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Data Sheet

AD7383-4/AD7384-4

MODES OF OPERATION

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to the external circuitry. Alternatively, if a more accurate reference

or higher dynamic range is required, an external reference can be

supplied. An externally supplied reference can range from 2.5 V to

3.3 V.

Reference selection, internal or external, is configured by the RE-

FSEL bit in the CONFIGURATION1 register. If the REFSEL bit is

set to 0, the internal reference buffer is enabled. If the REFSEL bit

is set to 1, the internal reference buffer is disabled. If an external

reference is preferred, set the REFSEL bit to 1 and supply an

external reference to the REFIO pin.

The external reference voltage of the AD7383-4/AD7384-4 is driven

through the REFIO pin. The external reference voltage must have

enough current to drive the AD7383-4/AD7384-4, which is a maxi-

mum of 2.4 mA. Connecting a 1 µF capacitor to the REFIO pin is

recommended. The recommended external voltage references are

the ADR4525 for 2.5 V and the ADR4533 for 3.3 V.

SOFTWARE RESET

The AD7383-4/AD7384-4 have two reset modes, a soft reset and a

hard reset. A RESET is initiated by writing to the reset bits in the

CONFIGURATION2 register.

A soft reset maintains the contents of the configurable registers but

refreshes the interface and the ADC blocks. Any internal state ma-

chines are reinitialized, and the oversampling block and FIFO are

flushed. The ALERT indication register is cleared. The reference

and LDO regulator remain powered.

A hard reset, in addition to the blocks reset by a soft reset, resets

all user registers to the default status, and resets the internal

oscillator block.

DIAGNOSTIC SELF TEST

The AD7383-4/AD7384-4 run a diagnostic self test after a power-on

reset or after a software hard reset to ensure that the correct

configuration is loaded into the device.

The result of the self test is displayed in the SETUP_F bit in the

ALERT indication register. If the SETUP_F bit is set to Logic 1, the

diagnostic self test has failed. If the test fails, perform a software

hard reset to reset the AD7383-4/AD7384-4 registers to the default

status.

Figure 32. Shutdown Mode Operation

Figure 33. Software Reset Operation

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