ETC BA6125

Audio ICs
LED level meter driver, 5-point,
linear scale
The BA6125 is a driver IC for LED linear level meters in stereo equipment and other display applications.
The IC displays the input level on five LEDs. The display level range is 35mVrms to 175mVrms in five equally-spaced
35mVrms steps.
The BA6125 includes a rectifier amplifier allowing direct AC input, and has constant-current outputs, so it can directly
drive the LEDs without variations in LED current due to supply voltage fluctuations.
Battery checkers, signal meters, and other display devices.
1) Rectifier amplifier allows either AC or DC input.
2) Constant-current outputs for constant LED current
when the supply voltage fluctuates.
3) Built-in reference voltage means that power supply
voltage fluctuations do not effect the display.
Absolute maximum ratings (Ta = 25c)
4) Wide operating power supply voltage range (3.5V to
16V) for a wide range of applications.
5) Low PCB space requirements. Comes in a compact
9-pin SIP package and requires few external components.
Audio ICs
Block diagram
Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 6.0V, and f = 1kHz)
Measurement circuit
Audio ICs
Application example
The response time (attack and release time) can be
changed by varying the values of C1 and R1.
C2 is a coupling capacitor, and the potentiometer VR varies the input level. Input the voltage level that you desire
for the center point, and adjust the potentiometer so that
the third LED (VC3) lights.
To reduce the LED current, connect a resistor either in
parallel (Fig. 3 (1)) or in series (Fig. 3 (2)) with the LED.
If a resister is connected in series with the LED, the LED
current will change if the supply voltage fluctuates.
Note: If the power supply voltage exceeds 9V, insert a resistor in series with the LED current supply line, or connect a heat sink so that
the maximum power dissipation Pd Max. is not exceeded (see Fig.
Audio ICs
Use with DC input
Use the potentiometer shown in Fig. 5 to adjust the input
level. Adjust the potentiometer so that the third LED (VC3)
lights for the desired input level.
For large input levels, input via pin 7 is also possible. In
this case, the dispersion in comparator level is less than
in the case of input via pin 8. Note that, if the resistance
value of the 100kΩ potentiometer shown in Fig. 6 is made
too small, the discharge time constant determined by C1
and R1 will change, and the response time will vary. The
maximum input level for pin 7 is 5V.
External dimensions (Units: mm)