Texas Instruments TPS2378 User manual

User's Guide
SLVU682–March 2012
TPS2378 EVM User’s Guide
This User’s Guide describes the evaluation module (EVM) for the TPS2378 (TPS2378EVM-105).
TPS2378 is an IEEE802.3at type 2 compliant powered device (PD) controller.
Contents
1 Introduction .................................................................................................................. 2
1.1 Features ............................................................................................................. 2
1.2 Applications ......................................................................................................... 2
2 Electrical Specifications at 25°C .......................................................................................... 2
3 Description ................................................................................................................... 3
4 Schematic .................................................................................................................... 4
5 General Configuration and Description .................................................................................. 5
5.1 Physical Access .................................................................................................... 5
5.2 Test Setup .......................................................................................................... 5
6 EVM Assembly Drawings and Layout Guidelines ...................................................................... 6
6.1 PC Drawings ........................................................................................................ 6
6.2 Layout Guidelines .................................................................................................. 9
6.3 EMI Containment ................................................................................................... 9
7 Bill of Materials ............................................................................................................. 10
List of Figures
1 TPS2378EVM Schematic.................................................................................................. 4
2 Typical TPS2378EVM Test Setup ........................................................................................ 6
3 Top Side Placement........................................................................................................ 6
4 Top Side Routing ........................................................................................................... 7
5 Layer Two Routing.......................................................................................................... 7
6 Layer Three Routing........................................................................................................ 8
7 Bottom Side Routing........................................................................................................ 8
8 Bottom Side Placement .................................................................................................... 9
List of Tables
1 TPS2378EVM Electrical and Performance Specifications............................................................. 2
2 Connector Functionality.................................................................................................... 5
3 Test Points................................................................................................................... 5
4 Jumpers ...................................................................................................................... 5
5 TPS2378EVM Bill of Materials .......................................................................................... 10
1
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Introduction www.ti.com
1 Introduction
The TPS2378EVM allows reference circuit evaluation of the TI TPS2378 PD controller. The TPS2378
features an auxiliary power detect (APD) input, providing priority for an external power adapter. It also
features a 100 V pass transistor, 140 mA inrush current limiting, type-2 indication, auto-retry fault
protection, and an open-drain power-good output.
1.1 Features
• Gigabit Ethernet pass through interface
• Switched output return for “ease of use” loading
• Adapter input capability
• IEEE 802.3at type-2 hardware classification with status flag (T2P) and LED
• DC/DC converter enable (CDB)
• Robust 100 V, 0.5 Ωhotswap MOSFET
• Operating current up to 1A typical
1.2 Applications
• IEEE 802.3at-compliant devices
• Video and VoIP telephones
• Multiband access points
• Security cameras
• Pico-base stations
2 Electrical Specifications at 25°C
Table 1. TPS2378EVM Electrical and Performance Specifications
PARAMETER CONDITION MIN TYP MAX UNITS
POWER INTERFACE
Input Voltage Applied to the power pins of connectors J1 or J3 0 – 57 V
Operating Voltage After start up. 30 – 57 V
Rising input voltage at device terminals. – – 40
Input UVLO V
Falling input voltage. 30.5 – –
Detection voltage At device terminals 1.4 – 10.1 V
Classification voltage At device terminals 11.9 – 23.0 V
Classification current Rclass = 63.4 Ω38 – 42 mA
Inrush current-limit 100 – 180 mA
Operating current-limit 850 – 1200 mA
Two input pairs:
Efficiency 97.4%
Measured from J1 to J6 with J5 shorted. 31W output power
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www.ti.com Description
3 Description
TPS2378EVM-105 enables full evaluation of the TPS2378 device. Refer to the schematic shown in
Figure 1. Ethernet power is applied from J1 to T1 and is dropped to the diode bridges (D4/D5/D10/D11 or
D6/D7/D12/D13) from the T1 center taps. The series R-C circuit from each center tap help balance the
Ethernet cable impedance and are critical for ESD and EMI/EMC performance. These circuits are
terminated at TP11 (EGND) through the high voltage capacitor, C11. At the output of the diode bridges is
the EMI/EMC filter and transient protection for the TPS2378. R9 provides the detection signature and R15
provides the class 4 signature resistance to the PSE.
