Embedded Files
Main Integrated Circuit Schematic
Main Integrated Circuit Schematic
In the main schematic shown above, the left side of the pins of the bq76pl455a IC are connecting to multiple inputs of the cell balancing schematic such as the VSENSE and EQ inputs. The top pins of the main IC connect to power supply and temperature monitoring circuit. the right side pins of the IC connect to the FAULT and COMML inputs of the right side of the main schematic. The bottom pins of the IC connect to the TX and RX inputs. The TX and RX are transmitters and receivers for data information. The right side of the main schematic illustrates the communication circuits that will allow multiple boards to be able to communicate data information with each other.
Cell Balancing Schematic
Cell Balancing Schematic
-Zener diodes are placed between VSENSE input pins for over-voltage protection and a path for inrush current during hot-plug.
-Resistors (R15 & R18) and capacitors (C18 & C19) functions as a Low Pass RC filter for high frequency noise on Analog Front End inputs
Cutoff Frequency Fc = 1/2*pi*R1C1
-A shunt resistor (R19 & R24) connected in series with the N-MOSFET in each battery channel. When the balancing is activated, current will flow through the shunt resistor and LED and will allow the battery cell to dissipate excess charge from battery cells.
Power Circuit:
Power Circuit:
- The circuit is designed such that the PCB will draw its power from the positive terminal from the top battery cell and from the negative terminal of the bottom battery cell. The NPN transistor is used so it will step down the voltage to 5 Volts so it will be safe to plug into a laptop for testing purposes.
HV-LV Isolation Circuit:
HV-LV Isolation Circuit:
- The isolation circuit will keep the BQ76PL455A integrated chip from being internally damaged from high voltage. While also preventing noise interference from the high to low voltages circulating through the circuit.
Temperature Circuit:
Temperature Circuit:
- This design contains eight temperature channels in order to test the remote temperature of the cells. This is able to measure the temperature of a pair of battery cells in real time while running the Texas Instrument software program to implement passive cell balancing.
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