Phase Control IC TCA 785

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

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.

Absolute Maximum Ratings

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 and 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 , .

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

Block Diagram

Pulse Diagram

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