Datasheet

LTC4290/LTC4271
27
429071fa
For more information www.linear.com/LTC4290
ApplicAtions inForMAtion
Figure 16. LTC4290 Discharge Protection
ESD/Cable Discharge Protection
Ethernet ports can be subject to significant ESD events
when long data cables, each potentially charged to thou
-
sands of volts, are plugged into the low impedance of the
RJ45 jack. To protect against damage, each port requires a
pair of clamp diodes; one to AGND and one to V
EE
(Figure
16). An additional surge suppressor is required for each
LTC4290 chip from V
EE
to AGND. The diodes at the ports
steer harmful surges into the supply rails, where they are
absorbed by the surge suppressor and the V
EE
bypass
capacitance. The surge suppressor has the additional
benefit of protecting the LTC4290 from transients on the
V
EE
supply.
S1B diodes work well as port clamp diodes, and an
SMAJ58A or equivalent is recommended for the V
EE
surge
suppressor.
LAYOUT GUIDELINES
Strict adherence to board layout, parts placement and
routing guidelines is critical for optimal current read
-
ing accuracy, IEEE compliance, system robustness, and
thermal dissipation. Refer to the DC1842A Demo Board
as a layout reference. Contact LTC Applications to obtain
a full set of layout guidelines, example layouts and BOMs.
0.22µF
0.25Ω
S1B
PORTn
OUTn
GATEn
SENSEn
A
GND
V
EE
S1B
429071 F16
–54V
SMAJ58A
LTC4290
0.1µF