TCA505BG Datasheet, PDF (7/18 Pages) Siemens Semiconductor Group – IC for Inductive Proximity Switches with Short-Circuit Protection

TCA 505 BG
Both the internal output stages and externally connected output stages can be protected
against sustained short-circuits or overload.
A limiting of the output current is an externally connected output stage during the turn-off delay
must be ensured. Normally the current limiting by the β of the output transistor is sufficient,
meaning that no further circuit devices are called for (see application circuits). The outputs
Q1 to Q4 are already internally protected against overcurrent so that, in the case of a short-
circuit, the current will not exceed 250 mA.
In order to prevent thermal overloads, the current-conducting output is to be connected to pin
SC (see application circuit 4).
Pins 8, 9, 10, 11; Outputs Q1, Q2, Q3, Q4
Q1 is the open collector, Q2 the open emitter of one output transistor, Q3 the open collector
and Q4 the open emitter of the second output transistor in antiphase with the first output
transistor (see operation schematic). Q1 and Q3 or Q2 and Q4 can be connected in parallel
as required. The function of the outputs is ensured when the emitter potential of the output
transistors (Q2, Q4) is between 0 V and the voltage on pin B. If B is not connected, the
operating range of Q2 and Q4 extends to approx. VS – 2 V. For current setting on the outputs,
see pin B.
Pin 12; VS
Outputs Q1 through Q4 are inhibited as long as the voltage on VS is below approx. 3.6 V. They
are enabled between approx. 3.6 and 4 V, the basic function of the circuit is then ensured.
During the turn-ON and turn-OFF of VS there are consequently no undesirable static states.
The operating data and characteristics apply upwards from 4 V. See pin CD for the avoidance
of erroneous pulses during oscillator buildup.
Pin 13; VREF
The internal stabilized voltage of the IC of approx. 2.9 V appears on this pin. A capacitor can
be connected between VREF and ground to improve the noise immunity of the overall circuit
function. If VREF is connected to VS, it is possible to operate the circuit in a supply- voltage range
of 3.1 through 4.5 V. In this case VREF is no longer stabilized. The analog functions of the circuit
e.g. switching distance, however, are then dependent on the supply voltage.
Semiconductor Group
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