Datasheet

   
   
SLUS488E − SEPTEMBER 2002 − REVISED JULY 2009
9
www.ti.com
APPLICATION INFORMATION
operational waveforms
Figure 3 illustrates how the voltage ramp is effectively added to the voltage across the current sense element
V
CS
, to implement slope compensation.
UDG−01085
OUTA
OUTB
V
RS
ADDED
RAMP
VOLTAGE
V
CS
, Pin 3
Figure 3. Typical Slope Compensation Waveforms at 80% Duty Cycle
In Figure 3, OUTA and OUTB are shown at a duty cycle of 80%, with the associated voltage VRS across the
current sense resistor of the primary push-pull power MOSFETs. The current flowing out of CS generates the
ramp voltage across the filter resistor R
F
that is positioned between the power current sense resistor and the
CS pin. This voltage is effectively added to VRS to provide slope compensation at VCS, pin 3. A capacitor C
F
is also recommended to filter the waveform at CS.