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SLUS794A – NOVEMBER 2007 – REVISED MARCH 2008
Interleaving Continuous Conduction Mode PFC Controller
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FEATURES
Interleaved Average Current-Mode PWM
Control with Inherent Current Matching
Advanced Current Synthesizer Current
Sensing for Superior Efficiency
Highly-Linear Multiplier Output with Internal
Quantized Voltage Feed-Forward Correction
for Near-Unity PF
Programmable Frequency (10 kHz to 300 kHz)
Programmable Maximum Duty-Cycle Clamp
Programmable Frequency Dithering Rate and
Magnitude for Enhanced EMI Reduction
– Magnitude: 3 kHz to 30 kHz
– Rate: Up to 30 kHz
External Clock Synchronization Capability
Enhanced Load and Line Transient Response
through Voltage Amplifier Output Slew-Rate
Correction
Programmable Peak Current Limiting
Bias-Supply UVLO, Over-Voltage Protection,
Open-Loop Detection, and PFC-Enable
Monitoring
External PFC-Disable Interface
Open-Circuit Protection on VSENSE and
VINAC pins
Programmable Soft Start
20-Lead TSSOP Package
APPLICATIONS
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High-Efficiency Server and Desktop Power
Supplies
Telecom Rectifiers
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DESCRIPTION
The UCC28070 is an advanced power factor
correction device that integrates two pulse-width
modulators (PWMs) operating 180° out of phase.
This
interleaved
PWM
operation
generates
substantial reduction in the input and output ripple
currents, and the conducted-EMI filtering becomes
easier and less expensive. A significantly improved
multiplier design provides a shared current reference
to two independent current amplifiers that ensures
matched average current mode control in both PWM
outputs while maintaining a stable, low-distortion
sinusoidal input line current.
The UCC28070 contains multiple innovations
including current synthesis and quantized voltage
feed-forward to promote performance enhancements
in PF, efficiency, THD, and transient response.
Features including frequency dithering, clock
synchronization, and slew rate enhancement further
expand the potential performance enhancements.
The UCC28070 also contains a variety of protection
features including output over-voltage detection,
programmable peak-current limit, under-voltage
lockout, and open-loop protection.
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Simplified Application Diagram
V
IN
L1
D1
V
OUT
+
C
OUT
–
12V to 21V
To CSB
C
CDR
R
RDM
R
A
1 CDR
2 RDM
3 VAO
4 VSENSE
5 VINAC
DMAX 20
RT 19
SS 18
GDB 17
GND 16
VCC 15
GDA 14
R
DMX
R
RT
C
SS
R
S
T1
M1
R
IMO
R
B
R
SYN
6 IMO
7 RSYNTH
8 CSB
9 CSA
10 PKLMT
L2
VREF 13
CAOA 12
To CSA
D2
CAOB 11
R
S
T2
R
A
From Ixfrms
C
ZV
C
PV
R
PK2
R
ZV
R
ZC
R
ZC
R
PK1
C
ZC
C
REF
C
PC
C
PC
C
ZC
M2
R
B
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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 © 2007–2008, Texas Instruments Incorporated
TI [ TEXAS INSTRUMENTS ]
