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 slowly but progressively invading every part of the automotive environment (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, some definitions: smart power or intelligent power indicates those families of integrated circuits which include both logic control circuits and components capable of delivering a significant amount of power to a generic load. In numbers, a circuit can be considered smart power if it is able to deliver more 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 STMicroelectronics has developed various technologies that allow the realization of smart power circuits (figure 3). The simplest way to classify these technologies is to refer to the process type, which can be purely bipolar or mixed, that is, including on a single piece of silicon both MOS structures (of control 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 leaving through the upper surface, or vertical, where the current enters through the upper surface and leaves through the lower surface; for this lower connection instead 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 NOTE

Figure 2.

Figure 3. Smart Power Technologies Matrix.

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AN471 APPLICATION NOTE

Figure 4. Integrated DMOS structures.

1OR MORE HV LDMOS DEVICES WITH COMMON SOURCE

MANY POWER VDMOS DEVICES ANY CONFIGURATION

1 OR MORE HC VDMOS DEVICES WITH COMMON DRAIN

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