NCL30000
http://onsemi.com
4
Overview
Figure 2 illustrates how the NCL30000 is configured to
implement an isolated power factor corrected flyback
switch mode power supply. On the secondary side is the
NCS1002, a constant voltage, constant current controller
which senses the average LED current and the output
voltage and provides a feedback control signal to the
primary side through an opto-coupler interface. One of the
key benefits of active power factor correction is that it makes
the load appear like a linear resistance similar to an
incandescent bulb. High power factor requires generally
sinusoidal line current and minimal phase displacement
between the line current and voltage. The NCL30000
operates in a fixed on-time variable frequency mode where
the power switch is on for the same length of time over a half
cycle of input power. The current in the primary of the
transformer starts at zero each switching cycle and is directly
proportional to the applied voltage times the on-time.
Therefore with a fixed on-time, the current will follow the
applied voltage generating a current of the same shape. Just
as in a traditional boost PFC circuit, the control bandwidth
is low so that the on-time is constant throughout a single line
cycle. The feedback signal from the secondary side is used
to modify the average on-time so the current through the
LEDs is properly regulated regardless of forward voltage
variation of the LED string.
Table 2. MAXIMUM RATINGS
Rating Symbol Value Unit
MFP Voltage V
MFP
−0.3 to 10 V
MFP Current I
MFP
10 mA
COMP Voltage V
Control
−0.3 to 6.5 V
COMP Current I
Control
−2 to 10 mA
Ct Voltage V
Ct
−0.3 to 6 V
Ct Current I
Ct
10 mA
CS Voltage V
CS
−0.3 to 6 V
CS Current I
CS
10 mA
ZCD Voltage V
ZCD
−0.3 to 10 V
ZCD Current I
ZCD
10 mA
DRV Voltage V
DRV
−0.3 to V
CC
V
DRV Sink Current I
DRV(sink)
800 mA
DRV Source Current I
DRV(source)
500 mA
Supply Voltage V
CC
−0.3 to 20 V
Supply Current I
CC
20 mA
Power Dissipation (T
A
=70C, 2.0 Oz Cu, 55 mm
2
Printed Circuit Copper Clad) P
D
450 mW
Thermal Resistance Junction-to-Ambient
(2.0 Oz Cu, 55 mm
2
Printed Circuit Copper Clad)
Junction-to-Air, Low conductivity PCB (Note 3)
Junction-to-Air, High conductivity PCB (Note 4)
R
q
JA
R
q
JA
R
q
JA
178
168
127
C/W
Operating Junction Temperature Range T
J
−40 to 125 C
Maximum Junction Temperature T
J(MAX)
150 C
Storage Temperature Range T
STG
−65 to 150 C
Lead Temperature (Soldering, 10 s) T
L
300 C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
1. This device series contains ESD protection and exceeds the following tests:
Pins 1–8: Human Body Model 2000 V per JEDEC Standard JESD22−A114E.
Pins 1– 8:Machine Model Method 200 V per JEDEC Standard JESD22−A115−A.
2. This device contains Latch-up protection and exceeds 100 mA per JEDEC Standard JESD78.
3. As mounted on a 40 40 1.5 mm FR4 substrate with a single layer of 80 mm
2
of 2 oz copper traces and heat spreading area. As specified
for a JEDEC 51 low conductivity test PCB. Test conditions were under natural convection or zero air flow.
4. As mounted on a 40 40 1.5 mm FR4 substrate with a single layer of 650 mm
2
of 2 oz copper traces and heat spreading area. As specified
for a JEDEC 51 high conductivity test PCB. Test conditions were under natural convection or zero air flow.
