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Control Register Demonstration

4.2.1

STATUS: 0x00

Bit 0 is the Power On Reset Flag (POR). It is set on a each power-up and wake up from sleep.

Bit 1 is the CRC Error Status Flag (CRC_ERROR). It is updated on every I2C write packet.

Bit 2 is the Overcurrent Alert Status Flag (ALERT). This reflects the state of the overcurrent comparator.

4.2.2

CELL_CTL: 0x01

Bits 0-2 are the cell select bits (CELL_SEL) that determine which cell voltage input (VC1

–

VC6) is sent to

the VCOUT pin.

Bits 4-5 are the VCOUT multiplexer selector bits (VCOUT_SEL). These bits determine the output of the
VCOUT pin: either VSS, VCn, Vref x 0.5, or Vref x 0.85.

4.2.3

BAL_CTL: 0x02

Bits 0-5 are for cell balance control (BAL_1

…

BAL_6).

4.2.4

CONFIG_1: 0x03

Bit 0 is the current amplifier gain select bit (I_GAIN). The gain can be set to 4 or 8.

Bit 2 is the current amplifier calibration bit (I_AMP_CAL). It is used to select the current measurement:
from SENSEN or SENSEP.

Bit 3 is the current comparator polarity select bit (I_COMP_POL). This determines the current direction
used to trip the comparator: charge or discharge.

Bits 4

–

7 determine the current comparator threshold setting (I_THRESH). Sixteen different mV levels are

available.

4.2.5

CONFIG_2: 0x04

Bit 0 is used to set the reference voltage level (REF_SEL). VREF has two different voltage levels.

Bit 7 is used to enable or disable the I2C CRC.

4.2.6

POWER_CTL: 0x05

Bit 0 is used to enable or disable the reference voltage (REF_EN).

Bit 1 is used to enable or disable the thermistors bias voltage (VTB_EN).

Bit 2 is used to enable or disable the cell voltage amplifier (VC_AMP_EN).

Bit 3 is used to enable or disable the current amplifier (I_AMP_EN).

Bit 4 is used to enable or disable the current comparator (ICOMP_EN).

Bit 6 is used to disable the sleep mode (SLEEP_DIS).

Bit 7 is used to enter sleep mode (SLEEP).

4.3

Modifying Control Registers

Control register bits that are writable can be modified by simply clicking on the bit that the user wishes to
change. The modification is immediately communicated by the Evaluation Software to the bq76925.

4.4

Sleep Mode and Wake Up

The bq76925 can be put into a low-power mode called Sleep. Bit 7 in the PWR_CTL register is called
SLEEP. When this bit is set to a 1, the part shuts down the V3P3 output and enters the low-power state.
To enter sleep mode, simply click the SLEEP bit in the Control Registers display.

19

SLUU514

–

July 2011

bq76925EVM Evaluation Module

Submit Documentation Feedback

Copyright

©

2011, Texas Instruments Incorporated

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Содержание bq76925EVM

Страница 1: ...iguration Switches and Jumpers 12 3 3 Power to the bq76925EVM 12 3 4 Connect USB TO GPIO Adapter 12 3 5 bq76925 Evaluation Software 13 4 Control Register Demonstration 16 4 1 View Control Registers 16 4 2 Control Registers Introduction 18 4 3 Modifying Control Registers 19 4 4 Sleep Mode and Wake Up 19 5 Control Panel Demonstration 21 5 1 Access to the Control Panel 21 5 2 Measurement Tab 22 5 3 A...

Страница 2: ...ll of Materials 37 9 Printed Circuit Board 38 List of Figures 1 Home Screen of the Evaluation Software 13 2 Poll Button in the Evaluation Software 13 3 Poll Button in the Evaluation Software 14 4 Demo With Two Power Supplies 15 5 Voltage Temperature and Current Measurement in the Evaluation Software 15 6 Select Cell Count Set to Three Cells 16 7 Volatile Control Registers Checkbox 16 8 Volatile Co...

