TCA 785 Phase Control IC TCA 785 - Infineon

TCA 785 

Phase Control IC TCA 785 

Pb-free lead plating; RoHS compliant 

Features 

● Reliable recognition of zero passage 

● Large application scope 

● May be used as zero point switch 

● LSL compatible 

● Three-phase operation possible (3 ICs) 

● Output current 250 mA 

● Large ramp current range 

●Wide temperature range 

PG-DIP-16-1 

Bipolar IC 

Type Ordering Code Package 

TCA 785 Q67000-A2321 PG-DIP-16-1 

This phase control IC is intended to control thyristors, triacs, and transistors. The trigger pulses 

can be shifted within a phase angle between 0 ˚ and 180 ˚. Typical applications include 

converter circuits, AC controllers and three-phase current controllers. 

This IC replaces the previous types TCA 780 and TCA 780 D. 

Pin Configuration 

(top view) 

Pin Definitions and Functions 

Pin Symbol Function 

1 GND Ground 

2 

3 

4 

Q2 

Q U 

Q2 

Output 2 inverted 

Output U 

Output 1 inverted 

5 VSYNC Synchronous voltage 

6 

7 

I 

Q Z 

Inhibit 

Output Z 

8 V REF Stabilized voltage 

9 

10 

R9 

C10 

Ramp resistance 

Ramp capacitance 

11 V11 Control voltage 

12 C12 Pulse extension 

13 L Long pulse 

14 

15 

Q 1 

Q 2 

Output 1 

Output 2 

16 VS Supply voltage 

Semiconductor Group 1 

02.05


Functional Description 

The synchronization signal is obtained via a high-ohmic resistance from the line voltage 

(voltage V5). A zero voltage detector evaluates the zero passages and transfers them to the 

synchronization register. 

This synchronization register controls a ramp generator, the capacitor C10 of which is charged 

by a constant current (determined by R9). If the ramp voltage V10 exceeds the control voltage 

V11 (triggering angle ϕ), a signal is processed to the logic. Dependent on the magnitude of the 

control voltage V11, the triggering angle ϕ can be shifted within a phase angle of 0˚ to 180˚. 

For every half wave, a positive pulse of approx. 30 µs duration appears at the outputs Q 1 and 

Q 2. The pulse duration can be prolonged up to 180˚ via a capacitor C12. If pin 12 is connected 

to ground, pulses with a duration between ϕ and 180˚ will result. 

Outputs Q 1 and Q 2 supply the inverse signals of Q 1 and Q 2. 

A signal of ϕ +180˚ which can be used for controlling an external logic,is available at pin 3. 

A signal which corresponds to the NOR link of Q 1 and Q 2 is available at output Q Z (pin 7). 

The inhibit input can be used to disable outputs Q1, Q2 and Q 1 , Q 2 . 

Pin 13 can be used to extend the outputs Q 1 and Q 2 to full pulse length (180˚ – ϕ). 

Block Diagram 

Semiconductor Group 2


Pulse Diagram 



Absolute Maximum Ratings 

Parameter 

Symbol 

Limit Values 

min. max. 

Supply voltage VS – 0.5 18 

Output current at pin 14, 15 IQ – 10 400 

Inhibit voltage 

Control voltage 

Voltage short-pulse circuit 

Thermal resistance 

system - air Rth SA 80 

V6 

V11 

V13 

– 0.5 

– 0.5 

– 0.5 

Synchronization input current V5 – 200 ± 200 

Output voltage at pin 14, 15 VQ VS 

Output current at pin 2, 3, 4, 7 IQ 10 

Output voltage at pin 2, 3, 4, 7 VQ VS 

Junction temperature 

Storage temperature 

Tj 

Tstg – 55 

VS 

VS 

VS 

150 

125 

Unit 

V 

mA 

V 

V 

V 

µA 

V 

mA 

V 

˚C 

˚C 

K/W 

Operating Range 

Supply voltage VS 8 18 

Operating frequency f 10 500 

Ambient temperature TA – 25 85 

V 

Hz 

˚C 

Characteristics 

8 ≤ VS ≤ 18 V; – 25 ˚C ≤ TA ≤ 85 ˚C; f = 50 Hz 

Parameter 

Supply current consumption 

S1 … S6 open 

V11 = 0 V 

C 10 = 47 nF; R 9 = 100 kΩ 

Synchronization pin 5 

Input current 

R 2 varied 

Offset voltage 

Control input pin 11 

Control voltage range 

Input resistance 

Symbol 

min. 

Limit Values 

typ. max. 

Unit 

IS 4.5 6.5 10 mA 1 

I5 rms 

∆V5 

V11 

R11 

30 200 µA 1 

30 

75 

mV 

0.2 V10 peak V 1 

15 

kΩ 5 

Test 

Circuit 

4 



Characteristics (cont’d) 

8 ≤ VS ≤ 18 V; – 25 ˚C ≤ TA ≤ 85 ˚C; f = 50 Hz 

Parameter 

Symbol 

min. 

Limit Values 

typ. max. 

