AK1575 Datasheet, PDF (26/35 Pages) Asahi Kasei Microsystems – Up Converter Mixer with Fractional-N Frequency Synthesizer and VCO

[AK1575]
14. Fast Lock mode
The fast lock mode becomes effective when set {FASTEN} of <Address 0x04> to”1”.
○Fast Lock Mode
When writing in <Address0x01> with {FASTEN}=1, Fast Lock Up mode starts after calibration. The
Fast Lock Up mode is valid only during the time period set by the timer according to the counter
value in {FAST [3:0]} in <Address0x04>, and the charge pump current is set to the value specified by
{CP2}. When the specified time period elapses, the Fast Lock Up mode operation is switched to the
normal operation, and the charge pump current returns to {CP1} setting
Operation mode
Normal
Charge pump current
CP1
Calibration
Hi-Z
Fast Lock Up time
specified by the timer
Fast Lock Up
Normal
CP2
CP1
Frequency setting （Write in <Address0x01>）
Fig.7. Fast Lock up Mode Timing Chart
○Timer period
{FAST [3:0]} in <Address0x04> is used to set the time period for this mode. The following formula
is used to calculate the time period
Counter Value =511＋FAST[3:0] × 512
MS1552-E-00
26
2013/8