The AP1662 is an active power factor control IC
which is designed mainly for use as a pre-converter
in electronic ballast, AC-DC adapter and off-line
SMPS applications.
.
The IC includes an internal start-up timer for
stand-alone applications, a one-quadrant multiplier to
realize near unity power factor and a zero current
detector to ensure DCM boundary conduction
operation.
The totem pole output stage is capable of driving
power MOSFET with 600mA source current and
800mA sink current.
Designed with advanced BiCMOS process, the
AP1662 features low start-up current, low operation
current and low power dissipation. The AP1662 also
has rich protection features including over-voltage
protection, input under-voltage lockout with
hysteresis and multiplier output clamp to limit
maximum peak current.
The AP1662 meets IEC61000-3-2 standard even at
one-quadrant load and THD lower than 10% at
high-end line voltage and full load.
The IC is available in SOIC-8 and DIP-8 packages.
Features
Comply with IEC61000-3-2 Standard
•
• Proprietary Design for Minimum THD
• Zero Current Detection Control for DCM
Boundary Conduction Mode
• Adjustable Output Voltage with Precise
Over-voltage Protection
• Low Start-up Current with 40µA Typical Value
• Low Quiescent Current with 2.5mA Typical
Va lu e
• 1% Precision Internal Reference Voltage @
T
=25°C
J
• Internal Start-up Timer
• Disable Function for Reduced Current
Consumption
• Totem Pole Output with 600mA Source and
800mA Sink Current Capability
BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant.
Products with “G1” suffix are available in green packages.
Input/Output of Error Amplifier,
Input of Multiplier
Current Sense Input VCS -0.3 to 7 V
V
INV
V
, V
MULT
COMP
,
-0.3 to 7 V
Zero Current Detector Input I
Power Dissipation and Thermal
characteristics @ T
=50°C
A
Thermal Resistance
(Junction to Ambient)
P
R
ZCD
TOT
θJA
mA
Sink 10
DIP-8 1
W
SOIC-8 0.65
DIP-8 100
ºC/W
SOIC-8 150
Operating Junction Temperature TJ -40 to 150 ºC
Source -50
Storage Temperature Range T
Lead Temperature (Soldering, 10
Seconds)
ESD (Human Body Model) V
ESD (Machine Model) V
-65 to 150 ºC
STG
260 ºC
T
LEAD
ESD(HBM)
ESD(MM)
3000 V
200 V
Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to
the device. These are stress ratings only, and functional operation of the device at these or any other conditions
beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute
Maximum Ratings” for extended periods may affect device reliability.
AP1662 is a high performance power factor
correction controller which operates in DCM
boundary conduction mode. The PFC converter's
switch will be turned on when the inductor current
reduces to zero and turned off when the sensed
inductor current reaches the required reference which
is decided by the output of multiplier.
Error Amplifier and Over-Voltage
Protection
The error amplifier regulates the PFC output voltage.
The internal reference on the non-inverting input of
the error amplifier is 2.5V. The error amplifier's
inverting input (INV) is connected to an external
resistor divider which senses the output voltage. The
output of error amplifier is one of the two inputs of
multiplier. A compensation loop is connected outside
between INV and the error amplifier output.
Normally, the compensation loop bandwidth is set
very low to realize high power factor for PFC
converter.
To make the over voltage protection fast, the internal
OVP function is added. If the output over voltage
happens, excess current will flow into the output pin
of the error amplifier through the feedback
compensation capacitor. (see Figure 22) The AP1662
monitors the current flowing into the error amplifier
output pin. When the detected current is higher than
40µA, the dynamic OVP is triggered. The IC will be
Figure 22. Error Amplifier and OVP Block
disabled and the drive signal is stopped. If the output
over voltage lasts so long that the output of error
amplifier goes below 2.25V, static OVP will take
place. Also the IC will be disabled until the output of
error amplifier goes back to its linear region. R1 and
R2 (see Fig. 22) will be selected as below:
1
V
R
R
O
1
−=
5.22
V
V
OVP
40
A
µ
R
1
=
Multiplier
The multiplier has two inputs. One (Pin 3) is the
divided AC sinusoidal voltage which makes the
current sense comparator threshold voltage vary from
zero to peak value. The other input is the output of
error amplifier (Pin 2). In this way, the input average
current wave will be sinusoidal as well as reflects the
load status. Accordingly a high power factor and
good THD are achieved. The multiplier transfer
character is designed to be linear over a wide
dynamic range, namely, 0V to 3V for Pin 3 and 2V to
5.8V for Pin 2. The relationship between the
multiplier output and inputs is described as below
equation:
VVkV
)5.2(
MULTCOMPCS
where VCS (Multiplier output) is the reference for the
current sense, k is the multiplier gain, V
COMP
voltage on pin 2 (error amplifier output) and V
the voltage on pin 3.
Current Sense/Current Sense
Comparator
The PFC switch's turn-on current is sensed through
an external resistor in series with the switch. When
the sensed voltage exceeds the threshold voltage (the
multiplier output), the current sense comparator will
become low and the external MOSFET will be turned
off. This insures a cycle-by-cycle current mode
control operation. The maximum current sense
reference is 1.8V. The max value usually happens at
startup process or abnormal conditions such as short
load.
AP1662 is a DCM boundary conduction current
mode PFC controller. Usually, the zero current
detection (ZCD) voltage signal comes from the
auxiliary winding of the boost inductor. When the
ZCD pin voltage decreases below 1.6V, the gate
drive signal becomes high to turn on the external
MOSFET. 500mV of hysteresis is provided to avoid
false triggering. The ZCD pin can be used for
disabling the IC. Making its voltage below 0.15V or
short to the ground will disable the device thus
reduce the IC supply current consumption.
Typical Application
Figure 23. 85 to 265V Wide Range Input 90W PFC Demo Board Electrical Schematic Circuit