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This project is a power supply for a portable measure device. It requires ease of use, the need to integrate all elements of charging, battery status control and processing the direct current (DC/DC).
- the system must support safely a full charge cycle of a single Li-Poly cell, in the sequence CC/CV
- the power source while charging is the USB port (5V/500mA) or a mobile phone power supply Nokia type APC-12E (5,7V/800mA)
- built-in charger must ensure indication of connecting the power supply and duration of the charging process. It also must ensure safe leaving connected device for any long time after the end of the charging process
- the charging system should allow the optional selection of parameters, such as the maximum charging current and maximum charge time; pre-selected parameters are 500mA and 4h
- the battery must be protected against excessive discharge current (>2A)
- the charger's impact on the self-discharge of the cell should be negligibly small
- the system must enable disconnecting the load by logic (digital) signal
- voltage converter (regulator) should provide gain of the output voltage 5,0V±5% at maximum current load up to 1000mA
- it should be possible to measure the battery voltage and output voltage through an external supervisory system
Analog Devices Inc. Chips used in this device:
- charger ADP2291
- pulse converter ADP1610
The system was implemented and tested. It works successfully at low output currents 100-150mA and then the powered device operates 6-8 hours.
Scheme of the power supply system 5V/1A is shown below:
Pictures showing assembled power system:
More details, schemes of other three variants, PCB drawings and assembly schematic can be found at: LINK.
Link to original thread (useful attachment) – Kompletny system zasilania na bazie akumulatora Li-Poly