At present, in the transition period of 4G and 5G, the construction of base stations is particularly attractive. In the 4G era, the operating frequency bands of China’s three major operators are mainly concentrated in 900MHz and 1.8GHz, while the outdoor 5G spectrum planning is 3.4~3.6GHz and 4.8~4.9GHz. According to the attenuation formula, the higher the frequency, the faster the attenuation. It is expected that the number of 5G base stations built by China’s three major operators will be several times that of the 4G era. Even if the three major operators choose the 4G+5G mixed-signal coverage method in order to maximize economic benefits, the number of new 5G base stations will reach millions.
In terms of structure, there is no difference between 5G base stations and 4G base stations. They are all BBU equipment, RRU equipment and antennas. Among them, the BBU device is responsible for baseband digital signal processing, the RRU device is responsible for signal digital-to-analog conversion, modulation and PA amplification, and the antenna is responsible for signal transmission. However, since the core networking of 5G is completely different from that of 4G, the help of 4G base stations for 5G network construction can be said to be minimal and must be rebuilt. Therefore, it is also a wise move for China’s three major operators to choose SA (independent networking).
In the process of reconstruction and new construction of 5G base stations, not only the antenna, BBU equipment and RRU equipment are changed, but also the supporting resources need to be updated. Among them, the power replacement is a very important step, including the base station power supply and power supply. The 5G base station power supply system mainly includes UPS (Uninterruptable Power System, uninterruptible power supply) and HVDC (High-Voltage Direct Current, high voltage direct current). UPS needs to expand the original 4G base station, and HVDC needs to be newly built.
With the gradual large-scale coverage of 5G signals, the construction and reconstruction of a large number of 5G base stations and the expansion of 4G base stations have gradually started, which will inevitably bring new opportunities to the power supply market, and demand for lithium batteries, computer room temperature control equipment, and basic components will proliferate.
At the same time, different power supply methods also pose different challenges to basic components. For base station power supplies and UPS, components are required to have higher reliability, protection and maintainability; for HVDC, components need to be able to withstand high voltage conditions, while also complying with the high efficiency and low operation of HVDC power supply cost.
As a world-renowned semiconductor manufacturer, ROHM has launched a variety of solutions for wireless base stations, including SiC power components, MOSFETs and DC/DC converters, etc., to help telecom operators and equipment manufacturers to better complete 4G to A smooth upgrade to 5G.
Schematic diagram of ROHM’s base station-oriented solution
This article will introduce the key products in the above solutions for base stations.
ROHM provides a buck-boost switch controller with external FET “BD9035AEFV-C”, a 1ch synchronous step-down DC/DC converter “BD9B304QWZ” and “BD9F800MUX” for the UPS power supply method (①).
First, the main features of the buck-boost switch controller “BD9035AEFV-C” are as follows:
·Buck-boost automatic control
·High-precision switching frequency: ±7% (Ta = -40~+125℃)
·PLL synchronization frequency: 100k~600kHz
·Dual-lever overcurrent protection using a single external resistor
·Equipped with UVP, OVP, UVLO, TSD protection functions
·Constant Output Monitor Pin (PGOOD)
The input voltage range of BD9035AEFV-C is 3.8V~30V, the switching frequency is 100kHz~600kHz, and it can operate stably in the operating temperature range of -40℃~+125℃. These high-quality features allow it to be used not only in base station construction, but also in automotive equipment, industrial equipment and other Electronic equipment.
BD9035AEFV-C application circuit
Secondly, the main features of the 1ch synchronous rectification step-down converter “BD9F800MUX” are as follows:
·1ch synchronous buck converter with built-in low ON-resistance power MOSFET
·Constant on-time control provides fast transient response without external compensation loops
·Wide input voltage range: 4.5V~28V
·Ideal for 12V system power
·Absolute Maximum Rated Supply Voltage: 30V (VIN)
·Equipped with over-current protection, short-circuit protection, over-temperature protection, under-voltage protection and other perfect protection circuits
The input voltage range of BD9F800MUX is 4.5V~28V, the switching frequency is 300kHz or 600kHz, the maximum output current is 8.0A, and the package size is 3.5mm×3.5mm×0.6mm. In terms of base station construction, it can be used as a step-down power supply for DSP, FPGA, microprocessor, etc. In addition, it can also be used in consumer electronic devices such as LCD TVs, DVD/Blu-ray players, VCRs, set-top boxes, etc.
