Unipolar Switches Handle Harsh Environments September 2004 Issue Published Date: September 22, 2004
The A114x and A118x two-wire, current output, unipolar Hall-effect switches are designed specifically for harsh environments such as found under the hoods of automobiles and industrial applications. Two types of programmability are available: the A118x is field programmable, allowing users to externally trim operating points to dial out mechanical stackups resulting from manufacturing processes. This allows optimization of switching performance. The A114x has preset magnetic operating points guaranteed over temperature. Included in both types are an internal current regulator for two-wire operation and a voltage regulator for operation from 3.75V to 24V. Other on-chip features are protection against supply transients, reverse battery, electrostatic discharge (ESD) and EMC events. The switches are designed with a high-frequency chopper- stabilization technique using the company’s Digital/Analog BiCMOS process. Two package styles are available: the LH is a miniature low-profile package (SOT-23W) for surface-mount and the UA is a 3-lead ultra-mini single-in-line (TO-92) for through-hole mounting. Both can operate over the automotive temperature range of –40°C to +150°C. Pricing ranges from $0.57 to $0.65 each/25,000. ALLEGRO MICROSYSTEMS INC., Worcester, MA. (508) 853-5000.
