BWR Series AEC-Q200 Chip Shunt Resistors
Ultra-low-resistance surface-mount chip shunt resistor for precision high-current sensing in automotive and power electronics applications
Single package: BWR, measuring 6.6 × 6.9 × 3.0 mm
Resistance range 0.3 mΩ to 3 mΩ (resistance values down to 0.0003 Ω)
Rated power 5 W at 0.3 mΩ, 0.5 mΩ, and 1 mΩ; derated to 4 W at 2 mΩ and 3 mΩ
TCR ≤50 ppm/°C maximum across the full resistance range
Tolerance options ±1%, ±2%, and ±5%; tighter tolerances available on request
Short-time overload rating: five times rated power for five seconds
High-temperature exposure limit: ±(1.0% + 0.5 mΩ) resistance change after 1000 hours at +170°C
AEC-Q200 qualified for automotive applications
RoHS compliant
What are the BWR Series AEC-Q200 Chip Shunt Resistors?
The BWR is a precision ultra-low-resistance chip shunt resistor designed for surface-mount assembly in applications requiring accurate measurement of very high currents within a compact PCB-mounted footprint. The series addresses the most demanding end of the milliohm shunt resistor range, with resistance values starting at 0.3 mΩ — low enough to limit the voltage drop across the sensing element to sub-millivolt levels even at currents of hundreds of amperes, minimising the power dissipated in the shunt relative to the load while still delivering a measurable signal to the current sense amplifier or ADC. The single BWR package measures 6.6 mm × 6.9 mm × 3.0 mm and is designed for direct PCB mounting, with the thermal path from the resistive element conducted into the board copper and connected busbars.
Five resistance values are defined in the standard range: 0.3 mΩ, 0.5 mΩ, 1 mΩ, 2 mΩ, and 3 mΩ. The three lowest values carry a 5 W power rating at the reference temperature of 70°C; the two higher values are rated at 4 W, reflecting the reduced current and correspondingly lower thermal load at these resistance levels. A TCR of ≤50 ppm/°C is maintained across all five values, ensuring that the resistance drift with temperature remains predictable and within the error budget of the current measurement system across the operating temperature range encountered in automotive and industrial environments. Tolerance grades of ±1%, ±2%, and ±5% are offered as standard, with tighter tolerances available on request for applications where the initial calibration margin is insufficient.
The BWR is qualified to AEC-Q200 and the full reliability test programme validates performance under the thermal, mechanical, and environmental stresses of automotive service. Thermal shock cycling from −55°C to +150°C over 1000 cycles with 15-minute dwell at each extreme is held to a resistance change limit of ±(1.0% + 0.5 mΩ). High-temperature exposure at +170°C for 1000 hours is tested unpowered to the same limit. Biased humidity testing at 85°C and 85% RH with 10% operating power for 1000 hours, mechanical shock at 100 g for six milliseconds over five pulses, vibration from 10 Hz to 200 Hz across three directions for 12 hours, and load life at 70°C for 1000 hours are all defined with resistance change limits of ±(0.5% + 0.5 mΩ). Resistance to solder heat is confirmed at 260°C solder for ten to twelve seconds, also to ±(0.5% + 0.5 mΩ). Low-temperature storage is tested at −65°C for 45 minutes. The combined absolute and percentage resistance change limits used throughout the test specification are appropriate to ultra-low-resistance components, where a fixed percentage limit alone would be an impractically tight absolute tolerance at sub-milliohm values.
BWR Series AEC-Q200 Chip Shunt Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: BWR
Resistor type: AEC-Q200
Description: Shunt
Power Rating: 4W, 5W
Resistance (Ω): 0.3~3m
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 50 max.
Applications of the BWR Series AEC-Q200 Chip Shunt Resistors
Where RARA metal clad resistors are deployed in the field.
