AMC7836IPAPRG4 datasheet(42/91 Pages) TI2

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AMC7836

SLAS986D – NOVEMBER 2014 – REVISED FEBRUARY 2018

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7.4.3 Mixed DAC Range Mode

In the AMC7836 mixed DAC range mode, a combination of DAC groups is set to a negative voltage output range

(–5 to 0 V or –10 to 0 V) and a positive voltage output range (0 to 5 V or 0 to 10 V).

Because the maximum DAC output for each group cannot exceed the common AVCC voltage for the device

(AVCC = AVCC_AB = AVCC_CD), a DAC group in the 0 to 10 V output range forces the AVCC voltage to a value

greater or equal to 10 V. If all positive DAC groups are in the 0 to 5 V range the AVCC voltage can be set to a

value as low as 5 V.

The minimum DAC output for each group cannot be lower than the voltage on the corresponding AVSS pins

(AVEE, AVSSB, AVSSC and AVSSD). The AVSS pins are not required to be tied to the same potential and typically

the negative voltage at each AVSS pin is dictated by the desired operating DAC negative output range. One

exception is the AVEE pin which must be the lowest potential in the device. The implication of this requirement is

that if either DAC group B, C or D is set to a negative output range, DAC group A must also be set to a negative

range. The thermal pad should be either tied to the same potential as the AVEE pin or left disconnected. Table 7

lists the typical configurations for this mode.

Table 7. Mixed DAC Range Mode Typical Configuration

NOTES

TYPICAL CONNECTION

AVDD

5 V

DVDD

DVDD must be equal to AVDD.

5 V

IOVDD

IOVDD must be equal to or less than DVDD.

1.8 V to 5 V

AVCC_AB, AVCC_CD

The AVCC_AB and AVCC_CD pins must be tied to the

same potential (AVCC).

AVCC must be greater or equal to the maximum

possible output voltage for any of the positive

output range DACs.

AVCC ≥ 5 V

AVCC ≥ 10 V

AVEE

AVEE must be the lowest potential in the device.

AVEE must be less than or equal to the minimum

possible output voltage for DAC group A.

AVEE

≤ –5 V

AVEE

≤ –10 V

AVSSB, AVSSC, AVSSD

AVSSn must be less than or equal than the minimum

possible output voltage for DAC group n (n = B, C,

D).

Negative Range

AVEE ≤ AVSSn ≤ –5 V

AVEE ≤ AVSSn ≤ –10 V

Positive Range

AGND

Thermal Pad

AVEE or,

Floating

After power-on or a reset event the output range for each DAC group is set automatically by the voltage present

in the corresponding AVSS pin. When the AVSS voltage of a DAC group is lower than the threshold value, AVSSTH,

the output for that DAC group is automatically configured to the –10 to 0 V range. Conversely, if the AVSS voltage

of the DAC group is higher than AVSSTH, the DAC-group output is automatically set to the 0 to 5 V range. The

output for any of the DAC groups can be modified after initialization by setting the corresponding DAC range

In addition to setting the default output range, the AVSS pins also set the clamp voltage for each DAC group.

Because the clamp voltage is only dependent on the voltage in the AVSS pin, changes to the DAC range

registers do not affect the clamp setting.

NOTE

Although not a recommended operating condition, the device allows a DAC group to

operate in a positive output range even if the clamp voltage is negative (AVSS connected

to a negative supply voltage).

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