Bq40370 _hot_ Jun 2026

Communicates with the host device (laptop) via SMBus, transmitting data like cycle count, cell voltage, temperature, and full charge capacity (FCC).

While NLBA1 can unseal, full reprogramming (changing capacity or cycle counts) typically requires TI’s bqStudio software and an communication interface. Missing Files: Standard bqStudio may not have the specific

New cells require a specific charge/discharge cycle—often with long "relax" periods—to sync with the chip's firmware. bq40370

| Hypothesis | Likelihood | Reasoning | |------------|------------|------------| | Typographical error | High | Common mistypes: bq4050, bq40z70 (exists as bq40z70-R2? No), bq40350, bq40570. | | Obsolete / pre-release part | Low | No archival evidence in TI’s retired product lists. | | Custom or OEM part number | Medium | Some manufacturers use non-public codes for customer-specific ICs. | | Non-TI product | Low | Prefix “bq” is almost exclusively TI battery management. | | Internal company code | Medium | Could be an internal tracking number (BOM, assembly, or test code). |

If the battery has been over-discharged below the UV threshold, the bq40370 enters . Connecting a charger to the PACK+ pin with >9V typically "wakes" it up by activating the BATFET. If this fails, check the REG25 pin. If REG25 is 0V with >6V on BAT, the chip is physically dead. Communicates with the host device (laptop) via SMBus,

Unlike general-purpose controllers, the BQ40370 is a custom chip designed for Dell, which often makes it difficult to repair or reprogram without proprietary tools.

Unlike the BQ27500 series (which uses a simple ROM), the bq40370 is a device. When you buy a blank bq40370 from Mouser or Digi-Key, it does nothing. It is a brick. You must program it with a "Golden Image" – a specific .srec or .bq.fs file that contains: | | Custom or OEM part number |

The BQ40370 acts as a "gas gauge" and protection unit for multi-series lithium-ion battery packs, typically ranging from . It monitors critical battery parameters, including:

The is a highly specialized, proprietary battery management and gas gauge Integrated Circuit (IC) developed by Texas Instruments . Primarily found in premium laptop battery packs—most notably across various Dell laptop series (such as the WDX0R, 3DDDG, and F3YGT battery models)—the BQ40370 plays a critical role in monitoring cell health, managing safety thresholds, and reporting accurate state-of-charge (SoC) metrics to the host computer.

: Many bq40370-based batteries feature a D6SA3-12 thermal fuse . If the battery is electrically "dead" but the cells have voltage, check if this fuse has blown; replacing it can often restore functionality.