- TI Readies Complete Plug-In Power Module
Implementing its newest IEEE 802.3af-compliant powered device (PD) controller for power-over-Ethernet (PoE) applications, Dallas-based Texas Instruments has readied a complete plug-in power module to simplify design and realization of Ethernet-powered industrial and commercial devices. The second-generation TPS2375 controller is based on the company's linear biCMOS, silicon-on-insulator (LBC-SOI) process technology, which allows it to withstand transients up to 100 V and operate over an industrial temperature range of -40°C to 85°C.
Designed to cut time to market for designers of Ethernet-powered IP phone consoles, security systems, card readers, point-of-sale terminals or other systems that need to quickly detect, classify and deliver appropriate levels of direct current power between the power source equipment and the powered device, the 10-W PTB48540 module requires no additional external components and offers a small profile (9 mm). In addition to the TPS2375 controller, the plug-in module incorporates an electromagnetic interference (EMI) filter, an input voltage transient suppression filter and a data and spare line bridge rectifier. In essence, the module includes all the necessary interface requirements to comply with IEEE 802.3af for managing input power to the PD from PoE power-sourcing equipment (PSE). According to TI, both the controller and the module passed independent IEEE 802.3af parametric and interoperability tests conducted at the University of New Hampshire's PoE Interoperability Lab (UNH IOL).
To support extreme PoE environments and minimize heat dissipation in the system, the TPS2375 features 15-kV system-level electrostatic device (ESD) capability and includes a 0.6-Ω FET. Other features of the controller include 450-mA operating current limit, thermal shutdown and inrush current limiting, in addition to detection, classification and under-voltage lockout (UVLO). The device uses a tiny external resistor to program in-rush current limit, enabling inter-operability between a wide range of IEEE 802.3af-compliant and pre-802.3af “legacy” PSE systems.
The TPS2375 is packaged in an 8-pin SOIC or 8-pin thin-shrink small-outline package (TSSOP), and the PTB48540 comes in a 16-pin double-sided surface-mount package.
Evaluation modules, complete reference designs, application notes and technical documentation are available through http://power.ti.com/poe.
- Thermal Solution Reduces Hot Spots
Tailored for applications where lightweight is critical and space is limited, the SpreaderShield thermal management solution from GrafTech International Ltd. (Cleveland, Ohio) is based on natural graphite. Joining the company's eGraf product line, the graphite-based SpreaderShield distributes heat evenly in two dimensions, eliminating “hot spots,” shielding components from heat sources and improving performance in consumer electronics.
eGraf SpreaderShield thermal management products are custom designed for use in applications such as laptop computers, flat panel displays, portable projectors, digital video cameras, wireless phones and personal digital assistants. Available with adhesive backing, SpreaderShield can be applied easily to electronic components.
For more information on the eGraf SpreaderShield, please visit www.graftech.com.
- Power Shifts to Taiwan-Supply Manufacturers
A market study compiled by Micro-Tech Consultants (Santa Rosa, Calif.) indicates the power balance has shifted toward Taiwan. With more manufacturing moving to the Far East, the power in the power supply business also has shifted from North American/European companies to Taiwan-based manufacturers.
A newsletter published by Micro-Tech Consultants showed the top five North American/European-based OEM power supply companies lost market share by more than 45% from 2000 to 2003, while the top five Taiwan-based OEM power supply companies displayed growth of more than 22% during the same period. Thus, the top five Taiwan-based OEM power supply companies have overtaken their North American/EU competitors to obtain a larger share of the power supply market.
- Chipscale P-Channel MOSFET Boasts Low RDS(on)
The Micro Foot Si8413DB p-channel MOSFET from Vishay Siliconix achieves a maximum on-resistance of 48-mΩ at a 4.5-V gate drive and a 1-A drain current despite its small size. The MOSFET comes in a 1.54-mm × 1.54-mm × 0.62-mm chipscale package, yet offers performance comparable to devices packaged in the larger TSOP-6. The Si8413DB is for use in battery switches, power amplifiers, load switches and chargers.
At a gate drive of 2.5 V and a drain current of 1 A, maximum on-resistance rises to just 63 mΩ, and breakdown voltage is -20 V. Available now, the Si8413DB is priced at $0.25 each in quantities of 100,000.
For more information, visit www.vishay.com.
- LDO Limits Dropout Voltage
Linear Technology's LT3020 very low dropout voltage (VLDO) regulator specifies a typical dropout of 150 mV at its maximum 100 mA of output. At the same time, it permits operation from inputs as low as 0.9 V. This low input capability lets the regulator operate directly from a single 1.5 V alkaline cell to the point of discharge. It accepts input voltages as high as 10 V and produces an adjustable output voltage as low as 200 mV.
Stable with low-ESR ceramic output capacitors, the LT3020 requires a minimum of 2.2 μF on its output. In addition, the regulator specifies 0% line regulation and 0.2% typical load regulation. Quiescent current is typically 120 μA, dropping to 3 μA in shutdown.
For more information, visit www.linear.com.
|Switch RDS(ON)||1 Ω||0.60 Ω|
|VDS_MAX (Abs Max)||100 V||68 V|
|Operating Temp. Range||-40°C to 85°C||0°C to 70°C|
|Inrush Current Equation||= 25 kΩ/RLIM||= 0.45 - (25 kΩ/RLIM)|
|PG Configuration||Open drain to RTN, 2 mA||Current sink to VEE, 80_A|
|Classification (nom)||13 V to 21 V, improved regulation||12.5 V to 22.5 V|
|802.3af UVLO (nom)||30.6 V/39.4V||31.4V/40.2 V|
|“Legacy” UVLO (nom)||30.5 V/35 V||30.5 V/35 V|
|Post-Inrush UVLO Delay||No||70-no, 71-yes|
|No.||PS Manufacturers||WW Sales|
|5||Acbel Polytech Inc. (API)||~$340|
|6||Tyco Electronics/PS Div.||~$340|
|7||Artesyn Technologies Inc.||~$314|
|13||FRIWO||~$215 to $225|
|14||Tamura||~$210 to $225|
|15||Power-One||~$170 to $180|
|Top-15 Power Supply Manufacturers: 2003 Worldwide sales of OEM power supplies|