Hello all, would really appreciate some help.
I'm designing a valve heater supply and need to raise the output of a 12V LDO regulator (278R12) by 0.6V. I tried using a 1N4148 diode on the earth leg, which works on standard regulators (78xx), but it just shuts down. I then tried using two shotky diodes(1N5158) in series in the same way and it works but only gives 12.4V.
The input voltage is 14Vdc (rectified from tx, with a 2200u smoothing cap) so I have to use an LDO regulator, the load takes around 1.2A.
I could use the circuit as is, but was wondering why it doesn't work with a normal silicon diode on the earth leg? Is it because the earth leg current on an LDO reg is higher?
Many thanks in advance,
Ned.
I'm designing a valve heater supply and need to raise the output of a 12V LDO regulator (278R12) by 0.6V. I tried using a 1N4148 diode on the earth leg, which works on standard regulators (78xx), but it just shuts down. I then tried using two shotky diodes(1N5158) in series in the same way and it works but only gives 12.4V.
The input voltage is 14Vdc (rectified from tx, with a 2200u smoothing cap) so I have to use an LDO regulator, the load takes around 1.2A.
I could use the circuit as is, but was wondering why it doesn't work with a normal silicon diode on the earth leg? Is it because the earth leg current on an LDO reg is higher?
Many thanks in advance,
Ned.