Power Conversion Solutions for Industrial ApplicationsJanuary 28, 2021 by ROHM Semiconductor
Learn about challenges designers face and some of the key considerations for choosing buck converters for power supply design in industrial applications.
Power converters are designed to provide long-term support for industrial applications over a wide range of input voltages and operating temperatures. This article takes a look at some important challenges designers face and the most important considerations for choosing buck converters for power supply design.
Higher Voltage Requirements in Today’s Industrial Applications
With the increasing use of automation as well as emerging technologies for Industry 4.0, power management and energy efficiency is becoming more critical. In the industrial space, 24V and 48V power supplies have become commonplace due to the higher power requirements for operating heavy-duty machinery, solenoid valves, and relays.
Figure 1. In today's industrial space, 24V and 48V power supplies have become commonplace due to the higher power requirements.
Today, many industrial control systems use 24VDC buses for a variety of reasons. Where high-power loads are involved, 48V power supplies are selected. Increasing the industrial supply voltage from 24V to 48V can lower the current by half and minimize power losses in the cables by a factor of four.
The Role of Buck Converters in Industrial Applications
Multiple voltage levels are required in various circuits in industrial equipment. DC-DC buck (step-down) converters solve this challenge by stepping down the high input voltage to suitable levels.
DC-DC buck converters can achieve very high step-down ratios (e.g., 48:1 or from 48VDC down to 1VDC). These devices work by temporarily storing the input energy in an inductor or transformer’s magnetic field and supplying it to various loads at lower voltage levels.
Considerations for Selecting the Right Buck Converter
Overcurrent, overvoltage, and over-temperature conditions are some of the most frequent issues facing power supplies for industrial applications. For many designers, choosing the right buck converter for industrial applications comes down to the following criteria:
- Wide input voltage range
- High switching frequencies
- Overtemperature protection
- Overvoltage protection
- Undervoltage lockout
- Soft start
Let’s look at each of these criteria in more detail.
Wide Input Voltage Range
An essential feature of any buck converter is a wide input voltage range which allows it to cover a wide range of industrial applications utilizing 24V/48V power that needs to be stepped down to a lower output voltage level.
Some examples include power supplies for industrial control, security systems, high-power devices, and telecoms systems.
High Switching Frequencies
Higher switching frequencies in buck converters improve load transient response and allows for smaller capacitors and inductors to be used in power supplies.
Due to the harsh temperature conditions where industrial power supplies operate, overtemperature protection is critical.
Buck converters should contain thermal shutdown (TSD) circuits to protect against thermal damage to the IC. The circuit shuts down the IC when the MOSFET's internal junction temperature rises above a temperature threshold and automatically resets after the temperature falls below the TSD limit.
Frequent causes of overcurrent in industrial power supplies include short-circuiting between the output and the ground or output load currents that exceed the maximum rating.
Overcurrent causes a rapid rise in temperature that can damage components, circuit traces, and the PCB. Overcurrent protection (OCP) in buck converters prevents damage to power supplies by interrupting current flow in the high-side MOSFET when a fault occurs.
Overvoltage or surge conditions deliver damaging voltages that can damage power supplies.
Today’s buck converters provide built-in overvoltage protection (OVP) to prevent surge damage to the IC. As soon as its output voltage feedback pin receives a surge voltage, it shuts down the high-side MOSFET. It automatically resets after the feedback pin voltage falls and the IC returns to normal operation.
The undervoltage lockout (UVLO) function shuts down the IC when the input voltage falls drastically up to a certain value to prevent malfunction and automatically resets after the voltage increases.
Most buck converters provide a soft start (SS) function that minimizes high inrush current and limits rapid voltage rise during start-up. This function is initiated when the input voltage reaches UVLO voltage and minimum operating voltage after switch on.
ROHM's Industrial Solution: The BD9G500EFJ-LA Buck Converter
ROHM's BD9G500EFJ-LA is a 5A non-synchronous DC-DC buck converter that offers a variety of protective functions, including overvoltage protection, under-voltage lockout, overcurrent protection, overvoltage protection, and more.
Figure 2. The BD9G500EFJ-LA DC-DC buck converter.
The converter has a wide operating voltage range (7V to 76V) and functions reliably in temperatures ranging from -40°C to +125°C with minimal performance degradation during continuous operation. With a small HTSOP-J8 package, this buck converter is suitable for use in space-constrained applications or component-dense circuits.
The operating frequency is adjustable between 100 kHz and 650 kHz and has a peak efficiency of 95%. The current mode architecture ensures fast load transient response and simple phase compensation set-up.
With an input voltage range from 7V to 76V, ROHM’s BD9G500EFJ-LA buck converter provides a power conversion solution for numerous applications. This buck converter provides sufficient power for low-voltage rails used in battery-powered applications, such as 11-17S Li-Ion, E-bikes, and power tools, while also having a shutdown current of 10uA max..
It is also capable of generating high-efficiency intermediate voltage rails, such as 60W/12V/5A rails sufficient for powering numerous low-voltage point-of-load regulators. The reference voltage accuracy is +/-1% enabling precise voltage regulation. Moreover, with an 80V absolute maximum, ROHM’s BD9G500EFJ-LA buck converter provides excellent design margin for products that use 48VDC rails, such as industrial base stations, servers, and Power over Ethernet (PoE/PoE++) systems.
For more information about ROHM's power conversion solutions, visit ROHM’s website.