A ceramic capacitor of at least a 0.1 μF must be connected to the output to improve stability and help filter out

high frequency noise. Add an additional 10 μF capacitor in parallel to improve transient performance in response

to sudden changes in load current; however, keep in mind that doing so increases the start-up time of the device.

Best performance and stability is attained with low-ESR, low-inductance ceramic chip-type output capacitors

(X5R, X7R, or similar). If using an electrolytic capacitor on the output, place a 0.1 μF ceramic capacitor in

parallel to reduce overall ESR on the output. Place the input and output capacitors as close as possible to the

device.

10.2.2.2.3 Selection of ADC

ADS7038 12-bit 8 channel multiplexed ADC is chosen for this application. The ADC offers low current operation

with averaging mode to increase the resolution to 16-bit with internal averaging modes while operating with slow

sampling speed.

10.2.2.3 Application Curves

Table 10-3 and Figure 10-3 show the captured measurement results for various DC inputs. The ADC output is

captured and analyzed for output accuracy error and code spread with REF35500 as power supply versus LDO

as power supply.

REF35 offers better accuracy and lower noise than the LDO device at lower quiescent current. This results in

lower error in measurement as well as lower ADC output code variation across various OSR settings.

Table 10-3. DC Input Performance Test Results

INPUT V

ADC OSR SETTING

REF35500

LDO

ERROR

CODE SPREAD

ERROR

CODE SPREAD

1.0 V

0

0.01 mV

32 LSB

8.9 mV

48 LSB

8

0.3 mV

10 LSB

9.21 mV

16 LSB

128

0.38 mV

6 LSB

9.26 mV

6 LSB

2.5 V

0

0.69 mV

32 LSB

22.89 mV

64 LSB

8

1.44 mV

10 LSB

23.63 mV

18 LSB

128

1.17 mV

3 LSB

23.41 mV

5 LSB

4 V

0

2.27 mV

32 LSB

37.84 mV

48 LSB

8

3.01 mV

24 LSB

38.62 mV

24 LSB

128

2.46 mV

3 LSB

38.09 mV

17 LSB

REF35

SNAS809A – DECEMBER 2021 – REVISED AUGUST 2022

www.ti.com

24

Submit Document Feedback

Copyright © 2022 Texas Instruments Incorporated

Product Folder Links: REF35