{
  "node": {
    "id": "term:afe",
    "type": "Term",
    "label": "Analog front end",
    "properties": {
      "id": "afe",
      "name": "Analog front end",
      "abbr": "AFE",
      "aka": [
        "cell monitoring IC",
        "battery monitor IC",
        "BMIC"
      ],
      "section": "topic-data",
      "definition": "The integrated circuit that measures a stack of series cells — typically 6 to 18 per chip — with millivolt accuracy, reads thermistors, switches balancing and talks to the controller over an isolated daisy chain. It is the part of a BMS that touches the cells, and its accuracy limits how well SOC can be known.",
      "related": [
        "cell-supervision-circuit",
        "isospi",
        "voltage-sense",
        "cell-balancing",
        "adc",
        "bmu"
      ],
      "url": "https://lemonergy.com/learn/glossary/afe/",
      "mentions": [
        "state-of-charge",
        "bms"
      ]
    }
  },
  "edges": [
    {
      "id": "edge:4049",
      "source": "term:afe",
      "target": "topic:topic-data",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:4050",
      "source": "term:afe",
      "target": "term:cell-supervision-circuit",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4051",
      "source": "term:afe",
      "target": "term:isospi",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4052",
      "source": "term:afe",
      "target": "term:voltage-sense",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4053",
      "source": "term:afe",
      "target": "term:cell-balancing",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4054",
      "source": "term:afe",
      "target": "term:adc",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:4055",
      "source": "term:afe",
      "target": "term:bmu",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/afe/state-of-charge",
      "source": "term:afe",
      "target": "term:state-of-charge",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:mentions/afe/bms",
      "source": "term:afe",
      "target": "term:bms",
      "type": "mentions",
      "properties": {
        "sourceFile": "terms.json",
        "method": "build_glossary.mention_index + mentions",
        "field": "definition",
        "meaning": "Text mention; not a causal claim"
      }
    },
    {
      "id": "edge:4058",
      "source": "term:afe",
      "target": "reference:ti-bms",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-data",
      "type": "Topic",
      "label": "Data, communication and electronics",
      "properties": {
        "id": "topic-data",
        "name": "Data, communication and electronics",
        "lede": "The control units, chips, protocols and file formats through which a battery is measured, controlled and logged.",
        "context": "Separate quantities from encoding and transport.",
        "example": "2500 in a log might mean 25.00 °C, 2.5 V or raw counts. Units and scale must accompany the value.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/battery-basics/",
        "lesson_label": "Open battery basics"
      }
    },
    {
      "id": "term:cell-supervision-circuit",
      "type": "Term",
      "label": "Cell supervision circuit",
      "properties": {
        "id": "cell-supervision-circuit",
        "name": "Cell supervision circuit",
        "abbr": "CSC",
        "aka": [
          "cell monitoring unit",
          "CMU",
          "slave BMS"
        ],
        "section": "topic-pack",
        "definition": "The board on each module that measures its cell voltages and temperatures and switches its balancing resistors, reporting to the central BMS controller. It is usually built around a dedicated monitoring chip and linked by isoSPI or CAN.",
        "related": [
          "bms",
          "cell-balancing",
          "isospi",
          "voltage-sense",
          "afe",
          "wireless-bms"
        ],
        "url": "https://lemonergy.com/learn/glossary/cell-supervision-circuit/",
        "mentions": []
      }
    },
    {
      "id": "term:isospi",
      "type": "Term",
      "label": "isoSPI",
      "properties": {
        "id": "isospi",
        "name": "isoSPI",
        "aka": [
          "daisy-chain interface"
        ],
        "section": "topic-pack",
        "definition": "A transformer-isolated, two-wire version of the SPI interface used to chain cell-monitoring chips across modules that sit at different voltages. It carries their measurements to the BMS controller without a separate isolated CAN node per module.",
        "related": [
          "cell-supervision-circuit",
          "bms",
          "can-bus"
        ],
        "url": "https://lemonergy.com/learn/glossary/isospi/",
        "mentions": []
      }
    },
    {
      "id": "term:voltage-sense",
      "type": "Term",
      "label": "Voltage sensing",
      "properties": {
        "id": "voltage-sense",
        "name": "Voltage sensing",
        "aka": [
          "cell tap",
          "sense line"
        ],
        "section": "topic-pack",
        "definition": "Measuring each series cell group’s voltage through a wire or flexible circuit from its busbar to the monitoring chip. Millivolt accuracy matters because the BMS reads SOC and detects faults from these numbers.",
        "unit": "mV",
        "related": [
          "cell-supervision-circuit",
          "bms",
          "busbar",
          "open-circuit-voltage",
          "afe"
        ],
        "url": "https://lemonergy.com/learn/glossary/voltage-sense/",
        "mentions": [
          "state-of-charge"
        ]
      }
    },
    {
      "id": "term:cell-balancing",
      "type": "Term",
      "label": "Cell balancing",
      "properties": {
        "id": "cell-balancing",
        "name": "Cell balancing",
        "section": "topic-state",
        "definition": "Equalising the state of charge of cells in series, since the pack is limited by its emptiest cell on discharge and its fullest on charge. Passive balancing bleeds charge from high cells through resistors; active balancing moves it between cells.",
        "related": [
          "bms",
          "series-parallel",
          "state-of-charge",
          "cell-to-cell-variation"
        ],
        "example": {
          "title": "Pack average versus cell limits",
          "text": "Average pack SOC can look acceptable while one series cell reaches its voltage limit. One aggregate SOC state does not demonstrate cell balancing."
