Datasheet

ADS5281

ADS5282

SBAS397I –DECEMBER 2006–REVISED JUNE 2012

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PROGRAMMABLE GAIN

ADDRESS

IN HEX D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 NAME

X X X X GAIN_CH1<3:0>

X X X X GAIN_CH2<3:0>

X X X X GAIN_CH3<3:0>

X X X X GAIN_CH4<3:0>

X X X X GAIN_CH5<3:0>

X X X X GAIN_CH6<3:0>

X X X X GAIN_CH7<3:0>

X X X X GAIN_CH8<3:0>

In applications where the full-scale swing of the analog input signal is much less than the 2V

range supported

by the ADS528x, a programmable gain can be set to achieve the full-scale output code even with a lower analog

input swing. The programmable gain not only fills the output code range of the ADC, but also enhances the SNR

of the device by utilizing quantization information from some extra internal bits. The programmable gain for each

channel can be individually set using a set of four bits, indicated as GAIN_CHN<3:0> for Channel N. The gain

setting is coded in binary from 0dB to 12dB, as shown in Table 7.

Table 7. Gain Setting for Channel 1

GAIN_CH1<3> GAIN_CH1<2> GAIN_CH1<1> GAIN_CH1<0> CHANNEL 1 GAIN SETTING

0 0 0 0 0dB

0 0 0 1 1dB

0 0 1 0 2dB

0 0 1 1 3dB

0 1 0 0 4dB

0 1 0 1 5dB

0 1 1 0 6dB

0 1 1 1 7dB

1 0 0 0 8dB

1 0 0 1 9dB

1 0 1 0 10dB

1 0 1 1 11dB

1 1 0 0 12dB

1 1 0 1 Do not use

1 1 1 0 Do not use

1 1 1 1 Do not use