need help about blanking pulse in sg3524

[ch wazir]

can anyone plz describe the blanking pulse being used in sg3524, is it for determining the percentage of duty cycle,if so how it can be obtained.it'll highly appreciable if it is explained by wave shape of oscilloscope.

 

[yura717]

BLANKING
The output pulse of oscillator is used as a blanking
pulse at the output. This pulse width is controlled
by the value of CT.If small values of CT are
required for frequency control, the oscillator output
pulse width may still be increased by applying
a shunt capacitance of up to 100pF from pin 3 to
ground. If still greater dead-time is required, it
should be accomplished by limiting the maximum
duty cycle by clamping the output of the error amplifier.
https://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000117.pdf

 

[dick_freebird]

The blanking is usually used to prevent a false pulse-shortening
from switching edge and subsequent supply / ground ringing.
It inhibits the reset of the timing cycle. This in turn creates a
minimum pulse width limit which can define the maximum step-
down ratio / minimum duty cycle.

 

[ch wazir]

The blanking is usually used to prevent a false pulse-shortening
from switching edge and subsequent supply / ground ringing.
It inhibits the reset of the timing cycle. This in turn creates a
minimum pulse width limit which can define the maximum step-
down ratio / minimum duty cycle.

my question is,is it possible, for example to get an output pulse of 5 ms on and 15 ms off ( 25% duty cycle) by clamping the error amplifier. regards

 

[FvM]

is it possible, for example to get an output pulse of 5 ms on and 15 ms off ( 25% duty cycle) by clamping the error amplifier.

Yes exactly, by clamping the error amplifier voltage at compensation pin. The method is different from built-in blanking during capacitor discharge, which provided only very limited adjustment.

 

[ch wazir]

ok thanks fvm