ncp1608 ON Semiconductor, ncp1608 Datasheet - Page 22

• Manufacturer Part Number: ncp1608
• Description: Critical Conduction Mode Pfc Controller Utilizing A Transconductance Error Amplifier
• Manufacturer: ON Semiconductor

BOOST DESIGN EQUATIONS
Input rms Current
Inductor Peak Current
Inductor Value
On Time
Off Time
Switching Frequency
On Time Capacitor
Inductor Turns to ZCD
Turns Ratio
Resistor from ZCD
Winding to the ZCD pin
Output Voltage and Output
Divider
Output Voltage OVP
Detection and Recovery
Output Voltage Ripple and
Output Capacitor Value
Output Capacitor rms
Current
V
V
out(OVPL)
out(OVP)
I
C(RMS)
Components are identified in Figure 1
V
f
C
SW
out
bulk
+
V
+
+
ripple(peak−peak)
+
+ V
N
w
R
R
L v
V
V
2 @ L @ P
R
V
B
V
out1
out2
Vac
OVP
OVP
Ct w
REF
REF
2 @ p @ V
ZCD
REF
: N
t
off
9 @ p @ Vac @ V
Vac
+
+
I
ZCD
@ V
L(peak)
@ V
2 @ V
2
@ R
w
+
@ h
2 @ P
t
I
R
REF
on
h @ Vac
bias(out)
2 @ 32 @ P
2
out
Iac +
I
REF
Vac@ sin q @ 2
v
V
FB
ZCD(MAX)
@
ripple(peak−peak)
http://onsemi.com
out
+
out
out1
@ 1 *
−V
@
t 2 @ V
+
V
out
@ R
V
2 @ L @ P
@ P
out
OVP(HYS)
V
out
h @ Vac
@
2
V
@ L
R
h @ Vac
out
LL
V
2 @ 2 @ P
2 @ Vac
*
REF
R
P
V
P
out
t
out1
out
R
h @ Vac
* Vac @ h
on
2
out1
MAX
out2
out
out
ZCD(ARM)
@ (N
out
out
out2
22
@ V
Vac @ | sin q | @ 2
@ f
* 1 * R
out(OVP)
@ R
2
2 @ Vac
@ h
@
out
) R
SW(MIN)
2
@ I
Ct(MAX)
@ R
@ R
B
* 1
HL
R
R
FB
: N
@ f
2
out
charge
out2
V
out2
* I
out1
FB
FB
line
out
ZCD
* V
HL
) R
) 1
load(RMS)
@
@ R
@ V
out1
R
)
R
out2
out2
out
FB
FB
out
) R
@ R
) 1
2
FB
FB
) 1
h (the efficiency of only the PFC
stage) is generally in the range of 90
− 95%. Vac is the rms ac line input
voltage.
The maximum inductor peak current
occurs at the minimum line input
voltage and maximum output power.
f
switching frequency. The maximum L
is calculated at both the minimum
line input voltage and maximum line
input voltage.
The maximum on time occurs at the
minimum line input voltage and max-
imum output power.
The off time is a maximum at the
peak of the ac line voltage and ap-
proaches zero at the ac line zero
crossings. Theta (q) represents the
angle of the ac line voltage.
Where Vac
put voltage and L
um inductor value. I
V
tion table.
Where Vac
input voltage. V
the specification table.
Where I
current for the ZCD pin (10 mA).
Where V
voltage and R
resistor used for FPP. V
are shown in the specification table.
I
put voltage divider.
V
shown in the specification table.
Where f
and V
peak output voltage ripple. Use f
47 Hz for universal input worst case.
Where I
rent.
SW(MIN)
bias(out)
Ct(MAX)
OVP
/V
ripple(peak−peak)
REF
ZCD(MAX)
line
load(RMS)
is the bias current of the out-
is the minimum desired
REF
are shown in the specifica-
LL
HL
is the ac line frequency
and V
is the internal reference
is the minimum line in-
FB
is the maximum line
ZCD(ARM)
is the pull−down
MAX
is maximum rated
is the rms load cur-
OVP(HYS)
charge
is the peak−to−
is the maxim-
REF
is shown in
and
are
and R
line
FB
=