Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 1/16 AI AP SB
12. Mar. 2001
Automotive Power Semiconductors
Application Note
Behavioural Models for SABER Simulations
(MAST)
PROFETs BTS 640 S2, BTS740 S2, BTS840 S2
by Dieter Metzner
Support: simulate@infineon.com
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 2/16 AI AP SB
12. Mar. 2001
A.Introduction
A behavioural model of Sense PROFET devices (highside switch) was implemented into the
simulation package SABER. The level of abstraction is suited to support the design of elec-
tronic systems.
Dynamic and static characteristics are implemented as well as selfheating effects, protec-
tion and feedback features.
With the aid of these models, expensive breadboard experiments can be reduced and criti-
cal operation modes can be identified.
B. Overview Types & Characteristics
The three types BTS740S2, BTS740S2, BTS840S2 are similar products (one or two chan-
nel highside switches) based on the same silicon design, with different packaging options.
Table 1 summarizes the most important data:
Type Rdson / Iload Vbbmax Package Rth
BTS 640S2 1x30mOhm
12.6A 34V TO 220 / TO 263 1.47 K/W
BTS 740S2 2x30mOhm
2x5.5A = 8.5A * 34V PDSO-20-9 12K/W each ch.
BTS 840S2 2x30mOhm
2x12A = 24A 34V Power SO 20 1K/W each ch.
Depending on the number of chips on one leadframe and the package type different (ISO-)
Current Ratings can be achieved
C. Modular Modelling concept, Interface declarations
The connection points are exclusively of physical nature, i.e electrical and thermal pins were
used to describe the interactions with the external system.
Interface declaration (example BTS640.sin):
-------------------------------------------------------------------------------------------------------------------------
template bts640 vbbx gnd in outx status is Tsens tj tcase = messages, distribu-
tion
electrical vbbx battery
electrical gnd ground
electrical in input
electrical outx power output
electrical status status pin
electrical is : current sense pin
thermal_c Tsens sensor temperature – do not connect!!! (only postproc.)
thermal_c tj DMOS temp. – do not connect! (to disenable selfheating)
thermal_c tcase case (leadframe) temperature – always connect !
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 3/16 AI AP SB
12. Mar. 2001
General remarks:
- In case of the two channel devices BTS 740, BTS840 electrical and thermal pins have
the suffix „1“ or „2“; Exception: only one tcase – pin for BTS740 (see also section „ther-
mal model“).
- Electrical Pins should never be left disconnected in order to avoid numerical instabilities
- The same applies to the thermal pin tcase, which is the only thermal interface from the
junction to the heatsink.
- For investigations at a constant chip temperature connect the pin tj directly to a tem-
perature source (eg. to investigate DC behaviour without influence of cooling)
- Don´t connect current sources directly to electrical pins, like in Rdson-„measurements“.
IN
ST
ESD
Logic
Voltage
sensor
Voltage
source
Charge pump
Level shifter
Temperature
sensor
Rectifier
Limit for
unclamped
ind. loads
Gate
protection
Current
limit
3
1
Signal GND
GND
2
V
Logic
Overvoltage
protection
+
bb
PROFET
OUT
4
6, 7
Load GND
Load
GND
R
O
Current
Sense
Output
Voltage
detection
R
IS
IS
5
I
IS
I
L
Figure 1 shows the functional concept of one channel which is adopted in the behavioural
model as well: The top level model of each channel accordingly consists of a netlist of basic
structural elements:
---------------------------------------------------------------------------------------------------------------------------------------------
logic_840.1 inp t usq ov lout ocd en ma st #logic processing block
ov_protec_l270.1 vbb gnd ov Tsens =mes=messages #overvoltage detection
undervoltage_l270.1 vbb gnd usq tcase #undervoltage detection
smt_840.1 inx gnd inp tcase=mes=messages #Schmitt Trigger input includ-
ing #ESD protection
cs.i in inx #current sensor for
#postprocesing purposes
openload_off.1 out gnd lout tcase #openload - detection
open_col.1 st status gnd tcase #open collector status output
tempdec.1 vbb gnd t Tsens=mes=messages #overtemperature detection
ssmart_dmos.1 vbb gate source tj =ns=50900 #output Power DMOS Model
current_sense_840.1 source out vbb out is gnd ma tj #current sense circuit
cs.out out outx #output current sense for
#postprocessing
chp_840.1 outrec out vbb gnd en tcase #charge pump&rectifier circuit
gdisch_840.1 outrec out vbb gate en ocd tcase #gate charge&discharge circuit
t640_tsense.1 tj Tsens tcase #thermal network:
#junction – sensor – case
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 4/16 AI AP SB
12. Mar. 2001
D. Model Parameters:
In general, the setup of parameters is done according to typical data sheet values. In some
cases, where only maximum (conservative) values are given in the data sheet, the model
represents a realistic, typical value (e.g. the thermal model, see below).
