Efficiency-Optimized, Synchronous Flyback, High-Power PoE Controller/Converter

Reference Design
SLVA475 – January 2012
Efficiency-Optimized, Synchronous Flyback, High-Power
PoE Controller/Converter
The TPS23754 is an IEEE 802.3at-compliant, powered-device (PD) controller and power supply controller
optimized for isolated converter topologies. TPS23754EVM-420 (SLVU301) is targeted at 25-W,
synchronous, flyback converter applications. The PMP6672B reference design starts with the
TPS23754EVM-420 platform and improves the overall efficiency of the design.
5
6
Contents
Description ................................................................................................................... 2
1.1
Design Improvement Summary .................................................................................. 2
1.2
Typical Applications ................................................................................................ 2
1.3
Features ............................................................................................................. 2
Electrical Performance Specifications .................................................................................... 3
Schematic .................................................................................................................... 4
Performance Data and Typical Characteristic Curves ................................................................. 5
4.1
Efficiency ............................................................................................................ 5
4.2
Load Regulation .................................................................................................... 5
4.3
Bode Plot ............................................................................................................ 6
4.4
Transient Response ............................................................................................... 7
4.5
Output Ripple ....................................................................................................... 7
4.6
Switch Node Voltage .............................................................................................. 8
4.7
Turnon Waveform .................................................................................................. 8
PMP6672B Assembly Drawing and PCB Layout ...................................................................... 10
Bill of Materials ............................................................................................................. 11
1
PMP6672B Schematic
1
2
3
4
List of Figures
2
3
4
5
6
7
8
9
10
11
.....................................................................................................
PMP6672B Efficiency ......................................................................................................
PMP6672B Load Regulation ..............................................................................................
PMP6672B Loop Response Gain and Phase ...........................................................................
PMP6672B Load Transient ................................................................................................
Output Ripple ................................................................................................................
Switching Node Waveform.................................................................................................
Enable Turnon Waveform – No Output Load ...........................................................................
Enable Turnon Waveform – Output Fully Loaded ......................................................................
Top-Side Layout ..........................................................................................................
Bottom-Side Layout .......................................................................................................
4
5
5
6
7
7
8
8
9
10
10
List of Tables
1
PMP6672B Electrical Performance Specifications (at 25°C) .......................................................... 3
2
PMP6672B Components List According to the Schematic Shown in
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Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
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11
1
Description
1
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Description
The PMP6672B allows reference circuitry evaluation of the TPS23754. It contains input and output power
connectors and an array of onboard test points for circuit evaluation. Modifications to TPS23754EVM-420
(SLVU301) are noted on the schematic shown in Figure 1.
1.1
Design Improvement Summary
•
•
•
•
•
•
•
•
•
•
•
•
1.2
Typical Applications
•
•
•
1.3
Voice over Internet Protocol – IP telephones
Wireless LAN – wireless access points
Security – wired IP cameras
Features
•
•
•
•
2
New flyback transformer design
Better selection of magnetizing inductance for CCM operation
New winding strategy to reduce copper losses
Uses same core and bobbin size and footprint
RCD clamp improvements
Diode used for faster primary FET turnoff
New dead-time resistor value for optimum efficiency at full load and acceptable efficiency at no load.
Use of feedforward resistor for better control of peak current and voltage at higher input voltage.
Other updates: Compensation, improved slope compensation, 40-V synchronized FET for low
drain-source stress.
