ncp4303a ON Semiconductor, ncp4303a Datasheet - Page 12

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

General Description
IC or as a companion IC to a primary side controller to help
achieve efficient synchronous rectification in switch mode
power supplies. This controller features a high current gate
driver along with high−speed logic circuitry to provide
appropriately timed drive signals to a synchronous
rectification MOSFET. With its novel architecture, the
NCP4303 has enough versatility to keep the synchronous
rectification system efficient under any operating mode.
voltage range from 10.4 V to 28 V (typical). The wide V
range allows direct connection to the SMPS output voltage
of most adapters such as notebook and LCD TV adapters. As
a result, the NCP4303 simplifies circuit operation compared
to other devices that require specific bias power supply (e.g.
5 V). The high voltage capability of the V
unique feature designed to allow operation for a broader
range of applications.
together with accurate offset current source allows the user
to adjust for any required turn off current threshold of the SR
MOSFET switch using a single resistor. Compared to other
SR controllers that provide turn off thresholds in the range
of −10 mV to −5 mV, the NCP4303 offers a turn off
threshold of 0 mV that in combination with a low R
MOSFET significantly reduces the turn off current
threshold and improves efficiency.
The NCP4303 is designed to operate either as a standalone
The NCP4303 works from an available bias supply with
Precise turn off threshold of the current sense comparator
CC
APPLICATION INFORMATION
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SR
CC
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NCP4303 provides adjustable minimum on time and off
time blanking periods. Blanking times can be adjusted
independently of IC V
If needed, blanking periods can be modulated using
additional components.
rectification systems in CCM applications (like CCM
flyback or forward). The time delay from trigger input to
driver turn off event is 12 ns (typically). Additionally, the
trigger input can be used to disable the IC and activate a low
consumption standby mode. This feature can be used to
decrease standby consumption of an SMPS.
used to automatically compensate for SR MOSFET
parasitic inductance effect. This technique achieves the
maximum available on−time and thus optimizes efficiency
when a MOSFET in standard package (like TO220 or
TO247) is used. If a SR MOSFET in SMT package with
negligible inductance is used, the compensation input is
connected to GND pin.
Zero Current Detection and parasitic inductance
compensation
circuitry on the current sense input. The synchronous
rectification MOSFET is depicted with it’s parasitic
inductances to demonstrate operation of the compensation
system.
To overcome issues after turn on and off events, the
An ultrafast trigger input helps to implement synchronous
Finally, the NCP4303 features a special input that can be
Figure 33 shows the internal connection of the ZCD
CC
using resistors connected to GND.