Страница 3: ...figuration 9 8 J4 V3P3 Pin Capacitor Circuit Configuration 9 9 J5 SENSEP Pin Circuit Configuration 9 10 J6 DVCC Pin Circuit Configuration 9 11 DIP Switch S4 9 12 DIP Switch S2 10 13 Test Points 10 14 Circuit Configuration 12 15 Default Register Values 18 16 Formulas to Convert VCOUT to either C or mV 23 17 Example Log File 26 18 Example of a Device Connect Command 28 19 Data From MSP430F2122 29 20...

Страница 4: ...ages and other important circuit nets EVM design files in Mentor Graphics PADs 2009 format available on request Gerber files available on request 1 2 Kit Contents The bq76925EVM includes the PWR008 printed circuit board PCB Evaluation software is downloadable from the Texas Instruments Web site www ti com 1 3 Equipment Requirements The bq76925EVM includes one PCB containing a bq76925 application c...

Страница 5: ...urrent The bq76925 expects a sense resistor value of 0 001 Ω and 1 mV is equal to 1 A A jumper J5 allows the sense resistor to be disconnected from the current input of the bq76925 and be replaced with a millivolt source A power supply that can accurately provide up to 100 mV can allow for simulated testing of up to 100 A without actually running this dangerously high current 1 3 6 Battery Lithium...

Страница 6: ...evaluation of waveforms or timing measurements is required Typical waveforms that a user may be interested in are the I2C signals 100 kHz cell balancing waveforms or capture of the activation time of the ALERT signal after an overcurrent event may be of interest These signals can happen down to the 10s of microseconds time base 2 Circuit Details and Configuration This section highlights the import...

Страница 7: ... connections are single heavy duty screw terminals that feature a 6 32 1 4 in screw This connector is rated to 30 A maximum Actual current is limited to a lower value 20 A by other circuit board components 2 1 4 USB Interface CN8 The USB interface connector CN8 is for connection to the USB TO GPIO Adapter The pin assignment is as follows Table 2 USB Interface Connection Header Name Terminal Label ...

Страница 8: ... Purpose CN5 1 GPIO1 GPIO RXD SOMI 2 GPIO2 GPIO TXD 1 SIMO 3 GPIO3 GPIO SCLK 4 GND Ground 1 Silkscreen on the board incorrectly reads RXD 2 2 Configuration Jumpers and Switches J1 J6 S2 S4 Two and three terminal headers allow the user to configure the operation of the EVM by installing a shunt at the header The description of each jumper header is shown in the following tables Shunts are provided ...

Страница 9: ...rom VCC Target 2 2 1 Cell Simulator DIP Switch S4 The eight position DIP switch S4 allows the user to simulate cell voltage inputs to the bq76925 rather than supply actual cell voltages See Table 11 for details of the operation of the DIP switch CAUTION Use silkscreen labeling and square pin 1 pad to determine orientation and operation of the eight position DIP switch Ignore numbers actually print...

Страница 10: ... S1 S3 The two pushbuttons on the EVM are normally open momentary style buttons The pushbutton labeled RESET S1 is the reset button for the MSP430 Pressing this button restarts the MSP430 The pushbutton labeled LEDs S3 is intended to be a display control for the state of charge SOC display formed by the four LEDs D8 D11 Pressing this button triggers an input on the MSP430 that incrementally lights...

Страница 11: ...SP430 circuitry is designed to allow the user to create custom firmware if desired 3 Quick Start Demonstration This section demonstrates the measurement system of the bq76925 using the onboard cell simulator To quickly get the bq76925EVM up and running follow the instructions in this section The following equipment and software are required bq76925EVM Evaluation Module A 24 Vdc power supply Power ...

Страница 12: ...closed position S4 ON All eight switches to the closed position 3 3 Power to the bq76925EVM Ensure that the configuration described in Table 14 has been verified The bq76925EVM must be powered from a power supply for this demonstration The power supply drives an onboard cell simulator as well as powers the bq76925 and MSP430 circuitry No battery is required at this point Connect a 24 V power suppl...

Страница 13: ...e Evaluation Software 3 5 2 Start Polling Data Data from the bq76925 can be polled and displayed in the application To start polling click on the Poll button Figure 2 Poll Button in the Evaluation Software With polling active the cell voltages and temperatures update on a periodic basis The poll indicator light next to the word POLL flashes between green and orange for each poll cycle 13 SLUU514 J...