However some selected parameters which are essential for certain investigations can be
adapted by the user within the actual statistical range. These are summarized in the MAST
– structure distribution.
----------------------------------------------------------------------------------
--
struc{ enum {min,typ,max} cur_sense = typ
number rdson =27m, # min:27mOhm max: 30mOhm,
slew_rate_on =1.0, # max:2.0 (1V/us), typ:1.0, min:0.5(0.1V/us)
slew_rate_off =1.0, # max:1.3 (1V/us), typ:1.0, min:0.1(0.1V/us)
cur_lim =4.6, # max:5.0 (58A@RT),typ:4.6 (50A@RT),min:4.2 (40A@RT)
i_gnd =1.2m # max:3.0m (3.0mA), min,typ:1.2m (1.2mA)
} distribution =()
Meaning of parameters in „distribution“:
cur_sense: The nonlinear characteristics of the current sense ratio (=f(Iload, Tj))given in the
datasheet is implemented by linear interpolation of current and temperature.
Only distinct values enum {min,typ,max} are allowed.
rdson: The onstate resistance @ 5A, 25°C, allowed values 27mOhm...30mOhm.
slew_rate_on: affects the resistance of gate charge path; allowed range:
0.5....2.0 ->covers the data sheet range of 0.1V/us....1V/us
slew_rate_off: affects the resistance of gate discharge path; allowed range:
0.1....1.3 ->covers the data sheet range of 0.1V/us....1V/us
cur_lim: affects the current limitation value by specifiing the corresponding gate voltage
allowed range: 4.2...5.0
! remark: Only for fine tuning of the short circuit behaviour to a particular device !
! Data sheet range is covered by temperature variations from –40°C....150°C !
i_gnd: operating current at ground pin
allowed range: 1.2m...3.0m covers the data sheet range of 0.6mA....1.5mA (per
channel)
Model parameter messages:
Can be switched either to „on“ or „off“. Summary of messages see section below.
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 5/16 AI AP SB
12. Mar. 2001
E. Model Features & validity limits
Dmos (Power Output MOS Transistor):
A physics-based model of a vertical DMOS in the actually used technology „Ssmart“ (self-
isolating). On state characteristics are modeled by partitioning the conducting region into
distinct areas, the temperature dependence of the mobility is included i.e. the static char-
acteristics are modeled temperature dependent (-40°C to 150°C). This is essential for the
simultation of self-heating effects.
Temperature levels from 150°C to 300°C can be simulated (like for short circuit), however
only for rough investigations of the peak junction temperature.
Dynamic characteristics (switching behaviour) are accounted for by physical formulations of
all relevant capacitances (nonlinear, but independent of temperature).
The temperature dependence of the dynamic characteristics is dominated by the gate
charge and discharge path, which is also modeled.
The inverse diode is included by a static model (no reverse recovery) with temperature de-
pendent characteristics.
Thermal Equivalent Network
In Figure 2a the thermal equivalent network of the BTS740 is shown.
Fig.2a thermal model BTS740 Fig.2b Comparison 3D Simulation <-> lumped model
In order to generate a compact thermal network, at first a transient finite element simulation
(fig 2b) was performed which yields the thermal step response at the heat generating junc-
tion (self heating, orange line) and at the neighbouring chip (cross-coupling, magenta).
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 6/16 AI AP SB
12. Mar. 2001
Next, a comprehensive lumped structure of the main heat paths was defined in analogy to
electrical RC networks (Fig. 2a), taking into account vertical and lateral components, but
leaving the parameter values of each element undefined.
With symbolic algebra software a closed form solution for the step responses can be cal-
culated with arbitrary network parameters. At last, an optimizer with adequate constraints
was used to find a reasonable combination of these parameters (Ri and Ci) which has the
most similar transient response.
