Audio ICs
BA6820F / BA6822S / BA6822F
(8) GND terminal (pins 10 and 11)
Pin 11 is the GND for the pin 12 to pin 21 driver circuits,
and pin 10 is the GND for the other signal circuits (see
Fig. 8).
Pins 10 and 11 are not connected internally, so both must
be connected to GND.
The large LED current that flows from pin 11 has a large
high-frequency component, so care must be taken with
regard to the PCB layout to avoid faulty operation of the
IC, and incorrect lighting of the LEDs due to noise.
FOperation notes
(1) Use the potentiometers VR1 and VR2 connected to
pins 1 and 3 to set the 0dB levels and adjust the channel
1 and channel 2 balance.
put may be fed back to the input and cause oscillation,
incorrect LED lighting, or faulty operation of the IC. De-
sign the PCB artwork so that there is no coupling be-
tween the input and output lines or with other units, in the
same way as for linear amplifier PCB design. If they must
be physically close, insert a capacitor between the input
andGNDtoreducetheACinputimpedance, andprevent
noise from entering the input.
(2) The recommended oscillator frequency is 4kHz
(pin 9). The external component values for C5 and R3 are
0.01µF and 41kΩ (or 39kΩ). If you wish to use other val-
ues, they should be in the ranges 0.001µF to 0.1µF and
10kΩ to 100kΩ. (see Fig. 9).
(3) The dynamic ranges for the BA6820F and
BA6822S/F comparators are large, and the compara-
tors will operate even with low-level signals.
For this reason, noise may cause the LEDs to light when
they should not, and to prevent this, GND line noise
should be kept sufficiently low.
(4) Takecaretoensurethenoneofthepinshaveavolt-
age applied to them that is higher than VCC or lower than
GND (e.g. supply the LED current from a source other
than VCC).
(5) In general, the level meter output block is switched
on and off in the range GND to VCC, and a large voltage
with a large high-frequency component is generated.
Therefore, if the input and output lines are close, the out-
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ROHM [ ROHM ]
