AD5253/AD5254

Rev. 0 | Page 17 of 28

1 READ

S

0

1

0

1

1

A

D

1

A

D

0

1

A

P

A

RDAC_N OR EEMEM_N

REGISTER DATA

RDAC_N + 1 OR EEMEM_N + 1

REGISTER DATA

SLAVE ADDRESS

(N BYTES + ACKNOWLEDGE)

A

Figure 29. RDAC Current Read. Restricted to Previously Selected Address Stored in the Register.

P

S

SLAVE ADDRESS

0 WRITE

SLAVE ADDRESS

INSTRUCTIONAL AND

ADDRESS

A

1

S

REPEATED START

1 READ

A

0A

(N BYTES + ACKNOWLEDGE)

RDAC OR

EEMEM DATA

A/A

Figure 30. RDAC or EEMEM Random Read

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

Figure 31. RDAC Quick Command Write (Dummy Write)

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

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

RDAC/EEMEM Quick Commands

AD5253/AD5254 feature 12 quick commands that facilitate

easy manipulation of RDAC wiper settings as well as provide

RDAC-to-EEMEM storing and restoring functions. The

command format is shown in Figure 31, and the command

descriptions are shown in Table 9.

When using a quick command, issuing a third byte is not

needed but is allowed. The quick commands Reset and Store

RDAC to EEMEM require acknowledge polling to determine

whether the command has finished executing.

consumes power. Issue the NOP command to return the device to the idle

state.