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Description
Demonstration circuit 2475A-A is an IEEE802.3bt (Draft 2.0)
compliant Power over Ethernet (PoE) powered device (PD).
It features the
LT
4295
PD interface and switching regulator
®
controller with the LT4321 PoE ideal diode bridge controller.
The LT4295 provides IEEE802.3af (PoE, Type 1),
IEEE802.3at (PoE + , Type 2), and IEEE802.3bt (PoE ++ ,
Type 3 and 4) compliant interfacing and power supply
control. It utilizes an external, low R
cal) N-channel FET for the Hot Swap function to improve
efficiency. The LT4295 controls a DC/DC converter that
utilizes a highly efficient flyback topology with synchro-
nous rectification.
The LT4321 controls eight low R
N-channel FETs to further improve end-to-end power
performance summary
PARAMETER
Port Voltage (V
)
PORT
Auxiliary Voltage
Output Voltage (V
)
OUT
Output Current (I
)
OUT
Output Voltage Ripple
Load Regulation
Efficiency
Switching Frequency
BoarD photo
High Efficiency IEEE802.3bt (PoE ++ , Type 3,
40W) PD with PoE Ideal Diode Bridge
(57mΩ typi-
DS(ON)
(57mΩ typical)
DS(ON)
CONDITIONS
At RJ45
+
–
From AUX
to AUX
Terminals
V
= 44V, I
= 3A
PORT
OUT
V
= 50V, I
= 3A, End-to-End
PORT
OUT
Top Side
DEMO MANUAL
delivery efficiency and ease thermal design. This solution
replaces the eight diodes typically found in a passive PoE
rectifier bridge.
The DC2475A-A accepts up to 40W of delivered power
from a power sourcing equipment (PSE) via the RJ45
connector (J1) or a local 48VDC power supply using the
auxiliary supply input. When both supplies are connected,
the auxiliary supply input has priority over the PoE input.
The DC2475A-A supplies a 12V output at up to 3A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2475A-A
L, LT, LTC, LTM, Linear Technology, the Linear logo and LTPoE ++ are registered trademarks of
Analog Devices, Inc. All other trademarks are the property of their respective owners.
VALUE
37V to 57V
37V to 57V
12V (Typical)
3A (Max)
85mV
(Typical)
P-P
±0.1% (Typical)
92% (Typical)
250kHz (Typical)
Bottom Side
DC2475A-A
LT4295, LT4321
dc2475aafb
1
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Related Manuals for Linear Technology DC2475A-A
Summary of Contents for Linear Technology DC2475A-A
- Page 1 L, LT, LTC, LTM, Linear Technology, the Linear logo and LTPoE ++ are registered trademarks of The LT4321 controls eight low R (57mΩ typical) Analog Devices, Inc. All other trademarks are the property of their respective owners.
-
Page 2: Typical Performance Characteristics
DEMO MANUAL DC2475A-A typicaL performance characteristics Bottom Side Top Side Figure 1. Thermal Pictures (Conditions: V = 44V, V = 12V, I = 3A) PORT 12.20 12.15 12.10 12.05 12.00 11.95 PORT PORT 11.90 11.85 11.80 LOAD CURRENT (A) LOAD CURRENT (A) - Page 3 DEMO MANUAL DC2475A-A typicaL performance characteristics Figure 4. Switch Node Waveforms (Conditions: V = 57V, V = 12V, I = 3A) PORT Figure 5. Output Voltage Ripple (Conditions: V = 44V, V = 12V, I = 3A) PORT dc2475aafb...
- Page 4 DEMO MANUAL DC2475A-A typicaL performance characteristics Figure 6. Load Transient Response (Conditions: V = 44V, Load Step: 1.5A to 3A to 1.5A) PORT Figure 7. Gain and Phase Margin of the Flyback DC/DC Converter (Conditions: V = 44V, V = 12V, I...
-
Page 5: Quick Start Procedure
® 4. Connect the output of the IEEE 802.3bt compliant PSE may be used to provide power to the DC2475A-A. The to the RJ45 connector (J1) of the DC2475A using a LTPoE ++ classification will not be 802.3bt compliant, but CAT5e or CAT6 Ethernet cable. - Page 6 DEMO MANUAL DC2475A-A QuicK start proceDure 4. Once the LED (D4) on the DC2475A is lit, check the Auxiliary Supply Input output voltage using a voltmeter. Output voltage should 1. Place and connect test equipment (voltmeter, ammeter, be within 12.0V ± 0.2V.
-
Page 7: Parts List
DEMO MANUAL DC2475A-A parts List ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER DC2475A General BOM CAP , CER, X7R 1000pF 2kV 10% 1808 MURATA GR442QR73D102KW01L CAP , CER, X7R 0.01µF 100V 20% 1206 AVX 12061C103MAT2A CAP , CER, OPT 2kV 1812 CAP , CER, X7U OPT 6.3V 10% 1210... - Page 8 DEMO MANUAL DC2475A-A parts List ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Q1, Q11, Q12, Q13, MOSFET, N-CH, PSMN075-100MSE 100V LFPAK33 NXP PSMN075-100MSE Q14, Q15, Q16, Q17, TRANSISTOR, PNP , MMBT3906 40V SOT23 FAIRCHILD MMBT3906 TRANSISTOR, NPN, MMBT3904 40V SOT23 FAIRCHILD MMBT3904...
- Page 9 DEMO MANUAL DC2475A-A parts List ITEM REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER MOSFET, N-CH, 100V TSON TOSHIBA TPN1600ANH MOSFET, N-CH, OPT SOT23 MOSFET, N-CH, 200V TDSON-8 INFINEON BSZ900N20NS3 RES, CHIP , 1.5k 5% 0805 NIC NRC10J152TRF RES, CHIP , 200Ω 5% 1206 NIC NRC12F2000TRF RES, CHIP , 200Ω...
- Page 10 DEMO MANUAL DC2475A-A schematic Diagram dc2475aafb...
-
Page 11: Schematic Diagram
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. - Page 12 Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods.
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