A1351KKTTN-T Allegro Microsystems Inc, A1351KKTTN-T Datasheet - Page 21

• Manufacturer Part Number: A1351KKTTN-T
• Description: IC,HALL-EFFECT SENSOR,SINGLE-ENDED,BICMOS,SIP,4PIN,PLASTIC
• Manufacturer: Allegro Microsystems Inc
• Type: Linear - Unipolar, Bipolarr

Specifications of A1351KKTTN-T

• Sensing Range: 0.055% ~ 0.095% DC/G
• Voltage - Supply: 4.5 V ~ 5.5 V
• Current - Supply: 10mA
• Current - Output (max): 1mA
• Output Type: Digital, Push-Pull
• Features: High Precision
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 4-SIP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A1351
To construct a current sensor using the A1351, first consider a
current carrying wire that we want to observe. As dictated by
Ampere’s Law, a magnetic field is produced around the wire
that is proportional to the amount of current flowing through
the wire. By passing this wire through a soft magnetic core, the
magnetic flux produced by the wire can be concentrated and
directed through a gap in the core. The magnetic flux density can
be measured by inserting the A1351 SIP into the gap in the core.
As a result, the output of the A1351 device will be proportional
to the amount of current flowing through the wire.
The example feedthrough current sensing setup shown below
(figure 7) has a core made of “mu metal” that is 2 mm thick
and 4 mm wide. The inner radius of the core is 14.5 mm and
the outer radius is 18.5 mm. The wire going through the center
Figure 7. The example current sensor setup used to generate the data in this section was
constructed with a split-ring concentrator and an A1351 device. A copper wire was fed
through the concentrator, and the A1351 placed in its gap. This approximates a typical
ammeter application on a thick wire, such as shown in the left view. Note that such
applications usually have a protective housing, which should be taken into consideration
when designing the fi nal application. The housing is beyond the scope of this example.
Constructing a Current Sensor Using the A1351
with a Push/Pull, Pulse Width Modulated Output
Ø18 mm
High Precision Linear Hall Effect Sensor IC
Application-specific housing
A136x
Ring concentrator
Current-conducting wire
of the core has a radius of 9 mm. Using this setup with a gap of
1.7 mm, a field strength results that is on the order of 7 G / A at
the Hall element in the A1351.
The recommended core material for construction of the concen-
trator depends on the specific application. If high flux saturation
is desired, then an alloy such as HyPerm49 is recommended.
For lower-current level sensing applications, a material such as
HyMu80 may be desired. (HyMu80 has lower magnetic flux
saturation than HyPerm49, therefore more HyMu80 mate-
rial is required to carry the same amount of flux compared
to Hyperm49.) If frequency response is a concern, then eddy
currents can be reduced by either laminating the HyPerm49 or
HyMu80 alloys, or by using a ferrite core.
1.7 mm
Center Hall element in gap
4 mm
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
2 mm
Ø37 mm
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