Data Sheet

AD7879/AD7889

Rev. D | Page 29 of 40

Power Management (Control Register 2, Bits[15:14])

The power management (PM) bits in Control Register 2 allow the power management features of the ADC to be programmed (see Table 23).

If the PM bits are set to 00, the ADC is in full shutdown. This setting overrides any setting of the mode bits in Control Register 1. Power

management overrides the ADC modes.

Table 23. Power Management Selection

PM1

PM0

Function

0

0

Full shutdown; ADC, oscillator, bias, and temperature sensor are turned off. The only way to exit this

mode is to write to the device over the serial interface and change the PM bits. This setting overrides

any other setting on the device, including the ADC mode bits.

0

1

The analog blocks to be powered down depend on the ADC mode setting. In master mode, the ADC,

bias, temperature sensor, and oscillator are powered down and must wake up when the user touches

the screen. In slave mode, the ADC and temperature sensor are powered down when not being

used. They wake up automatically when required. The oscillator and bias are powered up because

they are needed to measure time. This setting also applies to the single-conversion mode.

1

0

The ADC, bias, and oscillator are powered up continuously, irrespective of ADC mode.

1

1

The analog blocks to be powered down depend on the ADC mode setting. In master mode, the ADC,

bias, temperature sensor, and oscillator are powered down and must wake up when the user touches

the screen. In slave mode, the ADC and temperature sensor are powered down when not being

used. They wake up automatically when required. The oscillator and bias are powered up because

they are needed to measure time. This setting also applies to the single-conversion mode.