BQ40Z50RSMR‑R1: Highly integrated 10–15 series lithium battery monitoring IC, suitable for medium and large capacity battery pack management
Product Overview
BQ40Z50RSMR‑R1 is a highly integrated battery pack monitoring and management IC (Fuel Gauge) that supports 10 to 15 series lithium-ion/polymer battery packs and provides accurate voltage, current, temperature and remaining power estimation. It has multiple built-in SAFETY CELL modules and has battery protection features from the inside out, making it an ideal choice for modern large-capacity lithium battery systems.
Core technical features
Supported battery string number: 10-15 strings, suitable for extended applications.
Battery voltage monitoring: supports up to 65V total group voltage, accuracy ±1mV.
Current detection capability: integrated current detection function, can measure current directly or through external sampling resistor.
Temperature management: built-in 3-way thermistor sensing input, can be used with NTC for accurate temperature identification.
Fuel metering algorithm: uses intelligent algorithm to estimate remaining capacity (SOC) and can record health (SOH).
Complete safety protection: supports safety strategies such as overvoltage, undervoltage, overcurrent, short circuit, temperature anomaly, and balance control.
Communication interface: I²C/SPI dual interface selection, compatible with standard MCU or battery management master.
Package: compliant with RSM (MicroStar) package, small size, suitable for standard PMS system circuit board design.
Pin and function description (RSM package)
The chip provides multiple key pins as follows:
VIN+ / VIN-: connect to the total battery pack voltage input terminal.
SCL / SDA: I²C communication pin (supports standard mode and fast mode).
BUSY / INT: status interrupt output, which can output fault alarm or SOC reaches the specified value.
TSx: 3 independent temperature sensing inputs for monitoring battery temperature.
SPIx: compatible with SPI bus rotation control.
VSS: circuit ground, which can be connected to the system main ground.
GPIO: program configuration function pin, supporting wake-up, sleep, ALERT output and other functions.
Typical application framework diagram
Battery pack + → VIN+ ┬─ BQ40Z50R safety monitoring → SCL/SDA → master MCU ├─ TS1/TS2/TS3 → temperature monitoring ├─ current sampling → RSENSE └─ VIN- → battery pack– The IC automatically samples the battery pack voltage, core current, and temperature data, and the algorithm evaluates the remaining power and life, and reports the status or alarm through I²C/SPI communication. Support asynchronous balancing to improve battery pack consistency and life cycle.
Main application scenarios
⚡ Power tools and garden equipment: accurate fuel metering to improve user confidence in battery life
🛵 Electric bicycles/scooters: high-voltage battery pack monitoring and safety protection
🔋 Energy storage system (ESS/BESS): remote monitoring and safety interlocking of battery packs
🏎 Drones/robots: real-time remaining capacity assessment and system protection
🏭 UPS and portable power packs: simplify safety management and system control logic
Design suggestions and wiring precautions
Voltage sampling: The lead between VIN+ and VIN– should be short to avoid interference; Kelvin wiring is recommended.
Temperature monitoring optimization: The TS pin should be connected to the concentrated area of each battery cell to ensure true temperature perception.
Communication multiplexing: Select I²C or SPI according to the system timing, and the bus should use appropriate pull-up resistance or terminal resistance.
EMI protection: Add a 100nF bypass capacitor to the communication line; keep the wiring away from high-speed/high-current line interference.
Balance circuit: Output balance MOSFET can drive 30–40mA, and needs to be configured.
PCB design: A-Side/B-Side ground partition processing, high voltage area and low voltage are isolated from each other, and it is recommended to be isolated by jumper or ground slot.
Compatible models and system upgrade suggestions
BQ40Z50RQR2: Like RSMR, it is suitable for 10–15 strings but uses QFN package to adapt to different package board layouts.
BQ40Z60: Supports 6–16 strings of batteries, more suitable for highly scalable systems.
BQ40Z50: Low-cost version is suitable for cost-sensitive systems.
LTC6811: From Linear technology, multiple strings in parallel are suitable for high-power BMS environment.
MAX17261: Low-power solution for single-cell monitoring.
Summary
BQ40Z50RSMR‑R1 is a highly integrated battery management IC with rich functions, comprehensive voltage/temperature/capacity monitoring, and support for safe balance. It reduces complex peripheral design, improves system reliability and delivery efficiency, and is particularly suitable for application environments such as electric mobility, energy storage, and power tools that have high requirements for battery system endurance and safety.