Страница 14: ...te Current One way to easily simulate battery current is to apply a millivolt source to the current sense inputs of the bq76925 Tens of amperes can be simulated where each 10 mV is equal to 10 amperes 14 bq76925EVM Evaluation Module SLUU514 July 2011 Submit Documentation Feedback Copyright 2011 Texas Instruments Incorporated ...

Страница 15: ...o Power Supplies Remove the shunt from header J5 Use the second power supply to apply 50 mV between pin 1 of header J5 and the BATT terminal This simulates approximately 50 A or 50 000 mA of discharge current Figure 5 Voltage Temperature and Current Measurement in the Evaluation Software 15 SLUU514 July 2011 bq76925EVM Evaluation Module Submit Documentation Feedback Copyright 2011 Texas Instrument...

Страница 16: ...t Set to Three Cells 4 Control Register Demonstration The Quick Start demonstration from the previous section presents the fundamental measurement system of the bq76925 The method to access and modify the Control Registers using the Evaluation Software is presented in this section 4 1 View Control Registers 4 1 1 Introduction Open the Evaluation Software if not already open and click the checkbox ...

Страница 17: ...ne is shown as either a green background or as an orange background Clicking each bit toggles the bit value in real time If a bit turns green it is set to a 1 If a bit is white or grey it is a zero Each of the STATUS bits is displayed in orange when they are a value of 1 If the SLEEP bit is a 1 it halts communications so that the status of this bit is unable to be displayed The SLEEP bit always ap...

Страница 18: ...he Control Register Display Note that other bits are automatically updated written during polling but are not displayed read The update rate of the bits during polling is in the 10s of milliseconds and does not make sense to display 4 2 Control Registers Introduction The Control Registers of the bq76925 are used to configure and control the device A summary of the read write Control Registers foll...

Страница 19: ..._THRESH Sixteen different mV levels are available 4 2 5 CONFIG_2 0x04 Bit 0 is used to set the reference voltage level REF_SEL VREF has two different voltage levels Bit 7 is used to enable or disable the I2C CRC 4 2 6 POWER_CTL 0x05 Bit 0 is used to enable or disable the reference voltage REF_EN Bit 1 is used to enable or disable the thermistors bias voltage VTB_EN Bit 2 is used to enable or disab...

Страница 20: ...of the bq76925 via the USB TO GPIO Adapter input on pin 1 Figure 10 Sleep Mode Showing 3 3 V Status The method to wake the part from sleep is to apply a voltage 3 3 V in the case of the bq76925EVM to the ALERT pin This is accomplished easily by clicking the Wake button in the Hardware IO Section Figure 11 Wake Up From Sleep Mode 20 bq76925EVM Evaluation Module SLUU514 July 2011 Submit Documentatio...

Страница 21: ...anel The Control Panel is purposefully hidden from view when the software is first opened This approach eases the user into the complexity of the software Access to the control panel is gained by clicking on the small toggle switch in the top right corner of the home screen labeled Advanced Figure 12 Open Control Panel Figure 13 Control Panel Details 21 SLUU514 July 2011 bq76925EVM Evaluation Modu...

Страница 22: ...e analog to digital converter A D results on a 12 µs interval The bq76925 software writes to the control registers in the bq76925 to dictate how the measurement system operates The sequence of events is as follows 1 Set VCOUT to Read Internal Temperature 2 Delay 40 µs get A D Counts for Internal Temperature 3 Set VCOUT to Read VC6 4 Delay 40 µs get A D Counts for VC6 5 Set VCOUT to Read VC5 6 Dela...

Страница 23: ...ge or Temperature Units Name Tint Internal Temp C VC6 Cell 6 mV VC5 Cell 5 mV VC4 Cell 4 mV VC3 Cell 3 mV VC2 Cell 2 mV VC1 Cell 1 mV In Table 16 GCREF is defined as 1 And GVCOUT must be set to 0 6 for the bq76925EVM The VCn in Table 16 is the millivolt reading shown in the measurement window 5 5 VIOUT Readings The VIOUT readings are shown in millivolts and labeled as SENSEP and SENSEN The SENSEN ...

