kad2708c Kenet Inc., kad2708c Datasheet - Page 14

• Manufacturer Part Number: kad2708c
• Description: 8-bit, 275msps Analog-to-digital Converter
• Manufacturer: Kenet Inc.

KAD2708C 8-Bit, 275MSPS Analog-to-Digital Converter
Equivalent Circuits
Rev 1.1
Figure 25. LVCMOS Outputs
Figure 23. Analog Inputs
Figure 24. Clock Inputs
Layout Considerations
Split Ground and Power Planes
Data converters operating at high sampling frequen-
cies require extra care in PC board layout. Many
complex board designs benefit from isolating the
analog and digital sections. Analog supply and
ground planes should be laid out under signal and
clock inputs. Locate the digital planes under outputs
and logic pins. Grounds should be joined under the
chip.
Clock Input Considerations
Use matched transmission lines to the inputs for the
analog input and clock signals. Locate transformers,
drivers and terminations as close to the chip as possi-
ble.
Bypass and Filtering
Bulk capacitors should have low equivalent series re-
sistance. Tantalum is a good choice. For best per-
formance, keep ceramic bypass capacitors very
close to device pins. Longer traces will increase in-
ductance, resulting in diminished dynamic perform-
ance and accuracy. Make sure that connections to
ground are direct and low impedance. Avoid form-
ing ground loops.
LVCMOS Outputs
Output traces and connections must be designed for
50Ω characteristic impedance.
Unused Inputs
Three of the four standard logic inputs (RESET, CLKDIV,
2SC) which will not be operated do not require con-
nection for best ADC performance. These inputs can
be left open if they are not used. VREFSEL must be
held low for internal reference, but can be left open
for external reference.
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