Choose a correct MOS canal, can control production to make cost well, most important is, matched yuan of one parts of an apparatus with the most appropriate money for the product, this is in the use process of product future, will produce the effect of ” of its “ screw adequately, ensure equipment gets the the highest effect, stablest, most abiding application result.

 

So the MOS canal that faces the full of beautiful things in eyes on market, how should choose? Below, we divide 7 measure to elaborate the type selecting requirement that MOS provides.

 

It is the choice of raceway groove of affirmatory N, P above all

 

MOS canal has two kinds of configuration, namely N raceway groove with P raceway groove model, the structure is different, use voltage polarity also is met different, accordingly, before selecting which kinds of product certainly, need to use N raceway groove or pipe of MOS of P raceway groove certainly above all.

 

Two kinds of constructions that MOS manages: N raceway groove with P raceway groove model

 

In typical power application, provide ground contact when a MOS, and when laden join arrives on trunk voltage, this MOS canal made low-pressure side switch. In low-pressure side switch, should use pipe of MOS of N raceway groove, this is to stem from the consideration that connects place of parts of an apparatus to need voltage to shut or guiding.

 

When MOS tubal join arrives when bus line and laden ground connection, be about to use high-pressured side switch. MOS of P raceway groove is used to be in charge of in connecting regular meeting to attack in this develop, this also is the consideration that stems from pair of voltage drive.

 

Want to choose to suit applied parts of an apparatus, must decide the voltage that place of drive parts of an apparatus needs, and the most simple and easy in the design executive method.

 

The 2nd pace is affirmatory voltage

 

Rated voltage is bigger, the cost of parts of an apparatus is higher. From cost angle consideration, still need to decide needs rated voltage, namely parts of an apparatus can susceptive is the biggest voltage. The basis carries out experience, rated voltage ought to be more than trunk voltage or total line voltage, 1.2~1.5 of general meeting put apart the voltage surplus of times, such ability provide adequate protection, make MOS is in charge of won’t invalidation.

 

With respect to choice MOS canal character, must decide leakage pole comes the likelihood between source pole susceptive is the biggest voltage, namely the biggest VDS. Because MOS is in charge of,can change, design personnel must check the span of voltage inside limits of whole job temperature. Rated voltage must have enough surplus to enclothe this span, ensure circuit won’t invalidation.

 

In addition, design engineer still needs to consider other and safe factor: Be like by switch electron equipment (common have electric machinery or transformer) the voltage twinkling that cause changes. Additional, the rated tension that different applying also differs somewhat; Normally portable equipment chooses the MOS canal of 20V, FPGA power source is the MOS canal of 20 ～ 30V, the MOS when 85 ～ 220V AC applies is in charge of VDS to be 450 ～ 600V.

 

The 3rd pace is affirmatory electric current

 

After deciding voltage, what should decide next is the electricity that MOS provides. Need to decide according to circuit structure, the rated electricity that MOS provides should be laden fall in all circumstances can susceptive is the biggest electric current; With the circumstance likeness of voltage, the rated electricity that MOS provides must the demand when can contented system produces aiguille electricity.

 

Electric current needs to begin from two respects surely really: Progressive die type and pulse aiguille. In guide continuously connect mode to fall, MOS canal is in stable state, right now electric current carries parts of an apparatus or appliance continuously. Pulse aiguille is to point to a large number of report emerge (or aiguille electric current) had shed parts of an apparatus. Once decided the biggest electric current below these conditions, need to choose to be able to bear directly only the parts of an apparatus of this the biggest electric current but.

 

After choosing rated electric current, still must calculate guide a loss. Below actual condition, MOS canal is not ideal parts of an apparatus, because there can be electric energy loss in electric process, guide namely a loss. MOS canal guides an alterable resistor resembles when connecting ” in “ , by parts of an apparatus guide place of electrify block RDS(ON) decides, follow temperature and change significantly.

 

The power loss PTRON=Iload2×RDS(ON) of parts of an apparatus calculates (Iload: The biggest dc exports electricity) , because guide electrify block can change along with temperature, because this power consume also is met,change in proportion subsequently. The voltage VGS that to MOS the canal brings to bear on is taller, RDS(ON) can be jumped over small; Conversely RDS(ON) can be jumped over tall.

To systematic design personnel, this needs eclectic balance.

 

To portable design, use inferior tension can (relatively general) ; And to industrial design, can use taller tension. Those who need an attention is, RDS(ON) resistor is met as electric current slight rise.

