BA7746FS View Datasheet(PDF) - ROHM Semiconductor
Part Name
Description
Manufacturer
BA7746FS Datasheet PDF : 12 Pages
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Video ICs
•Operation notes
(1) preamplifier
The preamplifier in this IC is a high-gain amplifier for
FM audio. This amplifier has been carefully designed
for stability. However, the design of the PCB greatly
effects the stability of the preamplifier. A list of general
precautions are given below. Take note when design-
ing the PCB.
1)The oscillation margin is reduced when the input
and output patterns are physically close.
The input and output wiring should not come out of
the same side of tha IC.
Good example
Input
IC
Output
Bad example
Input
IC
Output
2)The GND pattern should be connected at one point
to the main IC GND (pin 16). In addition, the pream-
plifier input-side GND and output-side GND should
be as close as possible to the main IC GND.
Good example
Input
Output
BA7746S / BA7746FS
Bad example
Input
Output
RL
PRE
GND
IC MAIN
GND
Output
GND
3)A large GND pattern under the IC has a shielding
effect, and reduced the chance of picking up exter-
nal noise.
4)When the preamplifier is connected to a capacitive
load such as shilded wire, or when the output cur-
rent is large, the output may oscillate. In this case,
connect a resistor to the preamplifier output (approx.
390Ω).
BA7746S / FS
REC
270mVP-P
BH780XK series
REC
LPF
REC
LPF
MOD
MOD
PRE
660mVP-P
390
FM
DE
BPF
MOD
HEAD AMP
Hi-Fi AUDIO
Connection example for BA7746S / BA7746FS and BH780XK series.
RL
PRE
GND
IC MAIN
GND
Output
GND
11
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