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 are ultra-sensitive, pole-independent Hall-effect switches with latched digital output, designed for battery-operated hand-held equipment. They feature micropower operation with average supply current less than 15 µW at 2.75 V and utilize chopper stabilization for superior temperature stability and low offset voltage.
| Output On Voltage | 100 mV to 300 mV |
|---|---|
| Awake Time | 45 µs to 90 µs |
| Chopping Frequency | 340 kHz |
| Supply Current (Chip awake) | 2.0 mA |
| Supply Current (Chip asleep) | 8.0 µA |
| Operating Temperature Range (Range 'E-') | -40°C to +85°C |
| Operating Temperature Range (Range 'L-') | -40°C to +150°C |
| Hysteresis | 5.9 G |
Yes, either a north or south pole of sufficient strength will turn the output on in the A3212, and the A3211 provides an inverted output.
The average operating power requirements are less than 15 µW with a 2.75 volt supply.