 

The technology is having major effect to the character of parts of an apparatus, because some technologies are raising the biggest VDS (leakage source is rated voltage) when often can make RDS(ON) increases. To such technology, if plan to reduce VDS and RDS(ON) , have to increase chip size so, increase thereby to it of form a complete set enclose dimension and relevant development cost. Industry has several kinds of technologies that try to control chip dimension to increase, among them the mainest is raceway groove and charge balance technology.

 

In raceway groove technology, embedded in chip a deep trench, it is low voltage obligate normally, use at reducing to guide electrify block RDS(ON) . To reduce the effect of the biggest VDS to RDS(ON) , extension was used to grow in developing a process column / etch column craft. For example, the SupeRFET technology that flying million conductor develops, reduce and increased extra production step what be aimed at RDS(ON) .

 

This kind is very important to the attention of RDS(ON) , when because become,the puncture voltage of standard MOSFET lifts, RDS(ON) can show exponential level to increase subsequently, and bring about chip dimension increase. SuperFET craft turned the exponential concern between RDS(ON) and chip dimension into linear concern.

 

 

Such, superFET parts of an apparatus can be in small chip dimension, below the condition that obtains 600V in puncture voltage even, realize ideal low RDS(ON) . The result is chip dimension can be reduced amount to 35% . And to final user, this means those who enclose dimension to be reduced considerably.

 

Parameter of series of SuperFET III MOSFET

 

The 4th pace is firm hot demand

 

After affirmatory electric current, be about to calculate of the system medicinal powder hot demand. Design personnel must consider two kinds of different cases: Worst circumstance and true condition. The proposal uses the computational result that is aimed at worst circumstance, because this result offers larger safe surplus, can ensure system won’t invalidation. The data that provides in MOS still has what a few need notice to measure data on the watch, enclose the thermal resistance between the semiconductor knot of parts of an apparatus and environment for instance, and the biggest bear is lukewarm.

 

The knot of parts of an apparatus is lukewarm the product that is equal to temperature of the biggest environment to add thermal resistance and power dissipation, written guarantee namely lukewarm = is the biggest environmental temperature + (dissipation of power of thermal resistance × ) . Can divide a system according to this equation most high-power dissipation =I2×RDS(ON) .

 

Because design personnel to already will carry the biggest electricity of parts of an apparatus certainly, because this is OK,computation gives the RDS(ON) below different temperature. Notable is, when processing heats up a model simply, design personnel still must consider semiconductor to written guarantee / crust of parts of an apparatus and crust / environmental thermal capacity; Ask namely printed circuit board and enclose won’t warm up instantly.

 

Avalanche puncture (the retrorse voltage that points to semiconductor device to go up exceeds maximum, form strong electric field to make the electric current inside parts of an apparatus increases) formation electric current dissipation power, make temperature of parts of an apparatus elevatory, and possible attaint parts of an apparatus. Semiconductor company can undertake to parts of an apparatus the avalanche checks, computation its avalanche voltage, or have a test to the dovish sex of parts of an apparatus.

 

Computation is rated avalanche voltage has two kinds of methods; It is statistical law, another it is hot computation. And because hot computation is relatively practical and get be adoptioned extensively. Outside dividing computation, the technology also has very big effect to avalanche effect. For example, the addition of chip dimension can rise fight avalanche ability, raise the dovish sex of parts of an apparatus finally. To final user character, this is meant should use in the system bigger enclose.

 

The 5th pace is affirmatory switch function

 

The last situation that chooses MOS canal is to determine its switch performance. The parameter that affects switch performance has a lot of, but the most important is grid / leakage pole, grid / source pole reachs leakage pole / source pole capacitance. Because be in,should charge to these capacitance when switch every time, switch loss can produce in parts of an apparatus; The switch rate that MOS provides also is reduced accordingly, efficiency of parts of an apparatus drops subsequently; Among them, grid charge (Qgd) is the biggest to the influence of switch function.

 

For the total loss of the parts of an apparatus in computational switch process, design personnel must be calculated the loss in enlightened process (Eon) and the loss in closing a process (Eoff) , push then derive MOS provides switch general power: Psw=(Eon+Eoff)× switch frequency.

 

Increase model the switch circuit that NMOS canal makes

 

The 6th pace thinks to enclose an element

 

Enclose dimension MOS canal differently to have different thermal resistance and dissipation power, need those who consider a system to come loose hot condition and environmental temperature (if whether have wind,the appearance of cold, radiator and size limitation, environment closes wait for an element) , basic principle is namely below the premise of the temperature rise that makes sure power MOS is in charge of and systematic efficiency, choose parameter and enclose more general power MOS canal.

 

Common MOS canal seals of:

 

① inserts type to enclose: TO-3P, TO-247, TO-220, TO-220F, TO-251, TO-92;

② surface sticks outfit type: TO-263, TO-252, SOP-8, SOT-23, DFN.

