NCP1606 ON Semiconductor, NCP1606 Datasheet - Page 14

• Manufacturer Part Number: NCP1606
• Description: Cost Effective Power Factor Controller
• Manufacturer: ON Semiconductor

internally clamped to V
winding is negative. Similarly, the ZCD pin is clamped to
V
Because of these clamps, a resistor (R
necessary to limit the current from the ZCD winding to the
ZCD pin.
therefore no voltage signal to activate the ZCD
comparators. This means that the driver could never turn
on. Therefore, to enable the PFC stage to startup under
these conditions, an internal watchdog timer is integrated
into the controller. This timer turns the drive on if the driver
has been off for more than 180 ms (typical). Obviously, this
feature is deactivated during a fault mode (OVP, UVP, or
Shutdown), and reactivated when the fault is removed.
STARTUP
V
(12 V typical). Because of the very low consumption of the
NCP1606 during this stage (< 40 mA), most of the current
goes directly to charging up the V
provides faster startup times and reduced standby power
dissipation. When the V
QUICK START and SOFT START
pulled up to V
of control voltage which produces output drives. This
feature, called “quick start,” eliminates the delay at startup
CLPOS
CC
To prevent negative voltages on the ZCD pin, the pin is
At startup, there is no energy in the ZCD winding and
Generally, a resistor connected between the ac input and
At startup, the error amplifier is enabled and Control is
(pin 8) charges the V
(5.7 V typical), when the voltage rises too high.
1
2
3
4
EAL
(typically 2.1 V). This is the lowest level
Figure 31. NCP1606 Supplied by a Downstream SMPS Controller (NCP1230)
8
7
6
5
CLNEG
CC
CC
+
PFC_Vcc
capacitor to the V
voltage exceeds the V
(600 mV typ) when the ZCD
ZCD
CC
1
2
3
4
NCP1230
in Figure 29) is
capacitor. This
D
boost
CC(on)
8
7
6
5
http://onsemi.com
CC(on)
V
level
CC
+
+
14
C
level, the internal references and logic of the NCP1606 turn
on. The controller has an undervoltage lockout (UVLO)
feature which keeps the part active until V
V
for the auxiliary winding to take over and supply the
necessary power to V
power supply (SMPS), then it is often preferable to have the
SMPS controller startup first. The SMPS can then supply
the NCP1606 V
the NCP1230 or NCP1381, can control when to turn on the
PFC stage (see Figure 31) leading to optimal system
performance. This setup also eliminates the startup
resistors and therefore improves the no load power
dissipation of the system.
associated with charging the compensation network to its
minimum level. This also produces a natural “soft start”
mode where the controller’s power ramps up from zero to
the required power (see Figure 32).
bulk
V
CC(off)
When the PFC pre−converter is loaded by a switch mode
CC
Figure 30. Typical V
(9.5 V typical). This hysteresis allows ample time
CC
directly. Advanced controllers, such as
+
CC
V
V
CC(on)
CC(off)
(Figure 30).
CC
Startup Waveform
+
CC
drops below