A3245: Chopper-Stabilized Omnipolar Hall-Effect Switch

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 A1126LLHLX-T.

The A3245 integrated circuit is an omnipolar, ultrasensitive Hall-effect switch with a digital output. This device has an integrated regulator permitting operation to 24 V, making it the first omnipolar switch available for operation to 24 V. This device is especially suited for operation over extended temperature ranges, up to +150°C. Superior high-temperature performance is made possible through an Allegro^® patented dynamic offset cancellation, which reduces the residual offset voltage normally caused by device overmolding, temperature excursions, and thermal stress.

The A3245 Hall-effect switch includes the following on a single silicon chip: voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a short circuit protected open-drain output. Advanced BiCMOS wafer fabrication processing is used to take advantage of low-voltage requirements, component matching, very low input-offset errors, and small component geometries.

The omnipolar operation of the A3245 allows activation with either a north or a south polarity field of sufficient strength. In the absence of a magnetic field, the output is off. This patented magnetic-polarity-independence feature makes this device an excellent replacement for reed switches, with improved ease of manufacturing, because the A3245 does not require manufacturers to orient their magnets. These devices allow simple on/off switching in industrial, consumer, and automotive applications.

The A3245 is rated for operation between the ambient temperatures –40°C and 85°C for the E temperature range, and –40°C to 150°C for the L temperature range. The small geometries of the BiCMOS process allow these devices to be provided in ultrasmall packages. Package LH is an SOT23W, a miniature low-profile surfacemount package. It is lead (Pb) free, with 100% matte tin plated leadframe.

• Omnipolar operation
• Chopper stabilization
• Superior temperature stability
• Extremely low switchpoint drift
• Insensitive to physical stress
• Reverse battery protection
• Output short circuit protection
• Solid state reliability
• Small size
• Robust EMC capability
• High ESD ratings (HBM)