Page 108 - Rashid, Power Electronics Handbook

94 I. Batarseh

I BS and from the bulk to the drain I BD are simply diode It was decided that the device should have a blocking
currents and are given by voltage (V DSS ) of 600 V and drain current i of 3.6 A. The
d
V BS device selected is IRF CC30 with case TO220. This device is
I ¼ I e ÿ V T ÿ 1 ð6:44Þ
BS SS listed in the PSpice library under model number IRFBC30 as
V BD follows:
ÿ
I BD ¼ I DS e V T ÿ 1 ð6:45Þ
*Library of Power MOSFET Models *Copyright
Where I SS and I DS are the substrate source and substrate drain OrCAD, Inc. 1998 All Rights Reserved. *
saturation currents. These currents are considered equal and *$Revision: 1.24 $ *$Author: Rperez $
given as I in the MODEL statement with a default value of *$Date: 19 October 1998 10:22:26 $ * .
S
10 ÿ14 A. Where the equation symbols and their corresponding Model IRFBC30 NMOS NMOS
PSpice parameter names are shown in Table 6.1.
The PSpice code for the MOS device labeled S1 used in Fig.
In PSpice, a MOSFET device is described by two statements,
6.27 is given by
with ®rst statement starting with the letter M and the second
statement starting with .Model, which de®nes the model used MS13500 IRFBC30 .MODEL IRFBC30
in the ®rst statement. The following syntax is used: .Model IRFBC30 NMOS(Level=3 Gamma=0
Delta=0 Eta=0 Theta=0 Kappa=0.2
M<device_name> <Drain_node_number>
Vmax=0 Xj=0 + Tox=100n Uo=600 Phi=.6
Gate_node_number>
Rs=5.002m Kp=20.43u W=.35 L=2u
<Source_node_number> <Substrate_node
Vto=3.625 + Rd=1.851 Rds=2.667MEG
number> <Model_name> *
Cbd=790.1p Pb=.8 Mj=.5 Fc=.5
[<param_1>=<value_1>
Cgso=1.64n + Cgdo=123.9p Rg=1.052
<param_2>=<value_>....] .MODEL
Is=720.2p N=1 Tt=685) * Int'l Recti®er
<Model_name> <type_name>
pid=IRFCC30 case=TO220
[ (<param_1>=<value_1>
<param_2>=<value_2> .....]
6.7.2 Large Signal Model
Where the starting letter "M" in M<devic_name> state-
ment indicates that the device is a MOSFET and <device_ The equivalent circuit of Fig. 6.28 includes ®ve device parasitic
name> is a user speci®ed label for the given device, the capacitances. The capacitors C , C , and C GD , represent the
GB
GS
<Model_name> is one of the hundreds of device models charge-storage effect between the gate terminal and the bulk,
speci®ed in the PSpice library; and <model_name> or the source and drain terminals, respectively. These are nonlinear
same name speci®ed in the device name statement <type_ two-terminal capacitors expressed as functions of W, L Cox,
name>, is either NMOS of PMOS, depending on whether the V , V , V , and C GB0 , C GSO , C GDO . Capacitors C GB0 , C GS0 ,
T0
GS
DS
device is n-or p-channel MOS, respectively. An optional list of and C GD0 outside the channel region, are known as overlap
parameter types and their values follows. Length L and width capacitances that exist between the gate electrode and the
W and other parameters can be speci®ed in the M<device_ other three terminals, respectively. Table 6.2 shows the list of
name>, in the .MODEL or .OPTION statements. A user may MOSFET capacitance parameters and their default values.
select not to include any value, and PSpice will use the speci®ed Notice that the PSpice overlap capacitor keywords (C GB0 ,
default values in the model. For normal operation (physical C GSO , C GDO ) are proportional either to the MOSFET width
construction of the MOS devices), the source and bulk substrate or length of the channel as follows:
nodes must be connected together. In all the PSpice library ®les,
C ¼ C =L
defaultparametervaluesforL,W,AS,AD,PS,PD,NRD,andNDS GBO GBO
areincluded,andauserthenshouldnotspecifysuchvaluesinthe C GSO ¼ C GSO =W ð6:46Þ
device ‘‘M''statement or in the OPTION statement.
C ¼ C =W
The power MOSFET device PSpice models include relatively GDO GDO
complete static and dynamic device characteristics given in the
In the triode region, where v GS > v DS ÿ V , the terminal
Th
manufacturing data sheet. In general, the following effects are
capacitors are given by,
speci®ed in a given PSpice model: dc transfer curves, on-
2
resistance, switching delays, gate dive characteristics, and v GS ÿ v DS ÿ V Th
C ¼ L C 1 ÿ þ C :
reverse-mode ‘‘body-diode'' operation. The device character- GS W oX 2ðv GS ÿ V Þÿ V DS GS0
Th
istics that are not included in the model are noise, latch-ups,
2
v ÿ V
maximum voltage, and power ratings. Please see OrCAD C GD ¼ L C oX 1 ÿ GS Th þ C GDO :
W
Library Files. 2ðv GS ÿ V ðÿv DS
Th
C GB ¼ C GB0 L
EXAMPLE 6.3. Let us consider an example that uses IRF
MOSFET and connected as shown in Fig. 6.27. ð6:47Þ