The MSC is a monitored solar regulator providing a configurable stable output voltage (or optionally a +5V output on a standard female USB connector).
The HW2.x version is an upgrade of the HW1.x version. The two sub-boards were split in 2 PCB. The MB is the monitoring board, which embeds the following new features:
- Add a supercap to perform a continuous monitoring, so that the board can be powered by the same solar panel as the power board.
- Add multiplexer so that a single monitoring board can handle up to 4 power boards (MSC_HW2-0_PB).
- Adapt the mechanical form factor to a 5U DIN device.
- Add a temperature / humidity sensor.
See MSC_HW2-0_PB project for the power board:
NOTE : this version is not usable because of some design errors:
- The supercap voltage regulation with a ballast transistor is not efficient for high voltage solar input: the power dissipation of the transistor is very high because of the large drop out voltage. Power dissipation could be reduced by limiting the charge current, but the charge time would be too long. A front DC-DC converter is better suited to perform this regulation.
- The chosen multiplexers do not provide isolation when powered off. When the analog regulator is turned off (or the board is not powered at all), parasitic impedances could appear between channels. A normally-opened switch should be placed prior to the MUX, to ensure isolation in powered-down state.
- The multiplexers are powered at 3.0V. In the case of the current sensor circuit, the MUX cannot withstand the high common mode voltage comming from the power board (VOUT and VSH directly connected).
- The differential amplifier is powered at 3.0V, whereas it has to be powered by the high side voltage (VSH).
See MSC_HW2-1_MB project instead:
Below is the functional block diagram of the board.