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Products Power Management Trench MOSFET Synchronous buck regulator for dual-cell Li-Ion apps

A new family of ultra-high-efficiency, high-speed MOSFETs has been released by Toshiba Electronics Europe (TEE). The devices deliver improvements in low on resistance (RDS(ON)) and low input capacitance (Ciss). The new trench MOSFET series has voltage ratings from 60V to 120V allow- ing designers to reduce the size and im- prove the efficiency and performance of secondary synchronous rectification in switch mode power supplies. To develop the devices the company used its eighth generation N-channel U- MOSVIII-H process, enabling the reduc- tion of the RDS(ON) Ciss 'figure of merit' by up to 42 percent. This improves overall efficiency by driving down both conduction and drive losses at the same time as significantly improving switching speeds. The new process technology also helps to minimise radiated noise.

Among the first devices to be launched in the new family are the TK100E08N1 and TK100E10N1 in TO- 220 packages and the TK100A08N1 and TK100A10N1 in TO-220SIS 'smart isolation' package formats. Enter 216 Toshiba Electronics Europe

A 1.5A, high efficiency, synchro- nous buck regulator that can be easily paralleled for higher-cur- rent applications has been devel- oped by Linear Technology Corp. The device is adjustable down to 0V with a single resistor. The new switching regulator architec- ture uses a 50µA current reference,

combined with a single resistor to set the output voltage. This design enables easy current shar- ing between multiple regulators, setting the output voltage for all of the regulators with a single external resistor. The LTC3600 has a wide input voltage capability from 4V to 15V making it ideal for dual-cell Li- Ion applications, as well as fixed 5V and 12V intermediate bus sys- tems and synchronous rectifica- tion delivers efficiencies as high as 96 percent.

The design allows dynamic adjustment of output voltage from

0V to VIN-0.5V, offering virtually rail-to-rail performance.

The device has the ability to provide zero output enabling it to power down individual rails in the system as needed. The on-chip trimmed reference achieves accu- racy of ±1 percent.

Output regulation and tran- sient response are independent of output voltage.

Output voltage tracking or soft start is easily programmed via the ISET pin for applications that require power sequencing. Linear Technology Enter 217

Data and telecoms EMI filter for DC-DC converts

A high-density active EMI filter for DC-DC converters has been released by Vicor Corp. The company's QuietPower device supports 48V DC-DC converter designs up to 14A for data and telecommunication applica- tions. The QPI-21 input filter is claimed to provide more than 99.5 percent efficiency. The device is packaged in a high-density, 25 by 25mm Land

New DSCs for power applications

Digital Signal Controllers (DSCs) for Switch Mode Power Supplies (SMPSs featuring 50 MIPS per- formances have been announced by Microchip. The devices offer a 25 percent performance increase for the company’s dsPIC33F ‘GS’ series of DSCs.

The solution includes on-chip peripherals for digital-power applications, such as an Analogue-to-Digital Converter (ADC), Pulse Width Modulation


(PWM) peripheral and analogue comparators. The performance increase enables higher efficien- cies in power-supply applications. The family of devices supports applications such as induction cooking, Uninterrupted Power Supplies (UPSs), inverters, intel- ligent battery chargers, power factor correction, HID lighting, fluorescent lighting, LED lighting, and AC-to-DC, as well as DC-to- DC power-conversion.

The DSCs are available in 28 - to 100-pin packages, with 16 - 64K of Flash. The on-chip ADC operates at up to 4 Msps, and the PWM peripherals provide up to one nanosecond resolution, with modes supporting all power-con- version topologies. Microchip Enter 219

Grid Array (LGA) surface mount package that can reduce PCB board area consumed by EMI filtering, potentially ensuring ultra efficient board utilisation. The filter's 4.5mm height maximises airflow for space- constrained designs, which is good for advanced blade-archi- tecture applications.

The density advantages are assisted by new performance enhancements enabling higher frequency attenuation across various system configurations. The device attenuates con- ducted common mode (CM) and differential mode (DM)

noise over the CISPR22 fre- quency range of 150kHz to 30MHz (45dB for CM and 80dB for DM attenuation at 250KHz). The filter is designed for use in 48V bus (36 - 76V) systems, with 100VDC/100ms surge capability, and operates over a wide temperature range of -40°C to 125°C and up to an ambient temperature of 65°C without any derating.

The converters support the PICMG 3.0 specification for filtering system boards to the EN55022 Class B limits. Vicor Corporation Enter 218

New power package technology

components are integral for compliance with government regulations mandating higher standards for automotive fuel efficiency while also demanding lower overall emissions. To meet these standards, power MOS-

A new solution using package technology to provide high-current capability and high-efficiency for automotive applica- tions, including electric and hybrid vehicles has been released by Infineon Technologies. The new TO package is compliant with JEDEC standard H-PSOF (Heatsink Plastic Small Outline Flat lead). The first available products using the H-PSOF package tech- nology are 40V OptiMOS T2 power transistors offering up to 300A current capability in addition to ultra low R DS(on) values of only 0.76mΩ.

Higher performance power electronic

FETs with current capability above 200A and R DS(on) below 1mΩ are needed to reduce conduction losses and improve overall efficiency. Previously, MOSFETs addressing these needs were not available for the automotive market.

With the H-PSOF package, 40V power MOSFETs with up to 300A current capa- bility and R DS(on) of only 0.76m is pro- vided. In addition, the overall dimensions and the height of the package is reduced compared to a standard D 2PAK package (TO-263) which is typically used in these types of applications. Infineon Technologies Enter 220

MARCH 2012 Electronics

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