ERICSSON POWER MODULES

3E – Enhanced performance, Energy Management and increased End-user value with digital DC/DC converters

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Ericsson Power Modules has recently introduced a comprehensive set of products that establish an

innovative approach to the goals of end-user value, flexibility and system performance. These new products

contain several unique concepts spanning several disciplines in circuit and system design, all focused on

optimizing performance, flexibility and value for the end-user. Ericsson Power Modules refers to the high-

level end-user benefits of this product approach as “3E”, the 3 Es being:

• Enhanced Performance

• Energy Management

• End-user Value

This brochure describes the initial set of DC/DC converter offerings in this product family, which will be

referred to generically as “3E DC/DC converters”. These converters are intended to be a complement to the

3E Point of Load (POL) regulators described in reference (7).

The next section will describe some of the concepts, terminology and definitions used when working with

the 3E DC/DC converter designs and power system architectures enabled by the new products. This is

followed by a description of the 3E DC/DC converter offerings and then a more detailed treatment of the

benefits to the end-user in the areas of mechanical features, electrical performance, system power and

energy management, and overall value. The last part of this brochure will then expand the discussion of the

3E concept and explore its ramifications for the end-user.

1. Introduction

The internal design of the 3E DC/DC converters uses

digital power control techniques, and some of the op-

tional user implementations of these products can benefit

from utilization of system level digital power and energy

management approaches. While these products can be

successfully applied using the same techniques as with

conventional fully analog converters, it is beneficial for

the customer to become somewhat conversant with the

digital approaches so that he/she can make the optimal

choice for their particular system between conventional

and digital techniques. This section will briefly describe

the distinctions between digital power control and digital

power and energy management. Further information is

available in the cited reference material.

This discussion will assume the usage of a fairly conven-

tional Intermediate Bus Architecture (IBA) such as that

shown in Figure 1, with a board-level Intermediate Bus

Converter (IBC) or DC/DC converter feeding multiple

POL regulators which are located in proximity to the load

circuitry and supply the final operating voltages. The IBC

output voltage, and POL input voltages, will typically be

between 3.3 and 12 Vdc.

Conventional analog DC/DC converters use a Pulse

Width Modulation (PWM) control chip in conjunction

with a multitude of external resistors, capacitors, in-

ductors and active discrete semiconductor devices to

achieve the feedback and control functions needed by

the Board Mounted Power Supply BMPS. The required

time constants are formed with linear analog component

networks. Ericsson Power Modules uses the term “digital

power control” to describe a power converter or regulator

design in which much of the analog control functionality is

replaced with digital circuitry. Typically the digital content

will include the feedback loops, MOSFET gate drive gen-

eration, stability control, and fault detection. The MOS-

FET switches and the main output LC filter are often quite

similar to those in an analog DC/DC converter. The main

point to be made here is that digital power control can be

transparent to the end-user of the BMPS. Two devices,

one implemented digitally and one with analog circuitry,

can be plug-compatible and may even be indistinguish-

able as far as the end-user is concerned. However using

digital techniques internal to a DC/DC converter can

offer significant density and performance advantages to

the end-user as well as drastically increase the DC/DC

converter’s flexibility and configurability.

While digital power control only applies to circuitry

contained within a power supply and is designed and

controlled by the BMPS manufacturer, digital power

management and energy management extends beyond

the physical boundaries of a DC/DC converter or POL

regulator and into the end-use system. This extension

significantly increases the capabilities of the end-use

system, but will also require the power system designer

to participate in the implementation of the digital com-

2. Concepts, Terminology & Definitions

Figure 1 In an Intermediate Bus Architecture (IBA) a board-level Intermediate Bus Converter (IBC) feeds multiple POL regulators which are located in proximity to the load circuitry and supply the final operating voltages.

munications structure. The term “digital power manage-

ment” is used by Ericsson Power Modules to describe a

system in which DC/DC converters and/or POL regula-

tors communicate digitally with each other and/or other

elements in the system for the purposes of monitoring

and controlling the behavior of the power supplies. This

digital communication is typically used for the functions

of power monitoring, fault handling, power sequencing,

and efficiency optimization, and is facilitated by a digi-

tal interface referred to as the power management bus

(PMBus™). While digital power control must operate on

a cycle-by-cycle basis at the power supply’s operating

frequency to control the energy flow, digital power man-

agement usually operates on a slower time scale to react

to changes within the system.

