High Voltage, High Precision, Less Space: KOA HVD and MHVD Resistor Networks

How integrated high-voltage resistor dividers simplify precision voltage measurement in 400 V and 800 V systems while reducing PCB space, component count and assembly complexity.

Electric vehicles, high-voltage battery systems and modern power electronics are pushing voltage levels higher than ever before. While 400 V architectures remain widely used, 800 V systems are becoming increasingly important in electric mobility and high-performance power conversion.

For electronics engineers, this creates a familiar but surprisingly complex challenge:

How can hundreds of volts be measured accurately, reliably and safely without sacrificing valuable PCB space?

The traditional answer is a resistive voltage divider.

Simple in theory, considerably more demanding in practice.

High-voltage measurement circuits must account for working voltage, creepage distances, resistor tolerances, temperature coefficients, long-term stability and power dissipation.

Conventional designs often require ten or more individual resistors connected in series to distribute the applied voltage.

This approach works, but it also consumes PCB space, increases assembly complexity and introduces additional components and solder joints.

With its HVD and MHVD high-voltage resistor networks, Japanese resistor manufacturer KOA offers an integrated alternative.

Instead of building a voltage divider from numerous discrete components, engineers can use a compact, precision-matched resistor network specifically designed for high-voltage applications.

And the advantages extend far beyond simply saving space.

Why Resistor Ratio Accuracy Matters More Than Individual Tolerance

A conventional voltage divider consists of two resistors, R1 and R2.

The output voltage is calculated as:

Vout = Vin × R2 / (R1 + R2)

At first glance, selecting two precision resistors may appear sufficient.

However, the accuracy of a voltage divider depends primarily on the relationship between the two resistor values rather than their individual absolute tolerances.

This is where matched resistor networks offer an important advantage.

Relative Tolerance – Precision Where It Matters

KOA specifies not only the absolute resistance tolerance but also the relative tolerance between the resistors within the network.

The HVD thin-film series offers a relative tolerance of 0.1%, while the MHVD thick-film series achieves 0.25%.

Because the resistor values are matched, deviations in their ratio can be tightly controlled.

For engineers designing precision voltage monitoring circuits, this helps reduce measurement errors and improves the predictability of the complete system.

TCR Tracking – Keeping Measurements Stable as Temperatures Change

Temperature introduces another challenge.

Every resistor changes its resistance value to some extent as temperature varies. This behavior is described by the Temperature Coefficient of Resistance, or TCR.

For a voltage divider, however, the difference between the temperature coefficients of R1 and R2 is particularly important.

This parameter is known as TCR Tracking.

If both resistors change proportionally with temperature, their ratio remains nearly constant, helping maintain voltage measurement accuracy.

KOA specifies:

• HVD: TCR Tracking of 10 ppm/K

• MHVD: TCR Tracking of 25 ppm/K

This characteristic is especially valuable in automotive and industrial electronics, where operating temperatures can vary significantly.

HVD vs. MHVD: Two Technologies, Different Strengths

KOA offers two complementary high-voltage resistor network technologies.

Specification	HVD	MHVD
Technology	Thin Film	Thick Film
Maximum Working Voltage	1,000 V	1,500 V
Relative Tolerance	0.1%	0.25%
TCR Tracking	10 ppm/K	25 ppm/K
Divider Ratio	10:1 to 1,000:1	100:1 to 500:1
Automotive Qualification	AEC-Q200	AEC-Q200

The HVD thin-film series focuses on applications requiring particularly high resistor ratio accuracy and low temperature-related measurement drift.

The MHVD thick-film series extends the portfolio with a higher maximum working voltage of 1,500 V.

The MHVD is housed in a compact molded SMD package measuring approximately 11.5 × 7.0 × 4.35 mm.

With high-side resistance values up to 51 MΩ and an operating temperature range from −55°C to +155°C, it is designed for demanding high-voltage measurement applications.

Selecting the appropriate technology depends on the required working voltage, measurement accuracy, thermal conditions and system-level safety requirements.

Up to 70% Less PCB Area – A Significant Advantage for Modern Electronics

Space is becoming increasingly valuable in power electronics.

Traditional high-voltage divider circuits frequently use multiple discrete resistors in series to distribute voltage stress and meet electrical design requirements.

According to KOA's technical comparison, a conventional arrangement using approximately 10 to 14 individual chip resistors can require around 177 mm² of mounting area.

