TCA505BGXLLA1 - INFINEON TECHNOLOGIES AG

Semiconductor Group 1

TCA 505 BG

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.

TCA 505 BG

Bipolar IC

PG-DSO-16-1

Pb-free lead plating; RoHS compliant

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 BGQ67000-A8341PG-DSO-16-1 (SMD)

Type Ordering Code Package

TCA 505 B Q67000-A8342 Chip

IC for Inductive Proximity Switches

with Short-Circuit Protection

02.05

Semiconductor Group 2

TCA 505 BG

Pin Definitions and Functions

Pin Symbol Function

1 LC Oscillator

2 RDi Distance

3 N.C. Not connected

4 CIIntegrating 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 VSSupply voltage

13 VREF Reference voltage

14 B Base Output Transistors

15 CDTurn-ON delay / Short-circuit delay

16 VTTwo-wire regulator

Pin Configurations

(top view)

Semiconductor Group 3

TCA 505 BG

Functional Description and Application

Operation Schematic

Block Diagram

Semiconductor Group 4

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 5

TCA 505 BG

Circuit Diagram (simplified)

Semiconductor Group 6

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

I 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 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.

Semiconductor Group 7

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 8

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 9

TCA 505 BG

Absolute Maximum Ratings

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

VQ1;VQ3

VQ2;VQ4

– 1

VS + 1

VQ2;VQ4 ≤VS

VQ2;VQ1;VQ4

<VQ3

Output currents IQ1;IQ3

–IQ2; – IQ4 0

060

60 mA

mA does not apply to

shortcircuit

Voltage on VTVT– 0.3 14 V

Current on VREF –IREF 0 100 µA

Voltage on SC VSC 0VSV

Current from RDi –IRDi 02mA

Current to RHys IRHy 02mA

Voltage on B VSB – 0.3 VSV

Storage temperature Tstg – 55 110 ˚C

Thermal resistance

(system - air) Rth SA110K/WPG-DSO-16-1

Junction temperature Tj

Tj110

150 ˚C

˚C max. 70.000 h

Capacitor CV50 nF applies to short-

circuit at the

TCA 505 B only

Operating Range

min. max.

Supply voltage VS4

3.1 40

4.5 V

VVREF = VS

Ambient temperature TA– 40 110 ˚C

Distance and

Hysteresis resistance

RDi and RHy in series

RDi and RHy parallel

RDi

RHy

RDi/RHy

300

Ω

Output voltage on

Q2, Q4

B open

B connected VQ2;VQ4

VQ2;VQ4 – 0.3

– 0.3 VS – 2

VBV

Only the circuitry provided for passive components may be connected to pins LC, RDi,CI,CD

Semiconductor Group 10

TCA 505 BG

Characteristics

4 V ≤VS≤ 40 V; TA = – 40 to 110 ˚C

Parameter Symbol

min. typ. max.

Unit Test

Circuit

Power Supply (VS)

Oscillator (LC, RDi)

Demodulator, Threshold Switch (CI,RHy)

Reference Voltage (VREF); Base Output Transistors

Current consumption

Normal mode (S1 = S2 = OFF)

Two-wire operation

S1 = ON, S2 = OFF

4 V ≤VS≤ 12 V

IS550

625 740

840 µA

µA1

Turn-ON threshold

(outputs active)

S1 = OFF

VTON1 3.64 4 V 1

Turn-OFF threshold

(outputs disabled)

S1 = OFF

VTOFF1 3.0 3.6 V 1

Hysteresis VTON1 – VTOFF1

S1 = OFF ∆VHy1 40 mV 1

Oscillator frequency fOSC 3 MHz 1

Oscillator amplitude AOSC 0.8 Vpp 1

Threshold on CIVCI 2V1

Hysteresis on CIVHyCI 0.8 V 1

Current in CIICI 7µA1

Current from CI–ICI 6µA1

Switching frequency

CI < 50 pF fS5 kHz 1

(L = 70 µH)

Reference voltage

IREF = 0 to 100 µAVREF 2.65 2.9 3.10 V

Offset voltage VB = VQ2,4

VB = VREF;IQ2,4 = 5 mA VOB 110 155 mV 1

Limit Values

Semiconductor Group 11

TCA 505 BG

Characteristics (cont’d)

4 V ≤VS≤ 40 V; TA = – 40 to 110 ˚C

Parameter Symbol

min. typ. max.

Unit Test

Circuit

Two-Wire Regulator (VT)

Limit Values

Turn-ON, Turn-OFF and Short-Circuit Delay (CD)

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

Hysteresis VTON2 – VTOFF2, S1 = ON ∆Hy 21.6 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 tP0.36 0.5 0.65 ms/nF 2

Residual voltage

Q1-Q2, Q3-Q4

SQ2 0-1 = ON, SQ4 0-1 = ON

S1 = OFF

IQ = 5 mA

IQ = 60 mA

VQRes

VQR

VQR VS – 2.2

0.10

0.5

VS –1.8

0.14

0.99 V

Reverse current on Q1, 3 IQR 10 µA

Residual current on Q2, 4*)

Q2, 4 conducting but Q1, 3 open IQres 50 µA1

In case of short-circuit output current IQSC 300 500 mA 1

Trigger level ref. to VS, S1 = OFF VSCS 0.255 0.3 0.345 V 1

Trigger current S1 = OFF ISCS 30 µA1

Trigger level ref. to ground S1 = OFF VSCO 0.255 0.3 0.345 V 1

Trigger current S1 = OFF – ISCO 6µA1

Semiconductor Group 12

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 13

TCA 505 BG

Diagrams

Reference Voltage versus

Junction Temperature Tj

Current Consumption versus

Junction Temperature Tj

Switching Amplitude versus

Frequency f

Semiconductor Group 14

TCA 505 BG

Test Circuit 1

Test Circuit 2

Semiconductor Group 15

TCA 505 BG

Application Circuit 1

Input Circuitry (Use of pins LC, RDi,RHy,CI)

For explanation see under "Pin Function"

Semiconductor Group 16

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

For dimensioning of CDsee characteristics. CD is usually between 1 and 10 nF. Filtering of

VREF is for noise immunity. CREF 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 resistor RREF on pin VREF will improve the constant current operation.

Semiconductor Group 17

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

For dimensioning of CDsee 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.

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 resistor RREF on pin VREF will improve the constant current operation.

Semiconductor Group 18

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

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.

Short-circuit-current sampling: RSC =0.3 V

max. load current