AD9552

Rev. C | Page 24 of 32

Addr.

(Hex)

Register

Name

(MSB) Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

(LSB)

Bit 0

Default

0x1C

XTAL

control

Unused

Unused

Unused

Unused

Unused

Unused

Unused

Unused

0x00

0x1D

XTAL

control

Unused

Unused

Unused

Unused

Unused

Select 2×

frequency

multiplier

Unused

Use crystal

resonator

0x00

0x32

OUT1

driver

control

OUT1 drive

strength

OUT1

power-

down

OUT1 mode control[2:0]

OUT1 CMOS polarity[1:0]

Enable SPI

control of

OUT1

driver

control

0xA8

0x33

Select OUT2

source

Unused

Unused

Unused

Unused

OUT2

source

Unused

Unused

Unused

0x00

0x34

OUT2

driver

control

OUT2 drive

strength

OUT2

power-

down

OUT2 mode control[2:0]

OUT2 CMOS polarity[1:0]

Enable SPI

control of

OUT2

driver

control

0xA8

REGISTER MAP DESCRIPTIONS

Control bit functions are active high unless stated otherwise. Register address values are always hexadecimal unless otherwise indicated.

Serial Port Control (Register 0x00 to Register 0x05)

Table 18.

Address

Bit

Bit Name

Description

0x00

7

Unused

Forced to Logic 0 internally, which enables 3-wire mode only.

6

LSB first

Bit order for SPI port.

0 = most significant bit and byte first (default).

1 = least significant bit and byte first.

5

Soft reset

Software initiated reset (register values set to default). This is an autoclearing bit.

4

Unused

Forced to Logic 1 internally, which enables 16-bit mode (the only mode supported by

the device).

[3:0]

Unused

Mirrored version of the contents of Register 0x00[7:4] (that is, Bits[3:0] = Bits[7:4]).

0x04

[7:1]

Unused

Unused.

0

Readback control

For buffered registers, serial port readback reads from actual (active) registers instead of

from the buffer.

0 = reads values currently applied to the internal logic of the device (default).

1 = reads buffered values that take effect on next assertion of I/O update.

0x05

[7:1]

Unused

Unused.

0

I/O update

Writing a 1 to this bit transfers the data in the serial I/O buffer registers to the internal

control registers of the device. This is an autoclearing bit.