The excellent result of this optimization is shown in Fig 2b (green and blue curves).
When looking at the actual parameter values, one can roughly identify the actual physical
layers like silcon, solder, copper and mold.
For a detailed description please refer to [noe]
Thermal Protection:
Not shown in picture 2a are the additional components necessary for the temperature sen-
sor of each channel, integrated into the active DMOS area. Those are needed to account
for the dynamic characteristics of the sensor with a time constant of approximately 200us.
For thermal protection the sensor temperature is monitored and overtemperature turn-off is
initiated.
Retriggering via hysteresis is implemented.
Current Sensing:
Nonlinear characteristics of sense ratiois implemented according to datasheet:
Kilis = f(Temperature, Iload). The offset current is depending on the switching state (15uA on,
1uA off). The step response is modeled by a low pass behaviour.
Input Characteristic:
Leakage current and input resistance depending on temperature and switching state.
Overvoltage Protection & Shutdown
The protection threshold voltage is decreasing with temperature
The shutdown threshold voltage (with hysteresis) is increasing with temperature.
Undervoltage Protection & Shutdown
The protection threshold voltage is modeled with hysteresis decreasing with temperature
Internal Output Pull Down (Open Drain case):
Temperature dependent resistor
Status output characteristics:
Output resistance and leakage current are modeled dependent on temperatur.
ESD protection
A temperature dependent series resistance is used in the discharge path
Short Circuit Protection / Overcurrent protection
Depencies on Operating Voltage and temperature effects are dominated by DMOS Tran-
sistor, gate charge and discharge circuit and dynamic characteristics of temperature sensor.
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 7/16 AI AP SB
12. Mar. 2001
F. Errors, warnings and messages
Warnings associated with overvoltage protection and shutdown
Battery voltage is exeeding max value ~43V:
warning("\n Maximum allowed value for Vbb is out of spec at t=%s in %. Actual value: Vin=%(Volt)
, Maximum values: %(Volt) < Vin > %(Volt). \n ",time,instance(),vbb_gnd,ovt)
Drain source voltage is exceeding max value
warning("\n Over Voltage Protection is activated at t=%s in %. Actual value: Vin=%(Volt)
\n ",time,instance(),vbb_gnd)
Input voltage exceed maximum level
warning("\n Maximum allowed value for Vin is out of spec %s in %. Actual value: Vin=%(Volt),
Maximum values: %(Volt) < Vin > %(Volt).\n ",time,instance(),vpn,limit_esd)
Short circuit protection
warning("\n shortcircuit or over current detected at t=%s in % \n ",time,instance())
Warnings associated with overtemperature
Sensor temperature exceeds trigger level (170°C)
warning("\n Overtemperature Protection activated a T=%s in % actual sensor temperature: %degC
\n ",time,instance(),tc(Tic))
Active DMOS area ist heated above 175°C
warning("\n You are leaving maximum specified temperature range channel2 at t=%s in %
actual junction temperature: %degC \n ",time,instance(),tc(tj2))
warning("\n You are leaving maximum specified temperature range channel1 at t=%s in %
actual junction temperature: %degC \n ",time,instance(),tc(tj1))
Active DMOS area is approaching destruction temperature limit:
message("Warning !!!!: Overtemperature >300degC in % :",instance())
message("Model is leaving intended area of operation")
message("Please check your thermal network and/or operating conditions")
Status output
warning("\n Maximum allowed current at status pin is out of spec at t=%s in %. Ac-
tual value: ist=%(Amp),
Maximum values: 5mAmp \n ",time,instance(),ist)
Current through reverse diode
warning("\n reverse current at t=%s in % a ",time,instance())
Warnings associated with wrong input parameters or simulation domains
error("analysis type is not supported by the model in % ", instance())
error("statistical analysis is not supported by the model in % ", instance())
error("argument setting for slew_rate_on out ouf range: \n valid range: 0.5...2.0 in model % ", instance())
error("argument setting for slew_rate_off out ouf range: \n valid range: 0.1...1.3 in model % ", instance())
error("argument setting for rdson out ouf range:\n valid range: 27m...30m in model % ", instance())
error("argument setting for cur_lim out ouf range:\n valid range: 4.2...5.0 in model % ", instance())