Integrated KOA resistor networks offer a substantially smaller footprint:

Solution	Approximate Mounting Area
Conventional discrete resistor chain	177 mm²
KOA MHVD thick-film network	80 mm²
KOA HVD thin-film network	52 mm²

Depending on the reference design, PCB mounting area can be reduced by approximately 50–70%.

But PCB space is only part of the story.

Replacing multiple individual resistors with a single integrated network can also reduce component handling, feeder requirements, placement operations and inventory complexity.

For high-volume manufacturing, these benefits may translate into simpler assembly processes and lower overall production costs.

The actual savings depend on the application, manufacturing process and PCB design.

Importantly, an integrated resistor network does not eliminate the need to verify the required electrical clearances and insulation coordination of the complete assembly.

Up to 1,500 V: Understanding the Electrical Limits

The new KOA MHVD series supports a maximum working voltage of 1,500 V and a specified maximum short-time overload voltage of 3,000 V.

Its molded construction provides a creepage distance of 12.5 mm.

According to KOA, this creepage distance is suitable for 1,250 V under the specified conditions of IEC 60664-1, Pollution Degree 2.

An important engineering distinction must be made here:

The maximum working voltage of a component is not automatically equivalent to the permissible insulation voltage of every application.

The complete PCB design must still be evaluated against the applicable safety standards and environmental conditions.

Power dissipation is another essential consideration.

The MHVD series has a rated power of 1 W under specified conditions, with thermal derating required at elevated temperatures.

The permissible operating voltage is also limited by the resistance value and allowable power dissipation.

These parameters must be considered together when selecting a resistor network for high-voltage applications.

Practical Example: Measuring an 800 V Battery Voltage

A practical example from KOA demonstrates the use of the MHVD series in a Battery Management System (BMS).

The resistor network uses:

R1 = 8.06 MΩ

R2 = 26.9 kΩ

This produces a divider ratio of approximately 301:1.

At an input voltage of 800 V, the output voltage is reduced to approximately:

Vout ≈ 2.66 V

This lower voltage can be processed by a suitable measurement IC or analog-to-digital converter, provided the input characteristics and signal conditioning are correctly designed.

The total resistance is approximately 8.087 MΩ.

At 800 V, the divider current is approximately 99 µA, while total power dissipation is approximately 79 mW.

The example illustrates how high-voltage measurement can be implemented using a compact, high-resistance network.

Of course, a complete automotive BMS design must also consider input protection, filtering, ADC reference accuracy, diagnostic functions and functional safety requirements.

Long-Term Stability: Precision Must Last Beyond Initial Calibration

Accurate voltage measurement is not only important when a system is first commissioned.

In automotive and industrial applications, resistor networks must maintain predictable electrical characteristics throughout years of operation.

Temperature cycling, humidity, electrical loading and thermal stress can all influence resistance values.

KOA therefore specifies a range of performance tests for the MHVD series, including:

• 1,000 temperature cycles between −55°C and +155°C

• 1,000 hours of humidity testing at 85°C and 85% relative humidity

• High-temperature exposure at +155°C

• Resistance to soldering heat

• Endurance testing under defined electrical loading conditions

The MHVD series is AEC-Q200 qualified.

This qualification provides an important basis for automotive component selection, although the complete application must still undergo its own design validation.

Applications Beyond Electric Vehicles

While electric mobility is an obvious application area, high-voltage resistor networks are relevant wherever high DC voltages must be monitored accurately.

Potential applications include:

• Battery Management Systems (BMS)

• Electric and Hybrid Vehicles (EV/HEV)

• On-Board Chargers (OBC)

• Traction Inverters

• High-Voltage DC/DC Converters

• Industrial Power Electronics

• High-Voltage Monitoring and Control Circuits

• Energy Storage Systems

As power conversion systems become more compact and electrically demanding, precision-matched resistor networks can provide an attractive alternative to conventional discrete resistor chains.

Conclusion: Better Voltage Measurement Does Not Require More Components

The real innovation behind KOA's HVD and MHVD series is not simply the integration of multiple resistors into a single package.

It is the combination of precise resistor ratio matching, low TCR Tracking, high working voltage capability and compact construction.

The HVD thin-film series delivers particularly high ratio precision, while the new MHVD thick-film series extends the available working voltage range up to 1,500 V.

For engineers developing modern high-voltage electronics, both technologies offer an opportunity to simplify circuit design, reduce PCB area and optimize manufacturing processes.

Sometimes, better engineering really does mean using fewer components.

Technical Support from wittig ELECTRONIC

At wittig ELECTRONIC, we support engineers and development teams in selecting suitable electronic components for demanding applications.

Our technical team can assist with the evaluation of resistor technologies, voltage ratings, resistor ratios, temperature characteristics, power dissipation and package requirements.

Whether you are developing a new high-voltage measurement circuit, designing an automotive Battery Management System or looking to optimize an existing resistor network, we are ready to discuss your requirements.

Looking for a more compact and precise high-voltage divider solution?

Contact wittig ELECTRONIC to learn more about KOA HVD and MHVD resistor networks and discuss your next design.

Technical sources: KOA Europe – High Voltage Divider HVD/MHVD technical presentation; KOA MHVD Technical Datasheet, October 2026. Specifications are subject to change. Always refer to the latest manufacturer documentation when designing or selecting components.

Frequently Asked Questions (FAQ) – KOA HVD and MHVD High Voltage Dividers

What is a high voltage divider and how does it work?

A high voltage divider is a resistor circuit designed to reduce a high input voltage proportionally to a lower, measurable output voltage. Its operating principle is based on two resistors and the ratio between their resistance values.

In high-voltage battery systems, inverters and DC/DC converters, voltage dividers are used to reduce voltages such as 400 V or 800 V to levels suitable for electronic monitoring and control circuits.

The KOA HVD and MHVD series integrate precisely matched resistors into a compact component, reducing the complexity associated with conventional discrete resistor chains.

What is the difference between KOA HVD and MHVD?

The main differences are the resistor technology and electrical characteristics.

The HVD series uses thin-film technology, offering a relative resistance tolerance of 0.1% and TCR tracking of 10 ppm/K. It is designed for highly accurate voltage measurements and supports maximum working voltages up to 1,000 V.

The MHVD series uses thick-film technology and supports maximum working voltages up to 1,500 V, with a relative resistance tolerance of 0.25% and TCR tracking of 25 ppm/K.

The most suitable series depends on the required voltage rating, measurement accuracy and operating conditions.

Why is relative resistance tolerance important in a voltage divider?

The output voltage of a resistive voltage divider depends on the ratio between resistors R1 and R2.

Therefore, the accuracy of the resistance ratio is often more important than the absolute tolerance of each individual resistor.

Integrated resistor networks such as KOA HVD and MHVD provide precisely matched resistance ratios, helping to minimize measurement errors and improve the accuracy of high-voltage monitoring circuits.

What does TCR tracking mean in high voltage resistor networks?

TCR tracking describes the difference between the temperature coefficients of two resistors within a resistor network.

When both resistors change their resistance values proportionally as temperature varies, their ratio remains nearly constant.

KOA specifies TCR tracking of 10 ppm/K for the HVD series and 25 ppm/K for the MHVD series.

This characteristic is particularly important in automotive and industrial applications where accurate voltage measurement must be maintained across a wide temperature range.

Can KOA HVD and MHVD be used in 800 V battery systems?

Yes. KOA high voltage resistor networks are designed for applications including voltage monitoring in electric and hybrid vehicles.

A practical application example provided by KOA uses an MHVD voltage divider with a resistance ratio of approximately 301:1.

This reduces an input voltage of 800 V to approximately 2.66 V.

The resulting voltage can be processed by a suitable measurement IC or analog-to-digital converter (ADC), provided the input characteristics and signal conditioning are appropriately designed.

The complete measurement circuit must also be evaluated regarding voltage ratings, accuracy, input protection and functional safety requirements.

How much PCB space can be saved with integrated high voltage dividers?

According to KOA's technical comparison, integrated high voltage resistor networks can reduce the required PCB mounting area by approximately 50–70% compared with conventional arrangements using 10 to 14 individual resistors.

In addition to saving PCB space, integrated networks can reduce the number of components, placement operations and material handling requirements during manufacturing.

The actual savings depend on the original circuit design and the required electrical safety distances.

Are KOA HVD and MHVD qualified for automotive applications?

Yes. According to KOA, both series are AEC-Q200 qualified.

AEC-Q200 establishes reliability qualification requirements for passive electronic components under defined environmental and electrical test conditions.

This qualification is particularly relevant for automotive applications such as Battery Management Systems (BMS), On-Board Chargers (OBC) and traction inverters.

However, AEC-Q200 qualification does not replace the application-specific validation of the complete electronic system.