BA6810S View Datasheet(PDF) - ROHM Semiconductor

Part Name

Description

Manufacturer

BA6810S

Fluorescent display tube level meter driver, 12-point
2 channel, VU scale, bar display

ROHM Semiconductor 

Audio ICs

FCircuit 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 sig-

nal 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 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) MUTE function

The display can be turned off by driving the MUTE termi-

nal “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

±1.0dB.

BA6810S

(7) Grid and segment output timing chart. The grid and

segment output timing is shown in Fig. 6.

(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 tran-

sistors 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 cir-

cuits 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

level).

(Refer to Fig. 5.)

788

(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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