Allegro A3211 Manuals

The A3211 and A3212 integrated circuits are ultra-sensitive, pole indepen- dent Hall-effect switches with latched digital output. These sensors are es- pecially suited for operation in battery-operated, hand-held equipment such as cellular and cordless tele- phones, pagers, and palmtop comput- ers. A 2.5 volt to 3.5 volt operation and a unique clocking scheme reduce the average op- erating power requirements to less than 15 μW with a 2.75 volt supply. Unlike other Hall-effect switches, either a north or south pole of suf- ficient strength will turn the output on in the A3212, and in the absence of a magnetic field, the output is off. The A3211 provides an inverted output. The po- larity inde- pendence and minimal power requirements allow these devices to easily replace reed switches for superior reliability and ease of manufacturing, while eliminat- ing 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 depen- dencies, and thermal stress. This device includes on a single silicon chip a Hall-voltage generator, small-sig- nal amplifier, chopper sta- bilization, a latch, and a MOSFET output. Ad vanced BiCMOS processing is used to take advantage of low-voltage and low-power requirements, component matching, very low input-offset errors, and small com- ponent geometries. Four package styles provid- ed offer different sizes and cost.

The A3211 and A3212 integrated circuits are ultra-sensitive, pole independent Hall-effect switches with latched digital output. These sensors are especially suited for operation in battery-operated, hand-held equipment such as cellular and cordless telephones, pagers, and palmtop computers. They operate at a voltage range of 2.5V to 3.5V, and a unique clocking scheme reduces the average operating power requirement to less than 15μW with a 2.75V supply. The A3212 can be turned on by either a north or south pole of sufficient strength, while the output is off in the absence of a magnetic field. The A3211 provides an inverted output. These devices can easily replace reed switches for superior reliability and ease of manufacturing, eliminating the need for signal conditioning. Improved stability is achieved through chopper stabilization, reducing residual offset voltage caused by overmolding, temperature dependencies, and thermal stress. The devices integrate a Hall-voltage generator, small-signal amplifier, chopper stabilization, a latch, and a MOSFET output on a single silicon chip using advanced BiCMOS processing, providing low-voltage and low-power operation, component matching, very low input-offset errors, and small component geometries.

The A3211 and A3212 integrated circuits are ultra-sensitive, pole independent Hall-effect switches with latched digital output. These sensors are especially suited for operation in battery-operated, hand-held equipment such as cellular and cordless telephones, pagers, and palmtop computers.