TI SLVU136A

User's Guide
SLVU136A – July 2005 – Revised January 2011
TPS23750 Buck-Converter Evaluation Board – HPA107
This user’s guide describes the function and operation of the HPA107 evaluation module (EVM). A
complete description, schematic, bill of materials, assembly drawing, and printed-circuit board artwork are
included.
1
2
3
4
5
Contents
Introduction .................................................................................................................. 1
Specification, Schematic, and Bill of Materials .......................................................................... 2
Board Layout ................................................................................................................ 7
Using the EVM .............................................................................................................. 9
Related Documentation ................................................................................................... 10
1
Typical 3.3-V PD End-to-End Efficiency ................................................................................. 2
2
Typical 3.3-V DC/DC Converter Efficiency
3
3
Typical 5-V PD End-to-End Efficiency
3
List of Figures
4
5
.............................................................................
...................................................................................
Typical 5-V DC/DC Converter Efficiency.................................................................................
Typical Setup ................................................................................................................
4
9
List of Tables
1
1
HPA107 Electrical Specification........................................................................................... 2
2
HPA107 Bill of Materials ................................................................................................... 6
3
EVM I/O Interfaces.......................................................................................................... 9
Introduction
The HPA107 evaluation module implements an IEEE 802.3af-compliant class-3 power interface and a
non-isolated DC/DC switching converter using the Texas Instruments TPS23750 powered device (PD)
controller in a typical power-over-Ethernet (PoE) configuration. The DC/DC converter is a 5-V output buck
converter with a BOM option for 3.3 V. A small prototype area is included on the printed-circuit board. The
EVM accepts a TPS23770 in place of the TPS23750 to support a PD with a legacy undervoltage lockout
(UVLO) threshold.
The EVM has separate LEDs that show when the DC/DC converter and the PoE interface are active. Test
points are provided at all critical nodes. Power to the EVM is provided over the spare or data lines in an
Ethernet cable or by an auxiliary source like a wall adapter.
PowerPad is a trademark of Texas Instruments.
SLVU136A – July 2005 – Revised January 2011
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1
Specification, Schematic, and Bill of Materials
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2
Specification, Schematic, and Bill of Materials
2.1
Electrical Specification
Table 1 shows the electrical specification over a –40°C to 85°C operating temperature range. Input
voltages are measured at the RJ-45 connector unless otherwise noted.
Table 1. HPA107 Electrical Specification
PARAMETER
CONDITION
MIN
TYP
MAX
UNIT
0
–
57
V
POWER INTERFACE
Input voltage, VIN
Applied to the power pins of connectors J1 or J3
Operating voltage
After startup
36
–
57
V
Input UVLO
Rising input voltage
–
–
42
V
Falling input voltage
30
–
–
Detection voltage range
2.7
–
10.1
14.5
–
20.5
26
–
30
mA
Inrush current limit
100
–
180
mA
Operating current limit
405
–
495
mA
V
Classification voltage range
Classification current
V
V
DC/DC CONVERTER
Output voltage
36 V ≤ VIN ≤ 57 V,
ILOAD ≤ ILOAD (max)
3.3-V output
3.13
3.3
3.47
5-V output
4.75
5.0
5.25
Output current, ILOAD
36 V ≤ VIN ≤ 57 V
3.3-V output
–
–
2.5
5-V output
–
–
2
VIN = 44 V, ILOAD = 2.5 A
3.3-V output
–
30
–
VIN = 44 V, ILOAD = 2 A
5-V output
–
32
–
VIN = 44 V, ILOAD = 2.5 A
3.3-V output
–
75%
–
VIN = 44 V, ILOAD = 2 A
5-V output
–
80%
–
164
–
236
Output ripple voltage, peak-to-peak
Efficiency, end-to-end
Switching frequency
A
mV
kHz
The end-to-end efficiency curves in Figure 1 and Figure 3 include the losses at the PD switch, bridge
diode, and data transformer. The DC/DC converter efficiency curves in Figure 2 and Figure 4 exclude
these losses. The curves are plotted for the RJ-45 connector voltages shown.
