Audio ICs
Fluorescent display tube level meter
driver, 12-point 2 channel,
VU scale, bar display
The BA6810S is a two-channel, 12-point fluorescent display tube driver for VU-scale bar-level meters.
It uses a dynamic-drive system and has both AC and DC inputs. The AC input mode has a peak hold circuit. The IC
features a power-on mute, and the output block can directly drive fluorescent display tubes, so few external components
are required, allowing cost and space savings while improving reliability.
The grid output duty cycle is 1 / 8.
Level meters for all types of AV equipment
1) Uses dynamic-drive system to display two 12-point
channels. 30-pin SDIP package.
2) AC and DC inputs provided. Switching function allows two-mode display.
3) Upper 8 points have peak hold function in AC mode
(two seconds Typ.).
4) Power-on mute function.
5) Forced-mute function.
6) Terminal for meter sensitivity adjustment provided
(adjustment with one terminal is possible).
7) I2L injector current terminal provided.
8) Square root compression amplifier built in.
9) Dynamic-drive system reduces the power dissipation of the fluorescent display tube power supply.
Block diagram
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FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions
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FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 5.0V)
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Measurement circuit
Application example
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Circuit operation
(1) Input block
The AC input pins are pins 2 and 4, and the DC input pins
are pins 6 and 7. Pin 9 is used to switch between the AC
and DC inputs. When the input to pin 9 is “H”, AC input
is selected (pins 2 and 4).
Therefore, by using pin 9 to switch between the AC and
DC modes, the IC can do two jobs, using one fluorescent
tube. For example, pins 2 and 4 can be used for audio signal input, and pins 6 and 7 can be used as the input for
the signal meter output from a tuner (DC).
(2) Peak hold circuit
The BA6810S features a peak hold circuit that temporarily 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 oscillator frequency. It is 2 sec. (Typ.) for an oscillator frequency of 2kHz.
(3) MUTE function
The display can be turned off by driving the MUTE terminal “H”.
(4) Meter sensitivity adjustment terminal
Connect a potentiometer of about 10kΩ, and adjust it so
that the 8th point lights when the for an AC input of
400mVrms. The dispersion between L and R channels is
(5) Grid output
The pin 13 and 14 grid outputs are open-collector NPN
transistors. The logic is active low (the fluorescent tube
lights when the output is “L”), so connect two PNP transistors Q1 and Q2 as shown in the application example
circuit to drive the fluorescent tubes (see Fig. 4).
(6) Segment output block
Pins 15 to 28 are the segment outputs. The output circuits are open-collector PNP transistors. When grid 1 is
“L”, the ch1 level is output (pin 2 or 6 input level), and
when grid 2 is “L”, the ch2 level is output (pin 4 or 7 input
(Refer to Fig. 5.)
(7) Grid and segment output timing chart. The grid and
segment output timing is shown in Fig. 6.
(8) Attack and release times
The output response characteristic for AC input signals
is set by pins 3 and 5. The comparator level may change
somewhat due to the sag of the CR circuit discharge.
(9) Oscillator frequency
The resistor and capacitor connected to pin 30 determine
the oscillator frequency. The oscillator frequency (fosc)
and grid output period (T) are related as follows:
T (ms) = 16 / fosc (kHz)
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Electrical characteristics curves
External dimensions (Units: mm)