www.fairchildsemi.com
FEB111-001 User’s Guide
PWM and PFC Combo
100W Evaluation Board
Featured Fairchild Product: ML4824
www.fairchildsemi.com/FEBsupport
© 2005 Fairchild Semiconductor
Page 1 of 12
Rev 1.1 March 2005
www.fairchildsemi.com
Contents
1.
General Board Description .......................................................................................................................3
1.1
Contents of the FEB111-001 Evaluation Kit .........................................................................................3
1.2
Power Supply Specification Table ......................................................................................................3
1.3
Schematic.......................................................................................................................................3
2.
Test Procedure.........................................................................................................................................3
2.1
Theory of Operation ........................................................................................................................3
2.2
Test Driving the ML4824 Evaluation Board..........................................................................................3
3.
Performance Data ...................................................................................................................................5
3.1
Typical Waveforms ..........................................................................................................................5
4.
Parts List.................................................................................................................................................5
4.1
ML4824 Evaluation Kit (Rev. B) Parts List ............................................................................................5
4.2
Schematic.......................................................................................................................................9
5.
Transformer Specification .......................................................................................................................10
5.1
ML4824 T2 Forward Transformer Spec. ...........................................................................................10
6.
Printed Circuit Board .............................................................................................................................10
6.1
Layout Considerations ....................................................................................................................10
7.
Featured Products..................................................................................................................................11
7.1
ML4824 Description ......................................................................................................................11
7.1.1
ML4824 Features ...............................................................................................................11
8.
Resources/References ............................................................................................................................11
8.1
Application Notes..........................................................................................................................11
© 2005 Fairchild Semiconductor
Page 2 of 12
Rev 1.1 March 2005
www.fairchildsemi.com
1. General Board Description
The FEB111-001 Evaluation Board is a power factor corrected, 100 Watt, off-line switching power supply with
a single output of +12 VDC. The supply operates over the universal input range of 85 VAC to 265 VAC.
The ML4824 is a combination (“Combo”) power supply controller IC which consists of a PFC input stage and
a PWM output stage. The PFC “front end” is of the average-current, continuous-conduction type. The PWM
section allows the construction of either a current- or voltage-mode regulator as the power supply’s “back end.”
The Evaluation Board uses a two-switch, current-mode forward converter following the power factor corrector to
produce its 12V output. Both stages operate at 100 kHz, using Fairchild’s patented leading/trailing edge modu-
lation technique.
1.1 Contents of FEB111-001 Evaluation Kit
1.
2.
3.
FEB111-001 evaluation board
FEB111-001 evaluation board users guide
CD ROM containing the following datasheets and applications notes
•
•
•
•
•
•
•
FEB111-001 evaluation board users guide
ML4824 Data Sheet.
Additional Fairchild data sheets for parts listed on the Bill of Materials
AN-42009 - ML4824 Combo Controller Applications
AN-42045 - ML4824, A Novel Method for an Off-Line PFC-PWM Combo Controller
AN-42034 - Synchronizing the ML4824 to Wide Frequency Ranges
AN-42030 - Theory and Application of the ML4821 Average Current Mode PFC Controller
1.2 Power Supply Specification Table
Parameter
V
IN
V
OUT
I
LIMIT
Efficiency
T.H.D.
P.F.
83
Min
85
Typ
Max
265
Units
V
AC
V
DC
A
DC
%
% I
AC
12.09
10.50
83
8.5
.996
Conditions – V
IN
= 120V, I
LOAD
= 8.83A
1.3 Schematic
2. Test Procedure
2.1 Theory of Operation
For a complete theory of operation refer to Application Notes AN-42009 and AN-42045. In a departure from
the example given in AN-42009, the voltage loop bandwidth of the PFC “front end” has been set to approxi-
mately 15 Hz. This allows the use of a smaller boost capacitor (C5) while maintaining good values for power fac-
tor and harmonic distortion at low line frequencies (
e.g.
, 47 Hz).
2.2 Test Driving the ML4824 Evaluation Board:
The following steps will demonstrate the functionality of the FEB111-001 Evaluation Board, and allow the mea-
surement of its Power Factor (P.F.) and Total Harmonic Distortion (T.H.D.) under various conditions of AC
input voltage and DC output loading:
© 2005 Fairchild Semiconductor
Page 3 of 12
Rev 1.1 March 2005
www.fairchildsemi.com
Hot
AC Line
Return
Isolation
Xformer
240 VAC
Variac
0 to 265
VAC
AC
In
EVAL
Board
Figure 1
1.
Connect a variable autotransformer (such as a Variac) to the output of an isolation transformer, and to the
input of the ML4824EVAL Board. Both transformers should be rated for 500 VA or greater, and in combi-
nation should be rated for an output voltage range of 0 VAC to approximately 265 VAC. The connections
should be made as in Figure 1, with the Isolation Transformer NOT plugged into the AC line until step 5,
below.