100
90
36 V
80
Efficiency − %
70
44 V
60
57 V
50
40
30
20
10
0
0
0.5
1
1.5
Load Current − A
2
2.5
Figure 1. Typical 3.3-V PD End-to-End Efficiency
2
TPS23750 Buck-Converter Evaluation Board – HPA107
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100
90
36 V
80
Efficiency − %
70
44 V
60
57 V
50
40
30
20
10
0
0
0.5
1
1.5
Load Current − A
2
2.5
Figure 2. Typical 3.3-V DC/DC Converter Efficiency
100
36 V
90
80
Efficiency − %
70
44 V
57 V
60
50
40
30
20
10
0
0
0.5
1
1.5
2
Load Current − A
Figure 3. Typical 5-V PD End-to-End Efficiency
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Specification, Schematic, and Bill of Materials
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100
36 V
90
80
Efficiency − %
70
44 V
57 V
60
50
40
30
20
10
0
0
0.5
1
Load Current − A
1.5
2
Figure 4. Typical 5-V DC/DC Converter Efficiency
4
TPS23750 Buck-Converter Evaluation Board – HPA107
© 2005–2011, Texas Instruments Incorporated
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Specification, Schematic, and Bill of Materials
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Schematic
+
+
2.2
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Specification, Schematic, and Bill of Materials
2.3
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Bill of Material
Table 2. HPA107 Bill of Materials
–001
–002
3.3 V
Count
5V
Count
1
1
C1
Capacitor, Ceramic, 0.1 mF, 100 V, X7R, 10%
1206
Vishay
Std
1
1
C10
Capacitor, Aluminum, 100 mF, 6.3-V, 20%
6.3 × 5.8
Panasonic
EEVFK0J101P
1
1
C13
Capacitor, Ceramic, 1 mF, 16-V, X7R, 10%
805
Murata
GRM21BR71C105KA01L
1
1
C14
Capacitor, Ceramic, 0.22 mF, 10V, X7R, 10%
805
Std
Std
1
1
C8
Capacitor, Ceramic, 33 nF, 25V, X7R, 10%
603
Std
Std
1
1
C2
Capacitor, Aluminum, 47 mF, 63V, 20%
8×10 mm
Panasonic
EEVFK1J470P
1
1
C3
Capacitor, Ceramic, X7R, 0.1 mF, 25V, 10%
603
Vishay
Std
0
0
C15
Not used
603
2
2
C4, C5
Capacitor, Ceramic, 1 mF, 100 V, X7R, 10%
1210
Murata
GRM32ER72A105KA01L
1
1
C6
Capacitor, Ceramic, 560 pF, 50 V, X7R, 10%
603
Std
Std
1
1
C7
Capacitor, Ceramic, 15 pF, 50 V, C0G, 5%
603
Std
Std
3
3
C9, C11, C12
Capacitor, Ceramic, 10 mF, 6.3V, X5R, 10%
805
Murata
GRM21BR60J106KE19L
2
2
D1, D2
Bridge Rectifier, 100V, 0.8A, Glass Passivated,
SMD
MINI DIP4
Diodes Inc
HD01-T
2
2
D6, D7
Diode, LED, Red
0.114 × 0.049
Panasonic
LN1271R
1
1
D3
Diode, TVS, 58V, 1W
SMA
Diodes Inc.,
STMicro
SMAJ58A
1
1
D4
Diode, Dual Schottky, 7-A, 100-V
DPAK
IR
6CWQ10FN
1
1
D5
Diode, Rectifier, 1A, 100V
SMA
Diodes Inc.
