AD9643

Rev. A | Page 32 of 36

MEMORY MAP REGISTER TABLE

All address and bit locations that are not included in Table 14 are not currently supported for this device.

Table 14. Memory Map Registers

Addr

(Hex)

Register

Name

Bit 7

(MSB)

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

(LSB)

Default

Value

(Hex)

Default

Notes/

Comments

Chip Configuration Registers

0x00

SPI port

configuration

(global)1

0

LSB first

Soft reset

1

1

Soft reset

LSB first

0

0x18

The nibbles

are mirrored

so that LSB

first mode

or MSB first

mode

registers

correctly,

regardless

of shift

mode.

0x01

Chip ID

(global)

8-bit chip ID[7:0]

(AD9643 = 0x82)

(default)

0x82

Read only.

0x02

Chip grade

(global)

Open

Open

Speed grade ID

00 = 250 MSPS

Open

Open

Open

Open

Speed

grade ID

used to

differentiate

devices;

read only.

Channel Index and Transfer Registers

0x05

Channel index

(global)

Open

Open

Open

Open

Open

Open

ADC B

(default)

ADC A

(default)

0x03

Bits are

set to

determine

which

device on

the chip

receives the

next write

command;

applies to

local

registers

only.

0xFF

Transfer

(global)

Open

Open

Open

Open

Open

Open

Open

Transfer

0x00

Synchro-

nously

transfers

data from

the master

shift register

to the slave.

ADC Functions

0x08

Power modes

(local)

Open

Open

External

power-

down pin

function

(local)

0 = power-

down

1 = standby

Open

Open

Open

Internal power-down mode

(local)

00 = normal operation

01 = full power-down

10 = standby

11 = reserved

0x00

Determines

various

generic

modes of

chip

operation.

0x09

Global clock

(global)

Open

Open

Open

Open

Open

Open

Open

Duty cycle

stabilizer

(default)

0x01

0x0B

Clock divide

(global)

Open

Open

Input clock divider phase adjust

000 = no delay

001 = 1 input clock cycle

010 = 2 input clock cycles

011 = 3 input clock cycles

100 = 4 input clock cycles

101 = 5 input clock cycles

110 = 6 input clock cycles

111 = 7 input clock cycles

Clock divide ratio

000 = divide by 1

001 = divide by 2

010 = divide by 3

011 = divide by 4

100 = divide by 5

101 = divide by 6

110 = divide by 7

111 = divide by 8

0x00

Clock

divide

values

other than

000 auto-

matically

cause the

duty cycle

stabilizer to

become

active.