Sample N

Conversion N

Data For Conversion N−1

(Data Read without Latency)

CONVST

BUSY

D11−D0

CS

NAP MODE

A_PWD

(Held Low)

BUSY

SAMPLE

(Internal)

NAP

(Internal Active High)

Start section.

ADS7882

Figure 8. Back-To-Back operation With CS Toggling and RD Low

The device can be put in nap mode following the sequences shown in Figure 9. This provides substantial power

saving while operating at lower sampling rates.

While operating the device at throughput rates lower than 2.54 MSPS, A_PWD can be held low (see Figure 9). In

this condition, the device goes into the nap state immediately after BUSY goes low and remains in that state until

requirements section.

Alternately, A_PWD can be toggled any time during operation (see Figure 10). This is useful when the system

acquires data at the maximum conversion speed for some period of time (back-to-back conversion) and it does

not acquire data for some time while the acquired data is being processed. During this period, the device can be

put in the nap state to save power. The device remains in the nap state as long as A_PWD is low with BUSY

being low and sampling has not started. The minimum acquisition time for the first sampling after the nap state is

Figure 9. Device Operation While A_PWD is Held Low

Copyright © 2008, Texas Instruments Incorporated

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