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Interactive Design Tools: Integer-N RF PLLs : ADF4153/4 and ADF4251/2 Register Configuration Assistant (BETA)
Instructions | Troubleshooting | Related Information |


There are four 24-bit registers in the ADF4153/4 and seven such registers in the ADF4251/2. In this calculator, each of the four registers is illustrated with field labels and user inputs corresponding to the bit fields in the real device. The width of the labels and elements is in proportion to the bit field widths: a togglebox is used for 1-bit fields, appropriately-sized pulldown menus for 2-16 choice fields, and numerical text boxes for fields longer than 4 bits.

Changing the state of a bit field recomputes the combined register value, expressed in hex, in a text box located to the right of each register. Conversely, changing the hex value in this box updates the individual bit fields that compose the register.

The counter fields can be automatically computed from user specifications for reference frequency, VCO frequency and channel spacing (top left). Internal frequency limits are checked which depend on the part and supply voltage (top center). When changing channel spacing, R-counter or prescaler values, the calculator attempts to preserve the VCO frequency, however, due to precision of the various counters, the frequency will tend to drift slightly. The prescaler may be adjusted to keep the VCO and channel spacing targets.

RSET can be calculated from a maximum desired charge-pump current, ICP MAX, or the maximum current can be found for a given RSET. These fields are independent of the other calculator fields.

There is a dual-mode display at the bottom of the calculator which displays either bit-field help or shows a block diagram. Click on "Help" to the left of this display to select a help text field, and "Diagram" to show a block diagram of the ADF4153/4 or ADF4251/2. Help for most bitfields is available by clicking on the field title, and is shown in yellow in the bottom display with the field title similarly highlighted. When in block diagram mode, many of the blocks are selectable and will highlight when clicked, along with the corresponding register bitfield.

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This tool is BETA-quality, and as such is still being tested and improved. We would like your feedback, in particular any bugs that you come across. To send feedback email, please click on the "Interactive Tools Feedback" link below...

For further troubleshooting information, please visit our Interactive Tools troubleshooting page.

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Related Information

ADF4153, ADF4154, ADF4251 and ADF4252 product pages

Phase-locked loops for high-frequency receivers and transmitters

Part 1: Introduction

Part 2: Phase Noise and Reference Spurs

Part 3: Architecture of PLLs

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