error("argument setting for i_gnd out ouf range:\n valid range: 1.2m...3.0m in model % ", instance())
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 8/16 AI AP SB
12. Mar. 2001
G. Postprocessing Quantities&Signals
Analog variables of interest are collected by the group definition „post_info“ (see declara-
tions section)
##############################################################
#### analog postprocessing variables
##############################################################
#
# possible syntax of signal list: sigl /.../post_info
##############################################################
#
group {it1, it2, power1, power2, tmos1,tmos2,ibb, iin1, iin2, iout1, iout2, isen-
se1, isense2, irev1, irev2, vcp1, vcp2} post_info
values{
ibb=isense(cs.vbbsense) # current into the voltage supply pin
it1=idmos(current_sense_840.1) # dmos current (channel + rev. diode)
it2=idmos(current_sense_840.2)
power1=it1*v(vbb,source1) # total powerdissipation dmos1 + rev.diode1
power2=it2*v(vbb,source2)
tmos1=tc(tj1) # junction temperature dmos1
tmos2=tc(tj2)
iin1=isense(cs.i1) # current into input pin channel 1
iin2=isense(cs.i2)
iout1=isense(cs.out1) # current out of output pin channel 1
iout2=isense(cs.out2)
isense1=iso(current_sense_840.1)# current out of sense output 1
isense2=iso(current_sense_840.1)
irev1=-irev(ssmart_dmos.1) # current through reverse diode 1
irev2=-irev(ssmart_dmos.2) # (polarity: positive in reverse dir.
vcp1=vcp(chp_840.1) # voltage of charge pump (static model)
vcp2=vcp(chp_840.2)
}
#################################################################################
digital postprocessing variables (which could not be grouped)
#################################################################################
# type: state logic_4
# signalname meaning convention
# lout1, lout2 openload status "raw"signals l4_1 = Vds>3V
# ocd1, ocd2 current limitation status l4_1 = active
# t1, t2 overtemperature detection status l4_1 = active
# usq1, usq2 undervoltage detection status !!! !!l4_0 = active !!!!
# ov1, ov2 overvoltage de/Pro-tection status l4_1 = active
#
##################################################################################
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 9/16 AI AP SB
12. Mar. 2001
H. Example Simulation circuits
In order get a quick insight into the functionalities of the models, simulation test circuits have
been attached to the model files:
BTS640_test.sin, BTS740_test.sin, BTS840_test.sin
In Principle they consist of battery, wire inductances, a PROFET (single or double channel),
ohmic, inductive loads, sense and status terminations, a heatsink and pulsed voltage
sources as input signals.
Most relevant cases can be simulated with one netlist by using alter commands.
Some suggestions can be found in the command-scripts
tut_640.scs, tut_740.scs, tut_840.scs,
Example 1: Normal switching cycle on-off @ 5A/12V/ambient temperature
In addition to the measurable signals out1 (load voltage), in1 (input voltage) and iout1 (load
output current) some internal signals are displayed:
Vgs (green, gate source voltage of the output DMOS Transistor), tmos1, tsens1 (tempera-
ture at the DMOS junction and the sensor)
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 10/16 AI AP SB
12. Mar. 2001
Example 2:Shortcircuit1@ 25°C, 12V, 20mOhm: Thermal shut down with auto restart
The device is turned on into an existing short circuit, and turned off by its overtemperature protection
feature. Thermal toggling is initiated due to the hysteresis of the temperature protection. Self heating
of the device can be observed by the decreasing short circuit current. The actual junction temperature
can be considerably higher than the sensor temperature.
Although save turn-off is guaranteed under such conditions, the simulation example reveals the rea-
son for lifetime degradation, if the device is repeatedly switched into the short circuit: The maximum
junction temperature exceeds the specified value and temperature cycles of up to 70K occur at the
junction.
Example3: maximum switchable inductance according data sheet: 24A/2.0mH
active zehner clamping, junction is heated to 300degC
This simulation corresponds to the maximum specified energy dissipation at inductive load turn-off.
The junction temperature approaches the physical limit where the device loses its blocking capability.
