Datasheet

C
C
OUT
IN
REF
AIN
Microcontroller
ADC Input
REF33xx
Via to
GND Plane
Via to
Input Power
GND
Input Signal
REF3312 , REF3318 , REF3320 , REF3325 , REF3330 , REF3333
SBOS392D –AUGUST 2007–REVISED JUNE 2014 www.ti.com
12 Layout
12.1 Layout Guidelines
For optimal performance of this design, follow standard printed circuit board (PCB) layout guidelines, including
proper decoupling close to all integrated circuits and adequate power and ground connections with large copper
pours. Select a PCB size with connectors that connect directly to the MSP430 LaunchPad™.
Figure 25 illustrates an example of a PCB layout for a data acquisition system using the REF33xx.
Some key considerations are:
• Connect a low-ESR, 1-μF ceramic capacitor at the IN pin for bypass, and a 0.1µF to 10µF ceramic capacitor
at the OUT pin for stability of the REF33xx.
• Decouple other active devices in the system per the device specifications.
• Use a solid ground plane helps distribute heat and reduces EMI noise pickup.
• Place the external components as close to the device as possible. This configuration prevents parasitic errors
(such as the Seebeck effect) from occurring.
• Minimize trace length between the reference and bias connections to the ADC to reduce noise pickup.
• Do not run sensitive analog traces in parallel with digital traces. Avoid crossing digital and analog traces if
possible, and only make perpendicular crossings when absolutely necessary.
12.2 Layout Example
Figure 25. Layout Example
18 Submit Documentation Feedback Copyright © 2007–2014, Texas Instruments Incorporated
Product Folder Links: REF3312 REF3318 REF3320 REF3325 REF3330 REF3333