Truck Compatibility of MiniProfets™

Truck Compatibility of MiniProfets
Application Note
by Juergen Metzner
Application Note
Rev. 1.0, 2011-03-30
Automotive Power
Truck Compatibility of MiniProfets
Application Note
Abstract
1
Abstract
Note: The following information is given as a hint for the implementation of the device only and shall not be
regarded as a description or warranty of a certain functionality, condition or quality of the device.
Main objective of this application note is to benchmark existing MiniProfets in terms of “Truck Compatible”
characteristics.
All MiniProfets which are highlighted in this application note as “Truck Compatible” devices can also be regarded
suitable for “28V Powernet” applications.
2
Introduction
All terms of voltage levels within this application note are refering to voltage levels which are specified in the
respected MiniProfet Datasheets.
All MiniProfet Datasheets including their parameters and values have been evaluated in terms of “Truck
Compatibility”.
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Truck Compatibility of MiniProfets
Application Note
Criterias for Truck Compatibility
3
Criterias for Truck Compatibility
All below listed criterias or parameter have been applied to MiniProfets in order to classify them as “Truck
Compatible” High-Side Switches.
The parameters with its voltage levels which are stated in Table 1, column three (“Requirement For Truck
Application”) can be seen as an “umbrella” specification thus they can be regarded as a proposal list from Infineon.
•
Supply Voltage or Battery Voltage
•
Functional Operating Voltage
•
Supply Voltage or Battery Voltage for Short Circuit Protection
•
Supply Voltage or Battery Voltage for Protection Functions
•
Load Dump Protection, Overvoltage Protection
•
Reverse Battery Protection
•
EAS (Single Switch Off Energy)
Table 1
Parameter and required values for Truck Compatibility
Parameter
Datasheet symbol(s)
Requirement for truck application,
value/range, unit
Nominal Supply Voltage
Vs, Vbb
Vs = 28V
Functional Operating Voltage
Vs, Vbb
12V < Vs< 36V
Supply Voltage for Full Short Circuit
Protection
Vbb(SC), Vs(SC)
12V < Vs < 36V
Supply Voltage for Protection Functions
Vs, Vbb
12V < Vs < 36V
Load Dump Protection
Vs, Vbb
VS(LD) , Vbb(LD) = 58V
Overvoltage Protection
Vs, Vbb, VS(AZ), VBB(AZ)
VS(AZ) , Vbb(AZ) = 58V
Reverse Battery Protection
Vs, Vbb
-28V < Vs < 0V
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Truck Compatibility of MiniProfets
Application Note
EAS - Single Switch Off Energy
4
EAS - Single Switch Off Energy
During demagnetization of inductive loads, the energy which is stored in the inductive load has to be dissipated in
the MINIPROFETs power stage(s).
Since there is no freewheeling diode available in any MiniProfet all stored energy in inductive loads has to be
dissipated by the chip itself.
In general all MiniProfets are containing a clamping structure which are limiting the drain source voltage level of
the Power MOSFET to a certain clamping voltage level (VDS=VDS(CL)).
Figure 1 is showing a simplified internal circuit as an example for protecting the Power MOSFET of a MiniProFET
VS
ZDS(AZ)
IN
VDS
LOGIC
ZS(AZ)
VS
OUT I L
VIN
GND
L
VOUT
RGND
RL
Output _clamp_miniProfet.vsd
Figure 1
Schematic of MiniProfet protection circuit
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Truck Compatibility of MiniProfets
Application Note
EAS - Single Switch Off Energy
4.1
EAS Formula
With assuming VDS(CL) being constant over time, the resulting energy during switching off inductive loads can be
calculated with following equation:
(1)
V DS ( CL ) ⋅ L V S – V DS ( CL )
RL × IL 
EAS = ---------------------------- ⋅  --------------------------------- ⋅ ln  1 + -------------------------------- + I L
RL
RL
V DS ( CL ) – V S
Note: Equation (1) simplifies under the assumption of RL = 0 Ω to:
(2)
V DS ( DCL )
2
1
EAS = --- × L × I L × ------------------------------2
V DS ( CL ) – V S
Whereas Equation (2) is not of further interest here because the load which is switched in typical applications has
higher impedance. In general, the energy which is converted into heat, is limited by the thermal design of a
MiniProfet device.