Other benefits
Lower primary MOSFET peak drain-source voltage during overloads
Much better current-limit control
Efficient, general market design
Self-driven, synchronous, rectified secondary
25-W output power from Power over Ethernet (PoE) or from a 48-V adapter
5-V output voltage
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
SLVA475 – January 2012
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Electrical Performance Specifications
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2
Electrical Performance Specifications
Table 1. PMP6672B Electrical Performance Specifications (at 25°C)
Parameter
Condition
Min
Typ
Max
Units
Power Interface
Input voltage
Applied to the power pins of connectors J2 or J3
Operating voltage
After start-up
0
-
57
V
30
-
57
V
Rising input voltage
-
-
36
Falling input voltage
30
-
-
Detection voltage
At device terminals
1.6
-
10
V
Classification voltage
At device terminals
10
-
23
V
Classification current
Rclass = 63.4 Ω
mA
Input UVLO
36
-
44
Inrush current-limit
100
-
180
Operating current-limit
850
-
1100
V
DC/DC Converter
Output voltage
21.6 V ≤ Vin ≤ 57 V, ILOAD ≤
ILOAD (max)
5-V output
4.75
5
5.25
V
Output current
21.6 V ≤ Vin ≤ 57 V
5-V output
-
-
5
A
Output ripple voltage,
peak-to-peak
Vin = 48 V, ILOAD = 5 A
5-V output
-
50
-
mV
Efficiency, Vin at J2
Efficiency, Vin at J3
Efficiency, Converter
Vin = 48 V, ILOAD = 5 A
5-V output
275
kHz
Switching frequency
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89%
91%
92%
225
-
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
3
Schematic
Schematic
+
+
+
+
3
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Figure 1. PMP6672B Schematic
4
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
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Performance Data and Typical Characteristic Curves
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4
Performance Data and Typical Characteristic Curves
Figure 2 through Figure 9 present typical performance curves for the PMP6672B.
4.1
Efficiency
95
90
85
PoE Input
Converter
Adapter Input
Efficiency - %
80
75
70
65
60
55
50
0
1
2
3
4
5
IO - Output Current - A
Figure 2. PMP6672B Efficiency
4.2
Load Regulation
5.1
5.09
VO - Output Voltage - V
5.08
5.07
VOUT
5.06
5.05
5.04
5.03
5.02
5.01
5
0
1
2
3
4
5
6
IO - Output Current - A
Figure 3. PMP6672B Load Regulation
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Performance Data and Typical Characteristic Curves
4.3
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Bode Plot
Input voltage
48 Vdc
Gain/Phase
Crossover
Phase Margin
PMP6672B (5 V)
4.723 kHz
92°
Figure 4. PMP6672B Loop Response Gain and Phase
6
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
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Performance Data and Typical Characteristic Curves
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4.4
Transient Response
Figure 5. PMP6672B Load Transient
4.5
Output Ripple
VOUT
Figure 6. Output Ripple
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Controller/Converter
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Performance Data and Typical Characteristic Curves
4.6
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Switch Node Voltage
The following scope plot shows the waveforms on the drain of the secondary-side FET (Ch1) and
primary-side FET (Ch2). The output is loaded at 5 A. Vin = 48 Vdc at J2.
VQ1-D(SEC)
VQ2-D(PRI)
Figure 7. Switching Node Waveform
4.7
Turnon Waveform
The following scope plot shows the 5-V output voltage start-up waveform after the application of 48 Vdc at
J2 (PoE). The output was loaded to 0 A.
VOUT
Figure 8. Enable Turnon Waveform – No Output Load
8
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
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Performance Data and Typical Characteristic Curves
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The following scope plot shows the 5-V output voltage start-up waveform after the application of 48-Vdc at
J2 (PoE). The output was loaded to 5 A.
VOUT
Figure 9. Enable Turnon Waveform – Output Fully Loaded
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Controller/Converter
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9
PMP6672B Assembly Drawing and PCB Layout
5
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PMP6672B Assembly Drawing and PCB Layout
Figure 10 and Figure 11 show the design of the PMP6672B printed-circuit board. Note that the same
circuit board used on TPS23754EVM-420 (SLVU301) is used for PMP6672B.
