UCC2817A, UCC2818A
UCC3817A, UCC3818A
SLUS577B − SEPTEMBER, 2003 − REVISED FEBRUARY 2006
BiCMOS POWER FACTOR PREREGULATOR
FEATURES
D
Controls Boost Preregulator to Near-Unity
D
D
D
D
D
D
D
D
D
D
D
Power Factor
Limits Line Distortion
World Wide Line Operation
Over-Voltage Protection
Accurate Power Limiting
Average Current Mode Control
Improved Noise Immunity
Improved Feed-Forward Line Regulation
Leading Edge Modulation
150-µA Typical Start-Up Current
Low-Power BiCMOS Operation
12-V to 17-V Operation
DESCRIPTION
The UCC3817A and the UCC3818A family
provides all the functions necessary for active
power factor corrected preregulators. The
controller achieves near unity power factor by
shaping the ac input line current waveform to
correspond to that of the ac input line voltage.
Average current mode control maintains stable,
low distortion sinusoidal line current.
Designed in Texas Instrument’s BiCMOS process,
the UCC3817A/UCC3818A offers new features
such as lower start-up current, lower power
dissipation, overvoltage protection, a shunt UVLO
detect circuitry, a leading-edge modulation
technique to reduce ripple current in the bulk
capacitor and an improved, low-offset (±2 mV)
current amplifier to reduce distortion at light load
conditions.
VCC
15
BLOCK DIAGRAM
OVP/EN
10
16 V (FOR UCC3817A ONLY)
7.5 V
REFERENCE
9
VREF
SS
13
1.9 V
−
+
0.33 V
CURRENT
AMP
−
+
−
+
OSC
MIRROR
2:1
CLK
ZERO POWER
−
+
8.0 V
PWM
S
Q
PWM
LATCH
R
R
1
CLK
OSCILLATOR
GND
+
−
16
DRVOUT
OVP
X
÷
MULT
X
X2
ENABLE
UVLO
16 V/10 V (UCC3817A)
10.5 V/10 V (UCC3818A)
VCC
VAOUT
7
VSENSE
11
7.5 V
−
+
VOLTAGE
ERROR AMP
VFF
8
IAC
MOUT
6
5
4
CAI
3
CAOUT
−
+
2
PKLMT
12
RT
14
CT
UDG-03122
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Copyright
2006, Texas Instruments Incorporated
www.ti.com
1
TI [ TEXAS INSTRUMENTS ]
