USB-SOLAR can charge USB devices such as mobile phones, IPod, GPS
devices etc, from either a Lipoly battery or a solar cell. There are
four modes of operation:
- Use solar cell to charge SuperCaps, which in turn are
used to power USB +5V
-
Use
solar cell to charge LiPoly battery, which can then be used to power
USB +5V
- Use PC USB to charge LiPoly battery, which can
then be used to power USB +5V
-
- Use external +5V supply to charge LiPoly battery, which can then be used
to power USB +5V
| Charge Source |
Super Caps |
Description |
| Solar |
Yes |
Solar cell can be connected to either J2 pin-6,
or via USB-PWR adapter to
miniUSB (J6). Can be used with or without LiPoly
battery. If using with battery place jumper between
J1-2 and J1-3. If NOT using battery then place jumper
between J1-1 and J1-2. |
| USB |
Not required |
Connect USB to miniUSB (J6). |
| Ext +5V |
Not required |
External +5V can be connected to either J2
pin-6, or via USB-PWR
adapter to miniUSB (J6). External supply should be
capable of supplying 5V @ 500mA. |
| USB and Solar |
Yes |
Connect USB to miniUSB (J6), and solar to J2
pin-6. Battery will charge from both sources. |
| Ext +5V and Solar |
Yes |
Connect Ext +5V via USB-PWR
adapter to miniUSB (J6), and solar cell to J2 pin-6.
Battery will charge from both sources. |
Table (1) Charging power sources
Lithium
Polymer Battery
3.7V
LiPoly batteries
available from SparkFun plug directly into J7. The battery should be
capable of supplying 750mA if you plan on charging USB devices at 500mA. Also it
should be capable of being charged at 500mA, although you can change
resistor R24 to alter the charging current. Current drain during standby
is less than 1mA.
|
Name |
Pin Number |
Description |
| V_BATT |
J7-1 |
+ Supply. Polymer Lithium Ion Battery positive supply. Nominal
3.7V. Current drain 750mA max, <1mA during standby. Charge current
500mA max. |
| GND |
J7-2 |
- Supply. Polymer Lithium Ion Battery negative supply |
Table (2) Battery Connector
Solar Cell
Solar cells
available from SparkFun plug into the miniUSB (J6) via
USB-PWR
adapter. If the solar cell has an
open circuit voltage greater than 5.1V, then the short circuit current
should be less than 300mA, or you risk burning out the zener diode D1.
Alternatively you can change the zener for a part with a higher power
rating.
Power Switch
The V_USB output
voltage is available at USB connector J4 and also at J2 pin-5. The
voltage output can be switched on and off using momentary action switch
SW1, or by external switch connected between J2 pin-1 and GND (JP8)
Bicolor LED (D2)
The Bicolor LED indicates state of V_USB
output voltage and battery charging state.
| Red LED State |
V_USB Output Voltage |
| Off |
0V |
| Blinking |
+5V |
| Steady |
Reserved for future use |
| Green LED State |
Battery Charging State |
| Off |
No battery, or no charging supply |
| Blinking |
Battery charging |
| Steady |
Battery charging complete |
Table (3) Bicolor LED States
Microcontroller
A SiliconLabs C8051F330
microcontroller, controls the power supplies and reports status.
External systems can communicate with the microcontroller using I2C or
logic level RS-232 signals connected to J2-2 and J2-3. Four unused I/O
pins are available to the user at JP4, JP5, JP6, and JP7. You can use
the C2DBG port to run and debug your own custom program. You will need
C2DBG-ADPT to connect the SiLabs USB Debug
Adapter to the 3-pin J5 connector.
|
Name |
Pin Number |
Description |
| C2D |
J5-1 |
C2DBG Data |
| GND |
J5-2 |
Ground |
| C2CK |
J5-3 |
C2DBG Clock |
Table (4) C8051 Debug Connector
Host
System Connector
There is
provision for an external host to utilize USB-SOLAR as a smart battery.
If you have a system that uses a single +5V supply, then you can simply
connect your +5V supply to V_USB, and then use V_CHARGE to power your
system. The connector can also be used as an alternative connection
point for a solar cell (V_CHARGE), especially if you wish to retain the
miniUSB for USB charging, and thus have a dual charge source system.
Wires can either be inserted directly into the board, or you can use a
6-pin or 7-pin 0.1" pitch connector. Eg Molex 7pos header 22-27-2071 (Digikey
WM4116), Molex 7pos housing 22-01-3077 (Digikey WM2005), Molex crimp
terminal 08-50-0113 (Digikey WM1114CT). There is the possibility to
strip a lot of components if using the USB-SOLAR as a smart battery
controller. ie J6, J4, JP2, D2, U9, C1, C2, C71, C72, R17, R18, R19,
R20, R13, R21
|
Name |
Pin Number |
Description |
|
GND |
JP8 |
Ground. Positioned
next to J2-1, so J2 can be stuffed with 7-pin 0.1" pitch
connector, and this ground can be used in conjunction with J2-1. |
|
PWR_BUTTON |
J2-1 |
Connected in parallel
with SW1. Pulled up to +3.3V. Momentarily short to ground to
enable or disable V_USB. |
|
BATT_DATA |
J2-2 |
Reserved for I2C SDA
or UART TXD. Pulled up to +3.3V |
|
BATT_CLK |
J2-3 |
Reserved for I2C SCL
or UART_RXD. Pulled up to +3.3V |
|
GND |
J2-4 |
Ground |
|
V_USB |
J2-5 |
Output supply, +5V @
500mA |
|
V_CHARGE |
J2-6 |
Input supply. Connect
to solar cell or +5V 500mA power supply |
Table (5)
Host System Connector
Jumper Configuration
The power
source for the V_USB output voltage must be selected by jumper
placement. If using battery place jumper between J1-2 and J1-3. If NOT
using battery then place jumper between J1-1 and J1-2.
The state of USB data lines connected to device to be charged is
controlled by JP2. However, it seems that jumper JP2 can be left in, and
all devices tested so far appear to happy with this setting. The
conclusion being that R17 and R19 could probably be removed from the
board.
Base2Designs 
