Vertical Power MOSFET

Up to now, users of power semiconductors were faced with selecting cither power or speed take your choice. The thyristor. while able to handle kilowatts of power, is generally limited to line-frequency control of ac power. The planar MOSFET is amazingly fast, but can only control about one watt of power. As a compromise, the bipolar power transistor offers a moderate power capability at tnler-mediate switching speeds. Now. however, a new technology called vertical DMOS (double-diffused MOS) has...

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L is the channel length between drain and source, p. is the surface electron mobility, e is the dielectric constant of the semiconductor material. and tox is the gate oxide thickness. VDS and Vcs are drain and gate voltages respectively, both referenced to the source. The quantity VGS(th , (termed the threshold voltage, a complex quantity encompassing the substrate doping, the nature of the oxide, and the semiconductor oxide interface) provides a measure of the...

Acknowledgments

The authors wish to express their appreciation to the many people, too numerous to mention individually, who provided support and made contributions toward the successful development of the power MOS-technology process and device family. These people are a part of the several research groups within Hewlett-Packard Laboratories Integrated Circuits Lab. Integrated Circuits Processing Lab. Instrument Research Lab and Solid State Lab), and HP's New Jersey and Microwave Semiconductor Divisions. Karl...

By Arthur W Duell and W Vincent Roland

ONE OF THE EARLIEST and continuing problems with computer systems is ac power line disturbances on customer premises. The computer manufacturer is becoming increasingly concerned about the ac line transient and grounding environment that a computer system is subjected to at a customer site. Designing for immunity to power disturbances becomes prohibitively expensive if all of the conceivable power configurations and electrical noise sources are considered. For example, a forty-year-old house...

By Dennis W Gyma Paul W Bailey John W Hyde and Daniel R Schwartz

TWO NEW AUTORANGING dc power supplies are the first of a new family of precision power supplies based 011 power MOSFET technology and designed for a variety of laboratory, industrial, and systems applications. Model 6024A (Fig. 1 , rated at 200 watts, and Model 6012 A (Fig. 2), rated at 1000 watts, deliver rated power over a 20 to-S0-volt range, which is why they are termed autoranging. The 6(124A will supply a maximum voltage of 60 volts and a maximum current of 10 amperes, but is limited to...

By Richard Myers and Robert D Peck

NEW HP-DEVELOPED fast-switching power field-jUt effect transistor (FET has made possible a new series of 50 watt printed-circuit-board power supplies that feature very small size, light weight, and demonstrated reliability of 100,000 hours mean time between failures (MTBF). Fig. 1 shows some of the eight models in the fc> 5000A Series. They have one to six outputs in combinations of 5,12,15, aiid 18 volts dc. Intended for world wide use, the supplies operate from both 120Vac and 240Vac power...

Characterization of Power Sources

Improving the immunity of a computer system to electrical noise requires adequate characterization of theacpowrer source. The terms frequently used to describe power line anomalies are discussed in the box on page 27. The noise Fig. 1. The grounding within a building can consist of both (a) single-point (used lor lighting, motors, and appliances) and (b) multipoint (used lor computer systems) ground bus systems. Fig. 1. The grounding within a building can consist of both (a) single-point (used...

Customer Site Characteristics

Noise on the power line can be generated in many different ways at the computer user's site. Electric clock systems signal-modulate the power distribution within a facility once an hour to update all electric clocks. Flicker (momentary voltage dip due to the starting of a large appliance) can occur typically 10 times per hour and the duration can be from 160 to 670 ms. The maximum amplitude of a transient is directly proportional to the velocity with which a contact opens, and is independent of...

Detection of a Noise Problem OnSite

The service engineer's objective is lo prevent power line disturbances from reaching the computer by discerning their characteristics, and then either remove the source or isolate the computer from the source. A comprehensive set of site preparation guidelines is sent to the customer prior to delivery of a computer system. If the guidelines are followed, the likelihood of power line disturbance problems is minimized. The service engineer may participate in site preparation with the customer....

How It Is Made

The double-diffused MOS (DMOS) process (Fig. 6) for vertical power MOSFETs uses a polysilicon gate technology combined with ion implantation and diffusion techniques that provide self-alignment of the gate areas. This process provides very high gale packing density which together with the large area of the devices results in low drain-to-source resistance (Ros)- The devices are built on highly doped, low-resistivity 11-type wafer substrates. The first process step is the deposition of a lightly...

How It Works

A simplified cross-section drawing illustrating some of the principal elements of a Hewlett-Packard power MOS-FET is shown in Fig. 6. The gated channels are to the left the edge of the device is to the right. In the active region, an n-channel DMOS structure is used. The channel is defined fay two consecutive thermal diffusion processes rather than 'Edna's Note Throughout 'his discussion *eterence is made lo various impunty (doping) con oentrarion s by uamg the designations p-,p,p-,n-,n, and...

Impact on Customer and Manufacturer

Making positive determination that a computer installation problem is caused by power line disturbances can be very difficult. The occurrence may be random, and the effects on the system may be different depending on the state of the electronics at the precise time of the disturbance. Symptoms of such problems overlap with those that may be caused by intermittent electrical connections, electrostatic discharge (ESD) either directly to the computer or indirectly via other objects in the...

Minimum Output Operation

One problem that arises when applying pulse-width-modulated switching converters to laboratory power supplies is that inherent delays in control circuits and power switch devices may require that a certain minimum output power be dissipated for proper operation. In fixed-output supplies, this requirement is often satisfied by adding a load resistor to the supply to dissipate the minimum power. The main disadvantage of this approach is that this power is wasted. In variable-output supplies,...

