LTC2754 LINER [Linear Technology], LTC2754 Datasheet - Page 22

• Manufacturer Part Number: LTC2754
• Description: Quad 12-/16-Bit SoftSpan IOUT DACs
• Manufacturer: LINER [Linear Technology]

LTC2754
APPLICATIONS INFORMATION
As precision DAC applications move to 16-bit and higher
performance, reference output voltage noise may contrib-
ute a dominant share of the system’s noise fl oor. This in
turn can degrade system dynamic range and signal-to-
noise ratio. Care should be exercised in selecting a voltage
reference with as low an output noise voltage as practi-
cal for the system resolution desired. Precision voltage
references, like the LT1236, produce low output noise in
the 0.1Hz to 10Hz region, well below the 16-bit LSB level
in 5V or 10V full-scale systems. However, as the circuit
bandwidths increase, fi ltering the output of the reference
may be required to minimize output noise.
Grounding
As with any high resolution converter, clean grounding is
important. A low impedance analog ground plane and star
grounding techniques should be used. I
to the star ground with as low a resistance as possible.
22
OUT2X
must be tied
When it is not possible to locate star ground close to
I
pin to star ground. This minimizes the voltage drop from
this pin to ground caused by the code-dependent current
fl owing to ground. When the resistance of this circuit
board trace becomes greater than 1Ω, a force/sense am-
plifi er confi guration should be used to drive this pin (see
Figure 5). This preserves the excellent accuracy (1LSB
INL and DNL) of the LTC2754-16.
Layout
Figures 6, 7, 8, and 9 show the layout for the LTC2754
evaluation board, DC1546. This shows how to route the
digital signals around the device without interfering with
the reference and output op amps. Complete demo board
documentation is available in the DC1546 “Quick Start
Guide.”
OUT2
, a low resistance trace should be used to route this
2754f