BA6810 ROHM [Rohm], BA6810 Datasheet - Page 6

• Manufacturer Part Number: BA6810
• Description: Fluorescent display tube level meter driver, 12-point x 2 channel, VU scale, bar display
• Manufacturer: ROHM [Rohm]

FCircuit operation
(1)
The AC input pins are pins 23 and 25, and the DC input
pins are pins 27 and 28. Pin 2 is used to switch between
the AC and DC inputs. When the input to pin 2 is “H”, AC
input is selected (pins 23 and 25). Therefore, by using pin
2 to switch between the AC and DC modes, the IC can
do two jobs, using one fluorescent tube. For example,
pins 23 and 25 can be used for audio signal input, and
pins 27 and 28 can be used as the input for the signal me-
ter output from a tuner (DC).
(2)
The BA6810F features a peak hold circuit that temporari-
ly holds peak signal levels in AC input mode.
The peak hold function can be used with the upper 8
points (5 to 12). The peak hold time depends on the oscil-
lator frequency. It is 2 sec. (typ.) for an oscillator frequen-
cy of 2kHz.
(3)
The display can be turned off by driving the MUTE termi-
nal “H”.
(4)
Connect a potentiometer of about 10k , and adjust it so
that the 8th point lights when the for an AC input of
400mV
nels is "1.0dB.
(5)
The pin 6 and 7 grid outputs are open-collector NPN tran-
sistors. The logic is active low (the fluorescent tube lights
when the output is “L”), so connect two PNP transistors
Q
drive the fluorescent tubes (see Fig. 4).
(6)
Pins 8 to 19 are the segment outputs. The output circuits
are open-collector PNP transistors. When grid 1 is “L”,
the ch1 level is output (pin 23 or 27 input level), and when
grid 2 is “L”, the ch2 level is output (pin 25 or 28 input lev-
el). Refer to Fig. 5.
Audio ICs
1
and Q
Input block
Peak hold circuit
MUTE function
Meter sensitivity adjustment terminal
Grid output
Segment output block
rms
2
. The dispersion between left and right chan-
as shown in the application example circuit to
(7)
The grid and segment output timing is shown in Fig. 6.
(8)
The output response characteristic for AC input signals
is set by pins 24 and 26. The comparator level may
change somewhat due to the sag of the CR circuit dis-
charge.
(9)
The resistor and capacitor connected to pin 21 determine
the oscillator frequency. The oscillator frequency (f
and grid output period (T) are related as follows:
Grid and segment output timing chart.
Attack and recovery times
Oscillator frequency
BA6810F
795
osc
)