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Bypass diodes for solar modules

During construction of solar modules, single cells are switched in series to so called “strings” to achieve higher system voltages.

If one or more cells are shaded (e.g. by branches of trees, antennas, etc.), the affected solar cells are no more acting like a current source, but as power consumers. Non-shaded cells are delivering further current through them, generating high power losses. “Hot spots” may occur and even cell breakdowns.

To overcome this problem, bypass diodes are switched parallel to every single or some combined cells, bypassing current flow across the darkened strings.

Like every semiconductor device, also bypass diodes have got a certain leakage current, which in normal mode of operation reduces the current supplied by the cells and therefore decreases efficiency of the solar module. Therefore leakage current especially at higher temperatures (full sun irradiation!) should be as low as possible. Compared to that, partly shading of modules is only an extreme operation mode which should be completely avoided or at least occurs only during short time periods. For this mode of operation, low forward losses are desirable.

Finally, the bypass diode has to be rugged against overvoltage spikes. Such spikes may occur during assembly of the system, if
e. g. current conducting cables are interrupted, or during operation, caused by lightning etc.

You will find more information in our Application Note Solar Bypass Diodes - you can download the PDF down below.

Keeping (H)EVs Cool Under Pressure – Cooling Pump Driven by Diotec's 65 A / 80 V Power MOSFETs DI065N08D1-AQ in D-PAK

Diotec's 65 A / 80 V Power MOSFETs DI065N08D1-AQ in D-PAK

As electric vehicles continue to evolve, the demands on their thermal management systems grow more challenging. Fast charging, high-performance powertrains, and multi-motor configurations all generate significant heat that must be effectively controlled to ensure efficiency and longevity. A crucial component in this process is the coolant pump – driven by a brushless DC (BLDC) motor, delivering 120 W to 300 W in 12 V to 48 V systems.

At the heart of these BLDC motor drives is the power stage, where efficiency, reliability, and robustness matter most. This is where the DI065N08D1-AQ from Diotec Semiconductor excels.

Designed for Demanding Automotive Environments
The DI065N08D1-AQ is a 65 A / 80 V Power MOSFET, packaged in a compact TO-252AA (D-PAK), specifically developed for high-performance automotive applications such as coolant pumps, fan drives, battery management systems, and DC-DC converters.

With a typical RDS(on) of just 5.5 mΩ, low gate charge, and logic-level gate drive, this MOSFET offers excellent efficiency and fast switching behavior—ideal for modern motor control strategies. Its 175°C maximum junction temperature rating and avalanche robustness ensure long-term reliability, even under harsh thermal and electrical stress.

Key Features:

  • Logic-level gate drive for simplified control
  • Very low on-state resistance for high efficiency
  • Fast switching times for optimized motor control
  • Low gate charge to minimize driver power losses
  • Excellent thermal performance
  • Avalanche rated for rugged, real-world operation

Applications:

  • BLDC Motor Controllers (e.g., EV coolant pumps and auxiliary drives)
  • Battery Management Systems (BMS)
  • DC-DC Converters
  • Switching Power Supplies
  • General high-efficiency switching applications

Technical Specifications (Highlights): 

  • 80 V drain-source voltage (VDSS)
  • 65 A continuous drain current (ID)
  • Typical 5.5 mΩ on-state resistance (RDS(on))
  • 1 µA drain-source leakage current (IDSS)
  • 62.5 W power dissipation (Ptot)
  • 300 A peak drain current (IDM)
  • 52 A continuous body-diode current (IS)
  • 100 A peak body-diode current (ISM)
  • 25.6 mJ single pulse avalanche energy (EAS)
  • < 2.4 K/W thermal resistance junction to case (RthC)
  • -55°C to +175°C maximum operating junction temperature range (Tj)

Compact Power, High Performance: Meet the LDI51-4.0EN-AQ Ultra-Low Dropout Regulator

LDI51-4.0EN-AQ Linear Voltage Regulator

Designed to deliver up to 500 mA output current with exceptional stability and efficiency, the LDI51-4.0EN-AQ from Diotec is a high-performance, fixed +4.0 V low dropout (LDO) voltage regulator. Housed in a compact SOT-23-5 package, it offers ultra-low quiescent current and a very low dropout voltage, as well as built-in thermal overload and short circuit protection, ensuring reliable performance even in demanding environments.

