Instruction/ maintenance manual of the product AN-7502 Fairchild
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©2002 Fairch ild Semicond uctor Corpo ration Application No te 7502 Rev. A1 AN-7502 Power MOSFET Swit ching Wavefo rms: A New Insight The examination of power MOSFET voltage an d current wa vef or ms du ring switching t ransition s rev eal s that t he device characte rizati on now practiced by ind ustry is i nade- quate .
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 FIGURE 4. IDEALIZED POWER MOSFET WAVEFORMS FIGURE 5. STEP-VOLTAGE FORCING FUNCTION P ower MOSFET devices are hi ghly ca paci ti ve in nature; hence , simp le ca pacitor re sponses to the f orcing funct ions off er a g ood v ehicle for comparison.
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 Stat e 2: MOS A ctIv e, JFET ActIv e This st ate gr aphic ally illust rates the dram atic inf luence that the JFET has on the po wer MOSF ET drain -vol tage wa ve- f orm.
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 FIGURE 9. NORMALIZED RFM15N15 SWITCHING WAVE- FORMS FOR CANSTANT GATE-CURRENT DRIVE. Step-V oltag e Ga te Drive The majori ty of power MO SFET applica tions emplo y a step gate- voltag e input wit h a finite source re sistance R O .
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 Experimental V erification Since the s witching equa tions for step current s and voltages diff er only by gat e-current m.
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 F or pea k gate volta ges othe r than 10 v olts , and l oad resi s- tances other tha n BV DSS /I D(MAX) , the equati ons o.
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 Tu r n - O n State 1: M OS Off, JFE T Off I PK1 = V G /R O State 2: MO S Active, JFET Ac tive I PK2 = (V G - V GS(TH) )/R .
©2002 Fairch ild Semicond uctor C orpo ration Application N ote 7502 Rev. A1 Case 3 :Common-So urce Gate Drive, Figure B-3 FIGURE B-3. COMMON-SOURCE GATE-DRIVE CIRCUIT Tu r n - O n R O = R D (drain -to-gro und capacitan ce of driving de vice adds to C GS of driven MOSFET .
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY , FUNCTION OR DESIGN.
An important point after buying a device Fairchild AN-7502 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought Fairchild AN-7502 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Fairchild AN-7502 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Fairchild AN-7502 you will learn all the available features of the product, as well as information on its operation. The information that you get Fairchild AN-7502 will certainly help you make a decision on the purchase.
If you already are a holder of Fairchild AN-7502, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Fairchild AN-7502.
However, one of the most important roles played by the user manual is to help in solving problems with Fairchild AN-7502. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device Fairchild AN-7502 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
