The reference design is based on providing a low current providing Li-ion charger which can integrate with energy harvesting applications.
Energy harvesting (energy scavenging) is the process by which energy is derived from external sources (e.g., solar power, thermal energy, wind energy, salinity gradients, and kinetic energy, also known as ambient energy), captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks.
The type of battery used for this application is generally a compact battery with high power density. Li-ion and lithium polymer batteries are generally preferred for these type of applications requiring batteries for longer run and charge cycles.
The reference design helps in designing a charging system for a single cell Lithium-ion battery when the source is Solar based Systems. There are some parameters which play a vital role in designing of a charging system. These are some of the key parameters –
- The operating Voltage of the Charger.
- The type of batteries supported by the charger such as lithium polymer, lithium-ion, nickel-cadmium etc as all of these batteries has different nominal voltages. The output voltage of the charger also depends on the type of cell which is connected to the charger.
- The output current provided by the charger. As in energy harvesting applications, the generated output can be as low as 10 milliamperes, so the system should be designed to detect and charge the connected battery.
- The efficiency of the charger should be high to produce maximum output from the energy source.
- The charger should be equipped with circuit protection features like battery indicator, reverse polarity and over-voltage protection.
- As it is a charging device, the thermal losses are high. The charger should be equipped with a thermal sensor in order to monitor the battery efficiently and protecting it from overcharging.
These are some of the key parameters which should be used when we design a charging circuit. The design is based on a product of Analog Devices named DC1584A-ND.
Some features of the design referred are –
- The operating input voltage of the circuit ranges from 10 Volts to 16 Volts with an offset voltage of 12 Volts.
- The maximum continuous current provided by the circuit is 49.7 milli-amperes.
- The device supports different type of batteries such as Lithium-ion and Lithium Polymer with a nominal voltage of 3.7 V and cutoff Voltage of 4.2V.
- The output of the charger ranges from 4 to 4.2 Volts.
- The design is equipped with an onboard LED-based battery charging indicator.
- The circuit is equipped with features like Over-Voltage protection and thermal protection.
All these specifications make this reference design suitable in applications like Automotive
Industries, Energy Harvesting applications and Solar Powered Memory Back-up Devices.
These are some of the characteristics of the reference design provided by Analog Devices. All the documents are included with the reference design which can be downloaded here.