Datasheet

AD9553
Rev. A | Page 36 of 44
Address Bit Bit Name Description
0x0C [7:3] Unused Unused.
[2:0] Charge pump clock div. Enables the PFD clock dividers (used for test only via test mux).
000 = test clocks disabled, normal operation (default).
001 = divide feedback clock by 2.
010 = divide PFD reference input clock by 2.
011 = divide PFD reference input and feedback clocks by 2.
100 = divide pump-up clock by 2.
101 = divide pump-up and feedback clocks by 2.
110 = divide pump-up and PFD reference input clocks by 2.
111 = divide feedback, pump-up, and pump-down clocks by 2.
0x0D [7:6] Antibacklash control Controls the PFD antibacklash period of the PLL. These bits are ineffective unless
Register 0x0B[6] = 1.
00 = minimum (default).
01 = low.
10 = high.
11 = maximum.
[5:1] Unused Unused.
0 PLL lock detector power-down Controls power-down of the PLL lock detector.
0 = lock detector active (default).
1 = lock detector powered down.
VCO Control (Register 0x0E to Register 0x10)
Table 30.
Address Bit Bit Name Description
0x0E 7 Calibrate VCO Initiates VCO calibration (this is an autoclearing bit). This bit is ineffective unless
Register 0x0E[2] = 1.
6 Enable ALC Enables automatic level control (ALC) of the VCO.
0 = Register 0x0F[7:2] defines the VCO level.
1 = the device automatically controls the VCO level (default).
[5:3] ALC threshold Controls the VCO ALC threshold detector level from minimum (000) to maximum
(111). The default is 110.
2 Enable SPI control of VCO
calibration
Enables the functionality of Register 0x0E[7].
0 = the device automatically performs VCO calibration (default).
1 = VCO calibration controlled by Register 0x0E[7].
1 Boost VCO supply Selects VCO supply voltage.
0 = normal supply voltage (default).
1 = increase supply voltage by 100 mV.
0 Enable SPI control of VCO band
setting
Controls VCO band setting functionality.
0 = the device automatically selects the VCO band (default).
1 = VCO band defined by Register 0x10[7:1].
0x0F [7:2] VCO level control Controls the VCO amplitude from minimum (00 0000) to maximum (11 1111). These
bits are ineffective unless Register 0x0E[6] = 0.
The default is 10 0000.
[1:0] Unused Unused.
0x10 [7:1] VCO band control Controls the VCO frequency band from minimum (000 0000) to maximum
(111 1111). These bits are ineffective unless Register 0x0E[0] = 1.
The default is 100 0000.
0 Unused Unused.