RAJ240057A20DNP#HC1 vs BQ27Z746YAHR Battery Fuel Gauge ICs: A Detailed Comparison

Quick verdict

For multi-cell battery packs (2–4 cells) requiring dual communication interfaces and basic fault protections, the Renesas RAJ240057A20DNP#HC1 is the practical choice, simplifying integration and system monitoring. Conversely, for single-cell packs demanding advanced fault protections—including over-temperature, over/under-voltage, and configurable thresholds—and very low power consumption modes, the Texas Instruments BQ27Z746YAHR is more appropriate, especially when tight power budgets and safety features are critical.

Spec comparison table

SpecRAJ240057A20DNP#HC1BQ27Z746YAHRNotes
Battery chemistryLithium Ion/PolymerLithium Ion/PolymerEquivalent support for Li-ion/polymer chemistry.
Number of cells2 ~ 41RAJ240057 supports multi-cell packs; BQ27Z746 limited to single-cell packs.
Fault protectionOver Current, Short CircuitOver Current, Over Temperature, Over/Under Voltage, Short CircuitBQ27Z746 offers broader and more configurable fault protection.
InterfaceI2C, UARTI2CRAJ240057 offers UART in addition to I2C, useful for flexible communication options.
Operating temperature range-40°C ~ 85°C (TA)-40°C ~ 85°C (TA)Equivalent operating temperature range.
Package case32-VFQFN Exposed Pad15-XFBGA, DSBGARAJ240057 larger package (32 pins) vs BQ27Z746 smaller (15 pins), impacts PCB layout.
Supplier device package32-HVQFN (4x4)15-DSBGA (1.7x2.6)BQ27Z746 smaller footprint (1.7x2.6 mm) beneficial for space-constrained designs.
Supply voltage range minNot specified-0.3 VBQ27Z746 supports negative voltages slightly below ground, useful for certain fault conditions.
Supply voltage range maxNot specified6 VBQ27Z746 supports up to 6 V supply, suitable for 1 cell Li-ion (max ~4.2 V).
Absolute max input voltageNot specified40 VBQ27Z746 can tolerate high transient voltages, helpful for robustness.
Maximum output currentNot specified2 ABQ27Z746 supports up to 2 A output current for FET driver, relevant for protection circuits.
Output current typicalNot specified500 mABQ27Z746 drives moderate FET currents with typical 500 mA capability.
Output current maxNot specified1000 mABQ27Z746 max output current higher, allowing stronger FET control if needed.
ADC resolutionNot specified16-bitBQ27Z746’s 16-bit ADC enables fine voltage and current resolution.
I2C bus frequencyNot specified400 kHzBQ27Z746 supports fast I2C mode, better for high-speed communication.
Power consumption sleep modeNot specified20 μABQ27Z746’s 20 μA sleep current supports battery-powered designs better.
Power consumption ship modeNot specified10 μALower ship mode current reduces battery drain during storage.
Power consumption shelf modeNot specified5 μABQ27Z746 offers ultra-low shelf mode current for long-term storage.
Power consumption shutdown modeNot specified0.2 μAVery low shutdown current on BQ27Z746 benefits deep power-saving.
Input voltage minNot specified2.0 VBQ27Z746 supports operation down to 2 V, suitable for near-empty battery states.
Operating junction temperatureNot specified-40°C to 85°CMatches operating ambient temperature; junction spec useful for thermal design.
Thermal resistance (junction-to-ambient)Not specified70 °C/WBQ27Z746’s thermal resistance indicates moderate heat dissipation; no RAJ240057 data.
Package size (nominal)4x4 mm1.7x2.6 mmRAJ240057 is physically larger, increasing PCB footprint.
Number of pins3215RAJ240057 has more pins, increasing routing complexity but enabling more functions.
Fault detection configurableNot specifiedYes (configurable thresholds and delays)BQ27Z746 allows firmware-configurable fault thresholds, increasing system safety.
Communication interface voltage levelsNot specifiedHigh-level input voltage min 1.26 VBQ27Z746 compatible with typical I2C voltage levels, with integrated ESD protection.
ESD ratings (HBM/CDM)Not specified2000 V HBM / 500 V CDMBQ27Z746 has specified ESD robustness, important for manufacturing and field reliability.
Data flash cyclesNot specified20,000BQ27Z746 flash endurance suitable for firmware updates and logging.
Instruction flash cyclesNot specified1,000Limited instruction flash cycles on BQ27Z746 require careful firmware update planning.
Design capacity typicalNot specified5300 mAhBQ27Z746 example capacity, relevant for scaling and modeling accuracy.
Design voltage typicalNot specified4.0 VBQ27Z746 nominal cell voltage, consistent with Li-ion chemistry.
Sense resistor typicalNot specified10 mΩBQ27Z746 optimized for low-value sense resistors, minimizing power loss.
Sense resistor voltage thresholdNot specified-2.0 mV (typ)BQ27Z746’s low threshold enables accurate current sensing.
Authentication methodNot specifiedSHA-256BQ27Z746 supports cryptographic authentication for secure system design.
Firmware and device modesNot specified5 modesBQ27Z746 offers multiple operational modes allowing power and performance trade-offs.
Package mounting typeSurface MountSurface MountBoth parts are surface mount, compatible with standard SMT processes.

Design trade-offs

The most significant design difference is the supported number of cells: RAJ240057A20DNP#HC1 supports 2 to 4 cells, whereas the BQ27Z746YAHR is limited to a single cell. This means RAJ240057 is inherently better suited for multi-cell battery packs without additional hardware or complex external circuitry. In contrast, BQ27Z746 requires external methods or multiple ICs for multi-cell packs, increasing cost and complexity.

RAJ240057’s dual-interface capability (I2C and UART) offers flexibility in communication design. UART can be advantageous in noisy environments or long-distance communication where I2C limitations become problematic, or when a microcontroller lacks multiple I2C buses. BQ27Z746’s single I2C interface is standard but less versatile.

Fault protection is more comprehensive on the BQ27Z746, which includes over-temperature, over/under-voltage, and programmable thresholds with configurable delays. This level of protection is critical in safety-focused applications or where battery management must prevent damage under a wide range of fault conditions. RAJ240057 only lists overcurrent and short circuit protection, implying fewer integrated protections and likely requiring external supervisory circuits.

Power consumption data is only available for the BQ27Z746, showing ultra-low currents down to 0.2 μA in shutdown mode, which is essential in battery-powered devices requiring long shelf life or minimal parasitic drain. Without RAJ240057 power data, it’s unclear if it can compete in ultra-low-power scenarios.

The package size and pin count also differ markedly: RAJ240057’s 32-pin 4x4 mm HVQFN is physically larger and more complex to route but allows more functionality and signal pins. The BQ27Z746’s 15-pin 1.7x2.6 mm DSBGA is smaller and simpler to integrate in space-constrained designs, but with fewer signals and potentially less flexibility.

No thermal resistance or detailed gate drive specs are available for RAJ240057, but the BQ27Z746’s output current up to 2 A and FET driver timings (rise/fall times in hundreds of microseconds) imply it can actively control external MOSFETs for protection, adding complexity to the layout but improving safety. RAJ240057’s fault protection does not mention FET drivers, suggesting a simpler protection scheme.

Cost at volume is not provided but can be inferred: RAJ240057’s larger package and