MC34025, MC33025

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4

Oscillator

Figure 24. Dead Time Addition

5

6

Additional dead time can be added by the addition of a dead

more information.

5.0 V

0 V

Oscillator

Figure 25. External Clock Synchronization

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5

6

circuit is also used in voltage mode operation for master/slave

operation. The clock signal would be coming from the master

which is set at the desired operating frequency, while the slave

is set 10% slower.

Figure 26. Resistive Current Sensing

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The addition of an RC filter will eliminate instability caused by the

leading edge spike on the current waveform. This sense signal

can also be used at the ramp input pin for current mode control.

For ramp compensation it is necessary to know the gain of the

current feedback loop. If a transformer is used, the gain can be

calculated by:

RSense

turns ratio

Figure 27. Primary Side Current Sensing

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Figure 28. Primary or Secondary Side

Current Sensing

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turns ratio

The addition of an RC filter will eliminate instability caused by the leading edge spike on the current waveform. This sense signal can also

be used at the ramp input pin for current mode control. For ramp compensation it is necessary to know the gain of the current feedback

loop. The gain can be calculated by: