Last updated, Jun 24th, 2003
1) Controlling electric power generated by solar cells.
2) Sharing solar power between internal device and lithium ion battery charger suitably.
3) Regulating electric power high efficiently.
4) Measuring the solar cell generated voltage, current, Li-Ion charge/discharge current and bus voltage.
5) Measuring the temperature of circuit board, regulator, and battery.
Cirtcuit Diagram
Circuit Diagram
Click to enlarge.
CUTE-I EPS generally consists of comsumer devices except for the solar cells.

CUTE-I has lithium-Ion secondary batteries as the internal power storage. The following table showes the specification of the lithium-ion battery. CUTE-I battery consists of 4-parallel configuration (4160mAh).
Specifications of Lithium-Ion Battery
Nominal Capacity 1040mAh
Nominal Voltage 3.8V
Charging Voltage 4.2+/-0.05V
Cathode Materials Cobalt
Anode Materials Graphite
Dimensions (W,T,H) 33.8 x 6.5 x 66.6mm
Cycle Life 500cycle
Operationg Temperature Range Charge -0'C to 45'C
Discharge -20'C to 60'C
Storage -20'C to 40'C
Weight 32g
<Solar Cell>
CUTE uses high efficiency and thin silicon solar cells.
The following table shows the specifications and electrical performance.
The estimation of generated electric power is more than 1.5W.
Specifications of Silicon Solar Cells
Cell Dimension (Original size) 4 x 6 cm (Cut Available)
Cell Thickness 100um
Voc 630 mV
Isc 1125mA
VL 530mV
IL 1038mA
Pmax 550mW
Fill Factor 0.78
Efficiency 16.9%
AM0 135.3mW/cm2 , 28 degrees
CUTE-I required voltages are...
- 3.3V: OBC, sensors, TNC,...
- 5.0V: TCXO
- 3.8V: CW Tx, FM Tx, FM Rx.

CUTE-I EPS supplies the suitable and stable voltage using high-efficient DC-DC converter.
Circuit Board

Copyright(C) 2003 All rights reserved.
Tokyo Institute of Technology    Lab. for Space Systems (LSS)
Contact : Naoki MIYASHITA