AD7734

MD2 MD1 MD0

Operating Mode

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0

0

Idle Mode

The default mode after power-on or reset.

The AD7734 automatically returns to this mode after any calibration or after a single conversion.

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1

Continuous Conversion Mode

The AD7734 performs a conversion on the specified channel. After the conversion is complete, the relevant channel

data register and channel status register are updated, the relevant RDY bit in the ADC status register is set, and the

AD7734 continues converting on the next enabled channel. The part will cycle through all enabled channels until it is

put into another mode or reset. The cycle period will be the sum of all enabled channels’ conversion times, set by the

corresponding channel conversion time registers.

0

1

0

Single Conversion Mode

The AD7734 performs a conversion on the specified channel. After the conversion is complete, the relevant channel

data register and channel status register are updated, the relevant RDY bit in the ADC status register is set, the RDY pin

goes low, the MD2–MD0 bits are reset, and the AD7734 returns to idle mode. Requesting a single conversion ignores

the channel setup register enable bits; a conversion will be performed even if that channel is disabled.

0

1

1

Power-Down (Standby) Mode

The ADC and the analog front end (internal buffer) go into the power-down mode.

The AD7734 digital interface can still be accessed. The CLKDIS bit works separately, and the MCLKOUT mode is not

affected by the power-down (standby) mode.

1

0

0

ADC Zero-Scale Self-Calibration Mode

A zero-scale self-calibration is performed on internally shorted ADC inputs.

After the calibration is complete, the contents of the ADC zero-scale calibration register are updated, all RDY bits in the

ADC status register are set, the RDY pin goes low, the MD2–MD0 bits are reset, and the AD7734 returns to idle mode.

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0

1

For Future Use.

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1

0

Channel Zero-Scale System Calibration Mode

A zero-scale system calibration is performed on the selected channel. An external system zero-scale voltage should be

provided at the AD7734 analog input and this voltage should remain stable for the duration of the calibration. After the

calibration is complete, the contents of the corresponding channel zero-scale calibration register are updated, all RDY

bits in the ADC status register are set, the RDY pin goes low, the MD2–MD0 bits are reset, and the AD7734 returns to

idle mode.

1

1

1

Channel Full-Scale System Calibration Mode

A full-scale system calibration is performed on the selected channel. An external system full-scale voltage should be

provided at the AD7734 analog input and this voltage should remain stable for the duration of the calibration. After the

calibration is complete, the contents of the corresponding channel full-scale calibration register are updated, all RDY

bits in the ADC status register are set, the RDY pin goes low, the MD2–MD0 bits are reset, and the AD7734 returns to

idle mode.

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