Bandgap

Voltage

Reference

Buffer

+

VIN

OUT_S

OUT_F

FILT

VIN

GND_S

GND_F

Power Supply

SS

REF61xx

EN

GND

REF

+

R

R

R

Power Supply

R

THS4521

AINP

AINN

ADS8881

Copyright © 2016, Texas Instruments Incorporated

±4

±3

±2

±1

0

1

2

3

4

0

200

400

600

800

1000

Time (µs)

C04

Regular Voltage Reference Droop

REF61xx Droop

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

REF6125, REF6130, REF6133, REF6141, REF6145, REF6150

SBOS747B – MAY 2016 – REVISED AUGUST 2016

REF61xx High-Precision Voltage Reference With Integrated ADC Drive Buffer

1

1 Features

1

•

Excellent Temperature Drift Performance

–

8 ppm/°C (max) from –40°C to +125°C

•

Extremely Low Noise

–

–

•

Integrated ADC Drive Buffer

–

Low Output Impedance: < 50 mΩ (0-200 kHz)

–

First Sample Precise to 18 Bits With ADS8881

–

Enables Burst-Mode DAQ Systems

•

Low Supply Current: 820 μA

•

Low Shutdown Current: 1 µA

•

High Initial Accuracy: ±0.05%

•

Very-Low Noise and Distortion

–

SNR: 100.5 dB, THD: –125 dB (ADS8881)

–

SNR: 106 dB, THD: –120 dB (ADS127L01)

•

Output Current Drive: ±4 mA

•

Programmable Short-Circuit Current

•

Verified to Drive REF Pin of ADS88xx family of

SAR ADCs and ADS127xx family of Wideband ΔΣ

ADCs

2 Applications

•

ATE Testers and Oscilloscopes

•

Test and Measurement Equipment

•

Analog Input Modules for PLCs

•

Medical Equipment

•

Precision Data Acquisition Systems

3 Description

The REF6000 family of voltage references have an

integrated low output impedance buffer that enable

the user to directly drive the REF pin of precision

data converters, while preserving linearity, distortion,

and noise performance. Most precision SAR and

Delta-Sigma ADCs, switch binary-weighted capacitors

onto the REF pin during the conversion process. In

order to support this dynamic load the output of the

voltage reference must be buffered with a low-output

impedance (high-bandwidth) buffer. The REF6000

family devices are well suited, but not limited, to drive

the REF pin of the ADS88xx family of SAR ADCs,

and ADS127xx family of delta-sigma ADCs, as well

as other digital-to-analog converters (DACs).

The REF6000 family of voltage references are able to

maintain an output voltage within 1LSB (18-bit) with

minimal droop, even during the first conversion while

driving the REF pin of the ADS8881. This feature is

useful in burst-mode, event-triggered, equivalent-time

sampling, and variable-sampling-rate data-acquisition

systems. The REF61xx variants of REF6000 family

specify a maximum temperature drift of just 8 ppm/°C

and initial accuracy of 0.05% for both the voltage

reference and the low output impedance buffer

combined. For various temperature drift options in

REF6000 family, see the Device Comparison Table.

Device Information(1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

REF61xx

VSSOP (8)

3.00 mm x 3.00 mm

(1) For all available packages, see the package option addendum

at the end of the data sheet.

Typical Application

Reference Droop comparison

(1 LSB = 19.07 µV, With ADS8881 at 1 MSPS)