Features

• Micropower Operation
• Operate with North or South Pole
• 2.5 V to 3.5 V Battery Operation
• Chopper Stabilized
  Superior Temperature Stability
  Extremely Low Switch-Point Drift
  Insensitive to Physical Stress
• Solid-State Reliability
• Small Size
• Easily Manufacturable with Magnet Pole Independence

Description

The A3211 and A3212 integrated circuits are ultra-sensitive, pole independent Hall-effect switches with latched di*al output. These sensors are especially suited for operation in battery-operated, hand-held equipment such as cellular and cordless telephones, pagers, and palm* computers. A 2.5 volt to 3.5 volt operation and a unique clocking scheme reduce the average operating 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 sufficient 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 polarity independence and minimal power requirements allow these devices to easily replace reed switches for *ior 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.

This device includes on a single silicon chip a Hall-voltage generator, *all-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 *all component geometries.

Four package styles provide magnetically optimized solutions for most applications. Miniature low-profile surface-mount package t*es EH and EL (0.75 and 0.50 mm nominal height) are leadless, LH is a leaded low-profile SMD, and UA is a three-lead SIP for through-hole mounting. Packages are available in lead (Pb) free versions (suffix, –T) with 100% matte tin plated leadframe. EL package for limited release, engineering samples available.

Functional Block Diagram