ADS6123IRHB25 datasheet(44/67 Pages) TI1

44 / 67 page

www.ti.com

INP

INM

VCM

1 :1

5 W

0 .1mF

1 :1

50 W

0 .1mF

50 W

5 W

Using Differential Amplifier Drive Circuits

FIL

0.1 F

10 F

||R

INP

INM

ADS612x

THS4509

VCM

500 W

200 W

5 W

500 W

0.1 F

–V

ADS6125, ADS6124

ADS6123, ADS6122

SLAS560A – OCTOBER 2007 – REVISED MARCH 2008

Figure 94. Two Transformer Drive Circuit

Figure 95 shows a drive circuit using a differential amplifier (TI's THS4509) to convert a single-ended input to

differential output that can be interface to the ADC analog input pins. In addition to the single-ended to differential

conversion, the amplifier also provides gain (10 dB in Figure 95). RFIL helps to isolate the amplifier outputs from

the switching input of the ADC. Together with CFIL it also forms a low-pass filter that band-limits the noise (and

signal) at the ADC input. As the amplifier output is ac-coupled, the common-mode voltage of the ADC input pins

is set using two 200

Ω resistors connected to VCM.

The amplifier output can also be dc-coupled. Using the output common-mode control of the THS4509, the ADC

input pins can be biased to 1.5 V. In this case, use +4 V and -1 V supplies for the THS4509 so that its output

common-mode voltage (1.5 V) is at mid-supply.

Figure 95. Drive Circuit Using the THS4509

See the EVM User Guide (SLWU028) for more information.

Submit Documentation Feedback

Product Folder Link(s): ADS6125, ADS6124 ADS6123, ADS6122

ADS6123IRHB25 Datasheet(PDF) 44 Page - Texas Instruments

ADS6123IRHB25 Datasheet(HTML) 44 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67

Datasheet Download

Link URL