ADS8331IPWR datasheet(21/43 Pages) TI

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ManualChannelSelectChannel2

EnableAutoChannelSelect

ConversionStartisAutomaticorManual

Manual-orAuto-TriggerMode

Ch2

Ch5

Ch7

Ch3

Ch6

Ch4

1CCLKMinimum

CCLK

EOC

(activelow)

Channel#

ADS8331

ADS8332

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SBAS363 – DECEMBER 2009

Auto Channel Select Mode

Channel selection can also be done automatically if Auto Channel Select mode (default) is enabled (CFR_D11 =

'1'). If the device is programmed for Auto Channel Select mode, then signals from all channels are acquired in a

fixed order. In Auto Channel Select mode, the first conversion after entering this mode is always from the

channel of the last conversion completed before this mode is enabled. The channels are then sequentially

scanned up to and including the last channel (that is, channel 3 for the ADS8331 and channel 7 for the

ADS8332) and then back to the channel that started the sequence. For example, if the last channel used in the

conversion before enabling Auto Channel Select mode was channel 2, the sequence for the ADS8332 would be:

2, 3, 4, 5, 6, 7, 2, etc., as shown in Figure 39. If the last channel in Manual Channel Select mode happened to be

channel 7, the sequence would be: 7, 7, 7, etc. Figure 40 shows when the next channel in the sequence

activates during Auto Channel Select mode. This timing allows the next channel to settle before it is acquired.

This automatic sequencing stops the cycle after CFR_D11 is set to '0'.

Figure 39. Auto Channel Select for the ADS8332

Figure 40. Channel-Number Update in Auto Channel Select Mode Timing

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ADS8331IPWR Datasheet(PDF) 21 Page - Texas Instruments