S1B
2
2
J1, J2
Connector, Jack, Modular, 8 POS
TH
AMP
520252
2
2
J3, J4
Terminal Block, 2-pin, 6-A, 3,5 mm
TH
OST
ED1514
1
1
L1
Inductor, SMT, 10 mH, 1.1A, 160 mΩ
4.45×6.6 mm
Coilcraft
DO1608C-103
Wurth Electronics
7445510
Ref Des
Description
Size
MFR
Part No.
1
1
L2
Inductor, SMT, 33 mH, 3.9A, 41 mΩ
0.472 sq
Sumida
CDRH127/LD-330
1
1
Q2
MOSFET, N-ch, 100V, 3.75A, 0.25 Ω
DPAK
Vishay
SUD06N10-225L
1
1
R1
Resistor, Chip, 24.9 kΩ, 1/16W, 1%
603
Std
Std
0
1
R10
Resistor, Chip, 0.18 Ω, 1/4W, 1%
1206
Vishay, Susuma
WSL1206R1800FEA18,
1
0
R10
Resistor, Chip, 0.15 Ω, 1/4W, 1%
1206
Vishay
WSL1206R1500FEA18
1
1
R2
Resistor, Chip, 100 kΩ, 1/16W, 1%
603
Std
Std
1
1
R12
Resistor, Chip, 1 kΩ, 1/10-W, 5%
805
Std
Std
1
1
R13
Resistor, Chip, 20 kΩ, 1/10-W, 5%
805
Std
Std
1
1
R3
Resistor, Chip, 357 Ω, 1/4-W
1206
Std
Std
1
1
R4
Resistor, Chip, 75 kΩ, 1/16-W, 1%
603
Std
Std
1
1
R5
Resistor, Chip, 1.5 kΩ, 1/16W, 1%
603
Std
Std
0
1
R6
Resistor, Chip, 3.48 kΩ, 1/16W, 1%
603
Std
Std
1
0
R6
Resistor, Chip, 1.78 kΩ, 1/16W, 1%
603
Std
Std
1
1
R7
Resistor, Chip, 51.1 Ω, 1/16W, 1%
603
Std
Std
1
1
R8
Resistor, Chip, 10 Ω, 1/16W, 1%
603
Std
Std
2
2
R9, R11
Resistor, Chip, 0 Ω, 1/16W, 1%
603
Std
Std
1
1
T1
Xfmr, Center-tapped, Voice Over IP
0.500 × 0.370
Pulse
H2019
Wurth Electronics
749013011
RL1632R-R180-F
6
5
5
TP1, TP5
TP7–TP9
Test Point, Black
0.038
Keystone
5001
7
7
TP2–TP4, TP6,
TP10–TP12
Test Point, Red
0.038
Keystone
5000
1
1
U1
IC, IEEE 802.3af Integrated Primary Side
Controller
PWP20
TI
TPS23750PWP
1
1
–
PCB, 2.250 In × 4.350 In × 0.062 In
–
Any
HPA107A
TPS23750 Buck-Converter Evaluation Board – HPA107
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Board Layout
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Table 2. HPA107 Bill of Materials (continued)
–001
–002
3.3 V
Count
5V
Count
4
4
Ref Des
–
3
Board Layout
3.1
Top-Side Layout
Description
Rubber Bumper
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Size
–
MFR
SPC TECH
Part No.
2566
TPS23750 Buck-Converter Evaluation Board – HPA107
© 2005–2011, Texas Instruments Incorporated
7
Board Layout
3.2
Bottom-Side Layout
3.3
Layout Considerations
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The layout of the PoE front end must use good practice for power and EMI/ESD. A basic set of
recommendations include:
• The parts placement must be driven by the power flow in a point-to-point manner such as RJ-45 →
Ethernet transformer → diode bridges → TVS and 0.1-mF capacitor → TPS23750 → bulk capacitor →
converter input.
• There should not be any crossovers of signals from one part of the flow to another.
• All leads should be as short as possible with wide power traces and paired signal and return.
• Spacing consistent with safety standards like IEC60950 must be observed between the 48-V input
voltage rails and between the input and an isolated converter output.
