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POWER SUPPLY PROBLEM WITH MSP430F2013 BASED CIRCUIT
- Thread starter Sbrok82
- Start date
Dear sirs,
thank's for the replies!
I try to explain better my problem.
The scenario is illustred at this image.
A water spot must be sprayed at the pressur of a pushbutton.
My power supply is a 12V DC car battery.
I made a circuit for control a 12V DC solenoid valve (the MCU control the relay) that must be open for some milliseconds (fig. 1).
A 12V DC water pump is used (and run "forever") for put in pressure the water pipe. The pump needs about 7 Ampere when running.
A linear voltage regulator is used for give 3.3V DC from the 12V DC car battery, used for supply the control circuit.
My problem born when I close the circuit, all start for 1 or 2 seconds and then the MSP430 and display retroillumination coocks!
I suppose this is caused by the water pump current consumption and I made a little change to my circuit (fig. 2).
Now I have a second 9V battery with a second power on switch that supply only control circuit and all seem to function correctly.
My question is: how I can obtain a safe 3.3V from the 12V DC car battery without all listed problems?
Thank you in advance,
Silvio Vallorani.
thank's for the replies!
I try to explain better my problem.
The scenario is illustred at this image.
A water spot must be sprayed at the pressur of a pushbutton.
My power supply is a 12V DC car battery.
I made a circuit for control a 12V DC solenoid valve (the MCU control the relay) that must be open for some milliseconds (fig. 1).
A 12V DC water pump is used (and run "forever") for put in pressure the water pipe. The pump needs about 7 Ampere when running.
A linear voltage regulator is used for give 3.3V DC from the 12V DC car battery, used for supply the control circuit.
My problem born when I close the circuit, all start for 1 or 2 seconds and then the MSP430 and display retroillumination coocks!
I suppose this is caused by the water pump current consumption and I made a little change to my circuit (fig. 2).
Now I have a second 9V battery with a second power on switch that supply only control circuit and all seem to function correctly.
My question is: how I can obtain a safe 3.3V from the 12V DC car battery without all listed problems?
Thank you in advance,
Silvio Vallorani.
You can't use that transient diode rating on anything but a depleted 12V battery. In an operating vehicle it'll fry. You'll need to use at least the 16V type, preferably the 18V.
You have the input polarity of K1 the wrong way around, and you're missing a series resistor (unless the MSP430 is short-circuit proof, I didn't consult that datasheet).
Also, I'd want to put a diode in series with the track going between pin 4 of K1 and + of C10. This to prevent negative-going spikes to deplete the charge on C10.
You have the input polarity of K1 the wrong way around, and you're missing a series resistor (unless the MSP430 is short-circuit proof, I didn't consult that datasheet).
Also, I'd want to put a diode in series with the track going between pin 4 of K1 and + of C10. This to prevent negative-going spikes to deplete the charge on C10.
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