I have a KA7805A voltage regulator and i am placing 12V of p.d. across the Vin and GND pins. This is well below the max input voltage of 40V.
The Vout pin gives a nice steady roughly 5.05V when connected to my motor driver board. All the electronics work fine.
When i attach the Vout and GND to both my motor driver board and my main MCU board, which i send the power to down the 4Wire ICD cable (+5v,GND,SCL,SDA), the Vout pin becomes 2.6V.
The is hardly any current through the voltage regulator ( it is rated at 1Amp max). All it is powering is 2 PICs, a couple of LEDs and a Sharp IR. The voltage regulator doesn't noticably heat up.
Any ideas on what could be happening and how to fix it?