Страница 24: ...aluation Software initializes each time it is started or when the Find Target Command is issued This tab specifies the settings of the Control Registers 0x00 to 0x05 when the Enable checkbox is checked Figure 15 Startup Config Tab in the Control Panel 5 9 Configuration Control The Configuration Control section displays some of the options that a user may want to have preselected each time the soft...

Страница 25: ...ntrol Example As an example of how to use the Configuration Control change the Current Comparator Threshold to 175 mV and then press the F2 key to execute the Find Target Command The I_THRESH bits in the CONFIG_1 register changes to 0110 Figure 16 Change to the Current Comparator Threshold to 175 mV at Start Up 5 10 Power Control The Power Control section allows the user to have certain components...

Страница 26: ...rite File deletes any existing data in the specified log file csv each time logging is started The second checkbox labeled Include Uncorrected Values includes all of the uncorrected values for VCOUT and VIOUT 5 14 Enable Disable Logging Logging is enabled by clicking the checkbox on the home screen of the software marked Logging Then only after polling is started does the log file start to record ...

Страница 27: ... 27 4 26 8 50522 6 15 2011 9 53 3948 3940 3873 3938 3949 3940 27 4 26 9 49800 6 15 2011 9 53 3953 3940 3878 3938 3949 3944 27 4 26 8 49800 6 15 2011 9 53 3948 3940 3878 3938 3949 3944 27 4 26 8 49800 6 15 2011 9 53 3948 3940 3878 3943 3949 3944 27 4 26 8 50522 5 16 Communications Tab The communications tab is another convenience feature of the bq76925 Evaluation Software It gives the user insight ...

Страница 28: ...issued by the software 5 18 Transactions During a Connect to Device Command The typical transaction history after a Connect to Device command appears as shown in Table 18 Table 18 Example of a Device Connect Command Searching for I2C device I2C_R 20 1 49 Device found Base Address 0x20 I2C_W 21 10 1 I2C_R 21 10 14 I2C_R 20 1 49 I2C_W 23 0 25 I2C_R 23 0 30 I2C_R 20 1 49 I2C_W 24 81 7D I2C_R 24 81 68...

Страница 29: ... CRC value 0x1A does not appear 5 21 I2C Register Write To write a register select the desired register to write using the drop down box See the product data sheet to understand the meaning and usage of each register Enter the value to be written in hexadecimal notation Then click the Write button The result is displayed in the Monitor window If the Update GUI on write checkbox is selected then th...

Страница 30: ... Table 20 Example of a Device Connect Command I2C_W 25 1F 84 I2C_R 25 1F 91 I2C_W 21 16 13 I2C_R 40 0 0 2 30 1 9E 0 77 0 77 3 FF 2 2B I2C_W 21 15 1A I2C_R 40 0 0 2 30 3 36 0 AC 0 AB 3 FE 2 2F I2C_W 21 14 1D I2C_R 40 0 0 2 30 3 33 0 DB 0 DA 3 FF 2 2E I2C_W 21 13 8 I2C_R 40 0 0 2 30 3 26 1 5 0 FA 3 FE 2 30 I2C_W 21 12 0F I2C_R 40 0 0 2 30 3 32 1 22 1 21 3 FF 2 2F I2C_W 21 11 6 I2C_R 40 0 0 2 30 3 35...

Страница 31: ... cell packs that have 3 4 5 or 6 series connected cells There are some special considerations when operating with less than six series cells For complete information consult the bq76925 data sheet CAUTION Configure the bq76925EVM for the appropriate cell count prior to applying power to the board 6 2 Using Onboard Cell Simulator The cell simulator can be set up for 3 4 5 or 6 cell operation The pr...

Страница 32: ... to pin 2 on connector CN6 These are the inputs marked Cell 6 and Cell 5 4 Apply a jumper wire from pin 2 to pin 3 on connector CN6 These are the inputs marked Cell 5 and Cell 4 5 Apply a jumper wire from pin 3 to pin 4 on connector CN6 These are the inputs marked Cell 4 and Cell 3 6 Set the power supply to a safe level for 4 cell operation This would be somewhere below 15 V 7 Connect the power su...