Figure 10. Top-Side Layout
10
Figure 11. Bottom-Side Layout
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
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Bill of Materials
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6
Bill of Materials
Table 2. PMP6672B Components List According to the Schematic Shown in Figure 1
Count
RefDes
Value
Description
Size
Part Number
MFR
1
C1
1nF
Capacitor, Ceramic, 100V, X7R, 10%
0805
Std
Std
1
C100
330pF
Capacitor, Ceramic, 100V, X7R, 10%
0603
Std
Std
2
C10, C11
1uF
Capacitor, Ceramic, 1uF, 100V, X7R, 15%
1210
Std
Std
1
C14
10nF
Capacitor, Ceramic, 100V, X7R, 10%
0603
Std
Std
3
C15, C16,
C17
47uF
Capacitor, Ceramic, 10V, X5R, 15%
1210
Std
Std
2
C18, C19
330uF
Capacitor, Aluminum, 6.3V, 20%
0.260 x 0.276 inch
EEVFK0J331XP
Panasonic
1
C2
0.1uF
Capacitor, Ceramic, 100V, X7R, 10%
0805
Std
Std
1
C20
1uF
Capacitor, Ceramic, 16V, X7R, 15%
0603
Std
Std
2
C21, C32
1.0uF
Capacitor, Ceramic, 16V, X7R, 10%
0603
Std
Std
1
C22
1200pF
Capacitor, Ceramic, 50V, X7R, 15%
0603
Std
Std
1
C23
1000pF
Capacitor, Ceramic, 100V, X7R, 15%
0603
Std
Std
1
C24
2200pF
Capacitor, Ceramic, 2KV, X7R, 15%
1812
Std
Std
1
C25
1.0uF
Capacitor, Ceramic, 25V, X7R, 10%
0805
Std
Std
1
C26
22uF
Capacitor, Aluminum, 25V, 20%
5x5.8mm
EEVFK1E220R
Panasonic
2
C27, C28
0.47uF
Capacitor, Ceramic, 16V, X7R, 15%
0603
Std
Std
1
C29
3300pF
Capacitor, Ceramic, 50V, X7R, 15%
0603
Std
Std
4
C3, C4, C5,
C6
0.01uF
Capacitor, Ceramic, 100V, X7R, 15%
0603
Std
Std
1
C30
27nF
Capacitor, Ceramic, 50V, X7R, 15%
0603
Std
Std
1
C31
6.8nF
Capacitor, Ceramic, 50V, X7R, 15%
0603
Std
Std
1
C7
1000pF
Capacitor, Ceramic, 2kV, X7R, 15%
1210
Std
Std
3
C8, C12, C13
0.1uF
Capacitor, Ceramic, 100V, X7R, 15%
0805
Std
Std
1
C9
47uF
Capacitor, Aluminum, 63V, ±20%
0.328 x 0.390 inch
EEVFK1J470P
Panasonic
1
CL1
NA
Current Loop, 0.025 holes
0.120 X 0.075 inch
NA
NA
1
D1
B2100
Diode, Schottky, 2-A, 100-V
SMB
B2100-13
Diodes Inc
1
D100
1N4148W-7-F
Diode, Signal, 300-mA, 75-V, 350-mW
SOD-123
1N4148W-7-F
Diodes
2
D14, D18
SMAJ58A
Diode, TVS, 58-V, 1W
SMA
SMAJ58A
Diodes Inc.
1
D15
MURS120T3
Diode, UltraFast Rectifier, 1-A, 200-V
SMB
MURS120T3
On Semi
1
D16
BAV20WS
Diode, Small Signal, 250mA, 150V
SOD-323
BAV20WS
Micro Commercial
Components
2
D17, D19
BAV99
Diode, Dual Ultra Fast, Series, 200-mA, 70-V
SOT23
BAV99
Fairchild
2
D2, D3
LN1371G
Diode, LED, Green, 10-mA, 2.6-mcd
0.114 X 0.049 inch
LN1371G
Panasonic
1
D4
LN1271RAL
Diode, LED, Ultra Bright Red, 10-mA, 5-mcd
0.114 X 0.049 inch
LN1271RAL
Panasonic
9
D5, D6, D7,
D8, D9, D10,
D11, D12,
D13
B1100
Diode, Schottky, 1A, 100V
SMA
B1100
Diodes, Inc
4
FB1, FB2,
FB3, FB4
500
Bead, Ferrite, 2000mA, 60mΩ
1206
MI1206L501R-10
Steward
2
J1, J2
5520252-4
Connector, Jack, Modular, Rt. Angle,8 POS
0.705 x 0.820 inch
5520252-4
AMP
2
J3, J11
ED1514
Terminal Block, 2-pin, 6-A, 3.5mm
0.27 x 0.25
ED1514
2
J4, J10
PTC36SAAN
Header, Male 3-pin, 100mil spacing, (36-pin strip)
0.100 inch x 3
PTC36SAAN
Sullins
5
J5, J6, J7, J8,
J9
PTC36SAAN
Header, Male 2-pin, 100mil spacing, (36-pin strip)
