TCA 505 BG IC for Inductive Proximity Switches with Short-Circuit Protection TCA 505 BG Pb-free lead plating; RoHS compliant Bipolar IC 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 Type Ordering Code Package TCA 505 BG Q67000-A8341 PG-DSO-16-1 (SMD) TCA 505 B Chip Q67000-A8342 PG-DSO-16-1 Besides its basic functions (oscillator, demodulator and threshold switch), the bipolar monolithic IC TCA 505 B includes a number of useful extra functions that enable high-grade, inductive proximity switches to be designed for an attractive price/performance ratio and with space savings. Compared to earlier ICs for inductive proximity switches temperature drift, noise immunity and the switching frequency of the IC have been improved. Semiconductor Group 1 02.05 TCA 505 BG TCA 505 BG Pin Configurations (top view) Pin Definitions and Functions Pin Symbol Function 1 LC Oscillator 2 RDi Distance 3 N.C. Not connected 4 CI 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 12 VS Supply voltage 13 VREF Reference voltage 14 B Base Output Transistors 15 CD Turn-ON delay / Short-circuit delay 16 VT Two-wire regulator Semiconductor Group 2 TCA 505 BG Functional Description and Application Operation Schematic Block Diagram Semiconductor Group 3 TCA 505 BG Functional Description 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 (pin RDi) 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 RHy (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 to VREF, Q2 and Q4 can be used between 0 V and VREF. The maximum base voltage of the output transistors can be set on pin B. If B is connected to VREF, 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 on CD 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. Finally CD produces a turn-OFF delay of the output stages to prevent the turn-ON delay from running its full length at brief voltage dips on VS. 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 pin VT is connected to VS. The circuit has a stabilized voltage of approx. 2.9 V that is brought out on pin VREF. Supply-voltage range: The operating range in normal operation is between 4 and 40 V. If pin VREF is connected to VS, 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. Semiconductor Group 4 TCA 505 BG Circuit Diagram (simplified) Semiconductor Group 5 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 turnOFF cycle will start up anew. Semiconductor Group 6 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 shortcircuit, 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 7 TCA 505 BG Pin 14; B This pin serves for limiting the base voltage of the internal output-stage transistors. If this pin is connected to VREF 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; CD 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. If VS 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 by CD. In this way the delayed turn-ON operation described above is suppressed if there are just short glitches (voltage dips) on VS. 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 capacitor CD 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, CD can remain open. Pin 16; VT 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 a VS range of 6 to 8 V. At 8 V the outputs are turned on, until VS falls to 6 V. At 6 V the outputs are inhibited, until VS again reaches 8 V. In this mode VS should not exceed 14 V or fall below 4 V. Semiconductor Group 8 TCA 505 BG Absolute Maximum Ratings TA = – 40 to 110 ˚C Parameter Symbol Limit Values min. max. Unit Test Condition Supply voltage VS – 0.3 42 V Output voltages B open B connected VQ1; VQ3 VQ2; VQ4 VQ2; VQ4 –1 –1 –1 41 VS + 1 VB V V V VQ2; VQ4 ≤ VS VQ2; VQ1; VQ4 < VQ3 Output currents IQ1; IQ3 – IQ2; – IQ4 0 0 60 60 mA mA does not apply to shortcircuit Voltage on VT VT – 0.3 14 V Current on VREF – IREF 0 100 µA Voltage on SC VSC 0 VS V Current from RDi – IRDi 0 2 mA Current to RHys IRHy 0 2 mA Voltage on B VSB – 0.3 VS V Storage temperature Tstg – 55 110 ˚C Thermal resistance (system - air) Rth SA 110 K/W PG-DSO-16-1 Junction temperature Tj Tj 110 150 ˚C ˚C max. 70.000 h CV 50 nF 4 3.1 40 4.5 V V TA – 40 110 ˚C RDi and RHy parallel RDi RHy RDi/RHy 300 0 300 Output voltage on Q2, Q4 B open B connected VQ2; VQ4 VQ2; VQ4 – 0.3 – 0.3 Capacitor applies to shortcircuit at the TCA 505 B only Operating Range Supply voltage