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Battery Charger & Management System | Cypress Semiconductor

Block Diagram

Design Considerations

A typical Li-ion/Li-polymer/NiCd/NiMh battery charger circuit requires a

  • 10-12 bit ADC with pre-amplifier to measure the battery voltage, charging current and temperature
  • PWM for regulation of charging parameters (voltage and current)
  • Cell-balancing (for multi-cell batteries) and fuel gauge algorithms

One of the basic tasks in battery charger is the regulation of battery voltage and current without exceeding the temperature limits. This requires a control loop which involves measurement of the battery parameters (voltage, current and temperature) and controlling the PWM duty cycle that drives the external power network. PSoC with its precision ADC (max 14 bits) - implemented using analog blocks, PWM - implemented using digital blocks and a processor core forms such a control loop required for regulation. Other algorithms like cell balancing and fuel gauge can be implemented using a firmware logic.

The advantage of using PSoC lies in the implementation of custom protocol for charging the battery and integration of other functions like Capsense, Segment LCD drive etc which are not possible when using dedicated battery charger ICs.

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PSoC Resources

Functions
Linear/Switching* based chargers using PSoC 1
Battery voltage measurement and protection
1 Op amp, ADC
Battery current measurement and protection
2 Op amp, ADC
Battery voltage/current control
PWM and external regulator circuit
Temperature measurement using Thermistor
1 Op amp, ADC
Calibration of battery voltage measurement
External precision resistors, 1 op amp, ADC
Input Over-Voltage protection (OV)
1 Comparator
Input Over-Current protection (OC)
2 Op amp, 1 Comparator
Input under-voltage lockout
1 Op amp, ADC
Time out Protection
1 Timer
Note:
All components are internal to PSoC 1 unless specified with “external”
Op amp and ADC are multiplexed for battery voltage, current, temperature and input voltage measurement
 
* Linear chargers are good for noise sensitive equipment, but power dissipation is high at higher charging current. Thus, it is suitable for low charging current.
Switch-mode charging is suitable for higher charging currents due to its higher efficiency, but it is more complex and generates noise which can affect other functions on the board if care has not been taken.

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Technical Article

Selecting the right battery: www.eetimes.com/design/smart-energy-design/4375627/Battery--The-source-of-a-device---Part-1

Implementing Li-Ion Battery Charger: www.eetimes.com/design/smart-energy-design/4376071/Implementing-battery-charger-using-Li-ion

Development Kits/Boards

  • PSoC Programmer 3.24 or later and KitProg 2.14 or later are required to program the PSoC 4200L device on the PSoC 4 L-Series Pioneer Kit. PSoC Creator installation or the kit installation automatically installs PSoC Programmer and KitProg drivers.

Software and Drivers

  • PSoC Creator

    PSoC Creator is a state-of-the-art software development IDE combined with a revolutionary graphical design editor to form a uniquely powerful hardware/software co-design environment.

  • PSoC Designer

    PSoC Designer is the revolutionary Integrated Design Environment (IDE) that you can use to customize PSoC to meet your specific application requirements. PSoC Designer software accelerates system bring-up and time-to-market.