Communication equipment manufacturers need high power output and small size solutions

“Many communication systems are powered by a 48 V backplane. This voltage is usually reduced to a lower intermediate bus voltage, usually to 12 V, 5 V or even lower in order to power the Circuit board racks in the system. However, most of the sub-Circuits or ICs on these circuit boards need to work in the voltage range of 3.x V to as low as 0.5 V, and the current ranges from tens of milliamps to hundreds of amperes. Therefore, to drop from these higher bus voltages to the lower voltages required by sub-circuits or ICs, a point-of-load (PoL) DC/DC converter must be used.In addition to its own difficulty, these power rails also have strict timing, voltage accuracy, margin and monitoring requirements that need to be considered.

“

Introduction

Many communication systems are powered by a 48 V backplane. This voltage is usually reduced to a lower intermediate bus voltage, usually to 12 V, 5 V or even lower in order to power the circuit board racks in the system. However, most of the sub-circuits or ICs on these circuit boards need to work in the voltage range of 3.x V to as low as 0.5 V, and the current ranges from tens of milliamps to hundreds of amperes. Therefore, to drop from these higher bus voltages to the lower voltages required by sub-circuits or ICs, a point-of-load (PoL) DC/DC converter must be used. In addition to its own difficulty, these power rails also have strict timing, voltage accuracy, margin and monitoring requirements that need to be considered!

Since there may be hundreds of PoL voltage rails in communication equipment, system architects need a simple method to manage the output voltage, timing, and maximum allowable current of these rails. Many of today’s deep submicron IC digital processors require their I/O voltage to rise before their core voltage. On the other hand, many DSPs require their core voltage to be increased before I/O. In addition, the shutdown sequence is also essential. Therefore, system architects need an easy way to make changes to optimize system performance and store specific configurations for each DC/DC converter in order to simplify the design work.

Moreover, most communication equipment manufacturers are under pressure to increase the data throughput and performance of their systems, and to add more functions and features. At the same time, they are also under pressure to reduce the total power consumption of the system. For example, common challenges include the need to rearrange workflows and transfer jobs to underutilized servers in order to reduce overall power consumption, so that other servers can be shut down. To meet these requirements, it is necessary to understand the power consumption of end-user equipment. Therefore, a properly designed digital power management system (DPSM) can provide users with power consumption data to help make smart energy management decisions.

A major advantage of DPSM is that it reduces design costs and shortens time to market. To efficiently develop complex multitrack systems, you can use a comprehensive development environment with an intuitive graphical user interface (GUI). This type of system supports changes through the GUI instead of soldering and repairing the white wire, so it also simplifies in-circuit testing (ICT) and circuit board debugging. Another advantage is that it can predict power system failures and take preventive measures through the real-time telemetry data provided. Perhaps most importantly, DC/DC converters with digital management functions allow designers to develop green power systems that meet target performance (calculation speed, data rate, etc.), while minimizing load points, circuit boards, and racks. Even the energy used at the installation level, thereby reducing the cost of infrastructure and the total cost of ownership of the product life cycle. After all, the biggest operating cost of a data center is the cost of electricity used to power the cooling system, with the goal of keeping the interior of the data center below its predetermined optimal operating temperature.

In addition, system architects still need to use some relatively simple power converters to meet the requirements of various other power supply rails on the circuit board, but the area of ​​the circuit board where these power supply rails are placed is constantly shrinking. Part of the reason is that these converters cannot be mounted on the bottom of the circuit board because multiple circuit boards are placed side by side in a rack-mounted configuration, forcing the maximum component height to be limited to 2 mm. What they really want is a complete power supply in a small size, no more than 2 mm after being mounted on a printed circuit board (PCB). Fortunately, this solution does exist, and this article will discuss it in more detail.

Converter solution

ADI’s Power by Linear™ µModule® regulator is a complete system-in-package (SiP) solution that minimizes design time and solves common board space and power density issues in communication systems. These µModule products are complete power management solutions that integrate DC-DC controllers, power transistors, input and output capacitors, compensation components, and inductors in a compact surface-mount BGA or LGA package. Designing with Power by Linear µModule products can reduce the time required to complete the design process by as much as 50%, depending on the complexity of the design. This µModule regulator series shifts the design burden of component selection, optimization, and layout from designers to devices, thereby shortening overall design time, reducing system failures, and ultimately speeding up time to market.

These µModule solutions integrate key components commonly used in discrete power supplies, signal chains, and isolation designs in a compact IC-style form factor. Supported by Power by Linear’s rigorous testing and high reliability process, our µModule product series simplifies the design and layout of power management and power conversion. This product series covers a wide range of applications, including point-of-load regulators, battery chargers, DPSM products (PMBus digital management power supplies), isolated converters and LED light-emitting diode drivers. As a highly integrated solution and each device provides PCB Gerber files, these µModule power regulators can provide high efficiency and high reliability while meeting time and space constraints. In addition, many of our newer products can also implement low EMI solutions that comply with EN 55022 Class B standards. This allows system designers to be confident that the terminal system will meet strict noise performance criteria and thus meet many of the noise industry standards that the final system must meet.