This cost-effective power regulation solution is suitable for any kind of automotive systems. Typical applications include automotive clusters, battery backup regulated supplies, antenna power feeds and post-regulation for DC-DC converters.

 

Key features:

  •  Ultra-low dropout operation
  • Very low quiescent current
  • Tight output voltage tolerance (±2%)
  • Integrated thermal overload and short-circuit protection
  • Low power consumption
  • Enable (ON/OFF) function

 

Typical applications:

  • Automotive instrument clusters
  • Battery-backed power systems
  • RF and antenna power sourcing.

 

Specifications:

  • Input voltage: up to 18 V
  • Output current: up to 500 mA
  • Dropout voltage of only 120 mV at 100 mA.
  • Quiescent current as low as 1 µA.
  • Compact SOT-23-5 package.

NUP3105L-AQ: Reliable ESD Protection for Automotive CAN and LIN Bus Systems

NUP3105L-AQ ESD Protection Diodes

The NUP3105L-AQ from Diotec is a high-performance ESD protection diode designed to safeguard sensitive data lines in automotive communication networks such as CAN and LIN bus systems. With an ultra-low capacitance of just 30 pF and ESD protection up to 30 kV, it ensures signal integrity while providing robust protection against electrostatic discharge events.

Offering bidirectional protection for each data line, the NUP3105L-AQ delivers a peak pulse power capability of 295 W (8/20 µs) and maintains a very low reverse leakage current (<1 µA). The device comes in a compact SOT-23 package, it is AEC-Q101 qualified and PPAP capable, making it an ideal choice for automotive and industrial designs that demand long-term reliability.

Key Features:

  • Automotive-grade ESD protection diode
  • Bidirectional protection for data and I/O lines
  • Ultra-low capacitance (30 pF) to preserve signal integrity
  • Very low reverse leakage current (<1 µA)
  • Peak power dissipation up to 295 W (8/20 µs)
  • AEC-Q101 qualified and compliant with RoHS, REACH, and Conflict Minerals

Typical Applications:

  • CAN and LIN bus protection
  • Data line and I/O port ESD protection
  • Automotive gateway modules
  • Protection for USB, HDMI, Ethernet and sensor interfaces
  • Microcontroller-based systems

Key Specifications:

  • Stand-off voltage (VWM): 32 V
  • ESD immunity ± 30 kV
  • Maximum junction temperature (Tj max): 125°C
  • Maximum reverse current (IR): 1 µA

BAV99L-AQ: High-Speed Dual Small Signal Diode for 48 V Telecom and (H)EV Battery Systems

BAV99L-AQ High-Speed Dual Small Signal Diode

The BAV99L-AQ from Diotec is a dual small signal diode designed for universal use in 48 V telecom backup systems and (hybrid) electric vehicle ([H]EV) battery management systems (BMS). With a switching time of under 4 nanoseconds, a peak reverse voltage of 100 V and a forward current of 2 × 125 mA, it protects sensitive components while enabling reliable, high-speed logic paths.

Battery Management Systems play a critical role in multi-cell configurations, maximizing safety, reliability, and battery lifespan.

They monitor state of charge (SOC) and state of health (SOH), and prevent thermal risks, over/under voltage, overcurrent, short circuits and overheating. They also manage cell balancing, control charge/discharge and communicate with chargers or control units.

