AD9670EBZ datasheet(39/48 Pages) AD

39 / 48 page

AD9674

Data Sheet

Rev. A | Page 38 of 47

MEMORY MAP

READING THE MEMORY MAP TABLE

Each row in the memory map register table has eight bit locations.

The memory map is roughly divided into two sections: the chip

configuration register map (Address 0x000 to Address 0x1A1)

and the profile register map (Address 0xF00 to Address 0xFFF).

Registers that are designated as local registers use the device

index in Address 0x004 and Address 0x005 to determine to

which channels of a device the command is applied. Registers

that are designated as chip registers use the chip address mode

in Address 0x115 to determine whether the device is to be

updated by writing to the chip register.

The address hex column of Table 25 indicates the register address.

The default value is shown in the default value column. The Bit 7

(MSB) column is the start of the default hexadecimal value given.

For example, Address 0x009, the global clock register, has a default

value of 0x01, meaning that Bit 7 = 0, Bit 6 = 0, Bit 5 = 0, Bit 4 = 0,

Bit 3 = 0, Bit 2 = 0, Bit 1 = 0, and Bit 0 = 1, or 0000 0001 in binary.

This setting is the default for the duty cycle stabilizer in the on

condition.

For more information about the SPI memory map and other

functions, see the AN-877 Application Note, Interfacing to

High Speed ADCs via SPI.

RESERVED LOCATIONS

Do not write to undefined memory locations except when writing

the default values suggested in this data sheet. Addresses that have

values marked as 0 must be considered reserved and have a

0 written into their registers during power-up.

DEFAULT VALUES

After a reset, critical registers are automatically loaded with default

values. These values are indicated in Table 25, where an X refers

to an undefined feature.

LOGIC LEVELS

“Bit is set” is synonymous with “bit is set to Logic 1” or “writing

Logic 1 for the bit.” Similarly, “bit is cleared” is synonymous

with “bit is set to Logic 0” or “writing Logic 0 for the bit.”

RECOMMENDED START-UP SEQUENCE

To save system power during programming, the AD9674 powers

up in power-down mode. To start the device up and initialize

the data interface, the SPI commands listed in Table 24 are

recommended. At a minimum, the profile memory for an index of

0 must be written (Address 0xF00 to Address 0xF03). If additional

profiles and coefficient memory are required, these can be written

after Profile Memory 0.

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