AD9553SLASHPCBZ datasheet(38/44 Pages) AD

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AD9553

Rev. 0 | Page 38 of 44

REFB Frequency Control (Register 0x23 to Register 0x26)

Table 35.

Address

Bit

Bit Name

Description

0x23

[7:0]

REFB divider (RB)

Bits[13:6] of the 14-bit REFB divider.

0x24

[7:2]

REFB divider (RB)

Bits[5:0] of the 14-bit REFB divider (default: RB = 4096 decimal).

The REFB divider bits are ineffective unless Register 0x24[1] = 1.

Enable SPI control of RB

Enables SPI port control of the REFB divider value (RB).

0 = The A[3:0] pins define RB per Table 14 (default).

1 = The 14-bit value in the REFB divider register defines RB.

Unused

Unused.

0x25

Enable SPI control of x2B

Enables SPI control of the REFB 2x frequency multiplier (x2B) per Register 0x25[6].

0 = the device automatically selects x2B per Table 14 (default).

1 =Register 0x25[6] controls the selection of x2B.

Select x2B

Selects x2B.

0 = bypass x2B (default).

1 = select x2B.

This bit is ineffective unless Register 0x25[7] = 1.

Enable SPI control of /5B

Enables SPI control of the /5B prescaler per Register 0x25[4].

0 = the device automatically selects /5B per Table 14 (default).

1 = Register 0x25[4] controls the selection of /5B.

Select /5B

Selects /5B.

0 = bypass /5B (default).

1 = select /5B.

This bit is ineffective unless Register 0x25[5] = 1.

[3:0]

Unused

Unused.

0x26

[7:0]

Unused

Unused.

DCXO Frequency and Reference Switchover Control (Register 0x27 to Register 0x31)

Table 36.

Address

Bit

Bit Name

Description

0x27

[7:0]

XO divider (RXO)

Bits[13:6] of the 14-bit XO divider.

0x28

[7:2]

XO divider (RXO)

Bits[5:0] of the 14-bit XO divider (default: RXO = 2048 decimal).

The XO divider bits are ineffective unless Register 0x28[1] = 1.

Enable SPI control of RXO

Enables SPI port control of the XO divider value (RXO).

0 = The A[3:0] pins define RXO per Table 14 (default).

1 = The 14-bit value in the XO divider register defines RXO.

Unused

Unused.

0x29

[7:6]

Switchover mode

Selects the switchover operating mode.

00 = revertive switchover (default).

01 = nonrevertive switchover.

10 = selects REFA as the active reference.

11 = selects REFB as the active reference.

REFA diff

Enables the differential input reference function.

0 = normal single-ended operation of REFA and REFB (default).

1 = REFA configured as a differential reference in which the REFA pin functions as

one differential input and the REFB/REFA pin functions as the other differential input.

In this configuration, the REFB channel and switchover functionality are both

unavailable.

[4:0]

Unused

Unused.

0x2A to

0x31

[7:0]

Unused

Unused.

AD9553/PCBZ Datasheet(PDF) 38 Page - Analog Devices

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