Audio ICs LED level meter driver, 5-point, VU scale BA6144 The BA6144 is a driver IC for LED VU level meters in stereo equipment and other display applications. The IC displays the input level (range: 13dB to +17dB) on a 5-point, bar-type LED display.The BA6144 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. Applications VU meters, signal meters, and other display devices. Features 1) Rectifier amplifier allows either AC or DC input. 2) Wide display level range (13 to +17), so signals with large dynamic range can be displayed. 3) Constant-current outputs for constant LED current when the power supply voltage fluctuates. Absolute maximum ratings (Ta = 25C) 634 4) Built-in reference voltage means that power supply voltage fluctuations do not effect the display. 5) Wide operating power supply voltage range (5.5V to 16V) for a wide range of applications. 6) Low PCB space requirements. Comes in a compact 9-pin SIP package and requires few external components. Audio ICs BA6144 Block diagram Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 12V, and f = 1kHz) Measurement circuit 635 Audio ICs BA6144 Application example The response time (attack and release time) can be changed by varying the values of C1 and R1 to change the time constant. C2 is a coupling capacitor, and the potentiometer VR varies the input level. Input a fixed voltage level and adjust the potentiometer so that the LED lights at 0dB. To reduce the LED current, connect a resistor either in External dimensions (Units: mm) 636 parallel (Fig. 3 (1)) or in series (Fig. 3 (2)) with the LED. If a resistor 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. 4).