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Video ICs
High-voltage audio head selection
switch
BA7755A / BA7755AF
The standard audio circuits of video cassette recorders and the recording circuits of tape decks use AC bias record-
ing to record the audio signal onto the tape. This bias voltage is some tens of volts, and a high-capacity bias-side
switch is required to electronically switch the head when in playback or record mode.
The BA7755A and BA7755AF are high-voltage switching ICs designed to switch voltages as high as ± 65VDC or
AC120VP-P (f = 70Hz).
Two control systems, one for current control, and one for voltage control are provided, so the ICs can be used in cir-
cuits that employ either method.
By combining the BA7755A or BA7755AF with the BA7751ALS recording / playback amplifier, it is possible to con-
struct a compact recording / playback audio circuit. In addition, the BA7755A and BA7755AF are an excellent choice
for a wide variety of other high-voltage switching applications.
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Applications
Video cassette recorders and tape decks
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Features
1) High withstanding voltage ( ± 65VDC (Min.),
AC120VP-P (Min.), f = 70Hz).
2) Circuits for either current control or voltage control
are provided on the chip.
3) Compact SIP 5pin or SOP 8pin package.
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Block diagram
BA7755AF
12345
SW GND CTRL2 CTRL1
BA7755A
VCC
8765
1234
N.C. N.C. N.C.
HEAD
SWITCH
GND CTRL2
CTRL1
VCC