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UAA145 View Datasheet(PDF) - Temic Semiconductors

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UAA145 Datasheet PDF : 11 Pages
1 2 3 4 5 6 7 8 9 10
UAA145
Comparator (Differential Amplifier)
and Memory
In the (voltage) comparator stage, the ramp voltage is
compared with the shift voltage Vö applied to Pin 8. The
comparator switches whenever the instantaneous ramp
voltage is the same as the shift voltage (corresponding to
the desired phase angle), thereby causing the memory to
be set, i.e. the integrated thyristor in memory is to be
turned on. The time delay between the signal input and
the comparator output signal is proportional to the
required phase angle. Design of the circuit is such that the
memory content is reset only during the instant of zero
crossover, the reset signal always overriding the set
signal. This effectively prevents the generation of
additional output pulses and causes any pulse already
started to be immediately inhibited on application of an
inhibit signal to Pin 6. The memory content can also be
reset via Pin 6. Thus the memory ensures that any noise
(negative voltage transients) superimposed on the shift
signal at Pin 8 cannot give rise to the generation of
multiple pulses during the half-cycle.
Pulse Generator
(Monostable Multivibrator)
pulse can be monitored by means of an oscilloscope ap-
plied to Pin 6. The Pin 11 pulse waveform is that at Ct, and
the waveforms at Pin 10 and Pin 11 are those of the output
pulses.
The memory setting pulse also triggers a monostable
stage. The duration of the pulse produced by the mono-
stable is determined by Ct and Rt, connected to Pin 2 and
Pin 11.
Channel Selection and Output
Amplifier
A pulse is produced at either output Pin 10 or Pin 14 if
transistor T20 or T19 respectively is cut-off. The pulses
derived from the pulse generator are applied to the output
transistors via OR gates controlled by the half-cycle
signals derived from the sync stage. During the positive
half-cycle no signal is applied from the sync stage to T19
so that an output pulse is produced at Pin 14. The same is
valid for Pin 10 during the negative half-cycle.
Pulse Diagram
Figure 3 shows the pulse voltage waveforms measured at
various points of the circuit, all signals being time
" referenced to the sync signal shown at the top. The input
circuit limits any signal applied to 0.8 V at Pin 9. The
sync pulse can be measured at Pin 16, whereas the ramp
waveform and the pulse phasing rear limit (öh) are at
Pin 7. The time relationship between the shift voltage ap-
plied to Pin 8 and the ramp waveform is indicated by
dotted lines. A pulse trigger signal is produced whenever
the ramp crosses the shift level. The memory control
Figure 3. Pulse diagram
Influence of External Components,
Syncronization Time
An ideal 0 to 180_ shift range and perfect half-cycle pulse
timing symmetry are attained, if the sync pulse duration
is kept short. However, there is a lower pulse duration
limit, which is governed by the time required to charge
capacitor Cs (figure 5).
As can be seen, it takes about 35 ms to charge Cs. The sync
time can be altered by adjustment of Rp, the relationship
between Rp and the sync time being shown in figure 6.
The ratio of R and Rp determines the width of internal
sync pulse, tsync, at Pin 16. The pulse shape is valid only
for sync pulse of 230 V. The lower the sync voltage,
longer is the sync pulse.
x" A minimum of 50 ms (max. 200 ms) input sync pulse is
required for a pulse symmetry of 3°.
TELEFUNKEN Semiconductors
Rev. A1, 29-May-96
3 (11)
 

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