To the right of the TPS2378 (U1) is the switched side of the PD controller. The TPS2378 RTN pin
provides inrush limited turn on and charge of the bulk capacitor, C4. During inrush, the TPS2378 CDB pin
is pulled low (with respect to the RTN pin). Since the CDB pin is connected to the GATE of Q1, Q1 is off
during inrush and J6 pin 1 is not connected to the RTN pin. This allows the output load to remain
connected during EVM testing.
Input power can also be applied at J3 from a dc source. EMI/EMC filtering is provided at this connector as
well and diode D1 ensures reverse voltage protection. R4 and R7 provide a threshold for the TPS2378
APD pin so that the TPS2378 internal MOSFET is disabled when the voltage at J3 is above approximately
38V. This ensures that the adapter has priority over the PSE source. LED’s D2 and D3 provide operational
visual indications of T2P and ON respectively.
3
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PAIR36
PAIR78
PAIR45
PAIR12
VSS
VDD
APD
T2P
CDB
RTN
(ON)
(T2P)
CDB
RTN
T2P
VDD
LED BIAS
+
-
+
-
SWITCHED
OUTPUT
+48V, 1A
ADAPTER
INPUT
+33-57V, 1A
POE INPUT ETHERNET DATA
EGND
2a 2b
2
NOTES
1NOT USED
a. Use for switched RTN
b. Use to "OR" second TPS2378
1
1VDD
2DEN
3CLS
4VSS 5
RTN
6
CDB
7
T2P
8
APD
9PWPD
U1
TPS2378DDA
1
2
3
4
5
6
7
8
J1
1
2
3
4
5
6
7
8
J2
R15
63.4
FB3 500
D4
B2100
D8
SMAJ58A
C9
1000pF
R9
24.9k
C10
0.1uF
C11
1000pF
R10
75
C5
0.01uF
R11
75
C6
0.01uF
R12
75
C7
0.01uF
R13
75
C8
0.01uF
D10
B2100
D5
B2100
D11
B2100
D6
B2100
D12
B2100
D7
B2100
D13
B2100
FB4 500
+C4
47uF
R6
12.1k
1
2
J4
D2
LN1271RAL
D3
LN1371G
R8
12.1k
FB1 500 D1 B2100
C1
1000pF
C2
0.1uF
R4
237k
R7
10k
R3 75
R5 75
R2 75
R1 75
R14 100k
TP6
TP10
TP1
TP2
TP4
TP3
TP5
TP7
TP9
TP8
FB2 500
C3
0.01uF
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
T1
Q1
IRFL4310
D14
BZT52C18V D9 B2100
1
2
J5
C12
1000pF
1
2
3
4
J6
1
2
J3
TP11
Schematic www.ti.com
4 Schematic
Figure 1. TPS2378EVM Schematic
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www.ti.com General Configuration and Description
5 General Configuration and Description
5.1 Physical Access
Table 2 lists the TPS2378EVM connector functionality, Table 3 describes the test point availability and
Table 4 describes the jumper functionality.
Table 2. Connector Functionality
Connector Label Description
Power over ethernet (POE) input. Connect to power sourcing equipment (PSE) power and data
J1 PWR+DATA source.
J2 DATA Ethernet data pass through. Connect to downstream ethernet device.
DC adapter input. Connect to dc power supply. DC voltage above 38V will disable the TPS2378
J3 ADAPTER internal MOSFET and activate the T2P LED.
Output connector to load. Connect pin #4 (VDD) to positive input and pin #1 (RTN) to low side of
J6 J6 load. Pin #2 (CDB) can be used to inhibit the converter while the TPS2378 output is ramping up. Pin
#3 (T2P) can be used to notify the load of when high power source is present.
