LTC1856 Linear Technology, LTC1856 Datasheet - Page 22

• Manufacturer Part Number: LTC1856
• Description: 100ksps ADC Converters
• Manufacturer: Linear Technology

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LTC1854/LTC1855/LTC1856
APPLICATIO S I FOR ATIO
LTC1855/LTC1856 can be tied to the analog ground plane.
Placing the bypass capacitor as close as possible to the
power supply pins, the reference and reference buffer
output is very important. Low impedance common returns
for these bypass capacitors are essential to low noise op-
eration of the ADC, and the foil width for these tracks should
be as wide as possible. Also, since any potential difference
22
U
+
–
U
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
LTC1854/
LTC1855/
LTC1856
MUXOUT
MUXOUT
W
+
–
10
11 13
Figure 13. Power Supply Grounding Practice
12
ADC
ADC
ANALOG GROUND PLANE
U
+
–
V
REF
15
1μF
REFCOMP
16
10μF
AGND
LTC1854/LTC1855/LTC1856
in grounds between the signal source and ADC appears as
an error voltage in series with the input signal, attention
should be paid to reducing the ground circuit impedance
as much as possible. The digital output latches and the
onboard sampling clock have been placed on the digital
ground plane. The two ground planes are tied together at
the ADC through a wide, low inductance path.
14, 17, 18
AV
DD
19
10μF
DV
DD
20
10μF
DGND
24
OV
GROUND PLANE
DD
21
DIGITAL
10μF
18545 F13
SYSTEM
DIGITAL
185456fa