ncp4303a ON Semiconductor, ncp4303a Datasheet - Page 13

• Manufacturer Part Number: ncp4303a
• Description: Ncp4303a/b Secondary Side Synchronous Rectification Driver For High Efficiency Smps Topologies
• Manufacturer: ON Semiconductor

reverses, the body diode of M1 starts to conduct current and
the voltage of M1’s drain drops approximately to −1 V. The
CS pin sources current of 100 mA that creates a voltage drop
on the R
lower than V
parasitic impedances, significant ringing can occur in the
application. To overcome sudden turn−off due to mentioned
ringing, the minimum conduction time of the SR MOSFET
is activated. Minimum conduction time can be adjusted
using R
When the voltage on the secondary winding of the SMPS
_Min_Ton
shift_cs
th_cs_on
resistor. Once the voltage on the CS pin is
resistor.
threshold, M1 is turned on. Because of
Figure 33. ZCD Sensing Circuitry Functionality
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13
the CS pin is higher than V
reason, a minimum off time timer is asserted once the
turn−off is detected. The minimum off time can be
externally adjusted using R
channel conducts when the secondary current decreases,
therefore the turn−off time depends on its R
threshold provides an optimum switching period usage
while keeping enough time margin for the gate turn off. The
R
modify (increase) the actual turn−off current threshold.
shift_cs
The SR MOSFET is turned−off as soon as the voltage on
resistor provides the designer with the possibility to
_Min_Toff
th_cs_off
. For the same ringing
resistor. MOSFET M1
DS(on)
. The 0 mV