OUT

GND

IN

C

C

REF31xx

To ADC

To Input Power Supply

Via to Ground Plane

17

REF3112, REF3120, REF3125

REF3130, REF3133, REF3140

www.ti.com

SBVS046D – DECEMBER 2003 – REVISED MARCH 2016

Product Folder Links: REF3112 REF3120 REF3125 REF3130 REF3133 REF3140

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Copyright © 2003–2016, Texas Instruments Incorporated

10 Power Supply Recommendations

The REF31xx family of references features an extremely low dropout voltage. With the exception of the

REF3112, which has a minimum supply requirement of 1.8 V, these references can be operated with a supply of

only 5 mV above the output voltage in an unloaded condition. For loaded conditions, a typical dropout voltage

versus load is shown in the front page plot, Dropout Voltage vs Load Current. TI recommends a supply bypass

capacitor greater than 0.47

μF.

11 Layout

11.1 Layout Guidelines

Figure 33 illustrates an example of a printed-circuit board (PCB) layout using the REF31xx. Some key

considerations are:

•

Connect low-ESR, 0.1-

μF ceramic bypass capacitors at VIN of the REF31xx

•

Decouple other active devices in the system per the device specifications

•

Use a solid ground plane to help 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

•

Minimize trace length between the reference and bias connections to the INA and 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

11.2 Layout Example

Figure 33. Layout Example