The efficiency of DC/DC converters and POL regula-

tors has always been a key performance criterion. It is

receiving even more attention in recent years as more

emphasis is placed on energy consumption and the

environmental impacts of large scale data processing and

telecom installations. A fortuitous synergy results when

digital power control and digital power management are

combined. Digital power control allows for “on-the-fly”

reconfiguration of operating parameters within a power

supply as a function of system operating conditions.

If a digitally controlled DC/DC converter is operated in

a system with digital power management, the system

status can be used to dynamically program the operating

conditions of the power supply. For example, the power

transistor dead-time, which is the off-time between two

power pulses in the synchronous rectification circuitry,

could be varied as a function of the DC/DC converter’s

input and output voltage and output current to optimize

the real time efficiency over a broad variety of operating

conditions.

Similarly, the intermediate bus voltage provided by an

IBC can be dynamically varied to optimize the overall

efficiency of the combination of IBC and POL losses as a

function of the current system operating condition. Erics-

son Power Modules refers to this combined usage of

digital power management and digital power control for

the purpose of optimizing the overall power efficiency of

the end-use equipment as a function of actual operating

conditions as “digital energy management”. Impressive

savings in total energy consumption can be achieved in

this way. In effect, digital energy management replaces

compromise with optimization. Reference (1) describes

these general possibilities in greater depth while refer-

ences (2) and (3) discuss their application to DC/DC

converters.

2. Concepts, Terminology & Definitions

The fi rst 3E DC/DC converter product introduced by

Ericsson Power Modules is the BMR453 series. These

3E DC/DC converters are designed to complement the

3E POL regulators, and provide outstanding levels of

effi ciency, power density, fl exibility and performance. The

BMR453 is an isolated DC/DC converter capable of

400 W or 33 A of output in a quarter brick form fac-

tor. Unlike other quarter brick DC/DC converters, the

BMR453 achieves this power density while providing

tight +/– 2% output voltage regulation over an input volt-

age range of 36 to 75 V at effi ciency levels in excess

of 96%. The output voltage is variable from 8.5 to

13.5 V. The BMR453 is the fi rst DC/DC converter to offer

this combination of performance and power density,

making it a logical choice for high performance systems

operating with 48/60 V battery backup power architec-

tures. The fl exibility of this product will make it attractive

for a wide range of applications, some of which will be

described in this brochure. The BMR453 is shown in

Figure 2.

The BMR453 technical specifi cation should be consulted

for detailed performance data. The product offers an

extensive set of capabilities and features such as:

• PMBus interface

• Confi gurable OVP, OTP, OCP

• Remote sense

• Switching frequency synchronization

• Active current sharing

• Power good

• Voltage tracking

• Extensive power management programmability

• Optional baseplate

• High reliability

• Low parts count

• Start-up into pre-biased output

The importance of the BMR453 introduction can best be

understood by taking a broader view of the DC/DC con-

verter and IBC market. In recent years this market has

been somewhat segmented. Traditional DC/DC convert-

ers were considered “high performance” products with

tight output voltage regulation. The tradeoff for this more

precise regulation was lower power density and lower

effi ciency when compared with IBCs. The IBC eliminated

the output voltage regulation function in order to achieve

better power density, effi ciency and cost than was

available with DC/DC converter products. The BMR453

combines the best attributes of the traditional DC/DC

converter and the IBC along with the benefi ts of digital

power control and digital power/energy management.

This combination results in a product that is superior to

either the IBC or the traditional DC/DC converter.

Figure 3 depicts the genesis of this new product by

comparing its high level specifi cations to those of con-

temporary high performance DC/DC converter and IBC

products.

3. 3E DC/DC ProductOverview

Figure 2 The BMR 453 ¼-brick is offered in both open-frame and baseplated versions. The product can be used with or without the communications interface connector.

The comparisons are done at an output voltage of 12 V

and an input voltage of 48 V. All three converters shown

are packaged in a quarter brick form factor and are ca-

pable of operation over the 36 to 75 V input range. The

PKM4213CPI DC/DC converter has a maximum output

power of 204 W and a 94% typical efficiency at half load.

The PKM4304BPI IBC product has a maximum output

power of 377 W and a 96% typical efficiency at half load.

The BMR453, with an output power of 400 W and a

typical half load efficiency of slightly over 96% is an im-

provement over either former product, as it provides the

same output voltage regulation as the traditional DC/DC

converter. Consequently it represents an ideal product

for usage in either traditional or IBC converter applica-

tions. This significant advance in performance was made

possible by the use of digital techniques for both power

control and power management. The benefits of this ap-

proach to the end-user will be discussed in the following

section.