• The TPS23750 should be located over split, local ground planes referenced to VSS for the PoE input
and to RTN for the converter operation. Whereas the PoE side may operate without a ground plane,
the converter side must have one. The PowerPad™ must be tied to the VSS plane or fill area,
especially if power dissipation is a concern. Logic ground and power layers should not be present
under the Ethernet input or the converter primary side.
• Large copper fills and traces should be used on SMT power-dissipating devices, and wide traces or
overlay copper fills should be used in the power path.
Converter layout benefits from basic rules such as:
1. Pair signals to reduce emissions and noise, especially the paths that carry high-current pulses which
include the power semiconductors and magnetics.
2. Reduce the length of all the traces in step 1.
3. Where possible, use vertical pairing.
4. Use the ground plane for the switching currents carefully.
5. Keep the high-current and high-voltage switching away from low-level sensing circuits including those
outside the power supply.
6. The current sensing on RSP/RSN is the most critical, noise-sensitive signal. It must be protected as in
step 5, including exposure to the gate drive sign.
7. Pay special attention to spacing around the high-voltage sections of the converter.
8
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Using the EVM
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4
Using the EVM
4.1
Setup
Figure 5 shows a typical EVM setup. The user is encouraged to read the TPS23750 data sheet before
using the EVM.
Ethernet Cable
PSE
+
or
J1
VOUT
Power Supply
HPA107
J2
J4
−
R
LOAD
AUX
−
+
J3
Data
to Phy
+
−
Optional
Power Source
Figure 5. Typical Setup
4.2
Interface
Table 2 describes the EVM interface.
Table 3. EVM I/O Interfaces
Reference Designator
4.3
Description
J1
An Ethernet cable connects this port to the power-sourcing equipment (PSE). This port carries both
data and power.
J2
This port carries only data. Do not apply power to this port.
J3
This terminal block accepts auxiliary power from a source like a wall adapter.
J4
Output voltage
D6
This LED is lit if the DC/DC converter output is on.
D7
This LED is lit if the PD FET switch is on.
Making Measurements
Stray magnetic fields from inductor L2 can couple noise into measurements. This noise may be noticeable
when measuring a low-level signal like output ripple voltage. Keep the ground lead of the oscilloscope
probe short and away from L2 to reduce the amount of noise pick-up.
Ground loops can be created if test equipment is connected to the EVM. Avoid ground loops by floating
the test equipment and/or the power supply to the EVM.
4.4
EVM Operation
The TPS23750 data sheet describes the electrical operation and function of the various components in the
buck converter powered device. The circuit provided in the data sheet is similar to the circuit in this EVM.
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Related Documentation
5
www.ti.com
Related Documentation
1. TPS23750, TPS23770, Integrated 100 V IEEE 802.3af PD and DC/DC Controller data sheet
(SLVS590)
2. IEEE Std 802.3af
10
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FCC Warning
This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES
ONLY and is not considered by TI to be a finished end-product fit for general customer use. It generates, uses, and can radiate radio
frequency energy and has not been tested for compliance with the limits of computing devices pursuant to part 15 of FCC rules, which are
designed to provide reasonable protection against radio frequency interference. Operation of this equipment in other environments may
cause interference with radio communications, in which case the user at his own expense will be required to take whatever measures may
be required to correct this interference.
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EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of 0 V to 57 V.
Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are
questions concerning the input range, please contact a TI field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the
EVM. Please consult the EVM User's Guide prior to connecting any load to the EVM output. If there is uncertainty as to the load
specification, please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than 100°C. The EVM is designed to
operate properly with certain components above 100°C as long as the input and output ranges are maintained. These components
include but are not limited to linear regulators, switching transistors, pass transistors, and current sense resistors. These types of
devices can be identified using the EVM schematic located in the EVM User's Guide. When placing measurement probes near
these devices during operation, please be aware that these devices may be very warm to the touch.
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