11 Power Supply Recommendation

The REF70 family of references features a low-dropout voltage. These references can be operated with a supply

of only 50 mV above the output voltage for 0-mA output current conditions. The dropout voltage will vary with the

output current so refer to the dropout voltage to see typical dropout voltage requirements. TI recommends a

supply bypass capacitor ranging between 0.1 µF to 10 µF.

During start-up the REF70 can experience moments of high input current due to the output capacitors. The input

Load Current (mA)

0

1

2

3

4

5

6

7

8

9

10

0

0.025

0.05

0.075

0.1

0.125

0.15

0.175

0.2

0.225

0.25

-40

25

125

Figure 11-1. Dropout Voltage

12 Layout Guidelines

Figure 13-1 illustrates an example of a PCB layout for a data acquisition system using the REF70. Some key

considerations are:

• Connect low-ESR, 1-uF to 100-uF capacitor at OUTF of the REF70.

• 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.

www.ti.com

REF70

SNAS781 – OCTOBER 2020

Copyright © 2020 Texas Instruments Incorporated

Submit Document Feedback

15

Product Folder Links: REF70