BD9F800MUX application circuit
Third, the main features of the 1ch synchronous rectification step-down DC/DC converter BD9B304QWZ are as follows:
·Built-in low on-resistance power MOSFET
·Input voltage range: 2.7V~5.5V
·Output voltage range: 0.8V~VIN × 0.8V
·Reference voltage: 0.8V±1.0%
·Switching frequency: 1MHz/2MHz
·Output current: 3A
The main advantage of the BD9B304QWZ is low power operation through high efficiency. Deep-SLLM control (upgraded low-load high-efficiency mode) can achieve more than 80% efficiency. Meanwhile, the BD9B304QWZ is a synchronous rectifier with built-in MOSFET, eliminating the need for external FETs and diodes, saving installation space and realizing low cost.
Based on the above respective advantages, although BD9B304QWZ and BD9F800MUX have different characteristics, their application scope is basically the same. They can be used in the step-down power supply of DSP, FPGA, microprocessor, etc. in base station construction, and can also be used in LCD TVs, DVD/Blu-ray players. , video recorders, set-top boxes and other consumer electronic equipment.
BD9B304QWZ application circuit
For the HVDC power supply method (②), ROHM provides 80V/3A DC/DC converter “BD9G341AEFJ-LB” and other products.
The main features of “BD9G341AEFJ-LB” are as follows:
·Recommended input voltage: 12~76V
·Reference voltage accuracy: ±1.5% (25℃)
·Switching Frequency: 50k to 750kHz (typ)
·Maximum output current: 3.0A (Max)
·Minimum overcurrent detection threshold: 3.5A (min)@Tj=150℃
·Maximum junction temperature: Tjmax=150℃
The BD9G341AEFJ-LB has a built-in 80V/3.5A/150mΩ Nch power MOSFET and adopts current mode control to achieve high-speed transient response and easy phase compensation setting. In addition to the basic protection functions such as built-in overcurrent protection, undervoltage lockout, overheat protection, and overvoltage protection, it also achieves 0µA standby current and soft-start. Compared with general products, BD9G341AEFJ-LB has achieved breakthroughs in many aspects, including higher operating voltage, larger operating current and smaller package size. Under the working conditions of 300kHz, Vo=5V, VCC=24V, when the output current is in the range of 0~100mA, the energy efficiency of BD9G341AEFJ-LB is improved by 8%-17.6% compared with ordinary products.
In order to meet the huge market demand including base station power supply in the future, ROHM will continue to develop related products in DC/DC converters.
Of course, in addition to changes in power supply methods, the construction of 5G base stations also promotes changes in device materials. Due to the challenges of high frequency, high temperature, radiation resistance and high power, high-performance semiconductor materials led by SiC power components (③) will have important applications in 5G construction. In order to help customers better cope with the above challenges in the construction of 5G base stations, ROHM has launched the third-generation Schottky Barrier Diode (SiC-SBD) made of silicon carbide material.
ROHM SiC-SBD product development diagram
Compared with the second generation products, the third generation has better forward voltage (VF) characteristics and better reverse current (IR) characteristics.
Forward Voltage (VF) Characteristics Reverse Current (IR) Characteristics
Thanks to the better VF and IR characteristics of ROHM’s third-generation SiC-SBD, customers can use a lower turn-on voltage in the process of designing products. When switching from forward to reverse, in order to reduce power consumption, the device will produce smaller transient currents. However, because the transient current of SiC-SBD does not change with the forward current in nature, the recovery current generated during recovery is very small, which reduces the system noise.
Compared with general products, the third-generation 650V SiC-SBD shows better product performance, including achieving higher IFSM, lower leakage current, and further reducing VF.
Currently, ROHM has a rich product portfolio in 650V SiC-SBD.
ROHM 650V SiC-SBD Product Lineup
Facing the challenges brought by the diverse needs of 5G base station construction and the complex application environment, ROHM will continue to ensure the stability and durability of the power supply devices it supplies, helping operators and equipment manufacturers to achieve high-speed and stable network coverage. Of course, in addition to our well-known power supply devices, ROHM also supplies other components such as current sensors and LVDS receivers. For more devices, please visit ROHM’s official website for details.