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DAC7574

SLAS375 – JUNE 2003

Master Transmitter Writing to a Slave Receiver (DAC7574) in Standard/Fast Modes

All write access sequences begin with the device address (with R/W = 0) followed by the control byte. This

control byte specifies the operation mode of DAC7574 and determines which channel of DAC7574 is being

accessed in the subsequent read/write operation. The LSB of the control byte (PD0-Bit) determines if the

following data is power-down data or regular data.

With (PD0-Bit = 0) the DAC7574 expects to receive data in the following sequence HIGH-BYTE –LOW-BYTE –

HIGH-BYTE – LOW-BYTE

recognized (refer to the DATA INPUT MODE section of Table 4).

With (PD0-Bit = 1) the DAC7574 expects to receive 2 Bytes of power-down data (refer to the POWER DOWN

MODE section of Table 4).

Table 4. Write Sequence in F/S Mode

DATA INPUT MODE

Transmitter

MSB

6

5

4

3

2

1

LSB

Comment

Master

Start

Begin sequence

Master

1

0

0

1

1

A1

A0

R/W

Write addressing (R/W=0)

DAC7574

DAC7574 Acknowledges

Master

0

0

Load 1

Load 0

x

Buff Sel 1

Buff Sel 0

PD0

Control byte (PD0=0)

DAC7574

DAC7574 Acknowledges

Master

D11

D10

D9

D8

D7

D6

D5

D4

Writing data word, high byte

DAC7574

DAC7574 Acknowledges

Master

D3

D2

D1

D0

x

x

x

x

Writing data word, low byte

DAC7574

DAC7574 Acknowledges

Master

Data or Stop or Repeated Start (1)

Data or done (2)

POWER DOWN MODE

Transmitter

MSB

6

5

4

3

2

1

LSB

Comment

Master

Start

Begin sequence

Master

1

0

0

1

1

A1

A0

R/W

Write addressing (R/W=0)

DAC7574

DAC7574 Acknowledges

Master

0

0

Load 1

Load 0

x

Buff Sel 1

Buff Sel 0

PD0

Control byte (PD0 = 1)

DAC7574

DAC7574 Acknowledges

Master

PD1

PD2

0

0

0

0

0

0

Writing data word, high byte

DAC7574

DAC7574 Acknowledges

Master

0

0

0

0

x

x

x

x

Writing data word, low byte

DAC7574

DAC7574 Acknowledges

Master

Stop or Repeated Start (1)

Done

(1)

Use repeated START to secure bus operation and loop back to the stage of write addressing for next Write.

(2)

Once DAC7574 is properly addressed and control byte is sent, HIGH–BYTE–LOW–BYTE sequences can repeat until a STOP

condition or repeated START condition is received.

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