T2P (type 2 PSE) LED. When ON this indicates that either a type 2 PSE is detected or an adapter
D2 (RED) T2P voltage source (above 38V) is present at J3.
D3 (GREEN) ON TPS2378 Output Powered.
Table 3. Test Points
Test Point Color Label Description
TP1 WHT APD Auxiliar power detect
TP2 RED PAIR12 Data pair from pins 1 and 2 of J1
TP3 ORG PAIR36 Data pair from pins 3 and 6 of J1
TP4 RED PAIR45 Spare pair from pins 4 and 5 of J1
TP5 ORG PAIR78 Spare pair from pins 7 and 8 of J1
TP6 RED VDD High side output from bridge
TP7 WHT T2P Type 2 PSE output from TPS2378
TP8 BLK RTN Switched low side from TPS2378
TP9 WHT CDB Converter disable output from TPS2378
TP10 BLK VSS Low side output from bridge
TP11 SM EGND Earth or chassis ground point
Table 4. Jumpers
Jumper Label Description
J4 J4 LED bias jumper. Install to furnish LED bias for T2P and ON LED’s
J5 J5 Switched output return bypass jumper.
5.2 Test Setup
Figure 2 shows a typical test setup for TPS2378EVM. Connect J1 to the power sourcing equipment (PSE)
or alternatively connect J3 to a wall adapter or power supply. Power for the Ethernet device is available at
J6 and the pass through Ethernet data is available at J2.
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PSE
Ethernet
Device
DUT
TPS2378EVM
J1 J2
J3
J6
VDD
SRTN
- +
(Ethernet Cable)
Wall Adapter
T2P
CDB
EVM Assembly Drawings and Layout Guidelines www.ti.com
Figure 2. Typical TPS2378EVM Test Setup
6 EVM Assembly Drawings and Layout Guidelines
6.1 PC Drawings
The following figures show component placement and layout of the EVM.
Figure 3. Top Side Placement
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www.ti.com EVM Assembly Drawings and Layout Guidelines
Figure 4. Top Side Routing
Figure 5. Layer Two Routing
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EVM Assembly Drawings and Layout Guidelines www.ti.com
Figure 6. Layer Three Routing
Figure 7. Bottom Side Routing
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www.ti.com EVM Assembly Drawings and Layout Guidelines
Figure 8. Bottom Side Placement
6.2 Layout Guidelines
The layout of the PoE front end should follow power and EMI/ESD best practice guidelines. A basic set of
recommendations include:
• Parts placement must be driven by power flow in a point-to-point manner; RJ-45, Ethernet transformer,
diode bridges, TVS and 0.1-µF capacitor, and TPS2378.
• All leads should be as short as possible with wide power traces and paired signal and return.
• There should not be any crossovers of signals from one part of the flow to another.
• 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 TPS2378 should be located over split, local ground planes referenced to VSS for the PoE input
and to RTN for the switched output.
• 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.
6.3 EMI Containment
• Use compact loops for dv/dt and di/dt circuit paths (power loops and gate drives)
• Use minimal, yet thermally adequate, copper areas for heat sinking of components tied to switching
nodes (minimize exposed radiating surface).