Ensure that the variable autotransformer is set to “zero output.”
Connect an AC Voltmeter across the Evaluation Board’s AC Input terminals. Set the meter range to 300
VAC or greater.
Connect a DC Voltmeter between the Evaluation Board’s DC output terminals (+12V Out and +12V
Return). Set the meter range to 15 VDC or greater.
Connect the input of the isolation transformer to the AC power line.
Slowly increase the AC input voltage to at least 85 VAC (
DO NOT exceed 265 VAC).
The unloaded output voltage of the ML4824 Evaluation Board should be between 11.4V and 12.6V (
12V (5%).
Connect an 8.33 amp load across the Evaluation Board’s +12 VDC output terminals. The fully-loaded
(100W) output should remain between 11.4V and 12.6V while the line voltage is varied over the range of
85 VAC to 265 VAC.
With V
IN
= 120 VAC, increase the current loading on the output until the foldback current limit circuit
trips. This should occur at a load current of approximately 10.5 Amperes.
2.
3.
4.
5.
6.
7.
8.
9.
10. Turn the input voltage down to zero volts. Remove the load on the output. Bring the input voltage back to
120 VAC. Verify that the overcurrent condition has been “cleared,” and that the output of the ML4824
Evaluation Board is again at +12 VDC ( 5% for any load between 0 Amperes and 8.33 Amperes DC.
11. Disconnect the isolation transformer from the power line. Wait at least three (3) minutes for high voltages
stored on the board to bleed down.
12. Connect an AC Power Analyzer (a Power Factor Meter) between the output of the variable autotransformer
and the AC input to the Evaluation Board, in accordance with the manufacturer’s instructions.
Follow
these instructions carefully!
Failure to do so can result in erroneous readings, equipment damage, or per-
sonal injury. (Note: Different AC Power Analyzers/Power Factor Meters may give different results on the
same PFC board. We have had good results with the DSP-based Voltech series of AC Power Analyzers,
including the Model PM1000).
13. Connect the isolation transformer to the power line. Slowly raise the voltage at the output of the variable
autotransformer until the input to the Evaluation Board is between 85 VAC and 265 VAC.
Operation of the FEB111-001 Evaluation Board may now be evaluated over the full input voltage range.
If a variable load is used, operation may also be tested over the full output current range (0 ADC (I
LOAD
(8.33
ADC).
© 2005 Fairchild Semiconductor
Page 4 of 12
Rev 1.1 March 2005
www.fairchildsemi.com
3. Performance Data
A typical FEB111-001 Evaluation Board will have the following performance characteristics:
VAC
VOUT
ILIMIT
Efficiency
T.H.D.
P.F.
85
12.09
10.32
81
6.0
0.997
120
12.09
10.50
83
8.5
0.996
265
12.09
9.92
84
9.5
0.998
Units
VDC
ADC
%
% IAC
Test Conditions:
I
LOAD
= 8.33 ADC, T
A
= 25°C
Equipment:
Voltech PM1000 AC Power Analyzer
Kikusui PLZ152WA Electronic Load
Fluke Model 8050A DMM
3.1 Typical Waveforms
The FEB111-001 Evaluation Board functions as a continuous-current, average-mode (CCAM) PFC followed by
a synchronized PWM (DC/DC converter) stage. This is augmented by the leading/trailing edge modulation
used in the ML4824. For more information on CCAM power factor correction and its resulting waveforms,
please refer to AN-42030 (while AN-42030 specifically covers the ML4821 PFC IC, the ML4821 and the PFC
stages of the ML4824 are very similar in concept and performance).
4. Parts List
4.1 ML4824 Evaluation Kit (Rev. B) Parts List
Item
Qty Ref
Description
Vendor
Part #
Resistors
1
2
3
4
5
6
7
8
9
10
11
12
© 2005 Fairchild Semiconductor
2
2
1
1
4
1
2
1
1
1
1
1
R1A, 1B
R2A, 2B
R3
R4
R5A, 5B,
5C, 5D
R6
R7A, 7B
R8
R9
R10
R11
R12
499K, 1%, 0.25W, Metal Film,
Thru Hole
453K, 1%, 0.25W, Metal Film,
Thru Hole
75K, 1%, 1206 - Surf Mnt.
13K, 1%, 1206 - Surf Mnt.
1.2 Ohm, 5%, 0.25W, Thru Hole
41.2K, 1%, 1206 - Surf Mnt.
178K, 1%, 0.25W, Metal Film,
Thru Hole
2.37K, 1%, 1206 - Surf Mnt.
1K, 5%, 1206 - Surf Mnt.
6.2K, 5%, 1206 - Surf Mnt.
750K, 5%, 1206 - Surf Mnt.
27K, 5%, 1206 - Surf Mnt.
Page 5 of 12
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Rev 1.1 March 2005
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