Datasheet

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DAC7574

SLAS375–JUNE 2003

Broadcast Address Byte

MSB LSB

1 0 0 1 0 0 0 0

Broadcast addressing is also supported by DAC7574. Broadcast addressing can be used for synchronously

updating or powering down multiple DAC7574 devices. DAC7574 is designed to work with other members of the

DAC857x and DAC757x families to support multichannel synchronous update. Using the broadcast address,

DAC7574 responds regardless of the states of the address pins. Broadcast is supported only in write mode

(Master writes to DAC7574).

Control Byte

MSB LSB

0 0 L1 L0 X Sel1 Sel0 PD0

Table 1. Control Register Bit Descriptions

Bit Name Bit Number/Description

L1 Load1 (Mode Select) Bit

Are used for selecting the update mode.

L2 Load0 (Mode Select) Bit

00 Store I

C data. The contents of MS-BYTE and LS-BYTE (or power down information) are stored in the

temporary register of a selected channel. This mode does not change the DAC output of the selected

channel.

01 Update selected DAC with I

C data. Most commonly utilized mode. The contents of MS-BYTE and

LS-BYTE (or power down information) are stored in the temporary register and in the DAC register of

the selected channel. This mode changes the DAC output of the selected channel with the new data.

10 4-Channel synchronous update. The contents of MS-BYTE and LS-BYTE (or power down information)

are stored in the temporary register and in the DAC register of the selected channel. Simultaneously,

the other three channels get updated with previously stored data from the temporary register. This

mode updates all four channels together.

11 Broadcast update mode. This mode has two functions. In broadcast mode, DAC7574 responds

regardless of local address matching, and channel selection becomes irrelevant as all channels update.

This mode is intended to enable up to 16 channels simultaneous update, if used with the I

C broadcast

address (1001 0000).

If Sel1=0 All four channels are updated with the contents of their temporary register

data.

If Sel1=1 All four channels are updated with the MS-BYTE and LS-BYTE data or

powerdown.

Sel1 Buff Sel1 Bit

Channel Select Bits

Sel0 Buff Sel0 Bit

00 Channel A

01 Channel B

10 Channel C

11 Channel D

PD0 Power Down Flag

0 Normal operation

1 Power-down flag (MSB7 and MSB6 indicate a power-down operation, as shown in Table 2).