- SS-HQ1 Application Notes -
Ver.1.0.0 January 7, 2005
204
ECK-27MHz INT / ECK-27MHz LL Switching System (automatic setting)
With this system, ECK input is always operated at 27MHz, regardless of whether INT or LL is used. A block
diagram of this system is shown in
. ATMODEON is set to 1[h] in advance (see
addition, HVPLL (see
) is assigned to a port (Pn1 in the diagram), and the port driver is set so that
the HVPLL signal is output from port Pn1.
The following operations are performed to switch from INT to LL.
• When there is external VD input to S0 (pin 44), the internal system is automatically switched to LL mode.
• VCO is switched to LC oscillation by the HVPLL signal output from Pn1 in the diagram.
The following operations are performed to switch from LL to INT.
• When there is not external VD input to S0 (pin 44), the internal system is automatically switched to INT
mode.
• VCO is switched to X’tal oscillation by the HVPLL signal output from Pn1 in the diagram.
<Note>
When the VCO is switched, please terminate VCO oscillation on the unused side in order to prevent noise.
For details, see the applied schematic titled “Circuit Figure of Internal & Line Lock”.
Fig 12.2-13 ECK-27MHz INT/ECK-27MHz LL Switching System Block Diagram
* If you want to force the system to change to INT mode while external VD is being input, assign ATMODEON
to port Pn2 and connect a DIP switch, as shown in
. If the connected DIP switch is set to “Low”,
the mode is force-changed to INT mode. Note that in such cases, SGMODE must be set to 0[h].
CXD3172AR
ESCI
MC
K
27MHz
(X'tal)
LC
(LL mode)
LPF
(V-PLL)
EXT-VD
86
ESCO
87
ECK
88
PCOMP
42
Pn 1
43
S0
44
S1
46
EXVIDEOY
EXVIDEO
58
57
3.3V
INT : L
LL : H
Pn 2
3.3V
ATMODEON
Controll
X'tal
(INT mode)
VCO
LPF
(H-PLL)
LPF
HVPLL
signal
INT
Compulsion INT
DIP SW
LL