This device is no longer in production. The device should not be
purchased for new design applications. Samples are no longer available. Date of status change: October 31, 2011.
Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the following parts:
The A1242 Hall-effect latch is a two-wire latch especially suited for operation over extended temperature ranges, from –40 to +150°C. Superior high-temperature performance is made possible through the Allegro® patented dynamic offset cancellation technique, which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress.
The current-switching output technique allows for the reduction in cost in the wiring harness because only two connections to the sensor OC are required. The current-switching output structure also inherently provides more immunity against EMC/ESD transients. These sensor ICs have low magnetic thresholds, thereby enabling more flexibility in the magnetic circuit design.
The Hall-effect latch will be in the high output current state in the presence of a magnetic South Pole field of sufficient magnitude and will remain in this state until a sufficient North Pole field is present.
The A1242 includes the following on a single silicon chip: a voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a current source output. Advanced BiCMOS wafer fabrication processing takes advantage of low-voltage requirements, component matching, very low input-offset errors and small component geometries.
Suffix ‘L-’ devices are rated for operation over a temperature range of –40°C to +150°C; suffix ‘E-’ devices are rated for operation over a temperature range of –40°C to +85°C. Two A1242 package styles provide magnetically optimized solutions for most applications. Package LH is a SOT23W, a miniature low-profile surface-mount package, while package UA is a three-lead ultra-mini SIP for through-hole mounting. Each package is available lead (Pb) free, with 100% matte tin plated leadframes.