M61508FP
Zero-Crossing Detection Circuit
1. Meaning of Zero-Crossing Detection Circuit
In the conventional Serial Data Control Type Volume, Analog SW inside switches over simultaneously with Latch
Condition Detector. And the operation completes.
CLK
Latch Conditions
D32
D33
D34
DATA
Audio Signal
Noise Factor when
Signal is present
Signal GND (1/2VCC
)
In this case the changing noise occurs at the time of Latch Condition Detector, the Analog SW switches over (Zero-
cross Detector Strobe occurs) in the moment that the Analog Signal cross Signal Ground (1/2VCC).
CLK
Latch Conditions
D32
D33
D34
DATA
Zero-cross Detector Strobe
(Form signal from inside IC)
Analog SW changing
Signal GND (1/2VCC
)
Other, In the case of Audio Signal isn't inputted (No signal), even if only Zero-cross Detector Circuit detects Latch
Condition, Analog SW doesn't switch over for the Audio Signal never cuts Signal Ground (1/2VCC).
The Time Function switches the Analog SW after some time T.
The Timer Time can setting with the Serial Data of 5 ms, 10 ms, 15 ms, 20 ms.
REJ03F0203-0201 Rev.2.01 Mar 31, 2008
Page 16 of 24
RENESAS [ RENESAS TECHNOLOGY CORP ]
