+2.5V to +5.5V, Low-Power, Single/Dual,

8-Bit Voltage-Output DACs in µMAX Package

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11

Table 3. MAX549A Serial-Interface Programming Commands

DATA BYTE

UNASSIGNED COMMAND

X

X

X

X

X

0

X

1

0

X

X

0

0

0

1

X

0

X

0

X

1

0

XXXXXXXX

8-Bit DAC Data

Loaded First

Update both DAC registers with current contents of their

input registers. Both input registers unchanged.

Load DAC A input register. DAC registers unchanged.

X

X

0

X

1

X

0

1

X

0

X

1

X

1

0

8-Bit DAC Data

Load DAC A input register and update both DAC

registers. DAC B input register unchanged.

X

1

X

0

X

X

0

1

X

1

X

0

X

1

0

8-Bit DAC Data

Load DAC A input register and power down DAC A.

DAC B input register and both DAC registers unchanged.

X

8-Bit DAC Data

Load DAC B input register and power down DAC B.

DAC A input register and both DAC registers unchanged.

X

Loaded Last

X

1

X

0

X

1

1

8-Bit DAC Data

Load both DAC input registers and power down both

DACs. Both DAC registers unchanged.

X

8-Bit DAC Data

Load DAC B input register. DAC registers unchanged.

X

X

0

X

0

X

1

1

8-Bit DAC Data

Load both DAC input registers. DAC registers

unchanged.

X

8-Bit DAC Data

Load DAC B input register and update both DAC

registers. DAC A input register unchanged.

X

X

0

X

1

X

1

1

8-Bit DAC Data

Load both DAC input registers and update both DAC

registers.

X

COMMAND

(Commands executed on CS’s rising edge)

CONTROL BYTE

UB2

C2

UB3

C1

C0

A1

A0

D7........D0

UB1

X

X

X

0

X

0

0

XXXXXXXX

Unassigned command

X

COMMANDS LOADING INPUT REGISTER(S) ONLY

COMMANDS UPDATING DAC REGISTER(S)

COMMANDS POWERING DOWN AND LOADING INPUT REGISTER(S) ONLY

X = Don’t care

COMMANDS POWERING DOWN AND UPDATING DAC REGISTER(S)

X

1

X

1

X

0

1

8-Bit DAC Data

Load DAC A input register, power down DAC A, and

update both DAC registers. DAC B input register

unchanged.

X

X

1

X

1

X

1

0

8-Bit DAC Data

Load DAC B input register, power down DAC B, and

update both DAC registers. DAC A input register

unchanged.

X

X

1

X

1

X

1

1

8-Bit DAC Data

Load both DAC input registers, power down both DACs,

and update both DAC registers.

X