I am trying to use a BCD converter 7447 to display numbers on a seven segment display. Even before I apply any inputs or outputs, I observe that the VCC voltage of the 7447 drops (which is powered by a 7805 voltage regulator). The voltage drops to around 3V. I need this voltage to power up other ICs so can't afford it to go so low. I am unsure why is the voltage dropping so drastically. I have done some debugging and found the the 7447 is drawing just 7mA from the 7805 while the voltage is dropped to approximately 3V. I tried putting a resistor that draws 50mA and that only caused the voltage to drop to 4.85V. I am really confused why is the voltage dropping so much. I encourage the maker community to share their thoughts. I am stuck on this for the last two days.
ps. the input power supply to the 7805 is a 12V adapter capable of delivering 1A. It's output remained stable at 12V throughout all experimentation.
Thanks,
Best Answer
Thanks for everyone who commented and pointed in the right direction specially @Transistor. The problem was resolved by adding decoupling capacitors at input and output.