        },
        "url": "https://lemonergy.com/learn/glossary/cell-balancing/",
        "mentions": [
          "active-balancing"
        ]
      }
    },
    {
      "id": "term:adc",
      "type": "Term",
      "label": "Analog-to-digital converter",
      "properties": {
        "id": "adc",
        "name": "Analog-to-digital converter",
        "abbr": "ADC",
        "section": "topic-data",
        "definition": "The circuit that turns a voltage into a number. In a BMS its resolution, offset and drift set the floor for voltage and current accuracy: one millivolt of cell-voltage error is several percent of SOC on a flat LFP curve.",
        "related": [
          "afe",
          "current-sensor",
          "voltage-sense",
          "coulomb-counting",
          "ocv-soc-curve"
        ],
        "url": "https://lemonergy.com/learn/glossary/adc/",
        "mentions": [
          "state-of-charge",
          "bms"
        ]
      }
    },
    {
      "id": "term:bmu",
      "type": "Term",
      "label": "Battery management unit",
      "properties": {
        "id": "bmu",
        "name": "Battery management unit",
        "abbr": "BMU",
        "aka": [
          "BMS master",
          "master BMS"
        ],
        "section": "topic-data",
        "definition": "The master controller of a battery management system: it collects cell voltages and temperatures from the monitoring boards, runs the state estimation and protection logic, drives the contactors and talks to the vehicle. In some architectures the same name is used for a per-module slave, so a datasheet’s block diagram is the safe reference.",
        "related": [
          "bms",
          "cell-supervision-circuit",
          "bcu",
          "contactor",
          "can-bus",
          "bms-power-modes"
        ],
        "url": "https://lemonergy.com/learn/glossary/bmu/",
        "mentions": [
          "datasheet"
        ]
      }
    },
    {
      "id": "term:state-of-charge",
      "type": "Term",
      "label": "State of charge",
      "properties": {
        "id": "state-of-charge",
        "name": "State of charge",
        "abbr": "SOC",
        "section": "topic-state",
        "definition": "How full a cell is, as a fraction of its available capacity. State of charge, like temperature, affects how fast a stored cell ages.",
        "unit": "%",
        "related": [
          "depth-of-discharge",
          "ocv-soc-curve",
          "coulomb-counting",
          "state-of-health",
          "bms"
        ],
        "lesson": "fundamentals/battery-aging/#storage-soc",
        "example": {
          "title": "Interpret a charge inventory",
          "text": "If available capacity is 5 Ah and 3 Ah remains by the chosen estimator, SOC is 60%. A different estimate of available capacity changes this percentage, so compare SOC values only with the capacity convention recorded."
        },
        "url": "https://lemonergy.com/learn/glossary/state-of-charge/",
        "mentions": [
          "usable-capacity"
        ]
      }
    },
    {
      "id": "term:bms",
      "type": "Term",
      "label": "Battery management system",
      "properties": {
        "id": "bms",
        "name": "Battery management system",
        "abbr": "BMS",
        "section": "topic-pack",
        "definition": "The electronics and software that keep a battery inside its safe window: measuring every cell voltage and many temperatures, estimating SOC and SOH, balancing cells, computing current limits, controlling the contactors and reporting over the vehicle network.",
        "related": [
          "state-of-charge",
          "cell-balancing",
          "state-of-power",
          "cell-supervision-circuit",
          "contactor",
          "can-bus"
        ],
        "lesson": "fundamentals/battery-basics/#cell-module-pack",
        "url": "https://lemonergy.com/learn/glossary/bms/",
        "mentions": [
          "state-of-health",
          "cell-voltage"
        ]
      }
    },
    {
      "id": "reference:ti-bms",
      "type": "Reference",
      "label": "Getting Started with the BQ76925",
      "properties": {
        "title": "Getting Started with the BQ76925",
        "publisher": "Texas Instruments",
        "url": "https://www.ti.com/lit/an/slua619b/slua619b.pdf",
        "type": "Application report",
        "scope": "A concrete BMS analog front-end example: cell voltage, current, temperature measurement and MCU integration.",
        "year": 2019,
        "accessed": "2026-10-27"
      }
    }
  ]
}