TCA505B

TCA505BG SIEMENS | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 18

Technical content

Features

• Wide supply voltage of 3.1 to 4.5 V and 4 to 40 V
• Low current consumption of less than 0.8 mA
• Integrated output stage for up to 60 mA output current
• Short-circuit and overload protection of output stages and external components
• Temperature response of the IC compensates that of the coil
• High noise immunity
• High switching frequencies up to 5 kHz
• Useful extra functions
• Suitable for two-wire AC proximity switches
• Temperature range – 40 to 110 ˚C TCA 505 BG Q67000-A8341 P-DSO-16-1 (SMD) Type Ordering Code Package TCA 505 B Q67000-A8342 Chip IC for Inductive Proximity Switches with Short-Circuit Protection 01.96

Pin Definitions and Functions Pin Symbol Function

1 LC Oscillator

3 N.C. Not connected 4 C I Integrating capacitance

5 RHy Hysteresis

6 SC Short-circuit detector

7 GND Ground

8 Q4 Output

9 Q3 Output

10 Q2 Output

11 Q1 Output

13 VREF Reference voltage

14 B Base Output Transistors

D Turn-ON delay / Short-circuit delay

16 VT Two-wire regulator

(top view)

Functional Description and Application Operation Schematic Block Diagram

This circuit is used to design inductive proximity switches. The resonant circuit of the LC oscillator is implemented with an open half-pot ferrite and a capacitor in parallel (pin LC). If a metallic target is moved closer to the open side of the half-pot ferrite, energy is drawn from the resonant circuit and the amplitude of the oscillation is reduced accordingly. This change in amplitude is transmitted to a threshold switch by means of a demodulator and triggers the outputs (see operation schematic). By means of an external distance resistor on the oscillator (pinR Di) it is possible to set the switching distance within wide limits, the optimal distances being 0.1 to 0.6 of the diameter of the half-pot ferrite, although both of these parameters can be exceeded. The circuit also enables the setting of a path hysteresis by switching of the external distance resistor via pin R Hy (see application circuit 1). There are two antiphase output stages (Q1 / Q2 and Q3 / Q4) for max. 50 mA. The output transistors are driven in a floating state thus providing the user with optimal flexibility for evaluation of the output signals. It is therefore possible to use the output transistors either as emitter follower, open-collector, as a current source or in push-pull operation. When pin B is connected toV REF , Q2 and Q4 can be used between 0 V andVREF . The maximum base voltage of the output transistors can be set on pin B. If B is connected toVREF , any constant current up to 50 mA can be set on the outputs by means of resistors on Q2 or Q4 (see application circuits 2 and 3). Q1 through Q4 and also additional external output transistors can be protected against destruction by short-circuit or overload. This is the purpose of pin SC which turns off the output transistors periodically in the presence of overload. By means of a capacitor onC D it is possible to set the response delay and the turn-OFF time of short-circuit protection. The same capacitor also defines the turn-ON delay of the output stages when the supply voltage is applied, whereby the output stages are inhibited during buildup of the oscillator. FinallyC D produces a turn-OFF delay of the output stages to prevent the turn-ON delay from running its full length at brief voltage dips onVS. A switching regulator is incorporated for the voltage supply of the circuit when it is used as a two-wire AC proximity switch, and this is activated when pinVT is connected toVS. The circuit has a stabilized voltage of approx. 2.9 V that is brought out on pinVREF . Supply-voltage range: The operating range in normal operation is between 4 and 40 V. If pin VREF is connected toVS, the circuit is operating between 3.1 and 4.5 V. In this case, however, VREF is no longer internally stabilized, i.e. the analog IC functions depend on the operating voltage.

Circuit Diagram (simplified)

Pin 1; LC The resonant circuit of the proximity switch is connected between LC and ground. Pin 2;R Di 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;C I C I can remain open; if high noise immunity is to be achieved however, this pin should be provided with a series RC element (RI,C I). If pinC D 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;R Hy Depending on the status of the circuit,RHy will be high-impedance or low-impedance to ground (open collector). If the distance resistance (seeRDi) is split into two resistorsRDi and RHy, a distance hysteresis can be set by means ofRHy. If series hysteresis is applied,RHy is connected in series withRDi or shorted. If parallel hysteresis is applied,RHy is connected in parallel withRDi 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 orVS. The current sensing is made by a dedicated resistor in the output circuit. For a voltage drop≥ 0.3 V acrossVS 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.