Automotive battery management systems — precision inline current sensing for state-of-charge and state-of-health monitoring in high-voltage EV and HEV lithium-ion battery packs, where the sub-milliohm resistance values of the BWR allow accurate current measurement at the high continuous currents of traction battery charge and discharge cycles without introducing significant shunt power loss
On-board charger and vehicle-to-grid current measurement — sensing of charge and discharge current in bidirectional automotive AC-DC converters, where AEC-Q200 qualification and the stable ≤50 ppm/°C TCR maintain measurement accuracy through the full thermal cycle of automotive charging operation from cold start to thermal equilibrium
Traction inverter DC bus and phase current sensing — shunt sensing on the DC bus or at the low-side of the inverter half-bridge in high-power EV traction drives, where the 5 W power rating and ultra-low resistance of the BWR allow the shunt to be sized for the full DC bus current without excessive voltage drop or thermal loading of the PCB
Hybrid powertrain current monitoring — measuring current exchange between battery, motor-generator, and power electronics in parallel hybrid and 48 V mild-hybrid systems, where the compact surface-mount footprint allows the shunt to be integrated directly into the power module PCB alongside the gate driver and protection circuits
High-current DC power supply and server power current sensing — inline shunt measurement on the output rails of server power supplies, rack-mounted power distribution units, and high-current DC regulators, where the low resistance minimises impact on supply efficiency while enabling accurate load current monitoring for thermal management and power budgeting
Energy storage system charge and discharge current measurement — current sensing in stationary battery energy storage systems and supercapacitor banks used for grid peak shaving, renewable energy buffering, and UPS applications, where sustained high discharge currents require the power rating and thermal stability of the BWR
Motor drive current feedback in industrial applications — low-side shunt sensing of phase or DC bus currents in servo drives, spindle drives, and high-current variable-frequency drives, where the tight initial tolerance and low TCR support the accuracy requirements of closed-loop current control loops over the full drive operating temperature range
Test and validation equipment for power electronics — precision reference shunts in battery testers, dynamometer current measurement systems, and power analyser calibration fixtures, where the sub-milliohm range and stable resistance characteristics of the BWR allow calibrated current measurement at amplitudes beyond the reach of conventional low-power shunt resistors
Related Products of the BWR Series AEC-Q200 Chip Shunt Resistors
Model: TCS8536
Resistor type: AEC-Q200 E-beam
Description: E-beam welded shunt
Power Rating: 36W
Rated Current: 600~1200A
Resistance (Ω): 0.1m, 0.05m, 0.025m
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 100
Model: TCS8440T
Resistor type: AEC-Q200 E-beam
Description: E-beam welded shunt
Power Rating: 36W
Rated Current: 840A
Resistance (Ω): 0.05m
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 100
Model: ECS
Resistor type: AEC-Q200
Description: Chip shunt
Power Rating: 1W~15W
Resistance (Ω): 0.2~10m
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 100-200
Model: TCS
Resistor type: AEC-Q200 E-beam
Description: Shunt
Power Rating: 12W~36W
Rated Current: 200~350A
Resistance (Ω): 0.05~0.5m
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 100
Why Choose RARA Current Sensing Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
8 Sub-Categories
No other single supplier covers AEC-Q200 chip shunts, milliohm precision types, four-terminal Kelvin shunts, power metering, and 12,000A panel shunts under one ISO-certified roof.
02
Extreme Precision
HPS, UHPS, and PSS precision shunts deliver ±0.05% tolerance and 3 ppm/°C TCR — meeting the accuracy demands of EV battery coulomb counting, precision power analyzers, and billing-grade energy metering.
03
Automotive Qualified
Multiple AEC-Q200 certified models (BCS, LRA, ECS, BWR, TCS, PCBS) with IATF 16949 manufacturing certification — covering EV battery management, motor control, and charging applications.
04
Global Track Record
Trusted by Tesla, GM Korea, Proterra, Siemens, Rockwell, and Schneider Electric — deployed in EV powertrains, industrial drives, and utility metering systems across six continents.
