[AK1542A]
2. Charge Pump and Loop Filter
In AK1542A, the fast Lock Up could be achieved by changing a charge pump current and enabling the loop filter. This is
called Fast Lock Up mode. For details, see ”3. Fast Lock Up Mode” on page 13.
The loop filter is external and connected to [CP], [SWIN] and [CPZ] pins. The [CPZ] pin should be connected to the R2 and
C2, which are intermediate nodes, even if the Fast Lock Up is not used. Therefore, R2 must be connected to the [CP] pin,
while C2 must be connected to the ground.
Phase Detector
Loop Filter
up
R3
CP
VCO
C1
R2'
R2
down
C3
Timer
SWIN
CPZ
C2
Fig. 5 Loop Filter Schematic
MS1399-E-00
2012/3
- 12 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