• Use copper ground planes (possible stitching) and top layer copper floods (surround circuitry with
ground floods)
• Use 4 layer PCB if economically feasible (for better grounding)
• Minimize the amount of copper area associated with input traces (to minimize radiated pickup)
• Use Bob Smith terminations, Bob Smith EFT capacitor, and Bob Smith plane
• Use Bob Smith plane as ground shield on input side of PCB (creating a phantom or literal earth
ground)
• Use of ferrite beads on input (allow for possible use of beads or 0 ohm resistors)
• Maintain physical separation between input-related circuitry and power circuitry (use ferrite beads as
boundary line)
• Possible use of common-mode inductors
• Possible use of integrated RJ-45 jacks (shielded with internal transformer and Bob Smith terminations)
• End-product enclosure considerations (shielding)
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Bill of Materials www.ti.com
7 Bill of Materials
Table 5. TPS2378EVM Bill of Materials
Count REFDES Value Description Size Part Number Supplier
4 FB1-4 500 Bead, Ferrite, 2000mA, 60m-ohm 1206 MI1206L501R-10 Steward
5 C3 C5-8 0.01uF Capacitor, Ceramic, 100V, X7R, 10% 603 STD STD
2 C1 C9 1000pF Capacitor, Ceramic, 100V, X7R, 10% 603 STD STD
2 C2 C10 0.1uF Capacitor, Ceramic, 100V, X7R, 10% 805 STD STD
2 C11-12 1000pF Capacitor, Ceramic, 2kV, X7R, 15% 1210 Std STD
1 C4 47uF Capacitor, Aluminum, 63V, ±20% 0.328 x 0.390 inch EEE-FK1J470P Panasonic
2 J1-2 5520252-4 Connector, Jack, Modular, 8 POS 0.705 x 0.820 inch 5520252-4 AMP
1 D14 BZT52C18V Diode, Zener, Planar Power, 500mW, 18V SOD-123 BZT52C18-7-F Diodes, Inc
1 D2 LN1271RAL Diode, LED, Ultra Bright Red, 10-mA, 5-mcd 0.114 X 0.049 inch LN1271RAL Panasonic
1 D3 LN1371G Diode, LED, Green, 10-mA, 2.6-mcd 0.114 X 0.049 inch LN1371G Panasonic
9 D1 D4-7 D10-13 B2100 Diode, Schottky, 2-A, 100-V SMB B2100-13-F Diodes, Inc
0 D9 B2100 Diode, Schottky, 2-A, 100-V SMB B2100-13-F Diodes, Inc
1 D8 SMAJ58A Diode, TVS, 58-V, 1W SMA SMAJ58A-13-F Diodes, Inc
2 J4 J5 PEC02SAAN Header, Male 2-pin, 100mil spacing 0.100 inch x 2 PEC02SAAN Sullins
1 R14 100k Resistor, Chip, 1/16W, 1% 603 STD STD
1 R7 10k Resistor, Chip, 1/16W, 1% 603 STD STD
1 R4 237k Resistor, Chip, 1/16W, 1% 603 STD STD
1 R9 24.9k Resistor, Chip, 1/16W, 1% 603 STD STD
8 R1-3 R5 R10-13 75 Resistor, Chip, 1/16W, 1% 603 STD STD
1 R15 63.4 Resistor, Chip, 1/10W, 1% 805 STD STD
2 R6 R8 12.1k Resistor, Chip, 0.6W, 1% 2010 STD STD
1 J6 ED120/4DS Terminal Block, 4-pin, 15-A, 5.1mm 0.80 x 0.35 inch ED120/4DS OST
1 J3 ED555/2DS Terminal Block, 2-pin, 6-A, 3.5mm 0.27 x 0.25 inch ED555/2DS OST
3 TP2 TP4 TP6 5010 Test Point, Red, Thru Hole 0.125 x 0.125 inch 5010 Keystone
2 TP8 TP10 5011 Test Point, Black, Thru Hole 0.125 x 0.125 inch 5011 Keystone
3 TP1 TP7 TP9 5012 Test Point, White, Thru Hole 0.125 x 0.125 inch 5012 Keystone
2 TP3 TP5 5013 Test Point, Orange, Thru Hole 0.125 x 0.125 inch 5013 Keystone
1 TP11 5016 Test Point, SM, 0.150 x 0.090 0.185 x 0.135 inch 5016 Keystone
1 U1 TPS2378DDA IC, IEEE 802.3at PoE High Power PD Controller TPS2378DDA TPS2378DDA TI
1 Q1 IRFL4310 MOSFET, N-ch, 100V, 200-milliOhms SOT223 IRFL4310TRPBF IRF
Wurth
749022011 749022011 Electronics
1 T1 or PoE Plus Gigabit Ethernet Transfomer S024 or or
H6096NL H6096NL Pulse
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