MC33260DG ON Semiconductor, MC33260DG Datasheet - Page 9

• Manufacturer Part Number: MC33260DG
• Description: IC PFC CONTROLLER DCM 8SOIC
• Manufacturer: ON Semiconductor
• Series: GreenLine™r

Specifications of MC33260DG

• Mode: Discontinuous Conduction (DCM)
• Current - Startup: 100µA
• Voltage - Supply: 11 V ~ 16 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

INTRODUCTION
line current harmonic content, results in an increasing
demand for cost effective solutions to comply with the
Power Factor regulations. This data sheet describes a
monolithic controller specially designed for this purpose.
to a huge bulk capacitor to derive raw dc voltage from the
utility ac line.
poor power factor ratios. In effect, the simple rectification
technique draws power from the mains when the
instantaneous ac voltage exceeds the capacitor voltage. This
occurs near the line voltage peak and results in a high charge
current spike. Consequently, a poor power factor (in the
range of 0.5 - - 0.7) is generated, resulting in an apparent input
power that is much higher than the real power.
legislation requirements. They consist of inserting a PFC
pre- -regulator between the rectifier bridge and the bulk
capacitor. This interface is, in fact, a step- -up SMPS that
outputs a constant voltage while drawing a sinusoidal
current from the line.
with the goal of increasing its robustness while lowering its
global cost.
Line
The need of meeting the requirements of legislation on
Most off- -line appliances use a bridge rectifier associated
This technique results in a high harmonic content and in
Active solutions are the most popular way to meet the
The MC33260 was developed to control an active solution
AC
AC Line Voltage
Line
AC Line Current
AC
Rectified DC
Figure 23. Line Waveforms Without PFC
Figure 22. Typical Circuit Without PFC
Rectifiers
Figure 24. PFC Preconverter
V
Rectifiers
pk
0
0
+
PFC Preconverter
Bulk
Storage
Capacitor
Line Sag
Pin Numbers are Relevant to the PDIP- -8 Version
+
Converter
FUNCTIONAL DESCRIPTION
Converter
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Load
9
OPERATION DESCRIPTION
running as a synchronized discontinuous voltage mode.
undervoltage protection, overcurrent limitation, ...) that
make the PFC preregulator very safe and reliable while
requiring very few external components. In particular, it is
able to safely face any uncontrolled direct charges of the
output capacitor from the mains which occur when the
output voltage is lower than the input voltage (startup,
overload, ...).
control an innovative mode named “Follower Boost” that
permits to significantly reduce the size of the preconverter
inductor and power MOSFET. With this technique, the
output regulation level is not forced to a constant value, but
can vary according to the a.c. line amplitude and to the
power. The gap between the output voltage and the ac line
is then lowered, what allows the preconverter inductor and
power MOSFET size reduction. Finally, this method brings
a significant cost reduction.
REGULATION SECTION
regulated and the Pin 1, a feedback current is obtained.
Typically, this current is built by connecting a resistor
between the output voltage and the Pin 1. Its value is then
given by the following equation:
where:
so that the regulation block outputs a signal following the
characteristic depicted in Figure 25. According to the power
and the input voltage, the output voltage regulation level
varies between two values (V
corresponding to the I
current should equal the internal current source I
the output voltage exceeds the chosen upper regulation
voltage [(V
The MC33260 is optimized to just as well drive a free
It also features valuable protections (overvoltage and
In addition to the low count of elements, the circuit can
A description of the functional blocks is given below.
Connecting a resistor between the output voltage to be
The feedback current is compared to the reference current
The feedback resistor must be chosen so that the feedback
R
V
V
o
o
Regulation Block Output
pin1
is the feedback resistor,
is the output voltage,
is the Pin 1 clamp value.
Figure 25. Regulation Characteristic
o
)
1.5 V
regH
].
I
pin1
regL
(97%I
=
I
regL
and I
V o − V
ref
)
regH
R o
pin1
o
levels.
)
regL
I
(I
regH
ref
)
and (V
regH
o
when
I
)
o
regH