TLV5638

2.7 V TO 5.5 V LOW POWER DUAL 12-BIT DIGITAL-TO-ANALOG

CONVERTER WITH INTERNAL REFERENCE AND POWER DOWN

SLAS225A – JUNE 1999 – REVISED JANUARY 2000

12

POST OFFICE BOX 655303

APPLICATION INFORMATION

data format

The 16-bit data word for the TLV5638 consists of two parts:

(D15..D12)

(D11..D0)

D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

R1

SPD

PWR

R0

12 Data bits

SPD: Speed control bit

1

→ fast mode

0

→ slow mode

PWR: Power control bit

1

→ power down

0

→ normal operation

The following table lists the possible combination of the register select bits:

register select bits

R1

R0

REGISTER

0

0

Write data to DAC B and BUFFER

0

1

Write data to BUFFER

1

0

Write data to DAC A and update DAC B with BUFFER content

1

1

Write data to control register

The meaning of the 12 data bits depends on the register. If one of the DAC registers or the BUFFER is selected,

then the 12 data bits determine the new DAC value:

data bits: DAC A, DAC B and BUFFER

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

New DAC Value

If control is selected, then D1, D0 of the 12 data bits are used to program the reference voltage:

data bits: CONTROL

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

X

X

X

X

X

X

X

X

X

X

REF1

REF0

X: don’t care

REF1 and REF0 determine the reference source and, if internal reference is selected, the reference voltage.

reference bits

REF1

REF0

REFERENCE

0

0

External

0

1

1.024 V

1

0

2.048 V

1

1

External

CAUTION:

If external reference voltage is applied to the REF pin, external reference MUST be selected.