Power Electronics

Data Points

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IPD Enables Compact Automotive ECUs

The uPD166007 intelligent power device (IPD) from NEC Electronics America offers a solid-state alternative to the mechanical switches and relays that have typically been used in automotive electronic control units (ECUs). The IPD supports control of body applications such as headlights, turn signals and running lamps. It also has strong potential in other areas, such as anti-lock braking systems and air conditioners. In these applications, replacing a mechanical device with the IPD can produce an ECU that is smaller and lighter with improved on/off control and higher reliability.

Using stacked-chip construction, the uPD166007 co-packages two die in a five-pin TO-252. One of these die is an n-channel high-side MOSFET switch, while the other is a control circuit that implements a charge pump, current-controlled input, diagnostic feedback with load current sense and protection functions (see the figure).

The device implements overcurrent protection as well as overtemperature protection. With the former feature, the chip will sense an overcurrent condition such as a short in a wiring harness. However, not all shorts can be detected in this manner. For instance, when the short occurs at the end of a long wiring harness, the short-circuit current may not exceed the overcurrent threshold. But in such cases, the short would cause excessive heating in the IPD and be flagged as an overtemperature condition.

The IPD also protects itself against load dump and ESD conditions. Additionally, a specific switching control function limits rapid fluctuations in output current, and thereby reduces electromagnetic noise and improves ECU performance. The uPD166007 features a vertical-type MOSFET fabricated in the company's UMOS-2 trench technology, which yields a device with 10 mΩ max of on-resistance at a load current of 7.5 A, VCC = 12 V and a case temperature of 25°C.

Mass production of approximately 1 million units per month is scheduled to start in the second quarter of 2006. For more information, see www.am.necel.com/automotive.

Mobile Power Gains New Attention

Today's high data rates and the cellphone's evolution into a personal multimedia center means that handset power consumption and battery life will receive growing interest, according to a recent report by ABI Research. The report, “Power Management in Consumer Electronics,” states that as a result, the power management section, which is responsible for converting battery energy into voltages to power all parts of the handset, will see renewed focus and innovation.

Does this mean that revenues and healthy profit margins will increase for the semiconductor players in this area? “Not quite,” says Alan Varghese, principal analyst of semiconductor research for ABI Research. “Like any other part of the high-volume electronics industry, this sector will see falling [industry-average selling prices] due to technological advances, increased manufacturing output and supplier competition. And since tight coupling between handset components is crucial to reducing power consumption and increasing performance, companies that offer discrete power solutions are going to suffer at the hands of those offering integrated platform solutions.”

According to ABI Research, although the price of an individual power supply circuit continues to fall, the total number of these circuits required in a portable device continues to increase, offsetting some of the general downward trend in industry-average selling prices. The key for power management players will be a multi-tiered product strategy that leverages high volumes and manufacturing efficiencies in the mature standards, as innovation delivers its associated high profit margins in the more advanced segments.

The report discusses these issues in detail, examining market drivers and inhibitors, business models, technology trends and forecasts. For example, supply and demand for power management ICs in China is slated for growth. The same is true for India, whose large middle class — 250 million people — has great interest in the latest consumer electronics. For more information on this report, visit www.abiresearch.com.

Energy Star Available for Rechargeable Devices

Battery chargers for cordless tools and appliances can now earn the Environmental Protection Agency's (EPA's) Energy Star label. Americans use some 230 million products with rechargeable batteries, and Energy Star chargers will be at least 35% more efficient than chargers without the Energy Star rating.

In the United States alone, more energy-efficient battery chargers have the potential to save Americans more than 1 billion kWh of energy per year, saving Americans more than $100 million annually while preventing the release of more than one million tons of greenhouse gas emissions — equivalent to the emissions of 150,000 cars.

Battery chargers can draw as much as 5 to 20 times more energy than is actually stored in the battery, even when not actively charging a product. Energy Star guidelines for battery-charging systems focus on specific modes of the charger. This includes battery-maintenance mode, in which the charger is connected to a fully charged product, and standby mode, in which the charger is powered but no battery is connected. Some products, such as portable floor vacuums and even some power tools, may spend as much as 90% of their operating time in battery-maintenance mode, where lots of energy can be consumed by an inefficient design.

These new guidelines complement EPA's existing Energy Star external power adapter specification, announced in January 2005. To date, more than 20 external power adapter manufacturers have joined Energy Star and are producing energy-efficient models, which are available with mobile phones, digital cameras and other products.

For additional information on the Energy Star program, visit www.energystar.gov.

Digital Management for Analog Power Supplies

Linear Technology's LTC2970 is a dual I2C power supply monitor and margining controller that provides digital management of analog power supplies in high-availability systems. The LTC2970 works with almost any power supply, allowing designers to choose the optimal dc-dc converter with an analog control loop that provides smooth control of the output voltage and fast transient response. This controller offers a means of configuring power supply controllers that do not offer access to their internal voltage references. In addition, the chip implements a servo loop so that output voltage can be controlled precisely with 1% or better output voltage tolerance.

An on-chip reference with less than 10-ppm/°C drift and a 14-bit delta-sigma ADC with less than ±0.2% of total unadjusted error ensure accurate measurements of supply voltages, load currents or temperature (see the figure). Two voltage-buffered, 8-bit DACs drive the supplies' feedback nodes for improved accuracy or can be programmed by a slow, linear voltage servo to trim and margin the output voltages. This makes the LTC2970 useful in determining the sensitivity of the power supply during the prototype phase or in production to test for manufacturing variations.

User-configurable fault monitoring provides increased reliability by alerting a system's host to failures before they occur. The LTC2970's delta-sigma architecture was specifically chosen to average out power supply noise and allow the LTC2970 to ignore fast transients. The point-of-load ground reference for the DAC outputs minimizes errors that would otherwise occur in a power system that experiences ground bounce. By selecting two resistor values, the user can choose the appropriate resolution, providing an important hardware range limit beyond which the supply may not be driven.

All communication with the LTC2970 is performed over an I2C bus. It supports basic digital power commands such as setting the output voltage, readback of the output voltage, readback of the output current, and margin up and margin down. Using the I2C bus, designers can also set limits for overvoltage, undervoltage, overcurrent and undercurrent. The LTC2970-1 version incorporates a tracking feature that can turn on or off multiple power supplies in a controlled manner. The LTC2970 is offered in a 4-mm × 5-mm, 24-lead QFN or in a 28-lead SSOP. Pricing starts at $3.99 each in 1000-piece quantities. For more information, visit www.linear.com.

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