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3-Wire Serial Interface

POWER-DOWN MODE

DAC7553

SLAS477 – AUGUST 2005

TYPICAL CHARACTERISTICS (continued)

The DAC7553 digital interface is a standard 3-wire SPI/QSPI/Microwire/DSP-compatible interface.

Table 1. Serial Interface Programming

CONTROL

DATA BITS

DAC(s)

FUNCTION

DB15

DB14

DB13

DB12

DB11-DB10

0

0

0

0

data

A

Single Channel Store. The TMP register of channel A is updated.

0

0

1

0

data

B

Single Channel Store. The TMP register of channel B is updated.

0

1

0

0

data

A

Single Channel Update. The TMP and DAC registers of channel A are

updated.

0

1

1

0

data

B

Single Channel Update. The TMP and DAC registers of channel A are

updated and the DAC register of channel B is updated with input register data.

1

0

0

0

data

A

Single Channel Update. The TMP and DAC registers of channel B are

updated.

1

0

1

0

data

B

Single Channel Update. The TMP and DAC registers of channel B are

updated and the DAC register of channel A is updated with input register data.

1

1

0

0

data

A–B

All Channel Update. The TMP and DAC registers of channels A and B are

updated.

1

1

1

0

data

A–B

All Channel DAC Update. The DAC register of channels A and B are updated

with input register data.

In power-down mode, the DAC outputs are programmed to one of three output impedances, 1 k

Ω, 100 kΩ, or

floating.

Table 2. Power-Down Mode Control

EXTENDED CONTROL

DATA BITS

FUNCTION

DB15

DB14

DB13

DB12

DB11

DB10

DB9-DB0

0

0

X

1

0

0

X

PWD Hi-Z (all channels)

0

0

X

1

0

1

X

PWD 1 k

Ω (all channels)

0

0

X

1

1

0

X

PWD 100 k

Ω (all channels)

0

0

X

1

1

1

X

PWD Hi-Z (all channels)

0

1

X

1

0

0

X

PWD Hi-Z (selected channel = A)

0

1

X

1

0

1

X

PWD 1 k

Ω (selected channel = A)

0

1

X

1

1

0

X

PWD 100 k

Ω (selected channel = A)

0

1

X

1

1

1

X

PWD Hi-Z (selected channel = A)

1

0

X

1

0

0

X

PWD Hi-Z (selected channel = B)

1

0

X

1

0

1

X

PWD 1 k

Ω (selected channel = B)

1

0

X

1

1

0

X

PWD 100 k

Ω (selected channel = B)

1

0

X

1

1

1

X

PWD Hi-Z (selected channel = B)

1

1

X

1

0

0

X

PWD Hi-Z (all channels)

1

1

X

1

0

1

X

PWD 1 k

Ω (all channels)

1

1

X

1

1

0

X

PWD 100 k

Ω (all channels)

1

1

X

1

1

1

X

PWD Hi-Z (all channels)

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