 

TO encloses MOS canal

 

Enclose a form differently, the limiting current with MOS corresponding canal, voltage and medicinal powder hot effect the metropolis is different, simple introduction is as follows.

 

TO-3P/247: It is medium canal of MOS of high pressure, big electric current encloses a form commonly usedly, the product has compression tall, beat back wears ability to wait for a characteristic by force, comfortable at middling pressure big electric current (value of voltaic 10A above, compression is under 100V) use in the place that is worth 200V above in 120A above, compression.

 

TO-220/220F: These two kinds of MOS canal exteriors that enclose a style are about the same, can crossing-over is used, nevertheless TO-220 back has carbon fin, its come loose hot effect is close friends than TO-220F some, the price also wants relatively some more expensive. These two enclose a product comfortable at 120A of middling pressure big electric current the circumstance with the following, the following 20A of high-pressured big electric current applies.

 

TO-251: Should enclosing a product basically is to reduce cost and contractible product volume, basically apply at 60A of middling pressure big electric current the environment is medium under 7N of the following, high pressure.

 

TO-92: Should enclose only low-pressure MOS is in charge of (the following, compression is worth voltaic 10A 60V is the following) using with high-pressured 1N60/65, basically be to reduce cost.

 

TO-263: It is a mutation of TO-220, advocate if to increase production efficiency is mixed,come loose to heat up and be designed, support extremely tall electric current and voltage, in 150A the MOS of middling pressure big electric current of above of the following, 30V is in charge of in relatively much see.

 

TO-252: It is at present the mainstream is enclosed one of, apply to high pressure in 7N the following, middling pressure is in under 70A in the environment.

 

SOP-8: Should be being enclosed is to reduce cost design likewise, in the low-pressure MOS canal that controls in the middling pressure under 50A, 60V commonly relatively much see.

 

SOT-23: Comfortable use in electric current of a few A, 60V and environment of the following voltage, its are divided again have large volume and minor volume two kinds, main distinction depends on voltaic value differring.

 

DFN: On bulk, relatively SOT-23 is big, but be less than TO-252, mix in low pressure commonly 30A has in canal of MOS of the following middling pressure use, volume of profit from product is minor, basically apply in environment of DC small-power electric current.

 

The 7th pace should choose good brand

 

The manufacturing company that MOS runs is very much, say roughly, basically have Euramerican department, day department, Han department, station department, homebred a few old series.

 

Euramerican department represents a company: IR, ST, celestial being child, Ansenmei, TI, PI, Ying Feiling;

Day department represents a company: Sa of Toshiba, luck, new report yuan wait;

Han department represents a company: Accept of KEC, AUK, beautiful case, Sen Minghao, Weishidu, letter is installed, KIA;

Stage department represents a company: APEC, CET;

Homebred delegate enterprise: Jilin Hua Wei, person Lan Wei, Hua Runhua loves semiconductor brilliant, Dong Guangwei, greatly to wait.

 

In these brands, with the line of the products of Euramerican department business the most complete, technology reachs function best, from function effect consideration, it is the first selection that is in charge of for MOS; The day department business that is a delegate with lucky Sa, Toshiba also is the high-end brand that MOS manages, have very strong competition dominant position likewise; These brands also are be risked by copy on market most. Additional, because taste the card value, reason such as technical advantage, euramerican department and the product value that day is brand enterprise also often taller.

 

The MOS pipe business of Korea and Chinese Taiwan also is the main product supplier of the industry, go up in the technology nevertheless, wanting beauty of a bit weak Yu Ou and day is an enterprise, but in price respect, more Euramerican business of the department that reach day has an advantage more; Sexual price is compared relatively a lot of taller.

 

And in chinese mainland, a batch of likewise active indigenous industries, the cost advantage with their lower have the aid of and faster client service answer speed, in in low end and fractionize domain have very strong competition ability, the part came true homebred replace; Also be in at present product line of ceaseless concussion high end, in order to satisfy the requirement of native land client. Additional, indigenous industry still is run through capital, bought the company of power parts of an apparatus with the well-known international such as the semiconductor that bring a life successfully, will satisfy mainland to be opposite better the demand of power parts of an apparatus.

 

Brief summary

 

Small to anthology N or P, enclose a type, arrive greatly the compression of MOSFET, guide electrify block, diverse applied demand is Protean, when the engineer is choosing MOS to be in charge of, must be in charge of yard place to choose appropriate MOS to be in charge of according to circuit design requirement and MOS, gain experience of first-rate products plan thereby. Of course, considering performance while, cost also is one of elements of the choice, have the product that tall sex price compares only, the product that just can let an engineer design achieves a balance in character and accrual.