Buck-Converter with Record Step-Down Ratio

During the SPS IPC Drives Exhibition in Nuremberg, Rohm Semiconductor presented its new power supply IC in Nano Pulse Control® technology, achieving the industry’s highest step-down ratio of 24:1 between input and output voltages.

Automotive and industrial sectors are the prime focus of the European subsidiary of Rohm Semiconductor, with the sales in this region meanwhile taking 57% and 19%, respectively. Major growth is expected, especially based on four solution areas: High-performance analog, Power – centering on SiC devices, Sensors – introducing MEMS and motor drive solutions. 

 

Innovative Step-Down Power Supply IC 

The company announced the BD9V100MUF-C, a DC/DC converter with built-in MOSFET that can generate output voltages of just 3.3V or 5V (minimum 2.5V) from input voltages up to 60V at a switching frequency of 2MHz. The IC, therefore, achieves the highest step-down ratio in the industry – 24:1 – between input and output voltages. 

To obtain this voltage ratio, the chip uses the proprietary, patent-pending Nano Pulse Control technology with current mode control, which leverages high-voltage BiDCMOS processes and ultra-high-speed pulse control to realize an unprecedented ON time of just 9ns. The new technology enables single-stage voltage conversion in 48V systems such as those used in mild hybrid vehicles. At 2MHz the number of parts required is halved, reducing application size and simplifying system design, while high-frequency operation also permits the use of smaller external components, e.g. coils and output capacitors. 

 

Nano Pulse Control

Nano Pulse Control refers to ultra-fast pulse control technology achieved by combining analog circuit design, layout, and processes utilizing Rohm’s vertically integrated production system. This contributes to greater miniaturization and system simplification in 48V applications ranging from mild hybrid vehicles and industrial robots to base station sub-power supplies. 

The device features extensive protection features: over current, under voltage, thermal shutdown and short circuit protection in a VQFN24SV4040 package of 4.0mm x 40mm x 1.0mm.

 

Input voltage range	16V – 60V (absolute ratings 72V max)
Output voltage range	0.8V – 8V
SW minimum ON time	20ns (max)
Output current	1A (max)
Oscillation frequency range	1.9 – 2.3MHz
Reference accuracy	±2%
Standby current	0µA
Operating temp range	between -40°C and +125°C

Table 1. Key Specifications

 

Typical applications include automotive battery powered supplies, industrial equipment, and industrial battery-operated devices.

 

The Trend Toward 48V Systems 

Energy savings and environmental performance are the driving forces behind constant innovation in the automotive industry. Through optimized power distribution, mild hybrid vehicles with 48 V systems achieve significantly lower energy and fuel consumption, which in turn reduces CO2 emissions. Active systems for enhanced comfort in automobiles, such as brake-by-wire or electric power steering, increase the electrical power requirements. In traditional 12V systems, electrical energy has to be transported to loads at a low voltage level, causing increased losses in the wiring harness. The need for thicker copper wires also adds weight, with a negative impact on fuel consumption. Using 48V technology cuts the amount of electricity transferred by a quarter, so reducing losses in the wiring. 

At system level, automobile electronics and sensors typically require a supply voltage of between 1V and 5V. This means that the 48V bus voltage has to be stepped down to the lower voltages. At the same time, it makes sense to operate the DC/DC converter at 2MHz, as this will not affect the AM radio band (1.84MHz max.) and allows the most compact solution. 

To date, no power supply IC has achieved both a high conversion ratio and a high switching frequency. A two-stage solution meets these requirements, but has various disadvantages: it takes up more space, uses more components, and is a more complex system. Now, with the BD9V100MUF-C, Rohm is offering a single-stage voltage conversion solution.

 

About ROHM

Founded in 1958, ROHM provides LSI and discrete semiconductors characterized by outstanding quality and reliability for a broad range of markets, including automotive, industrial and consumer market via its global development and sales network. In the analog power field, ROHM proposes the suitable solution for each application with power devices such as SiC, driver ICs to maximize their performance, and peripheral components such as transistors, diodes and resistors.

 

This article originally appeared in the Bodo’s Power Systems magazine.