AD5370BSTZ datasheet(22/24 Pages) AD

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Preliminary Technical Data

AD5370

Rev. P

rF | Page 22 of 24

POWER SUPPLY SEQUENCING

When the supplies are connected to the AD5370 it is important

that the AGND and DGND pins are connected to the relevant

ground plane before the positive or negative supplies are

applied. In most applications this is not an issue as the ground

pins for the power supplies will be connected to the ground pins

of the AD5370 via ground planes. Where the AD5370 is to be

used in a hot-swap card care should be taken to ensure that the

ground pins are connected to the supply grounds before the

positive or negative supplies are connected. This is required to

prevent currents flowing in directions other than towards an

analog or digital ground.

INTERFACING EXAMPLES

The SPI interface of the AD5370 is designed to allow the parts

to be easily connected to industry standard DSPs and micro-

controllers. Figure 11 shows how the AD5370 could be

connected to the Analog Devices Blackfin

DSP. The Blackfin

has an integrated SPI port which can be connected directly to

the SPI pins of the AD5370 and programmable I/O pins which

can be used to set or read the state of the digital input or output

pins associated with the interface.

SYNC

SCLK

SDI

SDO

CLR

LDAC

RESET

BUSY

SPISELx

SCK

MOSI

MISO

PF8

PF9

PF10

PF7

AD537x

ADSP-BF531

537x-0101

Figure 11. Interfacing to a Blackfin DSP

The Analog Devices ADSP-21065L is a floating point DSP with

two serial ports (SPORTS). Figure 12 shows how one SPORT

can be used to control the AD5370. In this example the

Transmit Frame Synchronization (TFS) pin is connected to the

Receive Frame Synchronization (RFS) pin. Similarly the

transmit and receive clocks (TCLK and RCLK) are also

connected together. The user can write to the AD5370 by

writing to the transmit register. A read operation can be

accomplished by first writing to the AD5370 to tell the part that

a read operation is required. A second write operation with a

NOP instruction will cause the data to be read from the

AD5370. The DSPs receive interrupt can be used to indicate

when the read operation is complete.

SYNC

SCLK

SDI

SDO

CLR

LDAC

RESET

BUSY

TFSx

RFSx

TCLKx

RCLKx

DTxA

DRxA

FLAG2

FLAG1

FLAG0

FLAG3

AD537x

537x-0101

ADSP-21065L

Figure 12. Interfacing to an ADSP-21065L DSP

AD5370BSTZ Datasheet(PDF) 22 Page - Analog Devices

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