BA7658 查看數據表（PDF） - ROHM Semiconductor

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BA7658

Input selector switch for high definition displays

ROHM Semiconductor 

Multimedia ICs

•Circuit operation

(1) Analog switches

Switch between the two sets of R, G and B color sig-

nals. IN1 is selected by impressing the high level volt-

age on the CTL pin, IN2 by impressing the low level

voltage.

(2) Digital switches

These switch between the two sets of HD and VD syn-

chronization signals. HD and VD synchronization sig-

nals for IN1 are output by impressing the high level

voltage on the CTL pin, HD and VD synchronization

signals for IN2 by impressing the low level voltage.

(3) Synchronization separation block

Outputs the synchronization signals by separating

them from composite signals (Sync on Green). When

HD signals are being input, the synchronization signal

detector stops the synchronization separator. The low

BA7658AFS

level voltage is output. The time that the synchroniza-

tion separator is stopped can be set by changing the

time constant attached to the synchronization signal

detection pin.

(4) Signal detection block

When the signal input exceeds the level set inside the

IC (typically 400mVP-P, VCC = 5.0V), the high level volt-

age is output to the color signal detection output pin.

The low level voltage is output when the signal input is

lower than the set level. The quiescent circuit reaction

time can be set by changing the time constant attached

to pin used to set the time constant for color signal

detection. The signal detector stops while the high level

is being input to the blanking pulse input pin, thereby

preventing malfunctioning due setup signal block dur-

ing the synchronization signal period.

The relationship between inputs and outputs

Input

Output

HD VD Sync on Green HD VD Composite Sync

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