UCC3817D UNITRODE, UCC3817D Datasheet - Page 7

• Manufacturer Part Number: UCC3817D
• Description: POWER FACTOR CNTRLR, 3817, SOIC16
• Manufacturer: UNITRODE

Specifications of UCC3817D

• Primary Input Voltage: 15V
• No. Of Outputs: 1
• Output Voltage: 5.5V
• Voltage Regulator Case Style: SOIC
• No. Of Pins: 16
• Operating Temperature Range: 0°C To +70°C
• Operating Temperature Max: 70°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

85−270 V AC
The UCC3817 is a BiCMOS average current mode boost controller for high power factor, high efficiency
preregulator power supplies. Figure 1 shows the UCC3817 in a 250-W PFC preregulator circuit. Off-line
switching power converters normally have an input current that is not sinusoidal. The input current waveform
has a high harmonic content because current is drawn in pulses at the peaks of the input voltage waveform.
An active power factor correction circuit programs the input current to follow the line voltage, forcing the
converter to look like a resistive load to the line. A resistive load has 0° phase displacement between the current
and voltage waveforms. Power factor can be defined in terms of the phase angle between two sinusoidal
waveforms of the same frequency:
Therefore, a purely resistive load would have a power factor of 1. In practice, power factors of 0.999 with THD
(total harmonic distortion) of less than 3% are possible with a well-designed circuit. Following guidelines are
provided to design PFC boost converters using the UCC3817.
NOTE: Schottky diodes, D5 and D6, are required to protect the PFC controller from electrical over stress during
system power up.
V LINE
PF + cos Q
IAC
AC2
AC1
F1
383k
R21
1.5µ F
400V
C14
383k
R13
V REF
D3
6A 600V
R12
R11
10k
2k
VCC
D6
R8 12k
Figure 1. Typical Application Circuit
0.47µ F
600V
C13
C8 270pF
APPLICATION INFORMATION
4.02k
0.25 Ω
R9
R14
3W
100Ω
R7 100k
R16
C7 150nF
C9 1.2nF
4.02k
R15
R18
R10
24k
24k
C6 2.2µ F
C15 2.2µ F
R6 30k
D5
www.ti.com
D7
1mH
L1
1
2
3
4
5
6
7
8
C10
1 µ F
GND
PKLIMIT
CAOUT
CAI
MOUT
IAC
VAOUT
VFF
D8
UCC3817
DRVOUT
VSENSE
OVP/EN
C11
1 µ F
VREF
VCC
CT
SS
RT
6A, 600V
SLUS395J - FEBRUARY 2000 - REVISED MARCH 2009
D2
16
15
14
13
12
11
10
9
IRFP450
V REF
Q1
560pF
R3 20k
C1
R17
20Ω
D4
C5 1 µF
8A, 600V
VCC
C4 0.01µ F
R1 12k
D1
499k
1µ F CER
R2
100 µ F AI EI
220µ F
C3
450V
R20 274k
C12
C2
10k
R5
499k
R19
V O
385V−DC
UDG-98183
V OUT
249k
R4
V O
+
−
7