Ambient temperature Distance and Hysteresis resistance RDi and RHy in series VS VREF = VS Ω Ω VS – 2 VB V V Only the circuitry provided for passive components may be connected to pins LC, RDi, CI, CD Semiconductor Group 9 TCA 505 BG Characteristics 4 V ≤ VS ≤ 40 V; TA = – 40 to 110 ˚C Parameter Limit Values Symbol min. Unit Test Circuit typ. max. IS IS 550 625 740 840 µA µA 1 1 Turn-ON threshold (outputs active) S1 = OFF VTON1 3.64 4 V 1 Turn-OFF threshold (outputs disabled) S1 = OFF VTOFF1 3.6 V 1 Hysteresis VTON1 – VTOFF1 S1 = OFF ∆VHy1 40 mV 1 MHz 1 0.8 Vpp 1 Power Supply (VS) Current consumption Normal mode (S1 = S2 = OFF) Two-wire operation S1 = ON, S2 = OFF 4 V ≤ VS ≤ 12 V 3.0 Oscillator (LC, RDi) Oscillator frequency fOSC Oscillator amplitude AOSC 3 Demodulator, Threshold Switch (CI, RHy) Threshold on CI VCI 2 V 1 Hysteresis on CI VHyCI 0.8 V 1 Current in CI ICI 7 µA 1 Current from CI – ICI 6 µA 1 Switching frequency CI < 50 pF fS 5 kHz 1 (L = 70 µH) Reference Voltage (VREF); Base Output Transistors Reference voltage IREF = 0 to 100 µA Offset voltage VB = VQ2, 4 VB = VREF; IQ2, 4 = 5 mA Semiconductor Group 2.65 VREF VOB 10 2.9 3.10 V 110 155 mV 1 TCA 505 BG Characteristics (cont’d) 4 V ≤ VS ≤ 40 V; TA = – 40 to 110 ˚C Parameter Limit Values Symbol min. typ. max. Unit Test Circuit Two-Wire Regulator (VT) 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 Hysteresis VTON2 – VTOFF2, S1 = ON ∆Hy 1.6 2 2.4 V 1 2 Turn-ON, Turn-OFF and Short-Circuit Delay (CD) 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 Outputs (Q1, Q2, Q3, Q4) Residual voltage Q1-Q2, Q3-Q4 SQ2 0-1 = ON, SQ4 0-1 = ON S1 = OFF IQ = 5 mA IQ = 60 mA IQ = 60 mA VQR VQR VQR Reverse current on Q1, 3 IQR 10 µA Residual current on Q2, 4*) Q2, 4 conducting but Q1, 3 open IQres 50 µA 1 In case of short-circuit output current IQSC 300 500 mA 1 0.3 0.345 V 1 30 µA 1 0.345 V 1 6 µA 1 VQRes 0.10 0.14 0.5 0.99 VS – 2.2 VS –1.8 V V V 1 1 1 Shortcircuit Detector (SC) Trigger level ref. to VS, S1 = OFF VSCS Trigger current S1 = OFF ISCS Trigger level ref. to ground S1 = OFF VSCO Trigger current S1 = OFF – ISCO Semiconductor Group 0.255 0.255 11 0.3 TCA 505 BG Diagrams Temperature Response of Switching Point Resistor RLC 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. Semiconductor Group 12 TCA 505 BG Diagrams Reference Voltage versus Junction Temperature Tj Current Consumption versus Junction Temperature Tj Switching Amplitude versus Frequency f Semiconductor Group 13 TCA 505 BG Test Circuit 1 Test Circuit 2 Semiconductor Group 14 TCA 505 BG For explanation see under "Pin Function" Application Circuit 1 Input Circuitry (Use of pins LC, RDi, RHy, CI) Semiconductor Group 15 TCA 505 BG Application Circuit 2 Output Circuitry (Use of pins VREF, B, SC, Q1 through Q4, CD) P-switch, short-circuit-proof, LED indicator, configurable as normally closed or normally open Short-circuit-current sampling: RSC = 0.3 V max. load current Constant base current: 1) RQ = 2.9 V – VLED max. base current For dimensioning of CD see characteristics. CD is usually between 1 and 10 nF. Filtering of VREF is for noise immunity. CREF can be 10 nF for example. 1) When IQ > 10 mA, a resistor RREF on pin VREF will improve the constant current operation. Semiconductor Group 16 TCA 505 BG Application Circuit 3 Output Circuitry (Use of pins VREF, B, SC, Q1 through Q4, CD) N-switch, short-circuit-proof, LED indicator, configurable as normally closed or normally open Short-circuit-current sampling: RSC = Constant base current: 1) RQ = 0.3 V max. load current 2V max. base current + IRR For dimensioning of CD see characteristics. CD is usually between 1 and 10 nF. Filtering of VREF is for noise immunity. CREF can be 10 nF for example. RREF serves for discharging residual current of outputs Q2, 4. 1) When IQ > 10 mA, a resistor RREF on pin VREF will improve the constant current operation. Semiconductor Group 17 TCA 505 BG Application Circuit 4 Output Circuitry (Use of pins SC, Q1 to Q4, CD) P-switch, short-circuit-proof, configurable as normally closed or normally open Short-circuit-current sampling: RSC = 0.3 V max. load current During the sampling time, the short-circuit current within the IC is limited to a maximum of 250 mA. For dimensioning of CV, see characteristics. CD is usually between 1 and 10 nF. Semiconductor Group 18