TCA785 Datasheet, PDF (2/16 Pages) Siemens Semiconductor Group – Phase Control IC

TCA 785
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