[AK1546]
3. Fast Lock Up Mode
Setting {FAST[1:0]} in <Address2> to “11Bin” and {CPGAIN} in <Address1> to “1” enables the Fast Lock Up mode
for the AK1546.
The Fast Lock Up mode is enabled only during the time period set by the timer according to the counter value in
{TIMER[3:0]} in <Address2>. 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 {CPGAIN} in
<Address1> is reset to “0”.
{TIMER[3:0]} in <Address2> is used to set the time period for this mode. The following formula is used to calculate
the time period :
Switchover time = 1/FPFD × Counter Value
Counter Value = 3 + (Timer[3:0] setting × 4)
Fast Lock Up time
specified by the timer
Operation mode
Normal
CP1
Fast Lock Up
CP2
Normal
CP1
Charge pump current
Loop filter Switch
OFF
ON
OFF
Frequency setting （Write “1” into {CPGAIN} in <Address1>.）
Fast Lock Up Mode Timing Chart
MS1388-E-00
13
2012/3
AKM [ ASAHI KASEI MICROSYSTEMS ]
