LTC2205 Linear Technology, LTC2205 Datasheet - Page 29

• Manufacturer Part Number: LTC2205
• Description: (LTC2204 / LTC2205) 65Msps/40Msps
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
Grounding and Bypassing
The LTC2205/LTC2204 require a printed circuit board with a
clean unbroken ground plane; a multilayer board with an
internal ground plane is recommended. The pinout of the
LTC2205/LTC2204 has been optimized for a fl owthrough
layout so that the interaction between inputs and digital
outputs is minimized. Layout for the printed circuit board
should ensure that digital and analog signal lines are
separated as much as possible. In particular, care should
be taken not to run any digital track alongside an analog
signal track or underneath the ADC.
High quality ceramic bypass capacitors should be used
at the V
be located as close to the pins as possible. The traces
connecting the pins and bypass capacitors must be kept
short and should be made as wide as possible.
DD,
V
CM
ANALOG
INPUT
, and OV
AIN
AIN
+
–
DD
LTC2205/LTC2204
Figure 14. Functional Equivalent Block Diagram of Internal Dither Circuit
pins. Bypass capacitors must
CLOCK/DUTY
ENC
CONTROL
AMP
S/H
CYCLE
+
ENC
–
PRECISION
PIPELINED
ADC CORE
16-BIT
DAC
The LTC2205/LTC2204 differential inputs should run
parallel and close to each other. The input traces should
be as short as possible to minimize capacitance and to
minimize noise pickup.
Heat Transfer
Most of the heat generated by the LTC2205/LTC2204 is
transferred from the die through the bottom-side exposed
pad. For good electrical and thermal performance, the
exposed pad must be soldered to a large grounded pad
on the PC board. It is critical that the exposed pad and all
ground pins are connected to a ground plane of suffi cient
area with as many vias as possible.
SUMMATION
DIGITAL
PSEUDO-RANDOM
HIGH = DITHER ON
LOW = DITHER OFF
MULTIBIT DEEP
DITHER ENABLE
GENERATOR
NUMBER
LTC2205/LTC2204
DRIVERS
OUTPUT
DITH
22054 F14
CLKOUT
D15
D0
OF
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