www.ti.com
SLUS329E – MONTH 2003 – REVISED JANUARY 2008
ADVANCED HIGH-POWER FACTOR PREREGULATOR
1
FEATURES
Controls Boost PWM to Near-Unity Power
Factor
Limits Line Current Distortion To <3%
World-Wide Operation Without Switches
Accurate Power Limiting
Fixed-Frequency Average Current-Mode
Control
High Bandwidth (5 MHz), Low-Offset Current
Amplifier
Integrated Current- and Voltage-Amplifier
Output Clamps
Multiplier Improvements: Linearity, 500 mV V
AC
Offset (Eliminates External Resistor), 0 V to
5 V Multout Common-Mode Range
V
REF
GOOD Comparator
Faster and Improved Accuracy ENABLE
Comparator
UVLO Options (16 V/10 V or 10.5 V/10 V)
300-µA Start-Up Supply Current
•
•
•
•
•
•
•
•
DESCRIPTION
The UC3854A/B products are pin compatible
enhanced versions of the UC3854. Like the UC3854,
these products provide all of 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 the ac input line voltage. To do this the
UC3854A/B uses average current mode control.
Average current mode control maintains stable, low
distortion sinusoidal line current without the need for
slope compensation, unlike peak current mode
control.
A 1%, 7.5-V reference, fixed frequency oscillator,
PWM, voltage amplifierwith soft-start, line voltage
feedforward (V
RMS
squarer), input supply voltage
clamp, and over current comparator round out the lilst
of feataures.
Available in the 16-pin N (PDIP), DW (SOIC Wide),
and J (CDIP) and 20-pin Q (PLCC) package. See
Ordering Information table for availability by
temperature range.
•
•
•
•
BLOCK DIAGRAM
VAO
7
V
CC
(A) 16 V / 10 V
(B) 10.5 V / 10 V
ENA 10
2.65 V / 2.15 V
3V
VSENSE 11
IAC
VRMS
6
8
14
µA
SS 13
I
MOUT
+
A
C
B
X2
A
B
C
RUN
OSC
20 V
1 GND
R
R
S
MOUT
5
CAO PKLMT
3
2
REF
9
7.5 V REF
RUN
IC
POWER
7.1 V
15 VCC
Q
16 GTDRV
4
ISENSE
14
CT
12
RSET
1
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 the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2003–2008, Texas Instruments Incorporated
TI [ TEXAS INSTRUMENTS ]