Unit 

Test 

Circuit 

Ramp generator 

Charge current 

Max. ramp voltage 

Saturation voltage at capacitor 

Ramp resistance 

Sawtooth return time 

I10 

V10 

V10 

R9 

tf 

10 

100 

3 

225 

80 

1000 

V2 – 2 

350 

300 

µA 

V 

mV 

kΩ 

µs 

1 

1.6 

1 

1 

Inhibit pin 6 

switch-over of pin 7 

Outputs disabled 

Outputs enabled 

Signal transition time 

Input current 

V6 = 8 V 

Input current 

V6 = 1.7 V 

V6 L 

V6 H 

tr 

I6 H 

– I6 L 

4 

1 

80 

3.3 

3.3 

500 

150 

2.5 

5 

800 

200 

V 

V 

µs 

µA 

µA 

1 

1 

1 

1 

1 

Deviation of I10 

R 9 = const. 

VS = 12 V; C10 = 47 nF 

Deviation of I10 

R 9 = const. 

VS = 8 V to 18 V 

Deviation of the ramp voltage 

between 2 following 

half-waves, VS = const. 

I10 

I10 

∆V10 max 

– 5 

– 20 

± 1 

5 

20 

% 

% 

% 

1 

1 

Long pulse switch-over 

pin 13 

switch-over of S8 

Short pulse at output 

Long pulse at output 

Input current 

V13 = 8 V 

Input current 

V13 = 1.7 V 

V13 H 

V13 L 

I13 H 

– I13 L 

3.5 

45 

2.5 

2.5 

65 

2 

10 

100 

V 

V 

µA 

µA 

1 

1 

1 

1 

Outputs pin 2, 3, 4, 7 

Reverse current 

ICEO 

10 

µA 

2.6 

VQ = VS 

Saturation voltage 

IQ = 2 mA 

Vsat 0.1 

0.4 

2 

V 

2.6 



Characteristics (cont’d) 

8 ≤ VS ≤ 18 V; – 25 ˚C ≤ TA ≤ 85 ˚C; f = 50 Hz 

Parameter 

Outputs pin 14, 15 

H-output voltage 

– I Q = 250 mA 

L-output voltage 

IQ = 2 mA 

Pulse width (short pulse) 

S9 open 

Pulse width (short pulse) 

with C12 

Internal voltage control 

Reference voltage 

Parallel connection of 

10 ICs possible 

TC of reference voltage 

Symbol 

V14/15 H 

V14/15 L 

tp 

tp 

VREF 

αREF 

min. 

VS – 3 

0.3 

20 

530 

Limit Values 

typ. max. 

VS – 2.5 

0.8 

30 

620 

VS – 1.0 

2 

40 

760 

Unit 

V 

V 

µs 

µs/ 

nF 

2.8 3.1 3.4 V 1 

2 × 10 – 4 5 × 10 – 4 1/K 1 

Test 

Circuit 

3.6 

2.6 

1 

1 



Application Hints for External Components 

Ramp capacitance 

Triggering point 

Charge current 

min 

max 

C10 500 pF 1 µF 1) 

tTr = 

I10 = 

V11 × R9 × C10 2) 

VREF × K 

VREF × K 2) 

R9 

The minimum and maximum values of I10 

are to be observed 

Ramp voltage 

V10 max = VS – 2 V V10 = 

VREF × K × t 

R9 × C10 

2) 

Pulse Extension versus Temperature 

1) Attention to flyback times 

2) K = 1.10 ± 20 % 



Output Voltage measured to + VS 

Supply Current versus Supply Voltage 



It is necessary for all measurements to adjust the ramp with 

the aid of C10 and R 9 in the way that 3 V ≤ Vramp max ≤ V S – 2 V 

e.g. C10 = 47 nF; 18 V: R 9 = 47 kΩ; 8 V: R 9 = 120 kΩ 

Test Circuit 1 



The remaining pins are connected as in test circuit 1 


The remaining pins are connected as in test circuit 1 




Remaining pins are connected as in test circuit 1 

The 10 µF capacitor at pin 5 serves only for test purposes 


Test Circuit 5 Test Circuit 6 



Inhibit 6 Long Pulse 13 

Pulse Extension 12 Reference Voltage 8 



Application Examples 

Triac Control for up to 50 mA Gate Trigger Current 

A phase control with a directly controlled triac is shown in the figure. The triggering angle of 

the triac can be adjusted continuously between 0˚ and 180˚ with the aid of an external 

potentiometer. During the positive half-wave of the line voltage, the triac receives a positive 

gate pulse from the IC output pin 15. During the negative half-wave, it also receives a positive 

trigger pulse from pin 14. The trigger pulse width is approx. 100 µs. 



Fully Controlled AC Power Controller 

Circuit for Two High-Power Thyristors 

Shown is the possibility to trigger two antiparalleled thyristors with one IC TCA 785. The trigger 

pulse can be shifted continuously within a phase angle between 0˚ and 180˚ by means of a 

potentiometer. During the negative line half-wave the trigger pulse of pin 14 is fed to the 

relevant thyristor via a trigger pulse transformer. During the positive line half-wave, the gate of 

the second thyristor is triggered by a trigger pulse transformer at pin 15. 



Half-Controlled Single-Phase Bridge Circuit with Trigger Pulse Transformer and Direct 

Control for Low-Power Thyristors 



Half-Controlled Single-Phase Bridge Circuit with Two Trigger Pulse Transformers for 

Low-Power Thyristors

TCA 785 Phase Control IC TCA 785 - Infineon

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