a pplica tion
INFO
a va ila ble
UC2853A
High Power Factor Preregulator
FEATURES
DESCRIPTION
•
Complete 8-pin Power Factor
Solution
•
Reduced External Components
•
RMS Line Voltage Compensation
•
Precision Multiplier/Squarer/Divider
•
Internal 63kHz Synchronizable
Oscillator
The UC2853A provides simple, yet high performance active power factor
correction. Using the same control technique as the UC1854, this 8-pin device exploits a simplified architecture and an internal oscillator to minimize
external component count. The UC2853A incorporates a precision multiplier/squarer/divider circuit, voltage and current loop error amplifiers, and a
precision voltage reference to implement average current mode control
with RMS line voltage compensation. This control technique maintains constant loop gain with changes in input voltage, which minimizes input line
current distortion over the worldwide input voltage range.
•
Average Current Mode PWM
Control
•
Overvoltage Protection Comparator
•
High Current, Clamped Gate Driver
The internal 63kHz oscillator includes an external clock input, allowing synchronization to downstream converters. Additionally, the device features an
overvoltage protection comparator, a clamped MOSFET gate driver which
self-biases low during undervoltage lockout, and low startup and supply
current.
The UC2853A is identical to the UC2853 except the internal oscillator frequency has been reduced from 75kHz to 63kHz. The switching frequency
is lowered in order to keep the second harmonic of the switching frequency
below a 150kHz. For EMI specifications at 150kHz this makes it easier for
a design to meet system requirements.
BLOCK DIAGRAM
These devices are available in 8-pin PDIP (P) and SOIC (D) packages. The
UC2853A is specified for operation from –40°C to 105°C.
UDG-94120-1
SLUS650A - FEBRUARY 2005 - REVISED JANUARY 2006
UC2853A
CONNECTION DIAGRAM
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V
Output Drive Current,
Continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.125A
Peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5A
Output Minimum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V
IAC Maximum Input Current . . . . . . . . . . . . . . . . . . . . . . . . 1mA
IMO Maximum Output Current . . . . . . . . . . . . . . . . . . . . . –2mA
IMO Minimum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V
FB Maximum Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 5V
VCOMP Maximum Voltage. . . . . . . . . . . . . . . . . . . . . . . . . 6.2V
ICOMP Sourcing Current . . . . . . . . . . . . . . . . . . . . Self-Limiting
ICOMP Sinking Current . . . . . . . . . . . . . . . . . . . . . . . . . . 20mA
ICOMP Maximum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 7.2V
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
All voltages with respect to GND. Currents are positive into,
negative out of the specified terminal. Consult Packaging Section
of Databook for thermal limitations and considerations of
packages.
PDIP-8, SOIC-8 (Top View)
P or D Package
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these parameters apply for TA = –40°C to 105°C for the
UC2853A; VCC = 16V, VFB = 3V, IAC = 100mA, VVCOMP = 3.75V, VICOMP = 3V, TA
= T J.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
11.5
13
V
1.8
2.1
V
Undervoltage Lockout Section
VCC Turn-on Threshold
VVCOMP, VICOMP Open
Hysteresis
1.5
Supply Current Section
IVCC Startup
VCC = 8V, IAC = 100mA; VVCOMP, VICOMP Open
250
500
mA
IVCC
IAC = 0mA, VICOMP = 0V
10
15
mA
575
mmho
640
mmho
Voltage Loop Error Amplifier Section
Transconductance
Input Voltage
IOUT = ± 20mA 0-70C
300
Temperature
135
0-70C
2.925
Temperature
2.9
AVOL
VVCOMP = 1V – 4V
50
Output Sink Current
VFB = 3.2V, VVCOMP = 3.75V
20
Output Source Current
VFB = 2.8V, VVCOMP = 3.75V
Output Voltage High
450
3
5.5
V
3.1
V
60
dB
mA
50
–50
Output Voltage Low
3.075
–20
mA
0.9
V
6
mV
6
0.6
V
Current Loop Error Amplifier Section
Offset Voltage
Voltage Gain
0
VICOMP = 1V – 4V
Sink Current
VIMO = 100mV, VICOMP = 3V
Source Current
VIMO = –0.1V, VICOMP = 3V
70
1
mA
–150
Output High
IICOMP = –50mA
Output Low
IICOMP = 50mA
6
0.3
PWM Modulator Gain
VICOMP = 2V – 3V (Note 1)
20
2
dB
–80
mA
0.8
V
6.8
V
%/V
1
UC2853A
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these parameters apply for TA = –40°C to 105°C for the
UC2853A; VCC = 16V, VFB = 3V, IAC = 100mA, VVCOMP = 3.75V, VICOMP = 3V, TA
= T J.
