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”. Application Note 2 Rev. 1.0, 2011-03-30 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 Application Note 3 Rev. 1.0, 2011-03-30 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 Application Note 4 Rev. 1.0, 2011-03-30 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 Application Note 5 Rev. 1.0, 2011-03-30 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 '62 '3$. 2WKHUV %761 Application Note 6 Rev. 1.0, 2011-03-30 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 7 Rev. 1.0, 2011-03-30 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 8 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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