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 theβ 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.V S – 2 V. For current setting on the outputs, see pin B. Pin 12;V S Outputs Q1 through Q4 are inhibited as long as the voltage onVS 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 ofV S there are consequently no undesirable static states. The operating data and characteristics apply upwards from 4 V. See pinC D for the avoidance of erroneous pulses during oscillator buildup. Pin 13;V REF The internal stabilized voltage of the IC of approx. 2.9 V appears on this pin. A capacitor can be connected betweenVREF and ground to improve the noise immunity of the overall circuit function. IfVREF is connected toVS, it is possible to operate the circuit in a supply- voltage range of 3.1 through 4.5 V. In this caseVREF is no longer stabilized. The analog functions of the circuit e.g. switching distance, however, are then dependent on the supply voltage.

Pin 14; B This pin serves for limiting the base voltage of the internal output-stage transistors. If this pin is connected toVREF for example, it is possible to set a constant output current (IQ = VREF / external resistor) that is independent of the supply voltage by means of an external resistor across Q2 (or Q4) and ground (watch out for power dissipation!). Pin 15;C D A capacitor on this pin delays the activation of the outputs after the supply voltage is applied (turn-ON delay). In this way erroneous pulses are prevented on the output during buildup of the oscillator. IfV S falls to less than 3.6 to 4 V, the outputs are not inhibited until after a turn-OFF delay time, this also being determined byC D . In this way the delayed turn-ON operation described above is suppressed if there are just short glitches (voltage dips) onVS. This is of particular advantage for large core diameters, because in such cases a relativity long turn-ON delay has to be selected and the delayed twin-on operation would otherwise be activated each time there was a brief voltage dip. The capacitorC D also sets the turn-off delay and the pause duration in short-circuit operation. The sample / pause ratio is approx. 1:200 (see pin SC). If these functions can be dispensed with,C D can remain open. Pin 16;V T If this pin is connected to +VS, the supply voltage of the IC (when used as a two-wire proximity switch) can be generated by switching the outputs. The quiescent current can then be kept low. This mode is primarily suitable for AC switches with power supply by phase-control. The switching of the outputs is made in aV S range of 6 to 8 V. At 8 V the outputs are turned on, untilVS falls to 6 V. At 6 V the outputs are inhibited, untilVS again reaches 8 V. In this mode VS should not exceed 14 V or fall below 4 V.

TA = – 40 to 110 ˚C Parameter Symbol Limit Values Unit Test Condition Supply voltage VS – 0.3 42 V Output voltages B open B connected V Q1 ;VQ3 VQ2 ;VQ4 VQ2 ;VQ4 – 1 – 1 – 1 V S + 1 VB V V V V Q2 ;VQ4 ≤ VS VQ2 ;VQ1 ;VQ4 < VQ3 Output currents IQ1 ;IQ3 – IQ2 ; –IQ4 mA mA does not apply to shortcircuit Voltage onVT VT – 0.3 14 V Current onVREF – IREF 0 100 µA Voltage on SC VSC 0 VS V Current fromRDi – IRDi 02m A Current toRHys IRHy 02m A Voltage on B VSB – 0.3 VS V Storage temperature Tstg – 55 110 ˚C Thermal resistance (system - air) Rth SA 110 K/W P-DSO-16-1 Junction temperature Tj Tj 110 150 ˚C max. 70.000 h Capacitor C V 50 nF applies to short- circuit at the TCA 505 B only Operating Range min. max. Supply voltage VS 4 3.1 4.5 V V VREF =VS Ambient temperature TA – 40 110 ˚C Distance and Hysteresis resistance R Di andRHy in series RDi andRHy parallel RDi RHy RDi/RHy 300 300 Ω Ω Output voltage on Q2, Q4 B open B connected V Q2 ;VQ4 VQ2 ;VQ4 – 0.3 – 0.3 VS – 2 VB V V Only the circuitry provided for passive components may be connected to pins LC,RDi,C I,C D

4 V≤ VS ≤ 40 V;TA = – 40 to 110 ˚C

min. typ. max. Unit Test Circuit Power Supply (V S) Oscillator (LC,R Di) Demodulator, Threshold Switch (C I,R Hy ) Reference Voltage (V REF ); Base Output Transistors Current consumption Normal mode (S1 = S2 = OFF) Two-wire operation S1 = ON, S2 = OFF 4 V ≤ VS ≤ 12 V IS IS 550 625 740 840 µA µA Turn-ON threshold (outputs active) S1 = OFF V TON1 3.64 4 V 1 Turn-OFF threshold (outputs disabled) S1 = OFF V TOFF1 3.0 3.6 V 1 HysteresisVTON1 –VTOFF1 S1 = OFF ΔVHy1 40 mV 1 Oscillator frequency fOSC 3 MHz 1 Oscillator amplitude AOSC 0.8 Vpp 1 Threshold onC I VCI 2V 1 Hysteresis onC I VHyCI 0.8 V 1 Current inC I ICI 7 µA1 Current fromC I – ICI 6 µA1 Switching frequency C I < 50 pF fS 5 kHz 1 (L = 70µH) Reference voltage IREF = 0 to 100µA VREF 2.65 2.9 3.10 V Offset voltageVB =VQ2 ,4 VB =VREF ;IQ2 ,4 = 5 mA VOB 110 155 mV 1 Limit Values

