NCP1654
www.onsemi.com
5
DETAILED PIN DESCRIPTIONS
Pin Symbol Name Function
1 GND Ground −
2 V
in
Multiplier
Voltage
This pin provides a voltage V
M
for the PFC duty cycle modulation. The input impedance of the
PFC circuits is proportional to the resistor R
M
externally connected to this pin. The device
operates in average current mode if an external capacitor C
M
is connected to the pin.
Otherwise, it operates in peak current mode.
3 CS Current Sense
Input
This pin sources a current I
CS
which is proportional to the inductor current I
L
. The sense
current I
CS
is for overcurrent protection (OCP), overpower limitation (OPL) and PFC duty cycle
modulation. When I
CS
goes above 200 mA, OCP is activated and the Drive Output is disabled.
4 V
BO
Brown−Out / In Connect a resistor network among the rectified input voltage, BO pin, and ground. And connect
a capacitor between BO pin and ground. BO pin detects a voltage signal proportional to the
average input voltage.
When V
BO
goes below V
BOL
, the circuit that detects too low input voltage conditions
(brown−out), turns off the output driver and keeps it in low state until V
BO
exceeds V
BOH
.
This signal which is proportional to the RMS input voltage V
ac
is also for overpower limitation
(OPL) and PFC duty cycle modulation.
5 V
control
Control Voltage /
Soft−Start
The voltage of this pin V
control
directly controls the input impedance. This pin is connected to
external type−2 compensation components to limit the V
control
bandwidth typically below 20 Hz
to achieve near unity power factor.
The device provides no output when V
control
< V
control(min)
. When it starts operation, the power
increases slowly (soft−start).
6 V
FB
Feed−Back /
Shutdown
This pin receives a feedback signal V
FB
that is proportional to the PFC circuits output voltage.
This information is used for both the output regulation, the overvoltage protection (OVP), and
output undervoltage protection (UVP) to protect the system from damage at feedback
abnormal situation.
When V
FB
goes above 105% V
REF
, OVP is activated and the Drive Output is disabled.
When V
FB
goes below 8% V
REF
, the device enters a low−consumption shutdown mode.
7 V
CC
Supply Voltage This pin is the positive supply of the IC. The circuit typically starts to operate when V
CC
exceeds 10.5 V and turns off when V
CC
goes below 9 V. After start−up, the operating range is
9 V up to 20 V.
8 DRV Drive Output The high current capability of the totem pole gate drive (±1.5 A) makes it suitable to effectively
drive high gate charge power MOSFET.
