FAQ

1. What is EPS? What is for?
   Electrical Power System is a subsytem of satellite responsible to collect,stored and distribute for another modules the energy received from six solar panels. The energy received by solar panel is stored in two lithium-ion batteries connected is series. To distribute, has integrated DC-DC for each module, this is important because each ones need different voltage and current.

2. How much energy is harvested with solar panels? How EPS know the current of the solar painels?
   The energy is about Vmpp = 4800 mV ± 150 mV; Impp = 500 mA ± 50mA; at Spectrum: AMO WRC = 1367 W/m². To know the current, EPS use a resistor of 0.05 ohm and a High Precision, Low Voltage, Current-Sense Amplifier.

3. How much energy is stored in batteries?
   The batteries has a nominal voltage of 7.4 V ±200 mV (3.7 V ±100 mV each battery) and electrical charge capacity of 3Ah ± 200mAh.

4. How it control the charger of batteries?
   The board uses a BQ2057wsn chip that controls the batteries charging procedure.

5. How much power can be sourced to other modules?
   The Power Consumption Dynamic is approximately 5.4 W. But, each module need a different value for voltage and current:

• Main power bus: batteries voltage ± 200 mV/3A;
• EPS/Beacon: 3V3 ± 200 mV/2A;
• PA Transceiver Radio: 3V3 ± 200 mV/5A;
• PA Beacon: 3V3 ± 200 mV/5A;
• Antenna Module: 3V3 ± 200 mV/2A;
• OBDH/Transceiver radio/solar panel sensors: 3V3 ± 200 mV/1A;
• RUSH: 5V ± 200 mV/3A.

6. What if there is no batteries?
   The consume of all system depend directly from the satellite positioning as well as solar panels.

7. How does this module organize the output voltages and currents? The energy distribution is done by several integrated DC-DC converters. More information

8. Why the module use Crystals?
   To send a PWM that control the batteries charger and uncharged.

9. Why use microcontroller MSP430?
   Because, as OBDH FAQ, has Ultra-low-power design, a robust and flexible system (I2C interfaces, SPI, UART, internal flash memory, timers, ADC ...) and a step-by-step debugging interface through JTAG.

10. What is the efficiency of solar panels?

11. Why is there a temperature gauge?

12. What is the function of the 555 timer?