Страница 33: ...reen to 6 7 4 Five Cell Operation The procedure for five cell operation with a cell pack is as follows 1 Ensure that all switches on S4 are open 2 Wire the six cell tap wires to positions 2 through 7 on the mating plug of CN6 3 Apply a jumper wire from pin 1 to pin 2 on mating plug of CN6 These are the inputs marked Cell 6 and Cell 5 4 Connect BATT 5 Connect BATT 6 Connect CN6 to the EVM The cell ...

Страница 34: ...ts marked Cell 4 and Cell 3 6 Connect BATT 7 Connect BATT 8 Connect CN6 to the EVM The cell inputs can be connected in any order 9 Connect to the Evaluation Software 10 Change the Select Cell Count drop down box on the home screen to 4 7 7 Battery Removal Sequence The removal of the battery from the bq76925EVM requires a certain sequence for safe operation The connection removal sequence is 1 Remo...

Страница 35: ...com Schematic and Bill of Materials 8 1 Schematics Figure 19 Schematic Page 1 of 4 35 SLUU514 July 2011 bq76925EVM Evaluation Module Submit Documentation Feedback Copyright 2011 Texas Instruments Incorporated ...

Страница 36: ...ill of Materials www ti com Figure 20 Schematic Page 2 of 4 Figure 21 Schematic Page 3 of 4 36 bq76925EVM Evaluation Module SLUU514 July 2011 Submit Documentation Feedback Copyright 2011 Texas Instruments Incorporated ...

Страница 37: ...r 2x7 pin 100mil spacing Straight 4 Wall 0 338 x 0 988 inch N2514 6002 RB 3M 1 CN8 Connector 10 pin Shrouded Vertical 0 388 x 0 400 inch C 5103309 1 Tyco 1 CN5 Header 4 pin Friction Lock 100 mil spacing 0 250 x 0 400 inch 22 11 2042 Molex 4 CN1 4 Terminal PC Screw 6 30A 0 310 x 0 507 inch 8199 Keystone 1 D2 Diode Zener 30V 500mW SOD 123 BZT52C30V 13 F Diodes 0 D3 DNP Diode Zener SOD 123 STD Diodes...

Страница 38: ...ard Standard R44 3 R27 R37 R45 0 Resistor Chip 1 10W 5 0805 Standard Standard 4 R30 R25 26 300 Resistor Chip 1 10W 5 0805 Standard Standard R29 2 R34 R33 560K Resistor Chip 1 10W 5 0805 Standard Standard 6 R38 43 510 Resistor Chip 1 8W 5 0805 Standard Standard 2 R8 9 0 002 Res Power Metal Strip 1W 1 2512 WSL 2512 2L000FEA Vishay Dale 2 S1 S3 Switch Micro Push Button 12V 50mA 0 394 x 0 200 inch FSM...

Страница 39: ... com Printed Circuit Board Figure 24 Top Copper Layer Figure 25 Inner Copper Layer 39 SLUU514 July 2011 bq76925EVM Evaluation Module Submit Documentation Feedback Copyright 2011 Texas Instruments Incorporated ...

Страница 40: ...Circuit Board www ti com Figure 26 Inner Copper Layer Figure 27 Bottom Copper Layer 40 bq76925EVM Evaluation Module SLUU514 July 2011 Submit Documentation Feedback Copyright 2011 Texas Instruments Incorporated ...

Страница 41: ...www ti com Printed Circuit Board Figure 28 Drill Drawing 41 SLUU514 July 2011 bq76925EVM Evaluation Module Submit Documentation Feedback Copyright 2011 Texas Instruments Incorporated ...

Страница 42: ...ct This notice contains important safety information about temperatures and voltages For additional information on TI s environmental and or safety programs please contact the TI application engineer or visit www ti com esh No license is granted under any patent right or other intellectual property right of TI covering or relating to any machine process or combination in which such TI products or ...

Страница 43: ...horized for use in safety critical applications such as life support where a failure of the TI product would reasonably be expected to cause severe personal injury or death unless officers of the parties have executed an agreement specifically governing such use Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications and acknowledge ...

Страница 44: ...Mouser Electronics Authorized Distributor Click to View Pricing Inventory Delivery Lifecycle Information Texas Instruments BQ76925EVM ...

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