(continued)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
–230
–200
–170
mA
Multiplier Section
Output Current – IAC Limited
VCC = 11V, VVCOMP = 6V
Output Current – Zero
IAC = 0mA
Output Current – Power Limited
VCC = 12V, VVCOMP = 5.5V
Output Current
–2
–0.2
2
mA
–236
–178
–168
mA
VCC= 12V, VVCOMP = 2V
–22
mA
VCC= 12V, VVCOMP = 5V
–156
mA
VCC= 40V, VVCOMP = 2V
–2
mA
VCC= 40V, VVCOMP = 5V
Multiplier Gain Constant
VCC= 12V, VVCOMP = 5.5V (Note 2)
mA
–14
–1.05
–0.9
–0.75
V –1
Oscillator Section
Oscillator Initial Frequency
TA = 25°C
56
63
70
kHz
Oscillator Frequency
Line, Load, Temperature
50
63
74
kHz
100
kHz
Synchronization Frequency Range
Synchronization Pulse Amplitude
Pulse slew rate = 100V/msec (Note 3)
2
V
Output Driver Section
Maximum Output Voltage
Output High
0mA load, VCC = 20V
0mA load, VCC = 12V, ref. to VCC
–50mA load, VCC = 12V, ref. to VCC
Output Low (Device Inactive)
12
15
17.5
V
–2.7
–1.7
V
–3
–2.2
V
Vcc = 0V, 20mA load (Sinking)
0.9
2.0
V
Output Low (Device Active)
50mA load (Sinking)
0.5
1
V
OUT Rise Time
1nF from OUT to GND
55
100
ns
OUT Fall Time
1nF from OUT to GND
35
100
ns
OUT Maximum Duty Cycle
VICOMP = 0V
88
93
Volts Above EA Input V
90
150
mV
80
mV
%
OVP Comparator Section
Threshold Voltage
Hysteresis
Note 1:
1PWM
modulator gain =
Note 2:
Gainconstant (K ) =
DDutyCycle
DVICOMP
IAC · (VCOMP – 1. 5V )
VCC
IMO ·VCC ·
, VCC = 12V.
64
Note 3.
Synchronization is accomplished with a falling edge of 2V magnitude and 100V/msec slew rate.
3
UC2853A
UC2853A TYPICAL APPLICATION
UC2853A
Note: the application circuit shown is a 100W, 63KHz design.
Additional application information can be found in Application
Note U–159 (TI literature Number SLUA080) and Design Note
DN–78.
4
UC2853A
PIN DESCRIPTIONS
FB: Voltage Amplifier Inverting Input, Overvoltage
Comparator Input, Sync Input. This pin serves three
functions. FB accepts a fraction of the power factor
corrected output voltage through a voltage divider, and is
nominally regulated to 3V. FB voltages 5% greater than
nominal will trip the overvoltage comparator, and shut
down the output stage until the output voltage drops 5%.
The internal oscillator can be synchronized through FB by
injecting a 2V clock signal though a capacitor. To prevent
false tripping of the overvoltage comparator, the clock
signal must have a fast falling edge, but a slow rising
edge. See Application Note U-159 for more information.
vents excessive MOSFET gate-to-source voltage so that
the UC2853A can be operated with VCC and high as
40V. A series gate resistor of at least 5 ohms should be
used to minimize clamp voltage overshoot. In addition, a
Schottky diode such as a 1N5818 connected between
OUT and GND may be necessary to prevent parasitic
substrate diode conduction.
ICOMP: Current Loop Error Amplifier Output. The current loop error amplifier is a conventional operational
amplifier with a 150mA current source class A output
stage. Compensate the current loop by placing an impedance between ICOMP and IMO. This output can
swing above the oscillator peak voltage, allowing zero
duty cycle when necessary.
GND: Ground. All voltages are measured with respect to
GND. The VCC bypass capacitor should be connected to
ground as close to the GND pin as possible.
VCC: Input Supply Voltage. This pin serves two functions. It supplies power to the chip, and an input voltage
level signal to the squarer circuit. When this input is connected to a DC voltage proportional to the AC input RMS
voltage, the voltage loop gain is reduced by
IAC: AC Waveform Input. This input provides voltage
waveform information to the multiplier. The current loop
will try to produce a current waveform with the same
shape as the IAC signal. IAC is a low impedance input,
nominally at 2V, which accepts a current proportional to
the input voltage. Connect a resistor from the rectified input line to IAC which will conduct 500mA at maximum line
voltage.
64
VCC 2
.
This configuration maintains constant loop gain. The
UC2853A input voltage range extends from 12V to 40V,
allowing an AC supply voltage range in excess of 85VAC
to 265VAC. Bypass VCC with at least a 0.1mF ceramic
capacitor to ensure proper operation. See the Applications section for the recommended circuit configuration.
IMO: Multiplier Output and Current Sense Inverting Input.
The output of the multiplier and the inverting input of the
current amplifier are connected together at IMO. Avoid
bringing this input below –0.5V to prevent the internal
protection diode from conducting. The multiplier output is
a current, making this a summing node and allowing a differential current error amplifier configuration to reject
ground noise. The input resistance at this node should be
3.9k to minimize input bias current induced offset voltage.
