TCA505BG Datasheet, PDF (6/18 Pages) Siemens Semiconductor Group – IC for Inductive Proximity Switches with Short-Circuit Protection

TCA 505 BG
Pin Functions
Pin 1; LC
The resonant circuit of the proximity switch is connected between LC and ground.
Pin 2; RDi
A resistor between this pin and ground sets the current in the oscillator circuit. The greater the
value of the resistor, the smaller is the current feed from the oscillator into the resonant circuit
and the greater therefore is the switching distance. The greater the Q of the resonant circuit,
the greater is the value of the distance resistor necessary for setting a certain switching
distance.
Pin 4; CI
CI can remain open; if high noise immunity is to be achieved however, this pin should be
provided with a series RC element (RI, CI). If pin CD is not used, a correctly dimensioned RC
element on this pin will also prevent any erroneous pulses on the output when the supply
voltage is turned on (see application circuit 1).
Pin 5; RHy
Depending on the status of the circuit, RHy will be high-impedance or low-impedance to ground
(open collector). If the distance resistance (see RDi) is split into two resistors RDi and RHy, a
distance hysteresis can be set by means of RHy. If series hysteresis is applied, RHy is connected
in series with RDi or shorted. If parallel hysteresis is applied, RHy is connected in parallel with RDi
or made high-impedance (see application circuit 1).
Pin 6; SC
SC serves for short-circuit sensing in the output circuit that is to be protected. The current can
be sensed referred to ground or VS. The current sensing is made by a dedicated resistor in the
output circuit. For a voltage drop ≥ 0.3 V across VS and SC or across ground and SC, all outputs
are turned off after the turn-OFF delay (brief glitches on the outputs or the charging of line
capacitances therefore do not trigger the short-circuit protection). After a pause about 200
times the turn-off delay, the outputs turn-ON again. If the short-circuit is still present, the turn-
OFF cycle will start up anew.
Semiconductor Group
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