New high accuracy current sense amps compatible with negative and high voltages

ROHM has developed a new lineup of high-accuracy current sense amps – the BD1423xFVJ-C and the BD1422xG-C. They are qualified under the AEC-Q100 automotive reliability standard. The BD1423xFVJ-C series, provided in the TSSOP-B8J package, supports input voltages up to +80V, making it excellent for high-voltage environments such as 48V DC-DC converters, redundant power supplies, auxiliary batteries, and electric compressors. The series includes three models with different gain settings: BD14230FVJ-C, BD14231FVJ-C and BD14232FVJ-C.

For lower voltage use cases, the BD1422xG-C, offered in the compact SSOP6 package, supports input voltages up to +40V. This makes them suitable for automotive applications that require space-saving designs, such as current monitoring and protection (overcurrent) in 5V/12V power supply networks utilised in the body and drivetrain domains. Like its high-voltage counterpart, this series also consists of three different gain options: BD14220G-C, BD14221G-C and BD14222G-C.

In recent years, alongside conventional 5V/12V power supplies, the automotive market has seen an increasing adoption of 48V systems fuelled by the rising popularity of EVs. Furthermore, as vehicle functionality becomes increasingly advanced, the demand for precise monitoring and control across a wide range of applications continues to rise, placing a greater emphasis on high-accuracy current sensing.

A current sense amp indirectly measures the current flowing through a circuit by amplifying the minuscule voltage drop across a shunt resistor. The amplified signal is then sent to an ADC or comparator for system control and monitoring. The company's automotive-grade current sense amps meet market demands by employing proven analogue expertise. This allows high-accuracy current sensing with compatibility for negative and high-voltage environments, contributing to enhanced safety and reliability in automotive applications, particularly EVs.

These new products achieve greater space efficiency by integrating most of the current sensing circuitry, typically comprising an operational amplifier and discrete components, into a single package. As a result, current detection is achievable by simply connecting a shunt resistor. The devices also feature a two-stage amplifier configuration comprising a chopper amplifier at the input and an auto-zero amplifier at the output. Internal resistor matching for gain setting ensures stable, accurate, current sensing (±1%) while minimising the effects of temperature variations.

Furthermore, current detection accuracy is maintained even when an external RC filter circuit is added for noise suppression, greatly reducing design complexity and development time. Further features include -14V negative voltage tolerance that supports back electromotive force, reverse connection, and negative voltage input.

The company also offers the BD1421x-LA of current sense amps designed for industrial equipment applications.

Application examples:

• BD1423xFVJ-C (for 48V systems): Redundant power supplies, auxiliary batteries, DC-DC converters, electric compressors, and the like
• BD1422xG-C (for 5V/12V systems): Body DCUs/ECUs, etc.