AD5251/AD5252

Rev. 0 | Page 13 of 28

RDAC/EEMEM Quick Commands

The AD5251/AD5252 feature 12 quick commands that facilitate

easy manipulation of RDAC wiper settings and provide RDAC-

to-EEMEM storing and restoring functions. The command

format is shown in Figure 11 and the command descriptions are

shown in Table 9.

0 WRITE

1 CMD

S

0

1

0

1

1

A

D

1

A

D

0

0

A

C

3

C

2

C

1

C

0

A

2

A

1

A

0

A

P

RDAC SLAVE ADDRESS

CMD/

REG

FROM MASTER TO SLAVE

FROM SLAVE TO MASTER

S = START CONDITION

P = STOP CONDITION

A = ACKNOWLEDGE (SDA LOW)

A = NOT ACKNOWLEDGE (SDA HIGH)

R/W = READ ENABLE BIT, LOGIC HIGH/WRITE ENABLE BIT, LOGIC LOW

CMD/REG = COMMAND ENABLE BIT, LOGIC HIGH/REGISTER ACCESS BIT, LOGIC LOW

C3, C2, C1, C0 = COMMAND BITS

A2, A1, A0 = RDAC/EEMEM REGISTER ADDRESSES

Figure 11. RDAC Quick Command Write (Dummy Write)

Table 9. RDAC-to-EEMEM Interface and RDAC Operation Quick Command Bits (CMD/REG = 1, A2 = 0)

C3

C2

C1

C0

Command Description

0

0

0

0

NOP

0

0

0

1

Restore EEMEM (A1, A0) to RDAC (A1, A0)1

0

0

1

0

Store RDAC (A1, A0) to EEMEM (A1, A0)

0

0

1

1

Decrement RDAC (A1, A0) 6 dB

0

1

0

0

Decrement all RDACs 6 dB

0

1

0

1

Decrement RDAC (A1, A0) one step

0

1

1

0

Decrement all RDACs one step

0

1

1

1

Reset: Restore EEMEMs to all RDACs

1

0

0

0

Increment RDACs (A1, A0) 6 dB

1

0

0

1

Increment all RDACs 6 dB

1

0

1

0

Increment RDACs (A1, A0) one step

1

0

1

1

Increment all RDACs one step

1

1

0

0

Reserved

:

:

:

:

1

1

1

1

Reserved

Table 10. Address Table for Reading Tolerance (CMD/REG = 0, EE/RDAC = 1, A4 = 1)

A4

A3

A2

A1

A0

Data Byte Description

0

0

0

0

0

Reserved

:

:

:

:

:

1

1

0

0

1

Reserved

1

1

0

1

0

Sign and 7-bit integer values of RDAC1 tolerance (read only)

1

1

0

1

1

8-bit decimal value of RDAC1 tolerance (read only)

1

1

1

0

0

Reserved

1

1

1

0

1

Reserved

1

1

1

1

0

Sign and 7-bit integer values of RDAC3 tolerance (read only)

1

1

1

1

1

8-bit decimal value of RDAC3 tolerance (read only)