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| Battery voltage to 5V regulation - overcurrent shutdown protection: working |
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| HendriXML:
I’ve build the circuit and did benchmark the voltage regulation. The measurements were taken sinking into a 5R1 resistor shorted to ground by a IRLZ44N mosfet, driven by a signal gen. Square wave, 0-3 V, 26 hz, 20% duty cycle. Testcase 004 C3: 2200 uF C1: 0 nF R2: 0 Ω The reference psu measurements are of a Siglent SPD3303X. I used a BNC cable which I cut in half to do the probing directly at the terminals. This method gave a very different picture than measuring at the load which I did previously. Drawing about 1 A suddenly is probably quite sensitive for inductance. :-+ |
| HendriXML:
So I ended up with a circuit with no short (before mosfet) feedback loop. The circuit is stable using a non stabilized simple 9V adapter and on 5x AA batteries. It works still very well at only 5.2 V input and also driving a DC motor shows no "noise". With a short feedback loop a ripple on the adapter is noticeable and also some noise when driving a DC motor. So I think I leave it without. It’s handy that the module can also be used with an adapter. The circuit should run at 5.5 - 10V input and deliver 0-2 A with ease. I used a 3.8 K/W heatsink. The LED indeed goes off when it can not regulate the voltage anymore. This will signal that the battery voltages are to low. |
| HendriXML:
I think I have designed a working overcurrent protection at 2 Amp (Circuit 2.0.48). The idea is that it does a normal R-sense (R12) amplification until the zener IC (D4) starts conducting, at that moment the non-inverting input of op-amp will go down rapidly. The measured voltage of the other op-amp will go down as well, and thus shutting down the output mosfet and turning of the LED. Via R4 the op-amp might deliver a tiny bit of current, but that is ok. The circuit is about protecting the input supply (5 AA 1.25V batteries). I think using this circuit, I don't have to worry that the circuit starts in overcurrent mode due to charging of the capacitors of other modules or a ramp up of the input voltage. When C4 is discharged, the output ramps up slowly anyway. It also does not need a lot of extra parts, but it still will be hard to find space on the perfboard to place them. Feel free to comment! -edit updated the schematic moved R12 |
| Psi:
A fun, but mostly pointless, voltage regulator to build is a system that switches in/out different number of diodes in series based on control from ADC+discrete digital logic (or a MCU). Use a low voltage drop diodes like 1N5817 or better. Use a binary approach where each bit in a byte adds different diode numbers (or shorts them to remove from series string). eg bit0 might add 1 diode, bit1 might add 2 diodes so if bit 1 + bit 2 are both set then 3 diodes are in series. Also include a way to short input to output in case no diode drop is needed. Then you can control the output voltage by selecting the binary number from ADC/MCU. It's a pretty pointless and slow voltage regulator but is kinda cool and it does have the advantage of no drop-out voltage. |
| HendriXML:
--- Quote from: Psi on April 01, 2019, 11:12:55 pm ---A fun, but mostly pointless, voltage regulator to build is a system that switches in/out different number of diodes in series based on control from ADC+discrete digital logic (or a MCU). Use a low voltage drop diodes like 1N5817 or better. Use a binary approach where each bit in a byte adds different diode numbers (or shorts them to remove from series string). eg bit0 might add 1 diode, bit1 might add 2 diodes so if bit 1 + bit 2 are both set then 3 diodes are in series. Also include a way to short input to output in case no diode drop is needed. Then you can control the output voltage by selecting the binary number from ADC/MCU. It's a pretty pointless and slow voltage regulator but is kinda cool and it does have the advantage of no drop-out voltage. --- End quote --- Could be useful as a drop voltage regulator in a variable power supply. With 6 relays a drop of more than 38 V could be achieved (64x0.6V diodes). :-+ But I hope my circuit belongs to a different category... |
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