BA7657F 查看數據表（PDF） - ROHM Semiconductor
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BA7657F Datasheet PDF : 17 Pages
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BA7657F,BH7659FS
Technical Note
●Description of operations
○BA7657F
1) Analog SW block
Two channels of RGB signals can be switched. IN1 can be selected when high-level voltage is applied to the CTL pin,
and IN2 can be selected when low level voltage is applied.
2) Digital SW block
This block switches between two channels of HD and VD ynchronization signals. HD and VD synchronization signals are
output for IN1 when high-level voltage is applied to the CTL pin, and these signals are output for IN2 when a low-level
voltage is applied to the CTL pin.
3) Synchronization signal separation block
This block separates composite signals (Sync on Green) and synchronization signals and outputs positive-electrode
composite synchronization signals. When an HD signal is being input, the synchronization signal detector operates and
stops the synchronization signal separation circuit. A low-level output voltage is used for output. The time at which the
synchronization signal separation circuit will be stopped can be set using external time constants for the circuit detection
pin.
I/O relations
HD
VD
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Input
Sync on Green
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Output
HD
VD
Composite Sync
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○BH7659FS
1) Analog SW block
R, G, and B chroma signals are switched in two channels. INA is selected by applying a high-level voltage to the CTL pin,
and INB is selected by applying a low-level voltage. When the power save pin (pin 8) is set to high level, the current to
the SW block's output transistors is reduced to lower the circuit current. Even during low power mode, signal switching
can be performed normally as long as there is no drop in frequency characteristics.
2) CMOS analog SW block
SDA and SDC signals are switched via an I2C bus to handle two channels of HD and VD synchronization signals, and to
exchange information bidirectional between a computer and a monitor. The switching circuits used by this IC handle are
configured as CMOS analog switches in order to handle I2C BUS signals and to transmit input and output signals
bidirectional. (ON resistance: Ron 200 Ω typ.)
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© 2011 ROHM Co., Ltd. All rights reserved.
11/16
2011.04 - Rev.A
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