±4

±3

±2

±1

0

1

2

3

4

0

200

400

600

800

1000

Time (µs)

C042

Regular Voltage Reference Droop

REF60xx Droop

0.001

0.01

0.1

1

10

100

100

1k

10k

100k

1M

Frequency (Hz)

C063

REF20xx (C

L = 10 µF)

REF60xx (C

L = 10 µF)

Bandgap

Voltage

Reference

CFILT = 1 µF

CL = 47 µF

RESR = 5

PŸ

RFILT

Buffer

+

VIN

OUT_S

OUT_F

FILT

VIN

GND_S

GND_F

Power Supply

SS

REF60xx

RLIM = 120

NŸ

EN

GND

REF

+

VIN

R = 1

NŸ

RF = 5

Ÿ

CF = 10 nF

THS4521

AINP

AINN

ADS8881

Copyright © 2016, Texas Instruments Incorporated

R = 1

NŸ

R = 1

NŸ

R = 1

NŸ

RF = 5

Ÿ

Power Supply

21

REF6025, REF6030, REF6033, REF6041, REF6045, REF6050

www.ti.com

SBOS708B – MAY 2016 – REVISED AUGUST 2016

Product Folder Links: REF6025 REF6030 REF6033 REF6041 REF6045 REF6050

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Copyright © 2016, Texas Instruments Incorporated

Feature Description (continued)

The REF60xx family of voltage references have an integrated low output impedance buffer (ADC drive buffer);

therefore, there is no need for an external buffer while driving the REF pin of high-precision, high-throughput

SAR ADCs, as shown in Figure 50. The ADC drive buffer of the REF60xx is capable of replenishing a charge of

70 pC on a 47-µF capacitor in 1 µs, without allowing the voltage on the capacitor to droop more than 1 LSB at

18-bit precision. The REF60xx are trimmed at multiple temperatures in production, achieving a max drift of just 5

ppm/°C for both the voltage reference and the buffer combined, while operating at a typical quiescent current of

820 µA. Figure 51 compares the output impedance of a regular voltage reference (REF20xx) and a voltage

reference with integrated ADC drive buffer (REF60xx). Figure 52 compares the burst-mode, reference-settling

performance of a regular voltage reference and the REF60xx.

Figure 50. REF60xx Driving REF Pin of ADS8881 SAR ADC

Figure 51. Output Impedance Comparison

1 LSB = 19.07 µV, with ADS8881 at 1 MSPS

Figure 52. Reference Droop Comparison