Bq40370 Link

Batteries may stop charging/discharging if they detect a "Permanent Failure" (PF) flag.

If your laptop uses a battery with this chip and you are experiencing power issues, you can check its status using these built-in tools:

| Pin(s) | Name | Description | |--------|------------|------------------------------------| | 1–4 | VC1–VC4 | Cell voltage inputs (VC1 = lowest) | | 5 | VSS | Ground (negative of lowest cell) | | 6 | REG25 | 2.5V regulator output (cap to GND) | | 7 | TS1 | Thermistor input 1 (battery temp) | | 8 | TS2 | Thermistor input 2 (optional) | | 9 | SDA | I²C data | | 10 | SCL | I²C clock | | 11 | BAT | Pack positive voltage (for AFE) | | 12 | PACK | Pack+ terminal (through protection FETs) | | 13 | DSG | Discharge FET gate drive | | 14 | CHG | Charge FET gate drive | | 15 | SRP | Sense resistor positive | | 16 | SRN | Sense resistor negative | | 17–18 | NC / ALERT | Alert output (optional) | | 19–24 | Other | Cell balancing control, test pins |

is a custom Texas Instruments battery management chip frequently found in Dell laptop batteries bq40370

The bq40370 is a ROM-based device (firmware is fixed in ROM, not flash-programmable). Configuration is done via data flash parameters over I²C.

: Accessing the "unseal" codes or specific firmware features can be complex, as these chips are often password-protected by the manufacturer to prevent unauthorized repairs. How to Check Battery Health (Dell Laptops)

The is a specialized power management integrated circuit (IC) commonly used in high-performance lithium-ion (Li-ion) and lithium-polymer (Li-Poly) battery packs, particularly within the notebook computer market. As a sophisticated battery management unit (BMU), the BQ40370 is responsible for crucial tasks including fuel gauging, cell balancing, and safety protection. It is often found in Dell laptop battery packs, such as the WDX0R , where it enables precise battery monitoring and longevity. Chip Type: Power Management IC / Fuel Gauge. Common Packages: VQFN-32 (BQ40370RSMR) Go to product viewer dialog for this item. , as listed on eBay . Key Functions: Fuel Gauging, Protection, Cell Balancing. Batteries may stop charging/discharging if they detect a

| Command (hex) | Name | Description | |---------------|---------------|---------------------------------| | 0x02 | Temperature | Pack temperature (0.1°K) | | 0x04 | Voltage | Pack voltage (mV) | | 0x06 | Current | Pack current (mA) | | 0x08 | RemainingCapacity | mAh | | 0x0C | RelativeStateOfCharge | 0–100% | | 0x10 | CycleCount | Number of discharge cycles | | 0x16 | CellVoltage1–4 | Per-cell voltages (mV) | | 0x44 | ManufacturerAccess | Access to data flash, control functions |

: The physical chip is packaged in a compact, thermal-efficient 32-pin Quad Flat No-leads (VQFN) package (commonly designated as BQ40370RSMR ). This package design features an exposed bottom pad that acts as a primary ground connection ( VSScap V sub cap S cap S end-sub

Because the BQ40370 is a customized component built exclusively for major Original Equipment Manufacturers (OEMs), Texas Instruments restricts its full public datasheet and calibration maps. This structural design presents unique challenges and technical considerations for electronics engineers, repair technicians, and DIY hardware enthusiasts. Core Architecture and Functionality : Accessing the "unseal" codes or specific firmware

in laptop batteries, particularly those for Dell systems. It is responsible for monitoring battery health, managing charging cycles, and providing precise state-of-charge data. Key Technical Aspects Functionality

The primary challenge technician's face with the BQ40370 is its strict firmware lock capability. When a laptop battery ages or suffers from unbalanced cells, the BQ40370 is programmed to permanently disable the pack for safety. What Triggers the Lock?