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Power Management I Product News

New DC/DC regulator set for broad range of automotive applications

Intersil Corporation has developed an AEC- Q100 qualified version of the ISL8088 - a high efficiency, dual synchronous step-down DC/DC regulator. The ISL78228 is designed to provide regulated power for use in remote safety cameras, infotainment systems, control modules and many other space-constrained automotive applications.

New micro-size DC/DC-converters with high efficiency

RECOM has released the new R0.25S series in open frame SMD design with both improved efficiency and an extended ambient temperature. The compact 0.25W single output converters can be used in many industrial low power applications and are also approved for medical applications. The R0.25S converters offer quarter watt output power from input voltages of 3.3, 5, 12, 15 or 24VDC. The standard output voltage options are 3.3, 5, 9, 12, 15 or 24VDC. The conversion efficiency is up to 70%, which enables RECOM to guarantee an extended ambient temperature range of - 40°C to +100°C without derating. This series offers 1kVDC or 3kVDC isolation and optional continuous short circuit protection. They are UL60950-1, EN60950-1 and EN60601-1 certified; RoHS 6/6 conform and come with RECOM’s standard 3 year warranty. The converters are designed for a long, trouble-free working life with an MTBF of >1.3 million hours.

The R0.25S DC/DC-converters have a very

compact low profile case with dimensions of only 12.75x10.7x6.7mm. The converters are available pre-packed as “tape and reel” for use with automatic insertion machines and the enclosed open frame design means that they are suitable for vapour phase soldering in addition to standard reflow ovens. The graph compares the R0.25S-0505

(0.25W, 5Vin, 5Vout) and a standard 1W converter with loads of 0 to 50mA. For a 50mA load, the R0.25S offers >70% efficiency compared with the 1W converter’s efficiency of <60%. At lower loads, the difference is even more significant. With a 10mA load, the R0.25S delivers a still respectable 40% efficiency while the 1W converter struggles to reach 25%. The shaded area between the curves shows the efficiency savings gained by using the right converter for low loads.

RECOM Electronic |

Diodes unveils new ultra-low dropout regulators that use less power

With an ultra-low dropout voltage of only 220mV at 1.5A, the new AP7362 and AP7363 fixed and adjustable output linear regulators from Diodes Incorporated have been designed to help reduce power consumption and increase regulated voltage output stability. Their low dropout voltage performance combined with fast transient response to step changes in load make them suitable for a variety of energy sensitive microprocessor applications in monitor, printer and set top box products. The accuracy of both regulators' adjustable voltage output is tightly maintained irrespective of circuit conditions, varying typically just +/- 1.5% at 25ºC and +/-3% over the full line voltage, load and ambient temperature ranges. In shutdown mode, quiescent current is also extremely low at 25nA, helping to boost overall circuit efficiency. For circuit protection, the integration of precision current limit and thermal shutdown functions ensure target devices remain safe from damage during fault conditions. Offering a wide adjustable output voltage

range from 0.6V to 5.0V, the regulators enable a single part number to suit a broad

42 July/August 2011

The device delivers up to 800mA continuous current from each of its two independent outputs. Its 2.75V to 5.5V input voltage range permits powering from common 3.3V and 5.0V automotive supplies. The internal current-mode compensation provides fast transient response and allows for 100% duty cycle operation for low dropout. This also simplifies circuit design by eliminating the need for external compensation components. The ISL78228 operates at 2.25MHz switching frequency (and can be synchronized up to 4MHz) allowing the use of small, low cost inductors and capacitors. Each channel is optimised for generating an output voltage as

low as 0.6V. It also features an integrated 2ms digital soft start and Power Good output. The enable pin facilitates power sequencing and the soft-stop function ensures output capacitors are discharged when switching to shutdown. Its low 30uA quiescent current minimizes standby power consumption. The compact package and high (>90%) efficiency makes the ISL78228 an ideal design choice for in-car ultra-compact regulated power applications.

Intersil |

New automotive-qualified MOSFETs deliver for heavy load applications

International Rectifier has launched a family of automotive qualified MOSFETs for a range of applications requiring low on-state resistance (RDS(on)) including heavy load applications used in traditional Internal Combustion Engine (ICE) platforms, micro and hybrid vehicle platforms.

The new rugged planar devices feature low RDS(on) and are available across a range of voltages from 40 V to 75 V in a variety of Surface Mount Device (SMD) and through- hole packages. The AUIRL1404S is a logic level gate drive MOSFETs offered at 40 V and other devices included in the new family are standard gate drive MOSFETs offered at 40 V, 55 V and 75 V.

These rugged new planar MOSFETs offer good performance in linear mode operation and their wide voltage range makes them well suited to applications on vehicles using a higher board-net voltage such as trucks. IR’s automotive MOSFETs are subject to dynamic and static part average testing combined with 100 percent automated wafer level visual inspection as part of IR’s automotive quality initiative targeting zero defects. AEC-Q101 qualification requires that

there is no more than a 20 percent change in RDS(on) after 1,000 temperature cycles of testing. However, in extended testing IR’s new AU Bill Of Materials demonstrated a maximum RDS(on) shift of less than 10% at 5,000 temperature cycles, showing the strength and ruggedness of the Bill of Materials.

The new devices are qualified according to AEC-Q101 standards and feature an environmentally friendly, lead-free and RoHS compliant bill of materials.

International Rectifier |

Temperature-to-voltage converter measures remote diodes with 1°C accuracy

range of applications by use of a simple two resistor voltage divider. Alternatively, fixed output voltage options of 1V, 1.2V, 1.5V, 1.8V, 2.5V and 3.3V removes the need for the divider and helps reduce PCB component count.

For additional flexibility, the AP7362 and AP7363 are respectively provided with and without a logic high enable pin. Both devices are provided in DFN2030-8 and SO-8 exposed pad packages with the SOT223-3L package a further option for the fixed output AP7363 variants.

Diodes Incorporated |

Components in Electronics

Linear Technology has introduced the LTC2997, a high accuracy temperature-to- voltage converter with built-in series resistance cancellation for 2.5V to 5.5V systems. The device comes in response to the fact that many low voltage systems today rely on temperature to assess overall system health and reliability. Traditional implementations require a series of filters, a precise reference and a current source, resulting in a complex conversion scheme prone to inaccuracies if not carefully designed. The LTC2997 is a simple temperature monitoring solution that measures a remote diode’s temperature with ±1°C accuracy or local temperature with ±1.5°C accuracy, and outputs a voltage proportional to absolute temperature. The LTC2997 provides a precise, space-saving, micropower temperature monitoring solution. The LTC2997 combines simplicity and accuracy with micropower consumption and as a result caters to a wide variety of applications, including system thermal control, energy harvesting, desktop and notebook computers, network servers and environmental monitoring. Two current sense

inputs can be configured to measure either local or remote temperature. A built-in algorithm cancels the errors due to sensor series resistance when measuring a diode or transistor voltages. A 1.8V voltage reference output is also available to share with an external ADC or for generating temperature threshold voltages to compare against the VPTAT output. The LTC2997 is offered in commercial, industrial and automotive versions, supporting operating temperature ranges from 0°C to 70°C, -40°C to 85°C and -40°C to 125°C.

Linear Technology |

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