LT6236 datasheet(25/50 Pages) LINER

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LTC2372-16

237216f

For more information www.linear.com/LTC2372-16

Using Digital Gain Compression for Single Supply

Operation

The LTC2372-16 offers a digital gain compression (DGC)

feature which defines the full-scale input swing to be be-

tween 10% and 90% of the ±VREFBUF analog input range.

This feature allows the ADC driver to be powered off of a

single positive supply since each input swings between

0.41V and 3.69V with VREFBUF = 4.096V as in Figure 11a.

Needing only a positive supply and ground to power the

ADC driver results in additional power savings for the

entire system versus conventional systems that have a

negative supply for the ADC driver.

With DGC enabled, the LTC2372-16 can be driven by the

low power LTC6362 differential driver which is powered

fromasingle5Vsupply.Figure11bshowshowtoconfigure

the LTC6362 to accept a ±3.28V true bipolar single-ended

input signal and level shift the signal to the reduced input

range of the LTC2372-16 when digital gain compression

is enabled. Using the LT6236 to buffer the resistor divider

that creates VCM, the entire signal chain solution can be

powered from a single 5V supply, minimizing power

consumption and reducing complexity. The reduced input

signal swing of this single 5V supply solution limits the

achievable SNR to 94dB, as shown in the FFT of Figure 11c.

To enable DGC, set SEL=1 in the configuration word.

applicaTions inForMaTion

Figure 11b. LTC6362 Configured to Accept a ±3.28V Input Signal While Running from a Single 5V Supply When Digital

Gain Compression is Enabled in the LTC2372-16

Figure 11a. Input Swing of the LTC2372-16 with Digital Gain

Compression Enabled and VREFBUF = 4.096V

VREFBUF = 4.096V

3.69V

0.41V

237216 F11a

CH0

CH1

CH2

CH3

CH4

CH5

CH6

CH7

COM

MUX CHANNELS

CH0 AND CH1

SELECTED

VDD

MUXOUT+/–

SHORTED TO

ADCIN+/–

LTC2372-16

16-BIT ADC CORE

–

237216 F11b

REFBUF

1500pF

VSOURCE

RSOURCE = 50

35.7

1500pF

3.69V

0.41V

4.096V

3.69V

0.41V

DIGITAL GAIN COMPRESSION ENABLED BY SETTING

SEL = 1 IN THE CONFIGURATION WORD

3.28V

–3.28V

V+

V–

0.22µF

–

LTC6362

850

150

VCM

100

850

10µF

LT6236

47µF

0.1µF

10µF

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