LED level meter driver integrated circuit diagram

The picture shows the basic application circuit of the BA6104 five-digit LED level meter driver integrated circuit.

Since the input stage of BA6104 uses a PNP compound transistor base input method, its input impedance is very high. The output stage adopts the form of emitter follower. Adjusting the LED external resistor RL in the figure can change the LED drive current. Connecting an external resistor to pin 7 can change Vref. When pin 7 is open, the reference voltage Vref is controlled internally by the IC, and its value is approximately 1V. If the LED display level is required to be lower than 1V, you only need to connect a resistor RD between pin 7 and ground to reduce Vref, as shown in the figure; if the display level is required to be higher than 1V, you only need to connect pin 7 to the power supply Vcc If a resistor R is connected between them, Vref will increase. The relationship is: Vref= [Vcc+0.75R(kΩ)]]/[0.75R(kΩ)+1].