In all datasheets there is an specified EAS value (chapter Maximum Ratings) which can be used for calculation of
the maximum allowed load or current by using Equation (1).
Furthermore the correlation of the maximum allowed energy versus nominal load current (EAS = f (IL)) is shown
as a curve in many MiniProfet datasheets.
4.2
Parasitic Inductive Loads
As shown in Chapter 4 an important issue in truck applications is the impact of load inductances. Although the
parasitics inductance of wires to a load is increasing by using long supply lines to the load, this additional
inductance in most cases is not of relevance here because the resulting low inductances (please refer to Table 2
which sums up some wire cross sections and the resulting impedance / inductances for a cablewire over a ground
plane with 5mm distance to the ground plane or chassis). Please also note that the typical cable length to a load
in a truck is not exceeding 40m.
Table 2
Wire characteristics
Gauge
(AWG)
Cross section
(mm²)1)
Impedance
(Ω/km)1)
Inductance
(H/m)1)
16
1.31
13.6
6.9 x 10e-7
18
0.82
21.63
7.3 x 10e-7
20
0.52
34.39
7.7 x 10e-7
22
0.33
54.66
8.3 x 10e-7
1) Approximation only
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Truck Compatibility of MiniProfets
Application Note
Truck compatible MiniProfets
5
Truck compatible MiniProfets
The following table is showing all full and partly suitable MiniProfets in terms of truck compatibility.
Table 3
Truck compatible MiniProfets
627
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'3$.
2WKHUV
%761
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Truck Compatibility of MiniProfets
Application Note
MiniProfets In Truck Applications
6
MiniProfets In Truck Applications
Table 4 shows the main parameters and its values of the devices which are partly suitable for truck applications
(yellow marked in Table 3)
Table 4
Critical values or ranges of device parameter versus required device parameter in terms of
Truck Compatibility
Device
Parameter
Critical device
parameter, value,
range
IFX Proposal for truck
applications,
value/range, unit
BSP452
Functional Operating
Voltage1)
Vs, Vbb;
5V < Vbb < 34V
VS = 28V
BTS4141N,
BTS4142N
Supply Voltage for protection Vbb(SC), Vs(SC);
5V < Vbb < 30 V
functions2)
3)
15V < Vbb < 30V
All protection features
BTS4880R
1) Protection features of BSP452 which are out of range in terms of Truck Compatibility:
- Initial Peak Short Circuit Current Limitation (parameter is only specified at Vbb = 20V)
- Overvoltage Shutdown, Vbb(over) = 34V(min)
(Reverse Battery Protection is only valid with external resistor, RGND = 150Ohm for -30V <
12V < Unom < 28V
12V < Unom < 36V
Vbb< 0V)
2) Protection features BTS4141N and BTS4142N which are out of range in terms of Truck Compatibility:
- Initial Peak Short Circuit Current Limitation (parameter is only specified at Vbb = 30V)
- Repetetive Short Circuit Current Limitation (parameter is only specified for 15V < Vbb< 30V)
(Reverse Battery Protection is only valid with external resistor, RGND = 150Ohm valid for -45V < Vbb< 0V)
3) Protection features in BTS4880 which are out of range in terms of Truck Compatibility:
- Initial Peak Short Circuit Current Limitation (parameter is only specified at Vbb = 30V)
- Repetetive Short Circuit Current Limitation (parameter is only specified for 15V < Vbb< 30V)
(Reverse Battery Protection is only valid with external resistor, RGND = 150Ohm for -45V < Vbb< 0V)
Application Note
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Truck Compatibility of MiniProfets
Application Note
Conclusion
7
Conclusion
The main intention of this Application Note is benchmarking existing MiniProfets in terms of Truck Compatibility.
Together with an “umbrella” specification of Infineon, all existing MiniProfets have been evaluated in terms of Truck
Compatibility.
This application note includes a recommendation list (Table 3) of all MiniProfets which are suitable for truck
applications.
8
Additional Information
Reference list
•
•
9
MiniProfet Data sheets
For further information you may contact http://www.infineon.com/
Revision History
MINIPROFET
Revision History: Rev. 1.0, 2011-03-30
Application Note
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Rev. 1.0, 2011-03-30
Truck Compatibility of MiniProfets
Application Note
Revision History
Application Note
9
Rev. 1.0, 2011-03-30
Edition 2011-03-30
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2011 Infineon Technologies AG
All Rights Reserved.
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