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 are integrated circuits designed as ultra-sensitive, pole-independent Hall-effect switches with latched digital outputs. These devices are optimized for battery-operated, hand-held equipment such as cellular phones, pagers, and palmtop computers, offering low power consumption and high reliability.
| Supply Voltage Range | 2.5 V to 3.5 V |
|---|---|
| Output Leakage Current | < 1.0 uA |
| Output On Voltage | 100 to 300 mV |
| Average Supply Current (Awake) | 2.0 mA |
| Average Supply Current (Asleep) | 8.0 uA |
| Chopping Frequency | 340 kHz |
| Operating Temperature Range (Range 'E-') | -40°C to +85°C |
| Operating Temperature Range (Range 'L-') | -40°C to +150°C |
The devices operate with a supply voltage range of 2.5 V to 3.5 V.
The A3212 turns on with either a north or south pole, while the A3211 provides an inverted output.
They use chopper stabilization (dynamic offset cancellation) to reduce residual offset voltage caused by overmolding and temperature dependencies.