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Need 6V 6A OUT Solution: Pololu 6V Step-Up Voltage Regulator U3V50F6

Greetings, I have been enjoying reading about all the fantastic projects and solutions here. I am working on several robot projects, the computer requires 11.1V / 3A surge or 6V / 6A surge, with 10-12W nominal power consumption. I am using two 3.8V 5000 mAh Li-ion cells (2S) so output starts at 7.6V at full charge and discharges to roughly 3.8V (3.3V absolute lowest). As expected the the higher voltage (12V) step-up regulators have very low current out at 3.3V, so thinking of putting three 6V regulators into a parallel circuit to get 6A out at 3.3V. Thus far the Pololu 6V Step-Up Voltage Regulator U3V50F6 is the best match for size, weight and power. Tech support shared a related link: 12v Step regulator cuts out here where another put two in parallel with success albeit “risk”. As a follow on to that idea, has anyone come up with the input circuitry to do this safely? There must be a way to isolate each regulator from one another, I know on larger power supplies, you can set master / slave or one to constant voltage (CV) and others to constant current (CC), can this be done using the ENABLE pin in a cascading circuit where one, then two, then three regulators turn on as input voltage and output current require?

This would be an ideal situation:

  1. While battery is above 6V, the power feed would be pulling directly off the battery (no losses due to the step up regulator).
  2. Once battery voltage dipped <6V, the power feed would pull from one regulator up to the maximum current, then the 2nd regulator would kick in up to its maximum current, then the third up to maximum current. None fighting each other to maintain voltage.

Thinking there must be a way to effectively get this done with some connecting circuitry. My search continues, anyone having solved this or with good ideas, would love to hear them. Thanks again to all.

Hi.

Connecting multiple supplies together can be done with some kind of ORing circuit. The simplest is adding diodes to each source, but that an be pretty inefficient. Some kind of active ORing with MOSFETs is more efficient, but much more complicated. This article on the Fundamentals of power system ORing might be a good place for you to start. For switching power from battery to the regulator, you will probably want to look for something like a power multiplexer. We have power MUX carriers based on the TPS2113A and FPF1320, but they are nowhere near powerful enough for your load. You might also be able to fine a power controller that includes both functions.

-Claire