The A3213xx and A3214xx integrated circuits are ultra-sensitive, pole independent Hall-effect switches with a latched digital output. They are especially suited for operation in battery-operated, hand-held equipment such as cellular and cordless telephones, pagers, and palmtop computers. A 2.4 volt to 5.5 volt operation and a unique clocking scheme reduce the average operating power requirements the A3213xx to 825 W, the A3214xx to 14 W (typical at 2.75 V)! Except for operating duty cycle and average operating current, the A3213xx and A3214xx are identical. Unlike other Hall-effect switches, either a north or south pole of sufficient strength will turn the output on; in the absence of a magnetic field, the output is off. The polarity independence and minimal power requirement allows these devices to easily replace reed switches for superior reliability and ease of manufacturing, while eliminating the requirement for signal conditioning. Improved stability is made possible through chopper stabilization (dynamic offset cancellation), which reduces the residual offset voltage normally caused by device overmolding, temperature dependencies, and thermal stress. These devices include on a single silicon chip a Hall-voltage generator, small-signal amplifier, chopper stabilization, a latch, and a MOSFET output. Advanced BiCMOS processing is used to take advantage of low-voltage and low-power requirements, component matching, very low input-offset errors, and small component geometries. Suffix 'Ex' devices are rated for operation over a temperature range of -40C to +85C; suffix 'Lx' devices are rated for operation over a temperature range of -40C to +150C. Two package styles provide a magnetically optimized package for most applications. Package designator `LH' is a miniature low-profile surface-mount package while designator `UA' is a threelead SIP for through-hole mounting.