The A3212 integrated circuit is an ultra-sensitive, pole independent Hall-effect

switch with a latched digital output. This sensor is especially suited for opera-

tion in battery-operated, hand-held equipment such as cellular and cordless

telephones, pagers, and palmtop 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 absence of a magnetic field, the output

is off. The polarity independence and minimal power requirement allow these

devices to easily replace reed switches for superior reliability and ease of manu-

facturing, while eliminating the requirement for signal conditioning.

Improved stability is made possible through chopper stabilization (dynamic off-

set 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, small-sig-

nal 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 com-

ponent geometries.

Four package styles provide magnetically optimized solutions for most appli-

cations. Miniature low-profile surface-mount package types 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. Each package is

available in a lead (Pb) free version (suffix, –T) with 100% matte tin plated lead-

frame. EL package for limited release, engineering samples available.

FEATURES

■

Micropower Operation

■

Operation 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

■

ESD Protected to 5 kV

■

Solid-State Reliability

■

Small Size

■

Easily Manufacturable with Magnet Pole Independence

A3212

ABSOLUTE MAXIMUM RATINGS

Magnetic Flux Density, B .......... Unlimited

Range 'E-' .................... -40°C to +85°C

Range 'L-' .................. -40°C to +150°C

Storage Temperature Range,

Caution: These CMOS devices have input

static protection (Class 3) but are still sus-

ceptible to damage if exposed to extremely

high static electrical charges.

MICROPOWER, ULTRA-SENSITIVE

HALL-EFFECT SWITCH

2 x 2 mm MLPD

Package A3212EELLT-T

Approximate actual size