Analog Power Proprietary Fast, Accurate Spice Model

Analog Power Inc.
SPICE MODELING Revised August 2015
Analog Power Spice Model Goals
To provide simple, fast, accurate SPICE model to be used predominantly for
switching speed and loss calculations
To be able to support model and its use
To allow temperature modeling, but not at the expense of speed and simplicity
To focus on the useful modeling parameters, and do not include breakdown
voltage etc as stresses can be checked via model probing
To support on low cost universal platforms, WinSpice, NGSPICE, LT Spice
To be able to use SPICE to select the optimum part for PWM applications
Not Intended for (significant added complexity/run time):
Modeling of breakdown voltage, high temperature leakage
Thermal modeling including RDS variation with temperature
– Model can be adjusted for temperature
Qrr modeling
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Analog Power SPICE Subcircuit
Analog Power model R1.0:
Simple Level 1 model with 8
external components
Excellent fitting to data sheet
All parameters are devicederived not process derived
Very simple to see effects of
each parameter
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Analog Power SPICE Subcircuit 2.0
Improved implementation:
Non-Linear dependent voltage
sources used to set dv/dt over
diode and fixed capacitor =
zero appropriately , and
therefore isolate them when
not in circuit.
No switches used, but
identical concept
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Analog Power Spice Example (switch, L1)
.SUBCKT AM90N08-04B 1 2 3
*Nom Temp=25 deg C
Mos1 4 5 6 6 APLMOS w=1 l=1
.MODEL APLMOS NMOS (Level=1 VTO=1.94 KP=116 CGDO = 600p CGSO = 9100p)
Rdrain 1 4 4.7e-3
Dbody 6 1 BodyDiode
.MODEL BodyDiode D (RS=2e-3 IS=2e-12 vj=0.6 RS=2m CJO=1000p M=0.67)
Lsource 3 6 3e-9
Rgate 2 5 1.8
Dcgd 5 7 Crss
.MODEL Crss D (RS=1e-3 CJO=10.9n M=1.18)
Sdiode 7 1 1 5 Sfb1
Scap 8 1 5 1 Sfb2
.MODEL Sfb1 VSWITCH (RON=100m ROFF=10e11 VON=0 VOFF=-0.01)
.MODEL Sfb2 VSWITCH (RON=100m ROFF=10e11 VON=0.01 VOFF=0)
C2 8 5 10.9n IC=0
R2 8 5 1e8
NOTE some Spice versions (E.G. NGSPICE) use different syntax for the switches:
Sdiode 7 1 1 5 Sfb1 ON
Scap 8 1 5 1 Sfb2 Off
.MODEL Sfb1 SW (RON=0.1 ROFF=10e11 VT=0 VH=-0.01)
.MODEL Sfb2 SW (RON=0.1 ROFF=10e11 VT=0.01 VH=0)
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Analog Power Spice Example (no switch, L3)
* Analog Power Spice Level 3 Model - fixed temperature
* Rev 4/14/2014 PD
* Level 3 model is experimental, sub-threshold leakage is overestimated, which will affect VSD diode
.SUBCKT AM3446N 1 2 3
*Nom Temp=25 deg C
Mos1 4 5 6 6 APLMOS l=0.25u w=1
.MODEL APLMOS NMOS (LEVEL = 3 vto=0.91 KP =10u NSUB=2e+17 Kappa = 0.12 CGDO = 55p
CGSO = 336p)
Rdrain 1 4 28m
Dbody 6 1 BodyD
.MODEL BodyD D (IS=0.5e-12 RS=30e-3 CJO=10p M=0.2)
Lsource 3 6 0.3e-9
Rgate 2 5 3
Dcgd 5 7 Crss
.MODEL Crss D (RS=1e-3 CJO=400p M=0.91)
B1 7 1 V= (abs(v(5)-V(1))+(v(5)-V(1)))/2
C2 8 5 400p IC=0
R2 8 5 1e9
B2 1 8 V= (abs(v(1)-V(5))+(v(1)-V(5)))/2
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Level 1 and Level 3 Models
• Many vendors add many external components and use more
complicated BSIM models, but do they work any better?
• Parameter-derived level 1 model is recognized as suitable for
discrete devices for modeling switching time etc
– more complicated models are intended for use in IC modeling
and are process-derived
• However level 1 model does not model RDS variation with VGS well
for modern devices and switching characteristics may suffer
– Use Analog Power Level 3 model instead
• Analog Power models are device derived, as opposed to process
and theory derived and therefore more accurate
• Rather than include temperature dependencies, our simple model
can be accurately tweaked for any temperate and this provides a
faster iteration to modeling at higher temperatures
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Transfer Characteristics
Level 1 model uses simple equation:
ID α (VGS – VGS(TH))2
This model holds true for state of the art
Trench MOSFETs, especially surface mount
where current density is quite low
KP (Spice model parameter) easy to derive
from characterization data. L1 model gives
accurate transfer function, but inaccurate
Level 3 model allows KP to reflect accurate
RDS VDS VGS yet still provides accurate
Transfer characteristics
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CRSS – The key to accuracy
Three components:
CGDO – part of level 1 model
does not vary with VDS
Reverse biased diode
gives variation with VDS
removed when VGD>0
Fixed CDG2 capacitor
switched in when VGD>0
1.2 X value of diode at VDG = 0 to reflect
higher CRSS for +ve VGD
The combination of a diode with fixed
parallel capacitance gives fit with data
Alternate implementation with voltage
sources works in identical manner, but
use of switches is avoided – simplifies
syntax, and avoids SPICE transients
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Comparison Data Sheet Vs. Model
Capacitance (pF)
Data sheet
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Analog Power proposed SPICE subcircuit:
• Simple and therefore fast, no switches, no extra active components
• Device derived. Accurate in operation (switching, RDS)
• L3: Developed predominantly for optimum part selection in PWM
– L1 most accurate for linear regulator type aplications
• Device-derived and therefore contains accurate parameters
• Easily adjusted to any operating temperature
• Allows what-if experiments, parameters are easily identifiable and editable
• L3 model includes accurate transfer AND RDS Vs VGS modeling
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