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Data Sheet

AD7380/AD7381

Rev. 0 | Page 19 of 31

RESOLUTION BOOST

The default conversion result output data size for the AD7380 is

16-bits and for the AD7381 is 14-bits. When the on-chip

oversampling function is enabled, the performance of the ADC

can exceed the 16-bit level for the AD7380 or the 14-bit level for

the AD7381. To accommodate the performance boost achievable, it

is possible to enable an additional two bits of resolution. If the RES

bit in the CONFIGURATION1 register is set to Logic 1 and the

AD7380/AD7381 are in a valid oversampling mode, the

conversion result size for the AD7380 is 18-bits and for the

AD7381 is 16-bits. In this mode, 18 SCLKs are required to

propagate the data for the AD7380 and 16 SCLKs are required

for the AD7381.

ALERT

The alert functionality is an out of range indicator and can be

used as an early indicator of an out of bounds conversion result.

An alert event triggers when the conversion result value register

exceeds the alert high limit value in the

ALERT_HIGH_THRESHOLD register or falls below the alert

low limit value in the ALERT_LOW_THRESHOLD register.

The ALERT_HIGH_THRESHOLD register and the

ALERT_LOW_THRESHOLD register are common to all ADCs.

When setting the threshold limits, the alert high threshold must

always be greater than the alert low threshold. Detailed alert

information is accessible in theALERT register.

The register contains two status bits per ADC, one corresponding

to the high limit, and the other to the low limit. A logical OR of

alert signals for all ADCs creates a common alert value. This

value can be configured to drive out on the ALERT function of

the SDOB/ALERT pin. The SDOB/ALERT pin is configured as

ALERT by configuring the following bits in the

CONFIGURATION1 register and the

CONFIGURATION2 register:

•

Set the SDO bit to 1.

•

Set the ALERT_EN bit to 1.

•

Set a valid value to the ALERT_HIGH_THRESHOLD

The alert indication function is available in oversampling, both

rolling average and normal averaging, and in nonoversampling

modes.

The ALERT function of the SDOB/ALERT pin gets updated at

the end of conversion. The alert indication status bits in the

ALERT register get updated as well and must be read before the

end of next conversion. The ALERT function of the

SDOB/ALERT pin is cleared with a falling edge of CS. Issuing a

software reset also clears the alert status in the ALERT register.

ALERT

NO OVERSAMPLING OR

ROLLING AVARAGES OS

NORMAL

OVERSAMPLING

SDOA

INTERNAL

ALERT

SDOA

INTERNAL

tALERTS

tALERTC

tALERTS_NO

tALERTC

CONV

ACQ

CONV

ACQ

CONV

ACQ

CONV

ACQ

EXCEEDS THRESHOLD

Figure 34. Alert Operation

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