The document discusses the evolution and advantages of intermediate bus architecture (IBA) and intermediate bus converters (IBCs) in power distribution systems. It explains the transition from multiple DC-DC converters to IBCs for cost-effectiveness and improved efficiency, detailing various types of converters and their characteristics. Additionally, the document evaluates the trade-offs of different backplane configurations, emphasizing the efficiency and space savings associated with modern IBC technology.

1. VI Brick® IBC Intermediate Bus Converters
1

2. Topics of Discussion
› History of Intermediate Bus Architecture (IBA)
› Types of Intermediate Bus Converters (IBC)
› Regulated versus unregulated backplanes
– Pros and cons
– Real world examples
› Vicor IBC modules
– Origin
– Key attributes
– Competitive analysis
– Features versus benefits
2

3. History of Intermediate Bus Architecture (IBA)
› The proliferation in the number of lower voltage output requirements led to the development of a more
cost effective power architecture known as “Intermediate Bus Architecture” (IBA).
› IBA replaces the proliferation of the “brick” DC-DC modules used to generate each separate voltage with
one or more isolated brick modules called Intermediate Bus Converters (IBCs) for the Intermediate Bus.
› IBCs are configured in parallel arrays and are used to step down a higher backplane voltage to a lower
“Intermediate” voltage which is then tightly regulated down to the point of load using non-isolated Point-
of-Load regulators (NiPOL).
Distributed Brick DC/DC Architecture Intermediate Bus Architecture
IBC
36-75V DC/DC +5V 36-75V +12V
(Regulated)
NiPOL +5V
NiPOL +3.3V
IBC
DC/DC +12V NiPOL +2.5V
(Regulated)
NiPOL +1.7V
NiPOL +1.5V
DC/DC -5V
NiPOL +1.2V
DC/DC -12V
3

4. Intermediate Bus Architecture Advantages
› Cost
– NiPOLs are substantially less expensive than bricks
› Layout
– Non isolated 48 V is confined to a very small area near the backplane connector
– Discrete NiPOLs can easily fit on the bottom of the PCB freeing up valuable board
space for FPGAs, ASICs,…
4

5. Types of Intermediate Bus Converters (IBC)
› Over the years, in order to achieve higher efficiency and power density, IBC technology
advanced to include semi-regulated and fixed ratio topologies. These newer topologies offered
increased efficiency and power density at the expense of regulation.
Vout
Vout
Vout
13.75V
12.8V
12V 12V
12V
11.6V
9.5V
75V
48V
75V
36V
38V
48V
Vin Vin Vin
36V
55V
Regulated DC/DC Converter Semi-Regulated DC/DC Converter Fixed Ratio DC/DC Converter
Regulation: 0.2% typ Regulation: 7-10% typ Regulation: None (4:1 typ)
Efficiency: up to 93% Efficiency: up to 95% Efficiency: up to 98%
5

6. So Why Can’t I Get a Wide Input Fixed Ratio IBC?
› Although it is possible to design a Fixed Ratio IBC to operate from a wide 36 – 75 V input,
most view this as undesirable because it causes too large of an output voltage variation
which reduces the efficiency of the downstream NiPOLs.
› “The larger the step down ratio, the lower the NiPOL efficiency
Vout Vout
18.75V
5V
13.75V
12V 12V
9.5V
9V
38V
48V
36V
48V
75V
Vin Vin
55V
Fixed Ratio DC/DC Converter Fixed Ratio DC/DC Converter
Narrow Input (38-55V) Wide Input (36-75V)
(4:1 ratio) (4:1 ratio)
6

7. Typical Distributed Backplane Voltages
› Regulated, Isolated 12 V
– Provided by a regulated AC-DC or DC-DC front end supply
– Low to mid end systems
– 1U “pizza box” systems
12 V goes straight to NiPOLs so IBC modules are not required
› Non-regulated -48 V or -60 Vdc Battery Source
– Central Office (CO) or base station locations
Cannot use our fixed ratio IBCs
› Regulated “48 V”
– Provided by a regulated AC-DC or DC-DC front-end supply
– Data center and/or CO locations
– Typical set voltages: 42 V, 48 V, 50 V, 54 V
– 54 V is commonly used in systems that include Power over Ethernet (PoE)
 Can use our fixed ratio IBCs
7

8. Unregulated Backplane
-48V Un-Regulated
Backplane Regulated or Semi Regulated › Central Office locations (CO) typically use
Switch Card
large AC-DC UPS systems that distribute
NiPOL
-48 Vdc or -60 Vdc to the rack.
NiPOL
Daughter Board › Voltage range is specified by ETS 3000 132-2
IBC – -48 V: -40.5 to -57 Vdc
NiPOL
IBC
12V
NiPOL › -60 V abnormal
– -60 V: -50.0 to -72 Vdc
Blade Server
› -75 V abnormal
-36 to -75Vdc
From UPS › To provide a universal solution to address
both battery voltages, most systems are
NiPOL
NiPOL
designed to operate over a 36 – 75 V
Daughter Board
input range.
12V
NiPOL
› Because the backplane voltage can vary over
IBC NiPOL
a wide range, regulated and semi-regulated
IBC
IBCs must be used.
IBC
8

9. Unregulated Backplane Pros / Cons
-48V Un-Regulated
› Pro
– Two stage power conversion
Backplane Regulated or Semi Regulated
Switch Card
NiPOL from source to load
NiPOL
Daughter Board
IBC
12V
NiPOL
› Highest overall system
IBC NiPOL
efficiency
Blade Server
-36 to -75Vdc
From UPS
– Lowest cost of ownership
NiPOL
NiPOL
› No front-end supply
Daughter Board
NiPOL
– Lower utility costs
12V
IBC NiPOL
IBC
IBC
9

10. Unregulated Backplane Pros / Cons
-48V Un-Regulated
› Cons
Backplane Regulated or Semi Regulated – Pros listed previously only applicable in
Switch Card
locations that distribute 48 V
NiPOL
(i.e., CO locations)
NiPOL
Daughter Board – Requires additional AC-DC front-end supply
IBC NiPOL
for areas that do not distribute 48 V
IBC
12V
NiPOL – Require wide range input IBCs
Blade Server › Regulated or semi-regulated
-36 to -75Vdc
From UPS
› Cannot use higher efficient fixed ratio IBCs
NiPOL
› Lower overall efficiency if combined with
NiPOL
Daughter Board an AC-DC front end
NiPOL
– Lower board level efficiency
12V
IBC NiPOL
› Higher cooling requirements on the board
IBC
IBC
– Lower IBC module power density
› Requires more IBCs to supply source
power to NiPOLs which takes up more
board area
10

11. Regulated Backplane
48V Regulated
Backplane
Fixed Ratio
› Regulated backplanes are most
Switch Card
NiPOL
commonly used in products that are
For AC input locations NiPOL
Daughter Board
applicable for Data Centers (DC)
which typically distribute AC,
4:1
AC/DC 12V
NiPOL
85 to 264Vac IBC NiPOL
48V
Blade Server
usually from an AC-AC UPS.
For DC input locations
NiPOL › Fixed ratio DC-DC converters are
NiPOL
Daughter Board
-36 to -75Vdc
DC/DC
4:1 NiPOL
most commonly used in regulated
48V 12V
IBC
IBC
NiPOL
backplane applications where power
density and efficiency are critical.
11

12. Regulated Backplane Pros / Cons
48V Regulated
Backplane
Fixed Ratio
› Pros
– Higher board level efficiency
Switch Card
NiPOL
For AC input locations NiPOL
Daughter Board
AC/DC 4:1
12V
NiPOL
› Less board level cooling
85 to 264Vac
required
IBC NiPOL
48V
Blade Server
– Higher power density
For DC input locations
NiPOL
NiPOL
Daughter Board
› Reduced board area space for
DC/DC
-36 to -75Vdc
48V 4:1
IBC
12V
NiPOL
NiPOL
power provides more room for
IBC processors, memory, ASICs….
– Higher overall efficiency when
used with an AC-DC front end
– Provides common line card
design that can be used both in
AC and DC input source locations
12

13. Regulated Backplane Pros / Cons
48V Regulated
Backplane
Switch Card
Fixed Ratio › Cons
For AC input locations
NiPOL
NiPOL
Daughter Board
– Three stages of power conversion
85 to 264Vac
AC/DC
48V
4:1
IBC
12V
NiPOL
NiPOL › Lower overall efficiency in -48 V
Blade Server
distribution locations (i.e., CO)
For DC input locations
NiPOL
› Requires an additional AC-DC or
DC-DC front-end supply
NiPOL
Daughter Board
DC/DC
-36 to -75Vdc 4:1 NiPOL
48V 12V
– Higher cost in CO locations
IBC NiPOL
IBC
› Added cost of DC front end supply
› Added utility cost due to extra
DC-DC front-end losses
› Supply source power to NiPOLs
which takes up more board area
13

14. Features and Benefits
Features Benefits
Highest efficiency available today • Less losses
• Reduced cooling requirements
• Lower cost of ownership
Highest power density • Less board area space
• Less IBCs required
1 MHz ZVS/ZCS Sine Amplitude • Less bulk output capacitance
Converter Topology • Smaller input/output filters
• Mature topology
• Non-infringing
14

15. Regulated Backplane Example – Core Network Switch
› Power Supply
– Hot swappable
– N+1 redundant
– Load sharing
– Dual AC input
– 50 V, 6 kW
15

16. Regulated Backplane Example – Core Network Switch
Cisco 48 Port 1GE M1 Series I/O Module
Power Entry
Filter/Hot Swap
IBCs
Mezzanine BD
16

17. VI Chip BCM® to VI Brick IBC
› VI Chip BCM (2003, B048F096T24)
– Input voltage: 38 – 55 V
– Output voltage: 9.6 V (nom)
– In/Out ratio: 5:1
– Efficiency: 96.1% (peak)
– Output power: 240 W
– Package ‘Full-chip’
(1.28 x 0.87 x 0.265 in)
Re- Package
› VI BRICK IBC (2011, IB048Q096T40N1-00)
– Input voltage: 38 – 55 V, 36 – 60 V
– In/Out ratio: 5:1
– Efficiency: 97.4% (full load), 98% (peak)
– Output power: 300 W, 500 W
– Package standard 1/8 Brick pin out
(2.3 x 0.9 x 0.38 in)
17

18. VI Brick Eighth-Brick IBC – Key Attributes
› Input: 38 – 55 Vdc, 36 – 60 Vdc
› In/Out ratios: 4:1, 5:1
› Efficiency: Up to 98%
› Power: Up to 500 W
› Isolation: 1,500 Vdc, 2,250Vdc
› Package: Standard 1/8-brick pin-out
› Topology: Patented ZCS-ZVS Sine
Amplitude Converter
18

19. VI Brick Quarter-Brick IBC – Key Attributes
› Input: 38 – 55 Vdc, 36 – 60 Vdc
› In/Out ratios: 4:1, 5:1
› Efficiency: >98%
› Power: Up to 850 W
› Isolation: 1,500 Vdc, 2,250Vdc
› Package: Standard 1/4-brick pin-out
› Topology: Patented ZCS-ZVS Sine
Amplitude Converter
19

20. Available IBC Offerings
5:1
4:1
5:1
4:1
20