12 Layout

12.1 Layout Guidelines

Figure 12-1 illustrates an example of a PCB layout for a data acquisition system using the REF35. Some key

considerations are:

• Decouple other active devices in the system per the device specifications.

• Using a solid ground plane helps distribute heat and reduces electromagnetic interference (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.

• 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.

Figure 12-2 illustrates pin compatibility with TI REF30xx, REF31xx and REF33xx series references in SOT23-3

package when using REF35xxx family footprint. Key is to rotate the REF30xx, REF31xx and REF33xx reference

devices by 180º before assembly.

12.2 Layout Example

Not to scale

VREF

NR

VIN

GND

GND

EN

1

2

3

6

5

4

C

C

Figure 12-1. Layout Example

Not to scale

REF35

REF30

REF31

REF33

VREF

OUT (Pin 2)

NR

VIN

IN (Pin 1)

GND

GND (Pin 3)

GND

EN

1

2

3

6

5

4

C

C

Figure 12-2. Pin Compatibility with REF30xx,

REF31xx and REF33xx

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REF35

SNAS809 – DECEMBER 2021

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Product Folder Links: REF35