0.100 inch x 2
PTC36SAAN
Sullins
1
L1
3.3uH
Inductor, SMT, 2.0A, 80-mΩ
4.45x6.6mm
DO1608C-332
Coilcraft
1
L2
0.33uH
Inductor, SMT, 6.26A, 7.4-mΩ
0.300 sq"
DR74-R33
Cooper
1
Q1
SiR422DP
MOSFET, NChan, 40V, 50A, 2.8 mΩ
PWRPAK S0-8
SiR422DP
Vishay-Siliconix
1
Q2
Si7898DP or
FDMS2572
MOSFET, NChannel, 150V, 4.8A, 85-mΩ
PWRPAK S0-8 or
POWER 56
Si7898DP or
FDMS2572
Vishay or
Fairchild
1
Q3
MMBT3906
Bipolar, PNP, 40V, 200mA, 225mW
SOT23
MMBT3906LT1
On Semi
1
R1
100K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R100
121K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R12
39K
Resistor, Metal Film, 1/4 watt, ± 5%
1206
Std
Std
1
R13
24.9k
Resistor, Chip, 1/16W, 1%
0603
Std
Std
2
R14, R15
69.8K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R16
10
Resistor, Chip, 1/10W, 1%
0805
Std
Std
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Bill of Materials
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Table 2. PMP6672B Components List According to the Schematic Shown in Figure 1 (continued)
Count
12
RefDes
Value
Description
Size
Part Number
MFR
1
R17
22.1k
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R18
10
Resistor, Chip, 1/16W, 5%
0603
Std
Std
1
R19
63.4
Resistor, Chip, 1/10W, 1%
0805
Std
Std
1
R2
15K
Resistor, Chip, 1/4W, 1%
1210
Std
Std
1
R20
4.7
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R21
332
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R22
0.18
Resistor, Chip, 1/2W, 1%
2010
Std
Std
2
R23, R28
10K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R24
1.5K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R25
2K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R26
49.9
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R27
604
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R29
41.2K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
2
R3, R4
1K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R30
13.7K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R5
6.49K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R6
4.02K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
R7
8.87K
Resistor, Chip, 1/16W, 1%
0603
Std
Std
4
R8, R9, R10,
R11
75
Resistor, Chip, 1/16W, 1%
0603
Std
Std
1
T1
ETH1-230LD
XFMR, Mid-Power PoE Magnetics
S0 14 Wide
ETH1-230LD
Coilcraft
1
T2
JA4456-DL
Transformer, SMT For PoE/PD, 25W, 2.8A
0.810 x 1.181 inch
JA4456-DL
Coilcraft
1
T3
PA0184
XFMR, SMT Gate Drive
0.355 X 0.340 inch
PA0184
Pulse
1
U1
FOD817D
IC, Optocoupler, 70-V, 300 - 600% CTR
SMT-4PDIP
FOD817DS
Fairchild
1
U2
TPS23754PWP
IC, IEEE 802.3at PoE Interface and Isolated Converter
Controller
PWP20
TPS23754PWP
TI
1
U3
TCMT1107
IC, Photocoupler, 3750VRMS, 80-160% CTR
MF4
TCMT1107
Vishay
1
U4
TLV431A
IC, Shunt Regulator, 6V, 10mA, 1%
SOT23-5
TLV431ACDBVR
TI
6
—
Shunt, Black
100-mil
929950-00
3M
1
—
PCB, 5.90 In x 2.03 In x 0.062 In
HPA420
Any
Efficiency-Optimized, Synchronous Flyback, High-Power PoE
Controller/Converter
Copyright © 2012, Texas Instruments Incorporated
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