A3214

• Micropower Operation
• Operate With North or South Pole
• 2.4 V to 5.5 V Battery Operation
• Chopper Stabilized
  Superior Temperature Stability
  Extremely Low Switch-Point Drift
  Insensitive to Physical Stress
• High ESD protection
• Solid-State Reliability
• Small Size
• Easily Manufacturable With Magnet Pole Independence

Description

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 µW, the A3214xx to 14 µW (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 A3213xx and A3214xx 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.