HA16603 Datasheet, PDF (7/7 Pages) Hitachi Semiconductor – Contactless Switch

HA16603P/FP
The oscillator frequency is determined by the following formula.
The tank circuit formed by L and C0 has characteristic impedance shown in the figure. The condition for
oscillation for the HA16603P is Rd 1/g, and the condition for oscillation to stop is Rd > 1/g.
When Rd is connected to the hysteresis pin, (Rd + r_cs // Rh) 1/g is the condition for oscillation to start,
and (Rd + Rh) > 1/g is the condition for oscillation to stop. Note that r_cs is the internal resistance of the
hysteresis pin.
The relationship between oscillation occurring or not and the detection of a metallic object is as follows:
Oscillation occurs: When no metallic object is detected (i.e. the sensor coil and the metallic object are
separated)
Oscillation stops: When a metallic object is detected (i.e. the metallic object is near the sensor coil)
Setting the Detection Distance
Since the detection distance depends on the Q of the sensor coil and the shape, surface area, thickness, and
material of the metallic object, it can only be set by testing the completed system. Note that Rd sets the
detection distance.
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