UAA145

TELEFUNKEN Semiconductors

Rev. A1, 29-May-96

4 (11)

t

t

95 11299

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h

v

a

Figure 4. Pulse phasing

–0mA

–0V

95 10105

Figure 5.

Charging time 10

ms/div.

Pulse Phasing Limits

The pulse phasing front limit is determined by limiting

the maximum shift voltage applied to Pin 8 which is thus

adjustable by external circuitry. This can be done by

connecting a Z-diode between Pin 8 and Pin 3. The pulse

phasing rear limit,

(figure 14). Figure 10 shows the pulse phasing rear limit

Pulse Blocking

The output pulses can be blocked via Pin 6, the memory

(Pin 1). This effectively de-activates the pulse generator;

any output pulse in the process of generation is inter-

rupted.

Pulse blocking can be accomplished either via relay

contacts or a PNP switching transistor (figure 14).

0.1

1

10

100

0

100

200

300

400

600

1000

95 10106

500

Sync. Time

R=22k

W

2

Pin16

Figure 6.

Output Pulse Width

The output pulse always finishes at zero crossover. This

means that if there is a minimum pulse width requirement

(for example, when the load is inductive) provision must

be made for a corresponding pulse phasing rear limit. The

output stages are arranged so that the transistors are cut

off when a pulse is produced. Consequently, the thyristor

trigger pulse current flows via the external load resistors,

this current being passed by the transistors during the

period when no output pulse is produced. During this

period the output voltage drops to the transistor saturation

level and is therefore load dependent. Figure 12 shows

the relationship between saturation voltage and load

current.

Shift Characteristic

In figure 13 the angle of phase shift is shown plotted as a

function of the voltage applied to Pin 8 for a pulse phasing

rear limit of approximately 0

_. Because the ramp wave-

form is a part of the exponential function, the shift curve

is also exponential.

The limitation of the shift voltage to approximately 8.5 V

spread of 7 to 9 V.

The waveforms in figures 7 to 9 show the output pulse

oscillograms, the instants at which pulses are released

coincide with the intersections of the ramp and the shift

voltage.