Figure 3 The BMR453 combines the tight output tolerance of the traditional DC/DC converter and the high power density and efficiency of the IBC along with the benefits of digital power control and power management.

Intermediate Bus Converter PKM 4304B

Digitally controlled BMR453

Fully regulated PKM 4213C

4.1 MECHANICAL FEATURES

The BMR453 DC/DC converters are configured in a stan-

dard quarter brick package and are available both with

and without a baseplate. A communications pin header is

used for connection to the PMBus. For users who elect

to not use the PMBus interface an optional version of the

converter is available without the communications pin

header. While eliminating the opportunity for system level

digital power management, this option will still provide

the benefits of digital power control internal to the DC/DC

converter.

For the 3E BMPS products Ericsson Power Modules took

a fresh look at the interconnection issues and created a

new optimized communications header design. For the

normal DC/DC converter power input and output pins

carrying large amount of current thick low resistance pins

are used. For other interfaces such as remote sensing

and clock/data lines that conduct minimal current an

industry standard connector header is selected. This se-

lection, in addition to reducing the PCB area needed for

interconnection, results in cost savings to the end user.

The low current connector header is widely used in the

industry with high production volumes and low cost. This

selection also eliminates the technical risk of developing

a new pin design. A diagram showing the PCB footprint

dimensioning and pinouts is provided in Figure 4.

4.2 ELECTRICAL PERFORMANCE

This section highlights some of the electrical performance

characteristics of the 3E BMR453 DC/DC converter

product. As will be seen in the next section, these per-

formance parameters can in some cases be enhanced

when using digital power management and digital energy

management at the system level.

Figure 4 The BMR453 combines the standard size and footprint of the ¼-brick form-factor with the addition of a communications interface connector.

4. 3E DC/DC Benefits

Figure 5 shows the typical efficiency characteristics of

the BMR453 as a function of input voltage and output

current. Note that the curve is relatively flat over a wide

range of output current and extends above 96% for out-

put currents from 10 to 25 A with the most common 48 V

input voltage. This is outstanding efficiency performance.

Even though it is a fully regulated DC/DC converter the

efficiency is higher than that of most IBCs without load

regulation. Later in this brochure it will be shown how the

range of high efficiency operation can be extended over

an even broader range of output current.

Since the BMR453 is a fully regulated DC/DC converter

it provides an output voltage within +/– 2% of the initial

set-point over a broad range of input voltage and output

current as shown in Figure 6. This single product pro-

vides the power density and ultra-high efficiency of an

IBC as well as the wide input voltage range and tight load

regulation of a traditional DC/DC converter. This makes it

very attractive for systems that must use a telecom input

voltage with battery backup or both -48V and -60V nomi-

nal input voltages. Its inherent load regulation also allows

the BMR453 to be used as an IBC in systems where the

intermediate bus voltage directly powers devices such

as hard drives which cannot tolerate the wide variation in

bus voltage provided by a normal IBC.

BMR453 DC/DC converters can be directly connected

without external components in an automatic current

sharing configuration even in systems that do not utilize

the PMBus for digital power management purposes. The

current sharing is balanced within a maximum of 10%

Figure 5 Typical efficiency characteristics of the BMR453 as a function of input voltage and output current for both 12 and 9 Vout.

Figure 6 The digital control system in the BMR453 allows for regulation of the output voltage over line and load within +/-2% of the initial set point.

between the converters resulting in a maximum output

power of up to 720 W for two units. Two paralleled units

will have a typical efficiency of over 96% over an output

load range of 25 to 55 A. The ability to share current

under dynamic load conditions is also important.

Figure 7 shows the load sharing characteristics of two

BMR453 DC/DC converters with a 25% to 75% to 25%

output load transition. These converters are directly con-

nected without any ORing diodes and communicate in-

between each other to actively balance the load without

further need for external control supervision.

Most all DC/DC converters are deployed in a system

environment that requires an EMI filter between them and

the input power source so that the appropriate regula-

tory requirements can be met. Often the applicable

conducted emission standard is EN55022 (CISPR22)

class B, which can be difficult and/or expensive to

meet when using DC/DC converters with high levels of

reflected input ripple current. One of the design objec-

tives of the BMR453 was to minimize the input ripple

current so that the size and complexity of the EMI filter

could be minimized: a so-called “filter friendly” approach.

This objective was achieved by providing the capability to

automatically synchronize the operation of paralleled

DC/DC converters. The synchronization is accomplished

with a direct connection between the two convert-

ers so that no system intervention is needed from the

PMBus. The synchronization is done in a “master-slave”

implementation. The slave converter assumes the same

operating frequency as the master, but with a 90 degree

phase shift between them. This phase shift is critical

for the purpose of minimizing the input ripple current of

the combined converters with the interleaved full-bridge

topology. The effect of this approach on the input ripple

current is dramatic as shown in Figure 8. The maximum

ripple current (and most stringent EMI criteria) for this

topology actually occurs at light load, so the testing was

done with no load on the output. The left trace displays

the input current with the synchronization feature dis-

abled and the right trace the input current with the syn-

chronization featured enabled. The significant reduction in

ripple current in the right trace demonstrates the effec-

tiveness of this solution and allows for a very compact

implementation of the conducted EMI filter.

4.3 SYSTEM POWER AND ENERGY MANAGEMENT

4.3.1 Power Management Methodologies

The 3E BMR453 DC/DC converter offerings are extreme-

ly flexible in terms of available management method-

ologies that can be applied during the life cycle of the

end-use application. In order of increasing functionality

they can be summarized as follows:

1. The 3E BMR453 DC/DC converter can be treated the

same as a conventional converter with internal analog

circuitry. The communications connector could just be

ignored, but there is also a product version in which

it has been completely removed. The footprint and

pin-out would be the same as with an analog converter

– input voltage, output voltage, remote control, etc.

The output voltage would be pre-set during manufac-

turing of the BMPS. This would enable the 3E DC/DC

converters to be utilized in systems that have no need

for a more sophisticated control system or that have

Figure 7 BMR453 DC/DC converters can be directly connected without external components in an auto-matic current sharing configuration. The converters will actively balance the load even under steep load changes.

Current share under load changes

– Traces: Output current (12.5 A/div)– 48 V in and 12 V out– 25–75–25% load step

– Time scale: (2 ms/div)– 2.2 mF output capacitance– No ORing on output

Figure 8 The synchronization feature of the BMR453 may be used to attenuate input ripple current, thus facilitating EMI filter design.

Figure 9a The BMR453 DC/DC converter can be treated the same as a conventional converter with internal analog circuitry.

Figure 9b Dedicated converter to converter connections will allow the units to operate in a current sharing configuration and also enable the synchroni-zation feature without the need for a host controller.

Figure 9c Including a host controller in each board-level power system provides by far the most flexible option in terms of obtain-ing maximum benefit and optimization by means of digital power management.

an existing analog-based control implementation. Note

that with this scenario many of the performance benefits

of the 3E products such as increased efficiency, regula-

tion accuracy and power density could still be realized.

2. A dedicated converter to converter connection can be

used without having the PMBus connected to a host

controller during system operation. This converter to

converter bus will allow the units to operate in a current

sharing configuration and also enable the synchroniza-

tion feature. Both of these features will operate with

the same high level of performance as they would in a

system with a complete PMBus based power manage-

ment implementation.

3. The PMBus can be used for digital communication be-

tween the 3E DC/DC converters and a host controller.

This host controller can be a part of each board-level

power system or can be only a temporary connection

to an external host during the product development

and/or manufacturing process. This is by far the most

flexible option in terms of obtaining maximum benefit

and optimization by means of digital power manage-

ment.

A drawing showing these three levels of control imple-

mentation is provided in Figure 9.

AC input ripple current

– 48 V in and 12 V out– 0 A output– 200 mA/div– 5 ms/div

– 150 kHz– 90º interleaving– No filter on input

4.3.2 The PMBus

The PMBus is a bidirectional serial multi-node interface

that utilizes 4 conductors with the following functions:

• Clock (SCL)

• Data (SDA)

• Control (CTRL)

• Alert (SALERT)

The clock and data lines are used for the bidirectional

transfer of data between the host and the controlled

nodes (3E DC/DC converters in this case) in the network.

The alert line is used by the connected converters to gain

the attention of the host controller.

Individual 3E DC/DC converters are identifi ed to the host

controller by means of an assigned address. These ad-

dresses are physically assigned at each converter used in

the system by means of resistive programming. Two pins

in the communications connector are available on each

BMR453 for this purpose, and chip resistors are con-

nected from these pins to Gnd to establish the program-

ming. Eight pre-defi ned discrete values of resistance are

used per pin, providing a total of 62 combinations, which

is more addresses than enough for most systems. Note

that in a typical system some of these addresses would

be used by other power system unites such as POL

regulators, fans and AC/DC rectifi ers.

4.3.3 Usage of the PMBus

While usage of the PMBus is optional, its use will greatly

increase the fl exibility of the end application’s power

system. If BMPS products with PMBus connectivity are

used in the system, it really only requires the bussing of

the 4 conductors previously identifi ed to a host location

in order to take advantage of the benefi ts of digital power

management. One common misconception is that the

host controller must be resident in the end system. While

this is one option, it is not the only one. The following

three scenarios show how the PMBus could be used

during various phases of the end-use system develop-

ment, manufacture and deployment.

1. The PMBus is used during product development and

evaluation. The host controller in this case could be

an external PC connected to the prototype system or

sub-system. This is an extremely convenient and fast

way to experiment with such things as output voltage

settings, power sequencing routines, voltage margin-

ing, fault handling, etc. without the need for hardware

changes in the system. Ericsson Power Modules has

an evaluation kit for the 3E products that contains an

Confi guration Monitoring and Management (CMM)

software and is an excellent way to begin exploring this

type of capability. No host controller is required in the

system itself.

2. The PMBus is used during system manufacturing and

test, and the host controller could be part of the Auto-

mated Test Equipment (ATE). In this scenario the ATE

could automatically confi gure the 3E DC/DC convert-

ers during the system’s manufacturing process. No

host controller is required in the system itself.

3. Scenario with the most capability and fl exibility is to

include the host controller into each board-level power

system. With this confi guration the same host con-

troller can be used for all three phases of a system’s

lifetime – development, manufacture, and fi eld deploy-

ment. Another misconception is that the host control-

ler needs to be powerful and expensive. In reality, its

specifi cations are very modest and in many systems it

can be as simple as a general purpose microcontroller

or some spare gates of an FPGA that may already be

resident in the system.

4.3.4 Examples of Optimization using

Energy Management

This section assumes that the power system designer

has decided to use the PMBus in one of the implementa-

tions described previously, and will give some examples

of how the power system may be optimized by digital

power management techniques. These are only a very

few of the many possibilities. The reader is encouraged to

think about other ways to use these capabilities in his/her

own systems.

Using the PMBus together with a host controller in the

ATE during the manufacturing process provides fast

and reliable setting of power sequencing routines. This

represents a vast improvement in complexity relative to

traditional systems that used analog-based power con-

trollers for this purpose. The BMR453 series is particu-

larly flexible in this regard. It has a “power good” output

signal to indicate when it is in its regulation band and

operating normally, which is useful for event-based power

sequencing. The voltage tracking feature can be used

to create custom user-defined output voltage ramp-up

profiles based on a control voltage ramp. It is also easy

to implement voltage margin testing during manufactur-

ing to verify system operation over the extremes of the

design space. Fault detection and handling can be easily

optimized. The host controller can be programmed to

set customized limits on each of the fault sensors (tem-

perature, voltage and current) not only for absolute limits

but also for “warning” conditions.

The wide output voltage adjustment range of the

BMR453 can be used to optimize overall efficiency and

energy consumption in a system by means of digital

power management via the PMBus. Conventional analog

DC/DC converters and POL regulators are designed for

maximum efficiency under the most commonly expected

system operating conditions. But each system applica-

tion is unique and any individual system will experience

different operating conditions as a function of installed

features and operating mode. Consequently, the output

current of each BMPS will vary with time as will its ef-

ficiency. With the BMR453 the converter’s output voltage

can be dynamically programmed via the PMBus to opti-

mize either its own efficiency or that of the entire power

system. POL regulators, especially at light loads, are

generally most efficient at lower values of input voltage

(DC/DC converter output voltage). The total system

would then be optimized by using a low value of BMR453

output voltage – perhaps in the range of 9 to 10 V.

But during conditions of high output current the system

power demand may require a higher intermediate bus

voltage in order to increase the power output available

from the DC/DC converter. In this scenario, the con-

verter’s output voltage could be automatically increased

to 12 V or above by sensing the system current demand

and programming the BMR453 via the PMBus. The host

controller, knowing the efficiency curves of the POL regul-

ators and the DC/DC converter, can select the optimal

intermediate bus voltage to maximize the total system

efficiency. This technique can be very useful for system

energy management and can have significant impact on

the cumulative energy usage and power utility costs.

Figure 10 shows the combined efficiency of two paral-

leled BMR453 DC/DC converters as well as the efficiency

curve of a single unit. As noted earlier, the efficiency curve

of the paralleled units is exceptionally broad, exceeding

96% from 25 to 55 A. Note that at output current values

of less than 25 A the single DC/DC converter will be

more efficient than a paralleled pair. For systems in which

there is a very wide range of current demand combined

with a high priority on operating efficiency, digital power

management can be used for efficiency optimization.

The host power controller can automatically switch the

DC/DC converter function from a current shared paral-

leled connection to a single converter when the system

current requirements are low. This communication would

be done via the PMBus. The negotiated switching point

would need to contain a fair amount of “overlap” or

hysteresis so that a single converter would not be oper-

ated near its maximum current rating to avoid overcur-

rent conditions. With this type of automated converter

changeover capability the composite efficiency curve

of the BMR453 is truly impressive, with 96% efficiency

achieved from10 A to 55 A. The efficiency is above 90%

even at loads down to 2.5 A. This approach results in a

significant savings in power losses, since at light system

loads the switching losses of a single converter will be

about half those of two paralleled converters.

Practical implementation of the above automated con-

verter selection capability will require seamless switchover

without disruption of the system intermediate bus voltage

load or generation of any fault conditions. Ericsson Power

Modules has conducted some testing to assess the

performance of the automated reconfiguration, with the

results shown in Figure 11. The oscilloscope trace on

the left shows the effect on the output voltage of switch-

ing from a paralleled converter connection to an individual

converter. The test was done at an initial output load cur-

rent of 20 A, so the operational converter sees an output

current transition from 10 A to 20 A. This current change

results in a slight depression in the output voltage but it

stays within the +/- 2% regulation band.

A more demanding condition occurs when switching

from one converter to a paralleled connection. Synchro-

nous rectification is used in the converters to maximize

efficiency with the output rectification implemented with

MOSFETs, which can conduct current in either direc-

tion. This can create difficulties when starting up into a

pre-biased load, which is exactly the scenario presented

with the startup of the second converter in the paral-

leled configuration. Without proper management of the

startup, the converter could be overstressed by a reverse

current and there could be a significant dip in the output

Figure 10 Active utilization of parallel versus single DC/DC converter operation is a powerful tool that reduces energy consumption by optimization of the efficiency over the full load range.

voltage. ORing diodes could be used as a solution, but

were rejected due to their negative impact on efficiency

and packaging density. Instead, the ORing function is

implemented with intelligent control of the output transis-

tors. This approach would normally require the addition

of a specialized controller IC, but with the digital control

implementation of these converters the startup control

is handled by the existing self-contained microcontroller

without the need for any additional components. The ef-

fectiveness of this approach is demonstrated in the right

oscilloscope trace in Figure 11. The slight dip in the out-

put voltage is due to a very small reversed current during

the start-up going into the second converter, but this

current is at a safe level for the BMR453 product. These

results are very encouraging and represent a meaningful

advancement in the ability to achieve high efficiency over

a very wide range of output current.

Another possible extension of this capability, which could

be useful in some high availability systems, would be to

automatically disable a failed paralleled converter to per-

mit the system to continue operation at a reduced power

level in “limp along” fashion until a repair action could be

accomplished. These examples show just how powerful

the concept of digital power management can be. You

no longer need to accept compromise – you can have

optimization!

Figure 11 Enabling and disabling a second DC/DC converter during current share operation puts tough requirements on dynamic load performance and the ability to start against a pre-biased load.

Current share and pre-biased operation

– Top trace: Output voltage (500 mV/div)– Bottom traces: Output current (5 A/div)– 48 V in and 12 V out– 1 x 20 A or 2 x 10 A output

– Time scale: (1 ms/div)– 2.2 mF output capacitance– No ORing on output

4.4 END-USER VALUE

This brochure has so far concentrated on how the 3E

BMR453 DC/DC converters can provide measurable

benefits to the user in terms of the design, manufactur-

ing and utilization phases of the product lifecycle. These

benefits have been mostly technical in nature, relating

to electrical and mechanical performance. This section

we will explore other benefits of the 3E concept that are

perhaps secondary in nature but still are quite important

to most all designers of contemporary power systems

and create value for the end-user.

The most striking change that is seen when comparing

the BMR453 to a more traditional converter design is the

significant decrease in the number of components. In

addition to the resultant power density enhancements,

this reduced parts count has another significant benefit –

higher reliability. Since the techniques discussed here will

allow for optimization of system operating efficiency, the

average operating temperature of the 3E DC/DC convert-

ers and other system components can be lower. Fewer

parts operating at lower temperatures equates to lower

failure rates and higher system MTBF. This in turn leads

to reduced system maintenance and down time and

most importantly it leads to fewer site visits and lower

total cost of ownership, which means higher customer

satisfaction.

The wide programmable output voltage range of the 3E

DC/DC converters in conjunction with their ability to be

easily paralleled makes them very flexible in terms of the

types of systems and applications that they can service.

A single part number converter can find widespread ap-

plication within a system and across a broad spectrum

of systems at different power levels. Purchasing volume

can then be concentrated on a few part types for maxi-

mal cost savings while logistics management costs are

minimized.

Because of the extreme flexibility of these 3E products

and the programmable nature of the digital power man-

agement concept, Ericsson Power Modules has realized

the need to take a fresh look at the quality assurance and

design/manufacturing verification processes that support

them. In addition to the traditional quality assurance

provisions of a hardware manufacturing process, strin-

gent controls have been instituted on the software and

firmware elements associated with this new manufactur-

ing environment. Ericsson Power Modules’ approach

to these important parts of this product introduction is

discussed in reference (4). The net result is that usage

of these 3E DC/DC converters will provide the user with

pre-validated products. Compared with custom designed

converter solutions, usage of the 3E DC/DC convert-

ers will result in substantially reduced technical risk and

enhanced time-to-market.

The digital power management concept can be a power-

ful tool. While saving a few milliwatts in one small subas-

sembly may not seem terribly important, the cumulative

power savings in a system of even moderate size can

add up quickly. When several of these systems are oper-

ated many hours a day, the resultant energy savings is

substantial. Building heat load and air conditioning costs

go down. The electrical utility bill goes down. Fewer

natural resources are consumed for power generation

purposes. Everyone wins.

As digital power/energy management becomes more

commonplace it will become an enabling technology, with

ramifications beyond the specific system it is installed in.

It can easily become a powerful tool for the purposes of

data collection and analysis. The result will be increased

knowledge of reliability and failure root cause analysis

that will be invaluable in the design of next-generation

systems.

The above examples are a few ways in which the 3E

DC/DC converters can enhance the value of your system

and the value of the design experience when using them.

User value is, after all, one of the key elements of the 3E

concept.

The preceding pages have hopefully conveyed much of

the fl avor of the 3E concept as applied to these new

DC/DC converters and what it delivers to the end-user.

It has been shown that each of the three Es provides

important benefi ts – many of them new or best-of-breed

for the power conversion industry:

The list above is already a long one, and could be added

to. The reader has probably already thought of other ad-

vantages in their end-use application that 3E can provide.

To defi ne 3E more succinctly, it is about fl exibility – more

importantly, user-defi ned fl exibility. It is about optimization

– namely, user-defi ned optimization. Past products have

been based on some degree of compromise. Much of

this compromise is no longer required.

3E = Maximal Confi gurability with Minimal Compromise

5. 3E – Flexibility and Optimization without Compromise

Enhanced Performance

• Signifi cantly higher power and current density than

other fully regulated converters

• Industry-leading effi ciency

• Sophisticated automatic current sharing when

paralleled

• Automatic synchronization for superior

EMI performance

• Excellent feature set for “stand alone” operation

• Many levels of possible power management

solutions

• Flexible fault detection and error handling

Energy management

• Simple low cost PMBus

• Powerful system development tools

• Major advantages during manufacturing and test

• Unparalleled fl exibility during fi eld deployment

• Adaptable systems possible

• Optimization of effi ciency to actual application

• Reduced power dissipation

• Reduced energy consumption

• Reduced utility costs and environmental impact

End-User value

• Reduced number of DC/DC converters to stock

• Enhanced reliability

• Improved system MTBF

• Increased customer satisfaction

• Backed by comprehensive pre-validation

• Reduced technical risk

• Reduced time-to-market

• Enabling technology for data collection and

analysis

This brochure has presented several ways in which the

new Ericsson Power Modules 3E DC/DC converters can

be used to add value to your system while achieving

state-of-the-art performance. Many of these advantages

can be achieved without a commitment to utilize a digital

power management bus in the end application system.

For users who adopt that approach, application of the 3E

DC/DC converters will be quite similar to using conven-

tional analog converters, and the design and testing

process will seem very familiar.

Many users will elect to take advantage of the increased

functionality, flexibility and opportunity for system optimi-

zation that the PMBus offers by using it as an interface

during system development, manufacturing testing or in

the field environment. For some of these users, this will

represent their first power system design using digital

power management techniques. One of Ericsson Power

Modules’ goals is to make the transition from analog to

digital power management systems as convenient as

possible for the end-user by supporting the new products

with a wide variety of applications assistance. In addition

to the references cited earlier in the brochure, references

(5) and (6) are recommended as a source of more gen-

eralized information about digital approaches to power

conversion design.

These 3E DC/DC converters were designed to comple-

ment the 3E POL regulator products. Ericsson Power

Modules is the first to offer a complete range of isolated

DC/DC converters and non-isolated POL regulators using

the PMBus for digital power management capabilities.

To give our customers an opportunity to easily experience

the benefits to be derived from digital power manage-

ment, an evaluation kit that can be used as a develop-

ment platform for the 3E products is introduced in

parallel with the products. This evaluation kit, shown in

Figure 12, consists of a demonstration board with

provision for hosting two BMR453 3E DC/DC convert-

ers, up to 6 pcs of 3E POL regulators, USB cable, CMM

software on CD, device drivers, sample configuration files

and complete documentation. Using this evaluation kit in

conjunction with a PC and commonly available basic lab

equipment will allow the prospective user to conveniently

experiment with the digital development environment.

This evaluation kit is highly recommended as a first step

for customers that may be considering exploring usage

of the Ericsson Power Modules 3E products or designing

a power system configured with a PMBus.

The new Ericsson Power Modules 3E DC/DC convert-

ers will eliminate many of the compromises inherent in

current designs and create exciting opportunities for

power system designers in terms of system performance,

flexibility, configurability, optimization and end-user value.

Furthermore, system design using these products should

be a fun and rewarding experience!

6. Summary

Figure 12 The 3E evaluation kit consists of a demonstration board with provision for hosting BMR453 3E DC/DC converters, 3E POL regula-tors, USB cable and CMM software on a CD together with complete documentation.

▲

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All referenced papers can be found at Ericsson Power Modules’ web site:

http://www.ericsson.com/powermodules

1. Digital Power Forum 2007 – Intelligent Energy Management for Improved Effi ciency

2. APEC 2007 – Implications of Digital Control and Management for a High Performance Isolated DC/DC

3. Digital Power Europe 2007 – Digital Control in a MicroTCA Power System

4. Digital Power Forum 2007 – Qualifi cation and Verifi cation Considerations for Digital Power Supplies

5. Digital Power Forum 2007 - From Digital Confusion to Digital Conversion

6. Digital Power – Technical Brief

7. EN/LZT 146 246 – 3E – Enhanced performance, Energy management and increased End-user value with digital

POL regulators

ATEAutomated Test Equipment

BMPSBoard Mounted Power Supply

CDCompact Disk

CMMConfi guration Monitoring and Management

EMIElectromagnetic Interference

FPGAField Programmable Gate Array

FRUField Replaceable Unit

IBAIntermediate Bus Architecture

IBCIntermediate Bus Converter

ICIntegrated Circuit

MicroTCA™Micro Telecommunications Computing Architecture

MOSFETMetal Oxide Semiconductor Field Effect Transistor

MTBFMean Time Between Failure

PCPersonal Computer

PCBPrinted Circuit Board

PMBus™Power Management Bus POLPoint of Load

PWMPulse Width Modulation

3EEnhanced Performance, Energy Management, End-user Value

7. Glossary

8. References

Ericsson is shaping the future of Mobile andBroadband Internet communications through its continuous technology leadership.

Providing innovative solutions in more than 140 countries, Ericsson is helping to create the most powerful communication companies in the world.

Ericsson Power Modules is a supplier of world-class DC/DC power modules for distributed power architectures. With its global design, development, manufacturing and sales network Ericsson Power Modules is a leading supplier of power solutions to meet the customer demand for high quality and performance.

Telefonaktiebolaget LM Ericsson

SE-164 40 Kista, Sweden

Telephone +46 8 568 69620

Fax +46 8 568 69599

www.ericsson.com/powermodules

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