Characteristics (cont’d) min. typ. max. Unit Test Circuit Two-Wire Regulator (V T) Limit Values Turn-ON, Turn-OFF and Short-Circuit Delay (C D ) Outputs (Q1, Q2, Q3, Q4) Shortcircuit Detector (SC) Turn-ON threshold (outputs active) S1 = ON VTON2 6.7 8 9.3 V 1 Turn-ON threshold (outputs disabled) S1 = ON VTOFF2 5.0 6 7.0 V 1 HysteresisVTON2 –VTOFF2 , S1 = ON ΔHy 2 1.6 2 2.4 V 1 Turn-ON delay S1 = OFF tDON 0.49 0.65 0.82 ms/nF 2 Turn-OFF delay S1 = OFF; VS ≥ 3.6 V tVA 17.0 25 34.0 µs/nF 2 Shortcircuit turn-off delay S1 = OFF tSC 1.70 2.5 3.40 µs/nF 2 Shortcircuit pause S1 = OFF tP 0.36 0.5 0.65 ms/nF 2 Residual voltage Q1-Q2, Q3-Q4 SQ2 0-1 = ON, SQ4 0-1 = ON S1 = OFF I Q = 5 mA IQ = 60 mA IQ = 60 mA VQRes VQR VQR VQR VS – 2.2 0.10 0.5 V S –1.8 0.14 0.99 V V V Reverse current on Q1, 3 I QR 10 µA Residual current on Q2, 4*) Q2, 4 conducting but Q1, 3 open IQres 50 µA1 In case of short-circuit output currentIQSC 300 500 mA 1 Trigger level ref. toVS, S1 = OFF VSCS 0.255 0.3 0.345 V 1 Trigger current S1 = OFF ISCS 30 µA1 Trigger level ref. to ground S1 = OFFVSCO 0.255 0.3 0.345 V 1 Trigger current S1 = OFF – ISCO 6 µA1

Temperature Response of Switching Point ResistorRLC is set in each case so that the TCA 505 B just switches from D2 to D1. In this way the TCA 505 B, together with a suitably dimensioned resonant circuit, can form a proximity switch that exhibits a very good temperature coefficient ( ± 2.5 %) over the entire temperature range and without any kind of extra external wiring.

j Current Consumption versus Junction TemperatureTj Switching Amplitude versus Frequency f

Input Circuitry(Use of pins LC,RDi,RHy,C I) For explanation see under "Pin Function"

Output Circuitry (Use of pinsVREF , B, SC, Q1 through Q4,C D ) P-switch, short-circuit-proof, LED indicator, configurable as normally closed or normally open For dimensioning ofC D see characteristics.C D is usually between 1 and 10 nF. Filtering of VREF is for noise immunity.C REF can be 10 nF for example. Short-circuit-current sampling:RSC = Constant base current:1) RQ = 0.3 V max. load current

2.9 V –VLED

max. base current 1) When IQ > 10 mA, a resistorRREF on pinVREF will improve the constant current operation.

Output Circuitry (Use of pinsVREF , B, SC, Q1 through Q4,C D ) N-switch, short-circuit-proof, LED indicator, configurable as normally closed or normally open For dimensioning ofC D see characteristics.C D is usually between 1 and 10 nF. Filtering of VREF is for noise immunity.C REF can be 10 nF for example.RREF serves for discharging residual current of outputs Q2, 4. Short-circuit-current sampling:RSC = Constant base current:1) RQ = 0.3 V max. load current 2 V max. base current +IRR 1) When IQ > 10 mA, a resistorRREF on pinVREF will improve the constant current operation.

Output Circuitry (Use of pins SC, Q1 to Q4,C D ) P-switch, short-circuit-proof, configurable as normally closed or normally open During the sampling time, the short-circuit current within the IC is limited to a maximum of 250 mA. For dimensioning ofC V,see characteristics.C D is usually between 1 and 10 nF. Short-circuit-current sampling:RSC = 0.3 V max. load current