The A1250 is a continuation of Allegro's strategy for refreshing its highly successful family of chopper stabilized switches, latches, and bipolar switches, some of which having been in production for almost 10 years. Although this new device will be identical to its predecessor (A3230) in terms of functionality, there have been a few key performance upgrades. First, the device will be capable of surviving an ESD event up to 3.5 kV Human Body Model. Second, it will have a lower minimum VCC, which will allow customers to use higher series resistance for protection when the available supply voltage is <5 V. Third, the A1250 utilizes a new high-speed chopping circuit to null out offsets and dramatically improve switching repeatability.
The A1250 is an extremely temperature-stable and stress-resistant Hall effect bipolar switch. This device is especially suited for operation over extended temperature ranges to +150°C. Superior high-temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally resulting from device overmolding, temperature dependencies, and thermal stress. The A1250 design includes, on a single silicon chip, a voltage regulator, Hall voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a short-circuit protected, open-collector output. A south pole of sufficient strength will turn the output on, and a north pole is necessary to turn the output off.