A3212ELH Allegro Microsystems Inc, A3212ELH Datasheet - Page 7

• Manufacturer Part Number: A3212ELH
• Manufacturer: Allegro Microsystems Inc

Specifications of A3212ELH

• Magnetic Type: Latch
• Operating Supply Voltage (min): 2.5V
• Operating Supply Voltage (typ): 2.75V
• Operating Supply Voltage (max): 3.5V
• Output Current: 1mA
• Mag Sensor Operate Point (g): 55Gs
• Mag Sensor Release Point (g): 10Gs
• Mag Sensor Hysteresis(g): 5.9Gs
• Package Type: SOT-23W
• Pin Count: 3
• Mounting: Surface Mount
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Not Compliant

A3211
A3212
Low Average Power. Internal timing circuitry activates the
IC for 45 μs and deactivates it for the remainder of the period
(45 ms). A short "awake" time allows for stabilization prior to
the sam pling 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.
I
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 de pen den cies, and
thermal stress. The chopper-stabilizing technique cancels the
mismatching of the resistor circuit by changing the direction of
the current flowing 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 flux. 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
Sensing Using Dynamic Quadrature Offset Cancellation and
Technical Paper STP 99-1, Chopper-Stabilized Amplifiers With A
Track-and-Hold Signal Demodulator.
I
DD(DIS)
DD(EN)
0
and
SAMPLE &
OUTPUT LATCHED
"AWAKE"
"SLEEP"
PERIOD
FUNCTIONAL DESCRIPTION
Dwg. WH-017-2
Micropower, Ultrasensitive
+V
X
Hall-Effect Switches
+V
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
B
Dwg. AH-011-2
HALL
VOLTAGE
Dwg. EH-012-1
—
+
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