AK1548 Datasheet, PDF (18/42 Pages) Asahi Kasei Microsystems – 8GHz Low Noise Integer-N Frequency Synthesizer

[AK1548]
5．Reference counter
The reference input can be set with a dividing number in the range of 1 to 16383 using {R [13:0]}, which is an
14-bit address of {D[13:0]} in <Address0>. 0 cannot be set as a dividing number.
6．Prescaler
The dual modulus prescaler (P/P+1) and the swallow counter are used to provide a large dividing ratio.
The prescaler is set by {PRE[1:0]}, which is a 2-bit latch of {D[21:20]} in <Address2>.
{PRE[1:0]}=”00Bin”, P=8, Dual modulus prescaler 8/9
{PRE[1:0]}=”01Bin”, P=16, Dual modulus prescaler 16/17
{PRE[1:0]}=”10Bin”, P=32, Dual modulus prescaler 32/33
{PRE[1:0]}=”11Bin”, P=64, Dual modulus prescaler 64/65
The maximum prescaler output frequency is 300MHz. P should be set as “RF Input Frequency /P ≤ 300MHz”.
7．Power-down and Power-save mode
It is possible to operate in the power-down or power-save mode if necessary by using the external control pin.
Power On
Follow the power-up sequence.
Normal Operation
[PDN]
“Low”
“High”
“High”
“High”
<Address2>
{PD2} {PD1}
Function
X
X Power Down
X
0 Normal Operation
VBG & LDO : Power UP
0
1
Synthesizer Circuits : Asynchronous Power Down
VBG & LDO : Power UP
1
1
Synthesizer Circuits : Synchronous Power Down
X : Don’t care
MS1364-E-00
18
2012/1