PRELIMINARY

                 

Powerdown Operation

Synchronous and asynchronous powerdown modes are both available. Synchronously powerdown occurs if the respective

loop’s R18 bit (Do High Z State) is LOW when its N20 bit (Powerdown) becomes HI. Asynchronous powerdown occurs if

the loop’s R18 bit is HI when its N20 bit becomes HI. In the synchronous powerdown mode, the powerdown function is

gated by the charge pump to prevent unwanted frequency jumps. Once the powerdown program bit N20 is loaded, the

part will go into powerdown mode when the charge pump reaches a High Z condition. In the asynchronous powerdown

mode, the device powers down immediately after the LE pin latches in a HI condition on the powerdown bit N20. Activation

of either the IF or RF PLL powerdown conditions in either synchronous or asynchronous modes forces the respective

loop’s R and N dividers to their load state condition and debiasing of its respective fin input to a high impedance state. The

oscillator circuitry function does not become disabled until both IF and RF powerdown bits are activated. The control

register remains active and capable of loading and latching data during all of the powerdown modes. The device returns to

an actively powered up condition in either synchronous or asynchronous modes immediately upon LE latching LOW data

into bit N20.

Powerdown Mode Select Table

R18

N20

Powerdown Status

0

0

PLL Active

1

0

PLL Active (Charge Pump High Z State)

0

1

Synchronous Powerdown Initiated

1

1

Asynchronous Powerdown Initiated

Leadless Grid Array Package