VCC
VSS
VCC
GND
VSS
GND
VDD
+
5VA
+3.3VD
FSX
SDI
CLK
CS
(J1)
(J3)
(J6)
(P6)
(J2)
(P2)
VDD
TP1
V
DD
V
REF
I
OUT
R
FB
AGND
DAC Module
W3
U5
(J4)
(P4)
TP6
J5
TP7
W15
W5
VSS
W1
−V
REF
VCC
+V
REF
RF102
INA105
Output
Buffer
Module
TP5
DAC Out
PCB Design and Performance
www.ti.com
A block diagram of the DAC8801/11EVM is shown in
Figure 1. DAC8801/11EVM Block Diagram
5
PCB Design and Performance
This section covers the layout design of the PCB describing the physical and mechanical characteristics of
the EVM. It shows the resulting performance of the EVM, which can be compared to the device
specification listed in the data sheet.
5.1
PCB Layout
The DAC8801/11EVM is designed to demonstrate the performance quality of the installed MDAC device
under test, as specified in the data sheet. Careful analysis of the EVM physical restrictions and factors that
contributes to the EVM performance degradation is the key to a successful design implementation. The
obvious attributes that contributes to the poor performance of the EVM can be avoided during the
schematic design phase by properly selecting the right components and designing the circuit correctly.
The circuit should include adequate bypassing, identifying and managing the analog and digital signals
and knowing or understanding the components mechanical attributes.
A critical part to any design lies in the layout process. Placement of components and the proper routing of
signals can greatly improve the performance of the overall system. Bypass capacitors should be placed as
closely as possible to the pins and the analog and digital signals should be properly separated from each
other. The power and ground planes are very important and should be carefully considered in the layout
process. A solid plane is ideally preferred but sometimes impractical, so when solid planes are not
possible, a split plane will do the job. When considering a split plane design, analyze the component
placement and carefully split the board into its analog and digital sections starting from the device under
test. The ground plane plays an important role in controlling the noise and other effects that otherwise
4
DAC8801/11EVM
SLAU151A – January 2005 – Revised November 2009
Copyright © 2005–2009, Texas Instruments Incorporated
