TLV5626

2.7-V TO 5.5-V LOW-POWER DUAL 8-BIT DIGITAL-TO-ANALOG

CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN

SLAS236A –JUNE 1999 – REVISED JUNE 2000

13

POST OFFICE BOX 655303

APPLICATION INFORMATION

examples of operation: (continued)

at 1.024 V:

1.

Set reference voltage to 1.024 V (CONTROL register):

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

1

0

0

1

0

0

0

0

0

0

0

0

0

0

0

1

2.

Write data for DAC B to BUFFER:

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

0

0

0

1

New DAC B value

0

0

0

0

X = Don’t care

3.

Write new DAC A value and update DAC A and B simultaneously:

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

1

0

0

0

New DAC A value

0

0

0

0

X = Don’t care

Both outputs are updated on the rising clock edge after D0 from the DAC A data word is sampled.

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

X

X

1

X

X

X

X

X

X

X

X

X

X

X

X

X

X = Don’t care

linearity, offset, and gain error using single ended supplies

When an amplifier is operated from a single supply, the voltage offset can still be either positive or negative. With

a positive offset, the output voltage changes on the first code change. With a negative offset, the output voltage

may not change with the first code, depending on the magnitude of the offset voltage.

The output amplifier attempts to drive the output to a negative voltage. However, because the most negative

supply rail is ground, the output cannot drive below ground and clamps the output at 0 V.

The output voltage then remains at zero until the input code value produces a sufficient positive output voltage

to overcome the negative offset voltage, resulting in the transfer function shown in Figure 14.

DAC Code

Output

Voltage

0 V

Negative

Offset

Figure 14. Effect of Negative Offset (single supply)