SLAA476B February   2011  – July 2019 BQ2040 , BQ2040 , BQ2060A , BQ2060A , BQ2063 , BQ2063 , BQ2083-V1P3 , BQ2083-V1P3 , BQ2084-V143 , BQ2084-V143 , BQ2084-V150 , BQ2084-V150 , BQ2085-V1P3 , BQ2085-V1P3 , BQ20Z40-R1 , BQ20Z40-R1 , BQ20Z70-V160 , BQ20Z70-V160 , BQ20Z80A-V110 , BQ20Z80A-V110 , BQ28400 , BQ28400 , BQ78PL114 , BQ78PL114 , BQ78PL116 , BQ78PL116 , LM5145 , LM5145 , MSP430F5500 , MSP430F5500 , MSP430F5501 , MSP430F5501 , MSP430F5502 , MSP430F5502 , MSP430F5503 , MSP430F5503 , MSP430F5504 , MSP430F5504 , MSP430F5505 , MSP430F5505 , MSP430F5506 , MSP430F5506 , MSP430F5507 , MSP430F5507 , MSP430F5508 , MSP430F5508 , MSP430F5509 , MSP430F5509 , MSP430F5510 , MSP430F5510 , TPS40057 , TPS40057 , TPS40170 , TPS40170

 

  1.   Wide-Vin Battery Charger Using SMBus Communication Interface Between MSP430™ MCUs and bq Fuel Gauges
    1.     Trademarks
    2. 1  Introduction
    3. 2  Hardware
      1. 2.1 Overall System Description
      2. 2.2 MSP430F5510 Daughterboard Subsystem
        1. 2.2.1 Subsystem Description
        2. 2.2.2 MSP430F5510 Port Pins Functionality Description
      3. 2.3 Power Stage Board Subsystem
        1. 2.3.1 Subsystem Description
        2. 2.3.2 Input Protection Features
        3. 2.3.3 Constant-Voltage and Constant-Current Feedback
    4. 3  Software
      1. 3.1 SMBus Protocol Description
      2. 3.2 Software File Structure
      3. 3.3 API Calls Description
        1. 3.3.1  UCS_Init ( )
        2. 3.3.2  Timer_Init ( )
        3. 3.3.3  PWM_Init ( )
        4. 3.3.4  ADC_Init ( )
        5. 3.3.5  Fan_Init ( )
        6. 3.3.6  LED_Init ( )
        7. 3.3.7  SMBus_Initialize ( )
        8. 3.3.8  LED_Control ( )
        9. 3.3.9  Fan_Control ( )
        10. 3.3.10 VI_ADC_Read ( )
        11. 3.3.11 SMBus_Select ( )
        12. 3.3.12 Calibrate_Battery ( )
        13. 3.3.13 Delay_Timer ( )
        14. 3.3.14 PWM_Control ( )
        15. 3.3.15 Smbus_Access ( )
        16. 3.3.16 Smbus_Access_PEC ( )
        17. 3.3.17 crc8MakeBitwise ( )
      4. 3.4 Sample Application Description
    5. 4  SBS Supported Commands Using SMBus Protocol
    6. 5  Detailed Sample Application Flow Chart
    7. 6  Battery Status Register Description
      1. 6.1 BatteryStatus (0x16)
    8. 7  MSP430F5510 Daughterboard Schematics
    9. 8  Setting Up the MSP430F5510 Daughterboard Hardware
      1. 8.1 JTAG FET Debugger Interface (Power Up, Program and Debug Options)
      2. 8.2 eZ430 Emulator Interface (Power Up, Program and Debug Options)
      3. 8.3 Power Stage Board (Power Up Option Only)
    10. 9  Battery Calibration Circuit Setup
    11. 10 Battery Voltage and PWM Conversions
    12. 11 Battery Current and PWM Conversions
    13. 12 Power Stage Board Schematics (Generation 1: 40-V Input)
    14. 13 Bode Plot Measurement for Feedback Loop Stability Analysis
    15. 14 Power Stage Board Schematics (Generation 2: 60-V Input)
    16. 15 Setting Up the Power Stage Board Hardware
    17. 16 References
  2.   Revision History

2.2.1 Subsystem Description

Figure 3 shows the block diagram of the MSP430F5510 daughterboard subsystem.

MSP430F5510_daughterboard_sub_bd_laa476.gifFigure 3. MSP430F5510 Daughterboard Subsystem Block Diagram

The daughtercard subsystem has the following features:

  • The I2C USCI module within the MSP430F5510 is used to implement the SMBus protocol for communication with the battery fuel gauges.
  • A 1-to-2 demultiplexer (demux), TS3A24157, is used to separate the SMBus clock (SCL) and data (SDA) lines for the two batteries [15]. During the manufacturing process, all of the fuel gauges for a particular battery series are programmed to the same SMBus slave address. The advantage of using a demux is that one microcontroller with one I2C/SMBus USCI module can be used to communicate with multiple fuel gauges within multiple smart-batteries.
  • The MSP430F5510 outputs voltage and current PWM signals at a frequency of 20 kHz to control the power delivered by the DC/DC converters on the power stage subsystem.
  • The on-chip 10-bit ADC is used to convert voltage and current signals from the batteries. The voltage from the battery is divided down from the wide-input range to the ADC range by means of a resistor-divider circuit on the MSP430F5510 daughterboard. The current is fed into a shunt resistor on the power-stage board, and the resulting voltage is fed into the ADC channels directly.
  • Eight status LED indicators; seven are software programmable, and one indicates power-on status.
  • Two sets of power resistors for discharging two batteries independently. The discharge circuitry can be turned on or off by the microcontroller to calibrate battery pack voltages. Section 9 has details on setting up these circuits.
  • Fan control output to power a heat venting circulation fan on or off.
  • Two options to program the software on the MSP430F5510 daughterboard:
    • 14-pin JTAG interface (four-wire) for connecting the flash emulation tool (FET)
    • 6-pin Spy-Bi-Wire interface (two-wire) for connecting the eZ430 emulator
  • Three options to power the MSP430F5510 daughterboard:
    • JTAG interface (voltage level programmable in the integrated development environment (IDE) options)
    • eZ430 emulator interface (supply voltage fixed at 3.6 V)
    • The charger board supply power (approximately 10 V), which is routed through the TPS71533 LDO to supply 3.3 V to the MSP430F5510 [16]. For a wider input supply range up to 50 V, the TPS79801 LDO can also be used to supply 3.3 V [17].