LTC2662 datasheet(22/28 Pages) AD

22 / 28 page

LTC2662

Rev 0

For more information www.analog.com

OPERATION

The internal toggle-update circuit is edge triggered, so

only transitions (of TGB or TGP) trigger an update from

the respective input register.

To toggle all selected channels together using the SPI

port, ensure the TGP pin is high and that the bits in the

toggle select register corresponding to the desired chan-

nels are also high. Use the global command (1101b) to

alternate codes, sequentially changing the global toggle

bit TGB (see Figure 8). Changing TGB from 1 to 0 updates

the DAC registers from their respective input registers

A. Changing TGB from 0 to 1 updates the DAC registers

from their respective input registers B. Note that in this

way up to 5 channels may be toggled with just one serial

command.

To toggle all selected channels using an external logic

signal, ensure that the TGB bit in the global toggle register

is high and that in the toggle select register, the bits cor-

responding to the desired channels are also high. Apply

a clock or logic signal to the TGP pin to alternate codes.

TGP falling edges update the DAC registers from their

associated input registers A. TGP rising edges update

the DAC registers from their associated input registers B.

Note that once the input registers are set up, all toggling

is triggered by the signal applied to the TGP pin, with no

further SPI instructions needed.

To cause any combination of channels to update from

either input register A or B, ensure the TGP pin is high

and that the TGB bit in the global toggle register is also

high. Using the toggle select command set the toggle

2662 F09

LTC2662

CHANNEL 3

LOGIC

UPD

TOGGLE

SELECT

GLOBAL TOGGLE

BIT (TGB)

TGP

CS/LD

SCK

SDI

LDAC

TGB

TOGGLE SELECT BIT T3

INPUT REGISTER B

(16-BIT)

INPUT REGISTER A

(16-BIT)

A/B

MUX

DAC REGISTER

16-BIT

32-BIT SHIFT REGISTER

Figure 9. Conceptual Block Diagram—Toggle Functionality

LTC2662 Datasheet(PDF) 22 Page - Analog Devices

LTC2662 Datasheet(HTML) 22 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL