Data Points - Power Electronics

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Data Points
IC Combines PoE Power
Control, Power Conversion
National Semiconductor’s LM5070
simplifies the design of IEEE-802.3afcompliant
powered devices (PDs) for
Power over Ethernet (PoE) by com-
To PHY
To PHY
IEEE 802.3 af
Interface
UVLO
Signature Detection
Classification
Hot Plug Controller
In-rush and Fault
Current Limiting
LM5070
DC-DC
Converter
Controller
Current/ Mode
A PoE power manager, the LM5070 also generates a low-voltage supply.
bining PD interface and power conversion
functions in one chip. The
LM5070 integrates an 80-V, 400-mA
line connection switch and associated
PoE interface circuits with a current-
mode dc-dc controller that steps
down the 48-V input to power various
loads. Meant to replace existing
2- or 3-chip solutions, it comes in
either an LLP-16 or TSSOP-16 package.
The LM5070 combines National’s
strengths in ana-
VOC
log, power management,
Ethernet
networks, packaging
and process
technologies. The
chip offers userprogrammable
features such as
undervoltage
threshold and
hysteresis, inrush current limiting and
oscillator frequency at values up to
1 MHz. It also provides internal power
sequencing of the dc-dc converter,
integrating the communication be-
tween the PD interface and converter.
The part integrates the precision
voltage reference and error amplifier
for dc-dc feedback in nonisolated
converters and provides pull-up for
an optocoupler transistor in isolated
designs.
More information is available at
www.national.com/pf/LM/LM5070.
Ferrite Core Material
An innovative manganese-zinc ferrite
material from ACME Electronics
Corp. is designed to reduce power
losses in high-temperature power
applications. The new core material
will enable development of smaller,
more efficient power supplies and
transformers. Designated as A041, this
material exhibits optimum power loss
characteristics at frequencies between
1 kHz and 100 kHz, making it ideal
Power Electronics Technology October 2004 10
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for LAN filters and pulse transformers
with a dc-bias condition. The
material features a wide working
temperature range of -20°C to 100°C.
A041 ferrite material exhibits an
initial permeability of 4000 ±25% at
100 kHz and 0.1 mT (25°C). In
addition, saturation flux density is
1000A/m between 25°C and 100°C.
The A041 material comes in many
standard and custom shapes, including
popular low-profile geometries.
For more information, visit
www.acmemagusa.com.
Rad-Hard MOSFETs
International Rectifier’s radiationhardened
logic-level MOSFETs offer
a more efficient alternative to the
bipolar transistors typically used
in low-power rad-hard applications.
The IRHLUB7970Z4 p-channel device
and the
IRHLUB770Z4
n-channel
device may be
used in place
of bipolars
such as the
2N2222A and
the 2N2907A.
Compared to
the bipolars,
the MOSFETs
require less
drive power, fewer external components
and faster switching.
Packaged in 3LCC or through-hole
packages, the MOSFETs are compatible
with 3.3-V to 5-V TTL and CMOS
logic, are rated for a 60-V breakdown
voltage, and are radiation characterized
to 300 krad (Si) total dose capability
(TID). The MOSFETs also can
Data Points
Safe operating area of the IRH770Z4 logic-level MOSFET as a function of
single event effects tested with bromine (Br), iodine (I) or gold (Au) ions.
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withstand a single event effects, as reflected
in their SEE rating to a linear
energy transfer (LET) of 82 MeV (Au).
For more details, visit www.irf.com.
ACPI Specification Revised
The Advanced Configuration and
Power Interface (ACPI) specification
has been revised and may be down-
www.powerelectronics.com 11
Power Electronics Technology October 2004

Data Points
loaded from the ACPI Web site
(http://acpi.info). Revision 3.0 contains
general configuration enhancements
along with added support for
inter-processor power, performance
and throttling state dependency. The
revision also adds support for
>256 processors, NUMA Distancing,
PCI Express, SATA, and Ambient
Light Sensor and User Presence
device. The thermal model has been
extended beyond processor-centric
support.
P-Channel MOSFET Cuts
R DS(ON) in TSOP
Aimed at battery-powered applications,
the AAT7357 from Advanced
Visit us at PowerSystems World, Booth #2017
CIRCLE 211 on Reader Service Card or freeproductinfo.net/pet
Analogic Technologies is a 20-V lowthreshold
dual P-channel power
MOSFET that achieves low on-resistance
thanks to a high-density
TrenchDMOS process. Housed in a
3-mm × 2.85-mm TSOPJW-8 package,
the transistor specifies a typical
on-resistance (R DS(ON) ) of 30 m at
V GS of -4.5 V. At a V GS of -2.5V, R DS(ON)
is 49 m. Until now, this level of performance
has necessitated use of a
TSSOP-8 package, which occupies
about twice the board area of the
TSOPJW-8.
For more information, visit
www.analogictech.com.
Digital Power
Management Protocol
Artesyn Technologies and Astec
Power have formed a coalition of
power supply and semiconductor
manufacturers to develop and support
a new communications standard
defining an open architecture for
power systems control.
The digital protocol, called “Power
Management Bus” or PMBus, will
be implemented over the industrystandard
I 2 C serial bus. The founding
group also includes IC vendors—
Intersil, Microchip Technology, Texas
Instruments, Volterra Semiconductor,
Summit Microelectronics and Zilker
Labs.
The PMbus digital protocol addresses
the desire of OEM customers
to have open standards that result
in multi-sourced products. An open
standard could allow OEM customers
to continue to design their power
systems using discrete components
or turnkey converter solutions (dcdc
converter modules). Once the
new protocol is adopted, the OEM
will be able to control all compliant
dc-dc converters using the same
set of commands, without the need
for proprietary silicon or software
interfaces.
For more information, visit
www.artesyn.com or www.astec.com.
PETech
Power Electronics Technology October 2004 12
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