Diodes AH1903 - Manual (Page 6)

AH1903
Document number: DS36568 Rev. 2 - 2
6 of 12
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January 2014
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UC
T
AH1903
Application Notes
(cont.)
Applications Circuit 1 – Unipolar Operation
Connecting the SEL pin to V
DD
, a voltage greater than 1.4V or leaving the SEL pin unconnected configures the AH1903 into Unipolar mode, only
detecting South pole of sufficient strength from the part mark side of the package. In Unipoalr mode, North pole fields will not switch on the
output.
Applications Circuit 2 – Omnipolar Operation
Connecting the SEL pin to ground configures the AH1903 into Omnipolar mode, detecting both North and South magnetic fields of sufficient
strength.
AH1903
SEL
OUTPUT V
DD
Cin
GND
Applications Circuit 3 – Adjustable Sensor Type
To enhance flexibility within the application the sensor operation modes can be selected with a standard logic signal allowing it to be controlled
by a micro-controller or a logic source. This allows the sensor type to be changed within the application without a hardware change. Whenever
the Hall switch type is changed, the selection changeover should allow two awake period for the output to be valid.