Furthermore, as design resources become tense due to the increase in system complexity and the shortening of design cycles, the focus is on the development of key intellectual property rights of the system. This often means that the power supply is put aside and not taken into account until the latter part of the development cycle. Due to the short time and the limited resources of professional power supply design, there is an urgent need to develop a high-efficiency solution with the smallest possible size, and to use the reverse side of the PCB to maximize space utilization.

This is a key area where µModule regulators can provide ideal solutions. This concept is complicated internally, but simple externally-it has both the efficiency of a switching regulator and the ease of design of a linear regulator. Responsible design, PCB layout and component selection are very important for switching regulator design. Many experienced designers smell the unique scent of circuit board burning early in their careers. When the time is short or the power supply design experience is insufficient, the off-the-shelf µModule regulator can not only save time and space, but also reduce project risks.

One of the latest examples of ultra-thin µModule solutions is LTM4622. This is a dual 2.5 A or two-phase single 5 A output step-down power regulator in a 6.25 mm × 6.25 mm × 1.8 mm ultra-thin LGA package. Its ultra-thin height is close to the height of the soldering capacitor of the 1206 case size, allowing it to be installed on the top of the circuit board. The ultra-thin form factor enables it to meet demanding height restrictions, such as those required by advanced mezzanine cards in PCIe and embedded computing systems, as shown in Figure 1.

Figure 1. LTM4622A can be installed on the bottom of the PCB.

In addition, we recently launched LTM4622A. As a variant of LTM4622, this A version has a higher output voltage from 1.5 V to 12 V, instead of the non-A version from 0.6 V to 5.5 V. In this way, if the end system needs it, system designers can have a wider output voltage range at the higher end. In either case, the input voltage range is 3.6 V to 20 V. Through Power by Linear’s µModule DC/DC regulator, high power and DPSM functions can also be easily provided. Since many µModule regulators can be connected in parallel at high load currents and provide accurate current matching (within 1% of their respective nominal ranges), they can reduce the possibility of hot spots. In addition, only one µModule regulator needs to include the DPSM function, because even if the remaining parallel µModule devices do not have built-in DPSM functions, it can still provide a complete digital interface.

Figure 2. Combining an LTM4677 DPSM µModule device and three LTM4650 µModule regulators can be rated at 1 V

The 12 V input provides 186 A.

With DPSM devices, system designers can perform many different tasks, including:

· Configure voltage through the digital communication bus, define complex on/off timing arrangements, define fault conditions (such as overvoltage and undervoltage limits), and set important power supply parameters (such as switching frequency, current limit, etc.).

・On the same communication bus, you can read back important working parameters, such as input voltage and output voltage, input and output current, input and output power, internal and external temperature, and measure the energy consumed in some products.

・ Individuals can perform accurate closed-loop margin testing of the design and adjust the power supply voltage to a very accurate level.

・ These devices are designed as autonomous devices. Once they are configured and input power is applied, they sequence the power supply, regulate very precise voltage at the point of load, continuously monitor voltage and current while implementing a user-configurable fault management solution, and are equipped with non-volatility A fault recorder that stores information about the power system when a fault is detected.

・ DPSM devices can be cascaded to build a coherent large-scale power system. This is achieved through an inter-chip coordination bus running at wire speed.

・ They include internal NVM for device configuration and fault logging functions.

・ These devices include I2C/PMBus communication ports, and use the industry standard PMBus command set to control and manage the power system.

・ These PSM devices are all supported by the universal LTpowerPlay® GUI. LTpowerPlay is an engineering-level GUI that takes into account the design and debugging of the power supply system, as well as remote customer support during development.

Figure 2 correspondingly shows the application schematic diagram of an LTM4677 (36 A DPSM µModule regulator) and three LTM4650 (50 A µModule regulators) connected in parallel with a 180 A plus DPSM PoL solution.

in conclusion

If the DPSM function and ultra-thin power conversion devices are used in today’s communication equipment, power supply designers can transmit high-power output to a core voltage as low as 0.5 V in a simple and powerful way, and the maximum DC output within the temperature range The error is ±0.5%, which can meet the needs of the latest sub-20 nm ASICs, GPUs and FPGAs. If there is a size constraint, you can use the ultra-thin μModule regulator (such as LTM4622A), which is less than 2 mm in size after being installed on the circuit board, so that the originally idle bottom circuit board space comes in handy. This not only saves valuable PCB area, but also reduces the amount of cooling required due to the increase in overall operating efficiency.

Finally, it makes sense to use µModule regulators in communication equipment because it can significantly reduce debugging time and improve board area utilization. This will reduce the cost of infrastructure and the total cost of ownership of the system life cycle. This is a win-win situation for companies that design and manufacture such equipment, as well as companies that install and use such equipment in data centers.

About the Author

Tony Armstrong is the director of product marketing for the Power by Linear product division of Analog Devices. He is responsible for all matters of power conversion and management of products from launch to discontinuation. Before joining ADI, Tony held various positions in marketing, sales, and operations at Linear Technology (now part of ADI), Siliconix Inc., Semtech Corp., Fairchild semiconductors, and Intel. He graduated from the University of Manchester in England with a Bachelor of Applied Mathematics (Hons). Contact information:[email protected]