The BAV99L-AQ is perfectly suited for these tasks:

  • Steering fast transients to ground or battery rails in rail clamp configurations
  • Protecting microcontrollers, sensors, and MOSFETs from voltage spikes
  • Free-wheeling small relay coils (forward surge capability 1 A for 1 ms)
  • Isolating signals from reverse currents at sensor outputs or gateway ports

Its low capacitance (<2 pF) and ultra-fast switching make it ideal for distribution logic, alarm limits, and status flags. The fully AEC-Q101-qualified BAV99L-AQ is available in high volumes and provides a reliable, high-performance solution for automotive and telecommunications applications.

Key Features:

  • Dual diodes in series configuration
  • High-speed switching (<4 ns)
  • AEC-Q101 qualified

Applications:

  • Automotive electronics and digital dashboards
  • Infotainment systems
  • Telecom backup supplies
  • Lighting controls

Specifications:

  •  Repetitive reverse voltage (VRRM): 100 V
  • DC blocking voltage (VDC): 75 V
  • Average forward current: 125 mA with both diodes loaded, or 250 mA with a single diode loaded.
  • Typical forward voltage (VF): <0.855 V at 10 mA, 25°C
  • Package: SOT-23

BC846S: Dual NPN Transistor in Compact SOT-363 Package for Universal Switching and Amplifying Purposes

BC846S Bipolar Transistors by Diotec Semiconductor

The BC846S from Diotec Semiconductor is a dual NPN transistor designed to deliver the trusted performance of the industry-standard BC846, now in a space-saving SOT-363 package. Both transistors support a continuous collector current of 100 mA, a peak of 200 mA, and a maximum collector-emitter voltage of 45 V, with a typical DC current gain of 290. This makes them ideal for amplifying low input signals as well as various switching applications.

Thanks to its dual configuration in a single compact package, the BC846S helps to save valuable PCB space while maintaining robust performance. Typical applications include LED lighting, consumer electronics, and household appliances such as vacuum cleaners, hairdryers, shavers, power tools, and kitchen appliance.

Key Features:

  • Dual NPN transistor in one package
  • Space-saving SOT-363 case outline
  • Industry-standard BC846 parameters
  • Suitable for universal amplification and switching

Applications:

  • LED lighting systems
  • Consumer devices
  • Vacuum cleaners, hair dryers, and shavers
  • Power tools
  • Kitchen appliance

Key Specifications:

  • Collector current (IC): 100 mA nominal, 200 mA peak
  • Collector-emitter voltage (VCEO): 45 V
  • DC current gain (hFE): typ. 290 at 2 mA / 5 V
  • Total power dissipation (Ptot): 150 mW at 25°C
  • Package: SOT-363

Small Variations in Thermal Interface Application Found to Drive Long-Term Efficiency Losses in Power Converters

Small Variations in Thermal Interface Application Found to Drive Long-Term Efficiency Losses in Power Converters

Recent reliability assessments of industrial power converter systems suggest that inconsistencies in the application of thermal interface material (TIM) can result in measurable efficiency loss and long-term thermal degradation. Although heat issues are often attributed to circuit layout or load conditions, engineers are increasingly identifying the root cause within the heat sink assembly itself.

According to field data from multiple manufacturing environments, variations in paste thickness and distribution can introduce thermal resistance differences as small as 0.1 K/W - enough to cause gradual performance drift over time. These deviations may not be evident during initial testing but they can accumulate under continuous thermal cycling.

Common contributing factors include:

  • Excess or insufficient thermal paste volume
  • Uneven spread across contact surfaces
  • Missing or misaligned interface layers

“These are small manufacturing steps, but they have system-level consequences,” said Diotec's engineers involved in the analysis. “A stable thermal path depends not only on component selection, but on the uniformity of the interface between them and heatsink.”

Diotec made an impressive comparison on Power Schottky Diodes, which were subjected to a High Temperature Reverse Bias Test (HTRB). Without thermal paste between parts and heatsink, there were 36/77 failures after 135 h only, with Ir going into thermal runaway. With correctly applied thermal paste, there were 0/77 failures, and Ir reaching stable values over 1000 h.

These findings highlight a broader principle of reliability in power electronics: performance is not solely determined by materials or design, but also by the stability of the interfaces that connect them to the ambient.