kad5512p-21q72ep-i Intersil Corporation, kad5512p-21q72ep-i Datasheet - Page 28

• Manufacturer Part Number: kad5512p-21q72ep-i
• Description: Low Power 12-bit, 250/210/170/125msps Adc
• Manufacturer: Intersil Corporation

Equivalent Circuits
Layout Considerations
Split Ground and Power Planes
Data converters operating at high sampling frequencies
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 transformer inputs for
the analog input and clock signals. Locate transformers and
terminations as close to the chip as possible.
Exposed Paddle
The exposed paddle must be electrically connected to
analog ground (AVSS) and should be connected to a large
copper plane using numerous vias for optimal thermal
performance.
DATA
DATA
2mA OR
2mA OR
3mA
3mA
OVDD
FIGURE 46. LVDS OUTPUTS
DATA
DATA
(Continued)
28
OVDD
0.535V
OVDD
+
–
FIGURE 48. VCM_OUT OUTPUT
D[11:0]P
D[11:0]N
KAD5512P
Bypass and Filtering
Bulk capacitors should have low equivalent series
resistance. Tantalum is a good choice. For best
performance, keep ceramic bypass capacitors very close to
device pins. Longer traces will increase inductance, resulting
in diminished dynamic performance and accuracy. Make
sure that connections to ground are direct and low
impedance. Avoid forming ground loops.
LVDS Outputs
Output traces and connections must be designed for 50Ω
(100Ω differential) characteristic impedance. Keep traces
direct and minimize bends where possible. Avoid crossing
ground and power-plane breaks with signal traces.
LVCMOS Outputs
Output traces and connections must be designed for 50Ω
characteristic impedance.
Unused Inputs
Standard logic inputs (RESETN, CSB, SCLK, SDIO, SDO)
which will not be operated do not require connection to
ensure optimal ADC performance. These inputs can be left
DATA
AVDD
FIGURE 47. CMOS OUTPUTS
VCM
OVDD
OVDD
D[11:0]
January 16, 2009
FN6807.1