads and handles inductive loads up to 0.2 A without turn-off aid. A 0.35 A relay coil exceeds the 0.2 A inductive threshold, so external snubbing (e.g., RC network across coil) is recommended to manage dI/dt and ensure clean turn-off within the device's (dI/dt)c rating of 0.1–0.4 A/ms depending on load group.

Is the COM pin electrically isolated from the PCB ground plane?

No-COM is internally bonded to the TO-92 lead frame and must be connected to the same reference as the MCU ground and AC neutral. It is not isolated; it serves as the common return path for gate drive current and load current. PCB layout must treat COM as a high-current, thermally critical node-not a signal ground.

Does ACS108-5SA-AP require zero-crossing detection for safe operation?

No-it operates safely without zero-crossing control. Its clamping structure and high dI/dt immunity allow turn-on at any phase angle. However, zero-crossing switching reduces EMI and inrush stress on downstream components; the device itself does not mandate it, nor does it include internal zero-crossing logic.