Power FETs

The use of power FETs tor switches Q1 and Q2 provides many technical benefits that translate into customer features. For one. the turn-on and turn-off response of the FETs can be made quite rapid by driver circuit design, allowing operation at very small pulse widths (< 100 ns). which occur at low output power (light load). This is particularly advantageous in a laboratory supply where bizarre behavior at light loading is undesirable. In switching rapidly the power FETs dissipate almost an...

Power Mosfet Performance Useful for Many Applications

The vertical power MOSFET com bines the circuit advantages ot planar FETs with the surface packing density of vertical device structures Eo offer efficient and convenient control of highcurrents and voltages. Because of its exceptional switching speed as a majority carrier device, it can be operated at far higher switching rates than any of the alternative devices at equivalent power levels The applications that can benefit from this additional pe' -formance are Switching power supplies The...

Power Supply Circuit

An implementation oi this circuit tor voltage regulation is shown in Fig, 4. It is shown operating directly from a 120Vac 60-Hz power line. After conversion from 60-1 Iz ac to unregulated dc, the dc output voltage is regulated by the method shown in Fig. 3. In this circuit a bridge-doubler capacitor configuration is used to derive a 1 SOVdc supply from the ac power line. This voltage is unregulated and contains a significant percentage of HO-Hz and 120- Iz ripple. Rower FETs Q1 and CJ2 provide...

Semiconductor Power Switches

Designers and manufacturers of power conversion and control equipment are constantly seeking a more efficient switch. This is because the efficiency of controlling or converting electrical power using modern pulse modulation techniques as illustrated in Fig. 2 is direcdy related to the efficiency of the switch. A source of dc poweT usually rectified ac line voltage) is modulated by the switch Fig. 1. Speed versus power far various power semiconductor devices. Technology advances are generally...

Simplified Power Supply Schematics

The simplified schematic of Fig. 9 shows a single-output supply. The 320V peak-to-peak square wave output from Ql and Q2 drives the series resonant circuit consisting of inductor LI, the leakage inductance of transformer T1 and the reflected capacitance of capacitor CR. The nominal frequency of the clock driving the t'ETs is higher than the circuit's resonant frequency. Regulation is by frequency modulation. When the control circuit slows down the clock and the FET switching rate. Ihe voltage...

Sine Wave Voltage Regulation

The power conversion and voltage regulation technique used in the 65000A Series eliminates many of the bad effects of leakage inductance, 165-to-2G0-kIIz square waves are converted to sine waves as an integral part of the regulation process. This voltage regulation technique can be explained with the circuit shown in Fig. 2. The circuit is a simple series resonant tank, and the voltage source E is a Square-wave generator. The low-pass characteristic of the tank circuit effectively filters the...

Specifications

VI is the Mam Output v'2 and V3 are sem regutateo extra outputs Vi vs. and V8 are abatable ei the range given VI is the Mam Output v'2 and V3 are sem regutateo extra outputs Vi vs. and V8 are abatable ei the range given INPUT VOLTAGE 87-1 ZTVioM74-250Vac, 47-53 Hi TEMPERATURE OPERATING 0-50 C convection OOOled 0-70'C fan cooled CARRYOVER TIME 2S ms minimum al 115 or 230Vac 10 ms minimutn at 104 or 208Vae EFFICIENCY 70 to 70 typical REMOTE SHUTDOWN Latching shutdown via TTL pulse OUTPUT DRIFT J...

Power Line Disturbances and Their Effect on Computer Design and Performance by

Vincent Roland Proper site wiring, adequate grounding, and use of isolation devices help assure satisfactory performance. When we plug something into an electrical outlet we are connecting it to a voltage that alternates between positive and negative values 50 or 60 times per second, depending on the country. This voltage may be subject to random noise and to large, unpredictable, sudden fluctuations as the utility company supplying us with electric power experiences...

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Speed versus power far various power semiconductor devices. Technology advances are generally upward to the right. Fig. 2. A block diagram of a basic power controller using an ideal switching element Fig. 3. Simplified crass section of a planar MOSFET Current flows laterally from the dram under the gate to the source. Fig. 3. Simplified crass section of a planar MOSFET Current flows laterally from the dram under the gate to the source. small control signal. Once turned on. the thyristor...

Film Capacitors

The resonant circuit regulation scheme of the 65000A Series calls for a high-current I'i I m capacitor. The current in the capacitor is ahout 00 of the output current. This capacitor, required on the secondary of transformer T1 Cr in Fig. 4 , is physically large. Hs operating current approaches the wire lead current rating and exceeds most manufacturers' current ratings for the capacitor winding end connections. There were no commercially available capacitors with sufficient current ratings....

By Winfried Seipel

Designing magnetic components tor operation at 200 kHz requires careful consideration of the properties ot materials beyond any normally required at much lower frequencies. Each of the major magnetic components in the 65000A Series presented a different set of problems requiring resolution Our goals were lo develop components small in size, design to meel the most stringent of European safety specifications, and allow for the possibility of semiautomated manufacturing to reduce manufacturing...

By Karl H Tiefert Dah Wen Tsang Robert L Myers and Victor Li

POWER AND FREQUENCY are natural electronic enemies. In a variety of detailed technical ways, as well as in fundamental ones, the speed of operation of a device is limited by its operating power level. As new technology is developed, old speed and or power barriers are overcome and new limits are established, as described qualitatively in Fig. 1, A new component development leading to a major shift in power-frequency performance is the vertical power MOSFET metal-oxide-semi conductor...