TCA785(1994) Ver la hoja de datos (PDF) - Siemens AG
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TCA785 Datasheet PDF : 16 Pages
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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
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