Datasheet

AD8139
Rev. B | Page 23 of 24
Exposed Paddle (EP)
Because this is a single-ended-to-differential application on a
single supply, the input common-mode voltage swing must be
checked. From
Figure 64, β = 0.52, V
OCM
= 2.4 V, and V
ICM
is
1.1 V p-p swinging about ground. Using Equation 16, V
ACM
is
calculated to be 0.53 V p-p swinging about a baseline of 1.25 V,
and the minimum negative excursion is approximately 1 V.
The 8-lead SOIC and the 8-lead LFCSP have an exposed paddle
on the bottom of the package. To achieve the specified thermal
resistance, the exposed paddle must be soldered to one of the
PCB planes. The exposed paddle mounting pad should contain
several thermal vias within it to ensure a low thermal path to
the plane.
AD8139
+
–
8
2
1
6
3
4
2.4V
2V p-p
R
T
61.9Ω
5
V
OCM
200Ω
226Ω
205Ω
205Ω 25Ω
25Ω
0.01µF
0.01µF 0.01µF
AIN
AIN
GND C1
0.1µF
C2 VREF
0.1µF
AV
CC
DV
CC
5
V
3.3
V
AD6645
V
S
SIGNAL
SOURCE
50Ω
04679-054
Figure 64. AD8139 Driving AD6645, 14-Bit, 80 MSPS/105 MSPS ADC