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A3212LUA Schematic ( PDF Datasheet ) - Allegro MicroSystems

Teilenummer A3212LUA
Beschreibung MICROPOWER/ ULTRA-SENSITIVE HALL-EF FECT SWITCH
Hersteller Allegro MicroSystems
Logo Allegro MicroSystems Logo 




Gesamt 12 Seiten
A3212LUA Datasheet, Funktion
A3212
Package Sufx ‘LH’ Pinning
(SOT23W)
3
V
DD
1
2
Dwg. PH-016-1
Pinning is shown viewed from branded side.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VDD .............................. 5 V
Magnetic Flux Density, B .......... Unlimited
Output Off Voltage, VOUT ...................... 5 V
Output Current, IOUT ........................... 1 mA
Junction Temperature, TJ ................ +170°C
Operating Temperature, TA
Range 'E-' .................... -40°C to +85°C
Range 'L-' .................. -40°C to +150°C
Storage Temperature Range,
TS .............................. -65°C to +170°C
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
The A3212 integrated circuit is an ultra-sensitive, pole independent Hall-
effect switch with a latched digital output. This sensor is especially suited for
operation 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 sufcient
strength will turn the output on; in the absence of a magnetic eld, 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
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,
small-signal amplier, 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.
Three package styles provide a magnetically optimized package for most ap-
plications. Package sufxes 'EH' and ‘LH’ are for miniature low-prole (lead-
less and leaded, respectively) surface-mount packages while sufx ‘UA’ is for
a three-lead SIP for through-hole mounting. Each package is available in a lead
(Pb) free version (sufx, –T) with 100% matte tin plated leadframe.
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






A3212LUA Datasheet, Funktion
A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
FUNCTIONAL DESCRIPTION
Low Average Power. Internal timing circuitry activates the
sensor for 45 µs and deactivates it for the remainder of the pe-
riod (45 ms). A short "awake" time allows for stabilization prior
to the sensor sampling and data latching on the falling edge of
the timing pulse. The output during the "sleep" time is latched in
the last sampled state. The supply current is not affected by the
output state.
IDD(EN)
IDD(DIS)
0
"AWAKE"
PERIOD
"SLEEP"
SAMPLE &
OUTPUT LATCHED
Dwg. WH-017-2
B
+V
Chopper-Stabilized Technique. The Hall element can be
considered as a resistor array similar to a Wheatstone bridge. A
large portion of the offset is a result of the mismatching of these
resistors. These devices use a proprietary dynamic offset cancel-
lation technique, with an internal high-frequency clock to reduce
the residual offset voltage of the Hall element that is normally
caused by device overmolding, temperature dependencies, and
thermal stress. The chopper-stabilizing technique cancels the
mismatching of the resistor circuit by changing the direction of
the current owing through the Hall plate using CMOS switches
and Hall voltage measurement taps, while maintaing the Hall-
voltage signal that is induced by the external magnetic ux. The
signal is then captured by a sample-and-hold circuit and further
processed using low-offset bipolar circuitry. This technique
produces devices that have an extremely stable quiescent Hall
output voltage, are immune to thermal stress, and have precise
recoverability after temperature cycling. A relatively high sam-
pling frequency is used for faster signal processing capability
can be processed.
More detailed descriptions of the circuit operation can be
found in: Technical Paper STP 97-10, Monolithic Magnetic Hall
Sensor Using Dynamic Quadrature Offset Cancellation and
Technical Paper STP 99-1, Chopper-Stabilized Ampliers With A
Track-and-Hold Signal Demodulator.
+V
X
115 Northeast Cutoff, Box 15036
6 Worcester, Massachusetts 01615-0036 (508) 853-5000
HALL
VOLTAGE
+
Dwg. AH-011-2
Dwg. EH-012-1

6 Page









A3212LUA pdf, datenblatt
3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
www.allegromicro.com
The products described herein are manufactured under one or
more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283;
5,389,889; 5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719;
5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pend-
ing.
Allegro MicroSystems, Inc. reserves the right to make, from time to
time, such departures from the detail specications as may be required
to permit improvements in the performance, reliability, or manufactur-
ability of its products. Before placing an order, the user is cautioned to
verify that the information being relied upon is current.
Allegro products are not authorized for use as critical components
in life-support appliances, devices, or systems without express written
approval.
The information included herein is believed to be accurate and reli-
able. However, Allegro MicroSystems, Inc. assumes no responsibility
for its use; nor for any infringements of patents or other rights of third
parties that may result from its use.
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