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 11/16 AI AP SB
12. Mar. 2001
Example 4:overload channel 1; onstate 24A, rth ca =100K/W
slow self heating, turnoff at tmos1=170degC
A less extreme overload simulation with the assumption of bad cooling conditions
Example 5: paralleling of channel 1 and 2, effective load:1uH 10mOhm shortcircuit
asymmetrical current limitation assumed, thermal toggling
The purpose of this simulation is to demonstrate the independent protection features of each channel
It also gives an example how to adapt the current limitation value to a particular device.
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 12/16 AI AP SB
12. Mar. 2001
Example 6: Battery voltage ramped from 12V to 70V and back
Overvoltage turn-off when shut down voltage is reached, active zehnerclamping when the protection
level is reached, stress at the load is reduced. Self heating to Tjmax=400°C =>Destructive operation
mode !!!
Example 7: Shortcircuit 2 at t=1msec: Drain Current rises to 200A, Tj~200°C
A crtitical stress for any power switch, when the short circuit occurs during the conducting state.
Two cases are shown Vbat=12V and Vbat = 30V. When the overcurrent is detected, it is limited and
thermal toggling begins with a maximum junction temperature of 270°C.
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 13/16 AI AP SB
12. Mar. 2001
Example 8: Turn-on of a 100W – lamp:
When a lamp is turned on, the initial current exceeds the stationary value by a factor of 10.
The current limiting feature of the PROFET is activated and reset when the load voltage is
sufficiently high. A physical lamp model was used in combination with the PROFET model.
I. Validation Results, Range of Validity
In general, the concept of an electronic datasheet was introduced into the simulation model
Although this does not imply that simulation results guarantee device properties, most of
the data sheet values are represented in the model. Validation should therefore related to
typical data sheet values rather than to application measurements of a particular device.
However, especially in the thermal characteristics, conservative values are given in the da-
tasheet which would lead to too pessimistic simulation results. Therefore, electrothermal
characteristics have been modeled with more realistic assumtions and must therefore be
validated seperately.
A good method is to apply short circuit conditions because the load current level and the
toggling frequency is an excellent criteria for electrothermal validation.
Similar considerations apply to the dV/dt characteristics if EMI investigations have to be
performed.
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 14/16 AI AP SB
12. Mar. 2001
Measurement 1A/12V @25°C 20µs/div, 2V/div
Turn-On
Measurement 12A/12V @25°C
20µs/div,2V/div
Turn-On
Simulation 12A+1A /12V @25°C
Turn-On
Measurement 1A/12V @25°C 20µs/div, 2V/div
Turn-Off
Measurement 12A/12V @25°C
20µs/div,2V/div
Turn-Off
Simulation 12A+1A /12V @25°C
Turn-Off
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 15/16 AI AP SB
12. Mar. 2001
Turn_On into short circuit @25°C,
Vbat=24V (20mOhm)
Measurement: 10A/div, 2msec/div
Turn_On into short circuit @25°C,
Vbat=24V (20mOhm)
Measurement: 10A/div, 2msec/div
Simulation
Simulation
Application Note PROFET
Behavioural SABER - Models
BTS 640 S2, BTS 740 S2, BTS 840 S2
Page 1/16 AP APE PT
02. Feb. 2001
K. Installation hints, Simulator settings.
The selfextracting ZIP file „bts840.exe“ contains the following files:
- This application note: bts840_readme.pdf
- The include-file „components_l270.sin“:(encrypted) functional components of integrated fuc-
tions
- The include-file „dmos_comp_l270.sin“:(encrypted) functional components of DMOS Tran-
sistor
- The include-file „sthermal.sin“: (not encrypted) mainly thermal components
- The model files (templates) „bts640.sin“, „bts740.sin“and „bts840.sin“ which use the previ-
ously mentioned components
- Three test circuits „bts640_test.sin“, „bts740_test.sin“and „bts840_test.sin“
- Three saber command scripts „tut_640.scs“, „tut_740.scs“, and „tut_840.scs“.
For installation, copy all files into the simulation directory or into the saber data path
The recommended simulator settings are different from default only for transient analysis:
Saber> tr (tn 10...... „target newton iterations“
This is necessary because of the highly nonlinear nature of the model. Ignoring this advice will
lead extremely small timesteps, long simulation time and convergence problems.
For technical support please contact: simulate@infineon.com
References:
[noe]:
Noebauer, G., “Creating Compact Models Using Standard Spreadsheet Software“, Proc.
of 17th IEEE Semiconductor Thermal Measurement & Management Symp., 2001