See the Applications section for the recommended circuit
configuration.
VCOMP: Voltage Loop Error Amplifier Output. The
voltage loop error amplifier is a transconductance type
operational amplifier. A feedback impedance between
VCOMP and FB for loop compensation must be avoided
to maintain proper operation of the overvoltage
protection comparator. Instead, compensate the voltage
loop with an impedance between VCOMP and GND.
When VCOMP is below 1.5V, the multiplier output
current is zero.
OUT: Gate Driver Output. OUT provides high current gate
drive for the external power MOSFET. A 15V clamp pre-
5
PACKAGE MATERIALS INFORMATION
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3-Jun-2022
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
B0 W
Reel
Diameter
Cavity
A0
B0
K0
W
P1
A0
Dimension designed to accommodate the component width
Dimension designed to accommodate the component length
Dimension designed to accommodate the component thickness
Overall width of the carrier tape
Pitch between successive cavity centers
Reel Width (W1)
QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE
Sprocket Holes
Q1
Q2
Q1
Q2
Q3
Q4
Q3
Q4
User Direction of Feed
Pocket Quadrants
*All dimensions are nominal
Device
UC2853ADTR
Package Package Pins
Type Drawing
SOIC
D
8
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
2500
330.0
12.4
Pack Materials-Page 1
6.4
B0
(mm)
K0
(mm)
P1
(mm)
5.2
2.1
8.0
W
Pin1
(mm) Quadrant
12.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
3-Jun-2022
TAPE AND REEL BOX DIMENSIONS
Width (mm)
W
L
H
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
UC2853ADTR
SOIC
D
8
2500
356.0
356.0
35.0
Pack Materials-Page 2
PACKAGE MATERIALS INFORMATION
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3-Jun-2022
TUBE
T - Tube
height
L - Tube length
W - Tube
width
B - Alignment groove width
*All dimensions are nominal
Device
Package Name
Package Type
Pins
SPQ
L (mm)
W (mm)
T (µm)
B (mm)
UC2853AD
D
SOIC
8
75
506.6
8
3940
4.32
Pack Materials-Page 3
PACKAGE OUTLINE
D0008A
SOIC - 1.75 mm max height
SCALE 2.800
SMALL OUTLINE INTEGRATED CIRCUIT
C
SEATING PLANE
.228-.244 TYP
[5.80-6.19]
A
.004 [0.1] C
PIN 1 ID AREA
6X .050
[1.27]
8
1
2X
.150
[3.81]
.189-.197
[4.81-5.00]
NOTE 3
4X (0 -15 )
4
5
B
8X .012-.020
[0.31-0.51]
.010 [0.25]
C A B
.150-.157
[3.81-3.98]
NOTE 4
.069 MAX
[1.75]
.005-.010 TYP
[0.13-0.25]
4X (0 -15 )
SEE DETAIL A
.010
[0.25]
.004-.010
[0.11-0.25]
0 -8
.016-.050
[0.41-1.27]
DETAIL A
(.041)
[1.04]
TYPICAL
4214825/C 02/2019
NOTES:
1. Linear dimensions are in inches [millimeters]. Dimensions in parenthesis are for reference only. Controlling dimensions are in inches.
Dimensioning and tolerancing per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed .006 [0.15] per side.
4. This dimension does not include interlead flash.
5. Reference JEDEC registration MS-012, variation AA.
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EXAMPLE BOARD LAYOUT
D0008A
SOIC - 1.75 mm max height
SMALL OUTLINE INTEGRATED CIRCUIT
8X (.061 )
[1.55]
SYMM
SEE
DETAILS
1
8
8X (.024)
[0.6]
6X (.050 )
[1.27]
SYMM
5
4
(R.002 ) TYP
[0.05]
(.213)
[5.4]
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:8X
METAL
SOLDER MASK
OPENING
EXPOSED
METAL
.0028 MAX
[0.07]
ALL AROUND
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
EXPOSED
METAL
.0028 MIN
[0.07]
ALL AROUND
SOLDER MASK
DEFINED
NON SOLDER MASK
DEFINED
SOLDER MASK DETAILS
4214825/C 02/2019
NOTES: (continued)
6. Publication IPC-7351 may have alternate designs.
7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
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EXAMPLE STENCIL DESIGN
D0008A
SOIC - 1.75 mm max height
SMALL OUTLINE INTEGRATED CIRCUIT
8X (.061 )
[1.55]
SYMM
1
8
8X (.024)
[0.6]
6X (.050 )
[1.27]
SYMM
5
4
(R.002 ) TYP
[0.05]
(.213)
[5.4]
SOLDER PASTE EXAMPLE
BASED ON .005 INCH [0.125 MM] THICK STENCIL
SCALE:8X
4214825/C 02/2019
NOTES: (continued)
8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
9. Board assembly site may have different recommendations for stencil design.
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