.. include:: ./../../../macros.txt .. include:: ./../../../units.txt .. _LTC6813_1_BASED_18_CELL_SLAVE___V1_1_3___AND_ABOVE: LTC6813-1-based 18-Cell Slave ``v1.1.3`` and above ================================================== .. |local_slave_version_start| replace:: ``1.1.3`` .. |local_slave_version| replace:: ``above`` -------- Overview -------- .. important:: The following description only applies for the |ltc6813-1|\ -based 12 cell |BMS-Slave| hardware versions |local_slave_version_start| to |local_slave_version|. .. hint:: All connector pinouts described below follow the :ref:`CONVENTION_FOR_MOLEX_3_0_CONNECTOR_PIN_NUMBERING`. -------------- Specifications -------------- ^^^^^^^^^^^^^^^^^^ Electrical Ratings ^^^^^^^^^^^^^^^^^^ The current consumption from the module has been measured at 64.8 |_| V module voltage, which is equivalent to a cell voltage of 3.6 |_| V per cell. No sense lines have been connected from this measurement (as the impact of cell voltage sensing is negligible on the current consumption). The DC supply current has been measured with a voltage of 12 |_| V and no |VBAT| or cells connected. .. csv-table:: Electrical Ratings :name: 6813-1_slave_18cell_v1.1.3_electrical_ratings :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_electrical-ratings.csv ^^^^^^^^^^^^^^^^^^^^^ Mechanical Dimensions ^^^^^^^^^^^^^^^^^^^^^ .. csv-table:: Mechanical Dimensions :name: 6813-1_slave_18cell_v1.1.3_mechanical_dimensions :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_mechanical-dimensions.csv ^^^^^^^^^^^^^ Block Diagram ^^^^^^^^^^^^^ The block diagram of the |BMS-Slave| is shown in :numref:`Fig. %s <block_diagram_6813-1_slave_18cell_v1.1.3>` .. _block_diagram_6813-1_slave_18cell_v1.1.3: .. figure:: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3.png :width: 100 % |BMS-Slave| 18-Cell Block Diagram ^^^^^^^^^^^^^^^^^^^^^^^^^^ Schematic and Board Layout ^^^^^^^^^^^^^^^^^^^^^^^^^^ More information about the board schematic and layout files can be found in section :ref:`DESIGN_RESOURCES`. --------- Functions --------- The following general description applies to both, the primary and the secondary of the |BMS-Slave|. If there are any differences in hardware between the primary and the secondary they will be marked as such. ^^^^^^^^^^^^^^^^^^^^^^^^ Cell Voltage Measurement ^^^^^^^^^^^^^^^^^^^^^^^^ The cell voltage sense lines are input on the connector X200. The pinout is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_cell_sense_connector>`. .. figure:: ./../../img/molex_connector-24pin.png :width: 50 % .. csv-table:: Cell voltage sense connector :name: 6813-1_slave_18cell_v1.1.3_cell_sense_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_cell_voltage-sense-connector.csv Each of these lines is fused with a fast acting 250 mA surface-mount fuse (F301 - F319) on the board except of the |VBAT+| and |VBAT-| lines which are fused with a value of 500 mA (F300 and F320). This essentially is important for an evaluation environment. The |VBAT+| and |VBAT-| connection is used for the internal power supply of the slave board. If the battery module does not contain these separate wires to the positive and negative module terminal the solder jumpers SJ300 and SJ301 have to be shorted. In this case the slave will be supplied through the sense lines |CELL_0-| and |CELL_11+|. Running the slave in this configuration could result in cell measurement errors due to voltage drop on the sense wires. The cell input lines are filtered by a grounded or differential capacitor filter: both possibilities are provided on the PCB of the |BMS-Slave|. More information on the corner frequency of this filtering can be found in the schematic. The grounded capacitor filter should be used in environments affected with a high noise as it offers a high level of battery voltage ripple rejection. The differential capacitor filter can be used when noise is less frequent or the design is subjected to cost optimization. ^^^^^^^^^^^^^^^^^^^^^^ Passive Cell Balancing ^^^^^^^^^^^^^^^^^^^^^^ The passive balancing circuit is realized by a parallel connection of two 130 |Ohm| discharge-resistors that can be connected to each single cell in parallel. The MOSFET switches (T1500 - T1517) that control the connection to the cells are controlled by the primary |ltc6813-1| monitoring IC. The |ltc6813-1| on the secondary unit does not support balancing. The resistor value of 2x 130 |_| |Ohm| results in a balancing current of about 55 |_| mA at a cell voltage of 3.6 |_| V. This current results in a power dissipation of about 0.2W per balancing channel (at 3.6 |_| V). ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Global Cell Balancing Feedback ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In order to check the proper function of the balancing process or to detect a malfunction in the balancing control circuit, a global balancing feedback signal is connected to the |ltc6813-1|. This allows the system to check whether any balancing action is currently taking place at any time. The feedback signal is connected to the GPIO3 of the |ltc6813-1|. The signal remains in a logic zero state until any balancing action on any cell starts. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Temperature Sensor Measurement ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The cell temperature sensors are connected to the connectors X201 (primary) and X202 (secondary). The pinout is identical for the primary and secondary unit and is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_temp_sense_connector>`. .. figure:: ./../../img/molex_connector-16pin.png :width: 30 % .. csv-table:: Temperature sensor connector :name: 6813-1_slave_18cell_v1.1.3_temp_sense_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_temperature-sensor-connector.csv Standard 10 |_| |kOhm| NTC resistors are recommended for use. When using other values than these, the series resistors (R100-R107) on the board may have to be adjusted. Please note that the accuracy of the internal voltage reference VREF2 decreases heavily with a load of over 3 |_| mA. Using 8x 10 |_| |kOhm| NTC resistors with the corresponding 10 |_| |kOhm| series resistors results in a current of 1.2mA (at 20 |_| °C) which is drawn from VREF2. Each 8 temperature sensors are connected to an analog multiplexer. The analog multiplexer can be controlled via |I2C| by the |ltc6813-1| (7-bit address: 0x4C). In order to ensure fast settling times after switching the multiplexer input, the output signal of the multiplexer is buffered by an operational amplifier. Finally the analog voltage of the selected sensor is measured on the GPIO1 pin of the |ltc6813-1|. ^^^^^^^^^^^^^^^ On-board EEPROM ^^^^^^^^^^^^^^^ The primary unit as well as the secondary unit of the foxBMS BMS-Slave board is equipped with an EEPROM IC (IC801). The EEPROM for example can be used for storing data such as calibration values. Similar to the analog multiplexers, the EEPROM device is connected to the |I2C| bus of the |ltc6813-1| (7-bit address: 0x50). ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ On-board Ambient Temperature Sensor ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ For an additional monitoring of the ambient temperature an on-board temperature sensor is used. This temperature sensor can be read by the |ltc6813-1| via the |I2C| bus (7-bit address: 0x48). It is possible to program an alert temperature. Once the measured temperature reaches this alert temperature the alert pin of the IC is set to a logic low level. Currently this signal is not used on the BMS-Slave board, but it is accessible on the connector X404. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Additional Inputs and Outputs ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Several additional analog and digital inputs and outputs are provided on the BMS-Slave board via pin headers. Each 16 analog inputs are provided on connector X400 (primary) and X401 (secondary). The pinout for the connectors for the primary and secondary unit is identical and is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_analog_in_connector>`. .. csv-table:: Connector for analog inputs :name: 6813-1_slave_18cell_v1.1.3_analog_in_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_analog-inputs-connector.csv Each 8 analog inputs are connected to an analog multiplexer. The analog multiplexers can be controlled via |I2C| by the |ltc6813-1| (7-bit addresses: 0x4D and 0x4E). In order to ensure fast settling times after switching the multiplexer input, the output signals of the multiplexers are buffered by operational amplifiers. Finally the analog voltage of the selected sensor can be measured on the GPIO2 pin of the |ltc6813-1|. Each 8 digital inputs/outputs are provided on the connectors X402 (primary) and X403 (secondary). The pinout for the connectors for the primary and secondary unit is identical and is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_digital_io_connector>`. .. csv-table:: Connector for digital IOs :name: 6813-1_slave_18cell_v1.1.3_digital_io_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_digital-io-connector.csv Each 8 digital inputs/outputs are connected to an |I2C| controlled port expander (7-bit address: 0x20). The direction of the inputs/outputs as well as the logic levels on the pins can be selected by register settings. Each of the 8 digital inputs/outputs has a discrete pull up resistor that for example can be used for directly connecting a tactile switch. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ isoSPI Daisy Chain Connection ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The data transmission between the slaves and between the slaves and the basic board takes place using the isoSPI interface. The isoSPI signals are input/output on the connectors X500/X501 (primary) and X502/X503 (secondary). The isoSPI ports are bidirectional, that means they can be used in forward and reverse direction. The isoSPI connections are isolated galvanically using pulse transformers (TR1400). The voltage amplitude of the differential signal can be adjusted by setting resistors (see paragraph :ref:`hw_slave_daisy_current_18cell`). The pinout of the isoSPI connectors is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_daisy_input_connectors>` and :numref:`Table %s <6813-1_slave_18cell_v1.1.3_daisy_output_connectors>`. .. figure:: ./../../img/molex_connector-2pin.png :width: 5 % .. csv-table:: isoSPI Daisy Chain Input Connectors :name: 6813-1_slave_18cell_v1.1.3_daisy_input_connectors :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_daisy-input-connectors.csv .. csv-table:: isoSPI Daisy Chain Output Connectors :name: 6813-1_slave_18cell_v1.1.3_daisy_output_connectors :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_daisy-output-connectors.csv ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Hardware Settings / Options ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Software Timer """""""""""""" The internal software timer of the |ltc6813-1| can be enabled/disabled by a dedicated external pin (SWTEN, pin 36 of the |ltc6813-1|). In order to support all features, the foxBMS BMS-Slave board offers a possibility to switch the software timer. The software timer is enabled in the standard configuration, which means pin 36 is pulled to VREG via a zero-ohm resistor (R1407). The timer can be disabled by removing the resistor R1407 and placing a zero-ohm resistor to R1406. .. _hw_slave_daisy_current_18cell: Daisy Chain Communication Current """"""""""""""""""""""""""""""""" The daisy chain communication current can be set by the resistors R1400 and R1402. The default value is 820 |_| |Ohm| for R1402 and 1.2 |_| |kOhm| for R1400. This values result in a bias current of approximately 1mA and a differential signal amplitude of 1.18 |_| V. Theses values are suitable for high noise environments with cable lengths of over 50m. More information can be found in the |ltc6813-1| data sheet. Status LED """""""""" The status LEDs LD1400 show the current mode of each, the primary and secondary |ltc6813-1|. The LED is on in STANDBY, REFUP or MEASURE mode, whereas the LED is off in SLEEP mode. The LED can be disabled by removing the resistor R1403 next to the LED. GPIO Extension Connector """""""""""""""""""""""" The internal GPIO lines 1 to 5 of the primary or secondary |ltc6813-1| can be connected to the GPIO extension pin header X404 via optional zero-ohm resistors. In the standard configuration these resistors are not placed. Of course it is possible to place each both resistors for a parallel connection of the internal signals to the GPIO extension connector. For more information see the corresponding page of the schematics. The placement of the resistors and the resulting connection is shown in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_gpio_extension_connector>`. .. csv-table:: GPIO extension connector :name: 6813-1_slave_18cell_v1.1.3_gpio_extension_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_gpio-extension-connector.csv The pinout of the extension connector X404 is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_extension_connector>`. .. csv-table:: Extension connector :name: 6813-1_slave_18cell_v1.1.3_extension_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_extension-connector.csv The GPIO lines 6 to 9 are wired to the connector X405 permanently. There is no internal function for this GPIO lines. The pinout of the extension connector X405 is described in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_extension_connector_2>`. .. csv-table:: Additional GPIO extension connector :name: 6813-1_slave_18cell_v1.1.3_extension_connector_2 :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_extension-connector_2.csv ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ External Isolated |DC-| Supply ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ It is possible to supply the |BMS-Slave| by an external DC power supply with a voltage range of 8 |_| V to 24 |_| V. The DC input is protected against reverse voltage and over-current (with a 1.25 |_| A fuse). The external DC supply has to be connected on connector X1001 or X1002 (both connectors are in parallel for daisy chaining the supply). The pinout of the connectors X1001 and X1002 is shown in :numref:`Table %s <6813-1_slave_18cell_v1.1.3_external_dc_supply_connector>`. .. figure:: ./../../img/molex_connector-2pin.png :width: 5 % .. csv-table:: External DC supply connector :name: 6813-1_slave_18cell_v1.1.3_external_dc_supply_connector :header-rows: 1 :delim: ; :file: ./18-ltc-ltc6813-1-v1.1.3/18-ltc-ltc6813-1-v1.1.3_external-dc-supply-connector.csv