ST AN471 APPLICATION NOTE
AN471
APPLICATION NOTE
SMART POWER TECHNOLOGIES FOR
POWERTRAIN & BODY ELECTRONICS
by R. Ferrari
Smart power ICs are becoming increasing by common in automotive powertrain and body electronics.
This note provides a general introduction to the subject.
As is well known, electronics is slow ly but progress ively invading ev er y part of the automotive env ironment ( figure 1); entering first in the car radio, it has extended progressively and is now present in all of the subsystems
of an automobile. For those people who prefer a "historical" approach, the evolution of auto electronics has been
divided into three main sections, each subdivided into various phases , correlated with the state of the art in general electronics at that time. Today, at the beginning of the 90’s we are in the SMART POWER phase, and it is
precisely that which we intend to discuss briefly here (see fig. 2).
We will look at, first of all, so me definiti ons: sm art power or i ntelligent power indicates those fami lies of integr ated circuits which include both logic control circuits and components capable of delivering a significant amount
of power to a generic load. In numbers, a ci rcuit can be c onsidered sm art power if it i s able to deliver mor e than
0.5A to the load, or of withstanding more than 50V, or able to supply a power of at least 1W to the load.
Over the years ST Microelectronics has developed v arious t echnologies that a llow the reali zation of smart p ower
circuits (figure 3). The simplest way to classify these technologies is to refer to the process type, which can be
purely bipolar or mi xed, that is, includi ng on a sin g le pie ce of sili con both MOS struc tures (of c ontrol and power)
and bipolar structures. Another method (figure 4) is to examine the way in which the current flows through the
power section; horizontal, with the current entering and leav ing through the upper surface, or vertic al, where the
current enters through the upper surface and leaves thr ough the lower surface; for this lower connection i nstead
of wire the tie bar of the package is used.
The choice of one technology rather than another depends on various elements (figure 5) but simplifying as far
as possible the criteria, we can say that vertical technologies can guarantee, for a given area, lower resistances
but they have the limitation of being able to include just one power device per circuit (or more than one, but always with the collectors or drains short-circuited); while
Figure 1. Electronics in present and future automobiles.
SAFETY & CONVENIENCE BODY CONTROL POWER TRAIN DRIVER INFORMATION
Rear Window Defogger Cruise Control Ignition Digital Gauges
Climate Control Intermittent Wipar Spark Timing Digital Clock
Keyless Entry Antitheft Devices Voltage Regulator Multitons Alarms
Automatic Door Lock Electr. Suspension Alternator Engine Diagn. Results
Light Drimmer Electr. Steering Idle Speed control Service Reminders
Traction Control Multiplex Wiring Turbo Control Miles to Empty
Antiskid Braking Module to Module Emission System Shift Indicator
Window Control Communications Transmiss. Control Head-up Display
Memory Seat Load Sensit. Braking Diagnostics CRT Display
Heasted Windshield Hard/Soft Ride Control Audio Annunciator
Voice Controlled Trunk
Airbag Restraints
November 2003
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AN471 APPLICATION NO TE
Figure 2.
Figure 3. Smart Power Technol og ies Matrix .
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Figure 4. Integrated DMOS structures.
1OR MORE HV LDMOS DEVICES WITH COMMON SOURCE
AN471 APPLICATION NOTE
MANY POWER VDMOS DEVI CES AN Y CONFIGURAT ION
1 OR MORE HC VDMOS DEVICES WITH COMMON DRAIN
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