MAX5981A MAXIM [Maxim Integrated Products], MAX5981A Datasheet - Page 13
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MAX5981A
Manufacturer Part Number
MAX5981A
Description
IEEE 802.3af/at-Compliant, Powered Device Interface
Manufacturer
MAXIM [Maxim Integrated Products]
Datasheet
1.MAX5981A.pdf
(16 pages)
Figure 2. Typical Configuration When Using a 12V Wall Power Adapter
Careful PCB layout is critical to achieve high efficiency
and low EMI. Follow these layout guidelines for optimum
performance:
1) Place the input capacitor, classification resistor, and
2) Use large SMT component pads for power dissipat-
IEEE 802.3af/at-Compliant, Powered Device Interface
-54V
RECTIFIER
BRIDGE
transient voltage suppressor as close as possible to
the MAX5981A/MAX5981B.
ing devices such as the MAX5981A/MAX5981B and
the external diodes.
RJ-45
AND
SMAJ58A
GND
Applications Information
______________________________________________________________________________________
24.9kI
68nF
R
R
Operation with 12V Adapter
CLS
DET
Controllers with
CLS
DET
V
SS
V
DD
MAX5981A
MAX5981B
Layout Procedure
2EC/WAD
1.5mA
2EC
PG
WAD
RTN
Integrated Power MOSFET
BATTERY
3) Use short and wide traces for high-power paths.
4) Use the MAX5981A/MAX5981B evaluation kit layout
5) Place enough vias in the pad for the EP of the
12V
CLASSIFICATION
(ASSERTED ON)
as a reference.
MAX5981A/MAX5981B so that heat generated inside
can be effectively dissipated by the PCB copper.
The recommended spacing for the vias is 1mm to
1.2mm pitch. The thermal vias should be plated (1oz
copper) and have a small barrel diameter (0.3mm to
0.33mm).
2-EVENT
PROPER 2EC LOGIC WHEN
THIS CIRCUIT ACHIEVES
BATTERY IS < 12.5V
ENABLE
CONVERTER
DC-DC
IN+
IN-
GND
13