NCP4303AMNTWG ON Semiconductor, NCP4303AMNTWG Datasheet - Page 12

• Manufacturer Part Number: NCP4303AMNTWG
• Description: Power Switch ICs - Power Distribution SEC SIDE SYNC RECT DRV
• Manufacturer: ON Semiconductor

Specifications of NCP4303AMNTWG

• Product Category: Power Switch ICs - Power Distribution

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.
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.
turn-off delay time. This allows the SR controller to be used
in applications operating in shallow CCM mode without any
extra primary side synchronization circuitry (refer to
Figures 2 and 60). This circuit exhibits excellent 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
To overcome issues after turn on and off events, the
The NCP4303 ZCD comparator features very short
CC
using resistors connected to GND.
CC
APPLICATION INFORMATION
pin is also a
DS(on)
http://onsemi.com
SR
CC
12
results (refer to Figures 58 and 59). A typical example of
such an application is a flyback notebook adapter that
usually enters only shallow CCM when Vbulk is lower than
approximately 180 Vdc. On the other hand, the turn-off
delay could be too long for applications operating in deep
CCM (like high output current flyback or forward
converters). High reverse current spikes and also drain
voltage ringing are then usually present on the SR MOSFET.
This is because the SR MOSFET needs some time to fully
turn-off. The NCP4303 offers an optional ultrafast turn-off
trigger input to prevent these current spikes and drain
voltage ringing. This input can be used to turn-off the SR
MOSFET earlier, using a synchronization signal from the
primary side. The SR MOSFET is then turned-off prior to
it’s drain voltage reversing thus the reverse current is
minimized while the efficiency is maximized (refer to
Figure 46 for a deep CCM flyback converter example).
Using the trigger input is optional and only recommended
for applications operating in deep CCM. 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.
Finally, the NCP4303 features a special input that can be
Figure 33 shows the internal connection of the ZCD