Electronic Components Datasheet Search |
|
AN1889 Datasheet(PDF) 6 Page - STMicroelectronics |
|
AN1889 Datasheet(HTML) 6 Page - STMicroelectronics |
6 / 33 page ESBT: theory and evolution AN1889 6/33 As shown in Figure 3, a DMOS structure is diffused on a higher resistivity layer overlaying the highly doped emitter region (NBL in the cross section). In terms of diffused and deposited layers the DMOS structure is quite similar to that of a standard low voltage power MOSFET even if, of course, its layout is arranged to match the emitter geometry of the BJT stage. Finally the base contact are placed on a diffused layer deep enough to reach the base buried layer (PBL). As previously mentioned to switch-on the ESBT it is necessary to positively bias the gate with a voltage higher than its threshold (typically 3.5 V for the device in subject), this will generate, like in all voltage driven transistors, the inversion of the portion of the body region under the gate oxide of the vertical n-channel MOSFET, so that the emitter results connected to the ground. In the mean time the base driver supplies the current needed to saturate the BJT stage leading the ESBT to a high on-state current density due to the high injection of electrons from the N+ emitter region, similarly to the case of pure power bipolar transistors. The On-voltage drop is represented by the Collector-Source saturation voltage, say the VCS(sat), and it is consequently given by the contribution of the VCE(sat) of the bipolar stage plus the small voltage drop of the low voltage MOSFET. Being the bipolar behavior predominant, the voltage drop results not very sensitive to the temperature variations. With zero bias in the gate and with grounded base the device behaves like a reverse biased diode during the off state. The switching-off behavior had already been deeply analyzed at the beginning of this chapter. It is important to add that the sandwich structure gives an uniformity of the current density across the whole area of the device. In fact the MOSFET placed over the BJT (in series with its emitter) acts as a sort of "ideal ballast emitter resistor" for all of the elementary cells that form the whole transistor. This gives to the device not only excellent power dissipation but also the suitability to be paralleled with similar devices. |
Similar Part No. - AN1889 |
|
Similar Description - AN1889 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |