Data Sheet

AD9525

Rev. 0 | Page 33 of 48

REGISTER MAP DESCRIPTIONS

Table 29 through Table 49 provide a detailed description of each of the control register functions. The registers are listed by hexadecimal

address.

Table 29. SPI Mode Serial Port Configuration

Reg.

Addr.

(Hex)

Bits

Bit Name

Description

0x000

7

SDO active

Selects unidirectional or bidirectional data transfer mode.

0: SDIO pin used for write and read; SDO is high impedance (default).

1: SDO used for read; SDIO used for write; unidirectional mode.

6

LSB first/address

increase

0: data-oriented MSB first; addressing decrements (default).

1: data-oriented LSB first; addressing increments.

5

Soft reset

Soft reset.

1 (self-clearing): soft reset; restores default values to internal registers.

4

Unused

Unused.

[3:0]

Mirror[7:4]

Bits[3:0] should always mirror Bits[7:4] so that it does not matter whether the part is in MSB or LSB first mode

(see Register 0x000[6]). Set bits as follows:

Bit 0 = Bit 7

Bit 1 = Bit 6

Bit 2 = Bit 5

Bit 3 = Bit 4

0x004

0

Read back

active registers

Select register bank used for a readback.

0: reads back buffer registers (default).

1: reads back active registers.

Table 30. PFD Charge Pump

Reg.

Addr.

(Hex)

Bits

Bit Name

Description

0x010

7

PFD polarity

Sets the PFD polarity.

0: Positive (higher control voltage produces higher frequency) (default).

1: Negative (higher control voltage produces lower frequency).

[6:4]

CP current

Charge pump current (with CPRSET = 5.1 kΩ).

Bit 6

Bit 5

Bit 4

0

0

0

0.6

0

0

1

1.2

0

1

0

1.8

0

1

1

2.4

1

0

0

3.0

1

0

1

3.6

1

1

0

4.2

1

1

1

4.8 (default)

[3:2]

CP mode

Charge pump operating mode.

Bit 3

Bit 2

Charge Pump Mode

0

0

High impedance state

0

1

Force source current (pump-up)

1

0

Force sink current (pump-down)

1

1

Normal operation (default)

[1:0]

Antibacklash

pulse width

See

Table 7 for the maximum operating frequency for each setting.

Bit 1

Bit 0

Antibacklash Pulse Width Mode (ns)

0

0

2.9 (default)

0

1

1.3

1

0

6.0

1

1

2.9