±4

±3

±2

±1

0

1

2

3

4

0

200

400

600

800

1000

Time (µs)

C04

Regular Voltage Reference Droop

REF62xx Droop

Bandgap

Voltage

Reference

Buffer

+

VIN

OUT_S

OUT_F

FILT

VIN

GND_S

GND_F

Power Supply

SS

REF62xx

EN

GND

REF

+

R

R

R

Power Supply

R

THS4521

AINP

AINN

ADS8881

Copyright © 2016, Texas Instruments Incorporated

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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.

REF6225, REF6230, REF6233, REF6241, REF6245, REF6250

SBOS748 – SEPTEMBER 2016

REF62xx High-Precision Voltage Reference With Integrated ADC Drive Buffer

1

1 Features

1

•

Excellent Temperature Drift Performance

–

3 ppm/°C (max) from 0°C to +70°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 voltage references in the REF6000 family have

an integrated low output impedance buffer that

enables the user to directly drive the reference (REF)

pin of precision data converters, while preserving

linearity, distortion, and noise performance. Most

precision

SAR

and

delta-sigma

analog-to-digital

converters (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 precision digital-to-analog converters (DACs).

The REF6000 family of is 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

REF62xx variants of REF6000 family specify a

maximum temperature drift of just 3 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)

REF62xx

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)