NCP1901DR2G ONSEMI [ON Semiconductor], NCP1901DR2G Datasheet - Page 11

• Manufacturer Part Number: NCP1901DR2G
• Description: Primary Side Combination Resonant and PFC Controllers
• Manufacturer: ONSEMI [ON Semiconductor]

PFC Undervoltage
pin is left open. An undervoltage detector disables the
controller if the voltage on the PFB pin is below
V
current source, I
if the PFB pin is floating. The PFB pull down current source
affects the PFC output voltage regulation setpoint.
PFC Overvoltage
voltage and disables the PFC driver if the PFC output voltage
is greater than 5% of its nominal value. PFC drive pulses are
suppressed until the overvoltage condition is removed. The
overvoltage detector tolerance is better than ±2% across the
operating temperature voltage range. The overvoltage
comparator hysteresis is typically 30 mV (1.2%).
PFC Overcurrent
detector. The PCS pin provides access to the overcurrent
detector. The PFC drive pulse is terminated if the voltage
on the PCS pin exceeds the overcurrent threshold,
V
basis. The overcurrent threshold is typically 0.84 V.
caused by the power switch transitions. The NCP1901 has
leading edge blanking circuitry that blocks out the first
110 ns (typical) of each current pulse.
PFC Driver
60 and 15 W, respectively. Depending on the external
MOSFET gate charge requirements, an external driver may
be needed to drive the PFC power switch. A driver as the
one shown in Figure 9 can be easily implemented.
Half−Bridge Driver
The oscillator frequency is divided by two before it is
applied to the half−bridge controller.
PUVP(low)
PCS(ILIM)
The NCP1901 safely disables the controller if the PFB
An overvoltage detector monitors the PFC feedback
The PFC current is monitored by means of an overcurrent
The current sense signal is prone to leading edge spikes
The PFC driver source and sink impedances are typically
The half−bridge stage operates at a fixed 50% duty ratio.
. This comparison is done on a cycle by cycle
, typically 0.23 V. A 1.2 mA (typical) pull down
Figure 9. External Driver
PFB
, ensures V
PFB
falls below V
PUVP(low)
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11
HDRVlo, and a 600 V high side driver, HDRVhi. The built
in high voltage driver eliminates the need for an external
transformer or dedicated driver. A built−in delay between
each drive transition eliminates the risk of cross
conduction. The delay is typically 785 ns. The typical duty
ratio of each half−bridge driver is 48%.
and the HVS pins as shown in Figure 10.
the supply voltage for the high side driver. Once HDRVlo
turns on, the HVS pin is effectively grounded through the
external power switch. This allows C
Once HDRVlo turns off, HVS floats high and D
reversed biased. An undervoltage detector monitors the
HBoost voltage. Once the HBoost voltage is greater than
V
The low side driver generally starts before the high side
driver because the boost voltage is generated by the low
side driver switch transitions.
impedances are typically 75 and 15 W, respectively. The
half−bridge high side driver source and sink impedances
are typically 75 and 15 W, respectively. Depending on the
external MOSFETs gate charge requirements, an external
driver may be needed to drive the low and high side power
switches.
Analog and Power Ground
ground, PGND, terminal. GND is used for analog
connections such as VREF and OSC. PGND is used for
high current connections such as the gate drivers. It is
recommended to have independent analog and power
ground planes and connect them at a single point,
preferably at the ground terminal of the system. This will
prevent high current flowing on PGND from injecting
noise in GND. The PGND connection should be as short
and wide as possible to reduce inductance−induced spikes.
Boost(UV)
The half−bridge controller has a low side driver,
The high side driver is connected between the HBoost
A boost circuit comprised of D
The half−bridge low side driver source and sink
The NCP1901 has an analog ground, GND, and a power
Figure 10. Half−bridge High Side Driver
, typically, 6.1 V, the high side driver is enabled.
boost
boost
and C
to charge to V
boost
generates
boost
CC
is
.