Application Note MLX81100 Power Dissipation Table of contents 1 Introduction...................................................................................................................... 2 2 Schematics of example Applications............................................................................. 2 3 Calculation ....................................................................................................................... 4 4 Disclaimer......................................................................................................................... 9 MLX81100 application note Author: FJE Page 1 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation 1 Introduction This document is intended to give a description of how to calculate the power dissipation of the chip if an external regulator transistor is connected to pin VDD5V or if the internal regulator transistor is used. 2 Schematics of example Applications All following schematics are sample schematics, which need to be adjusted depending on the application. VBAT VS VDRV RTG CLKO VDD5V HSBC2 HS2 V1V8 BRMID2 VBAT PS VCC HSBC1 IO4 HS1 IO5 BRMID1 VCC Hall sensor M VCC Temperature sensor SW0 SW1 SW3 SW4 SW5 SW6 SW7 LS1 LS2 SW2 GND SPI Interface MLX 90316 LIN IO0 IO1 IO2 IO3 LIN GND GND Fig. 1 Shunt VBAT Reverse Polarity Protection SHNT_L CWD TI0 TI1 TO GND GND Sample application circuitry for DC-motor control using internal VDD5V voltage regulator MLX81100 application note Author: FJE Page 2 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation VBAT VS VDRV RTG CLKO VDD5V HSBC2 HS2 V1V8 BRMID2 VBAT PS VCC HSBC1 IO4 HS1 IO5 BRMID1 VCC Hall sensor M VCC Temperature sensor SW0 SW1 SW3 SW4 SW5 SW6 SW7 IO0 IO1 IO2 IO3 LIN LIN GND GND Fig. 2 LS1 LS2 SW2 GND Shunt SHNT_L VBAT Reverse Polarity Protection CWD TI0 TI1 TO GND GND Sample application circuitry for higher VCC loads and higher ambient temperatures MLX81100 application note Author: FJE Page 3 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation 3 Calculation The real power dissipation has to be calculated by the user depending on the user’s application. Main points where power dissipation can be saved are: 1 using an external regulator transistor -> Preg 2 =0 consider DC-load at pins carefully. P =U *I P = PVS I + Pchip + Preg + PLS X P = (VSI * IVS I ) + ( IVDD 5V * VDD5V ) + ( IVDD 5V (VS I − VDD5V )) + ( I PU * RDSon ) 2 If an external regulator transistor is used Preg = I VDD 5V (VS I − VDD5V ) = 0 . P = (VS I * IVS I ) + ( IVDD 5V *VDD5V ) + ( IVDD 5V (VS I − VDD5V )) is the basic power dissipation in all applications when no DC-load is present at any of the pins and internal regulator transistor is used. Case 1: • internal voltage regulator transistor is used • no DC-load at pins • IVS I = 0 • I PU = 0 P = (VSI * IVS I ) + ( IVDD 5V * VDD5V ) + ( IVDD 5V (VS I − VDD5V )) + ( I PU * RDSon ) 2 P = ( IVDD 5V * VDD5V ) + ( IVDD 5V (VS I − VDD5V )) P = (30mA * 5V ) + (30mA(18V − 5V )) P = 540mW ∆ϑ = Rth * P K * 0,54W W ∆ϑ = 21,6 K ∆ϑ = 40 MLX81100 application note Author: FJE Page 4 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation Case 2: • external voltage regulator transistor is used • no DC-load at pins • IVS I = 0 • I PU = 0 P = (VSI * IVS I ) + ( IVDD 5V * VDD5V ) + ( IVDD 5V (VS I − VDD5V )) + ( I PU * RDSon ) 2 P = ( IVDD 5V * VDD5V ) + ( IVDD 5V (VS I − VDD5V )) P = (30mA * 5V ) + 0 P = 150mW ∆ϑ = Rth * P K * 0,15W W ∆ϑ = 6 K ∆ϑ = 40 Any additional DC-load at pins will be added to P the power dissipation of the chip, e.g. pull-up resistors etc. depending on their internal used voltage they cause load to VDD5V or VS. IVS = I VDD 5V + IVS I + I PU IVS I = I PS + IVDRV + I SW + I PSclamp Explanation of the symbols and indexes: IVS = current flowing through reverse polarity diode, the sum of all currents flowing through the chip IVS I = and through possible external regulator transistor. current flowing inside the chip at pin VS. IVDD 5V = I PS = IVDRV = I SW = I PU = I PSclamp = current flowing into pin VDD5V. current flowing through devices connected to pin PS. current flowing while driving bridge drivers with PWM, mainly the current needed for charge/discharge of the gate capacities. current flowing through the pull-up/-down current sources connected to the SW-pins ( max value 4mA). current flowing through low side drivers when a pull-up resistor is connected to these pins. current flowing through chip-internal clamping diode when MLX81100 application note Author: FJE Page 5 of 9 VS > VPSclamp . Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation All terms using the index VS I are related to chip internal voltage VS. VS I = VDD5V = VS = PS = PS clamp = 5V supply system voltage. supply voltage. switchable supply voltage. P= PVS I = power dissipation caused by the chip. power dissipation caused by any load attached to chip internal power line VS. Pchip = power dissipation caused by the MelexCM chip and any circuit connected to VDD5V. Preg = power dissipation caused by VDD5V voltage regulator. PLS X = power dissipation caused by low side drivers when a pull-up resistor is connected to these chip internal voltage VS. clamped switchable supply voltage. pins and the drivers force current down to GND. MLX81100 application note Author: FJE Page 6 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation The following schematic is a sample schematic, which needs to be adjusted depending on the application. VBAT Ivs VS Ivdrv Ivsi VDRV RTG CLKO Ivdd5v VDD5V HSBC2 HS2 V1V8 BRMID2 VBAT Ips PS VCC HSBC1 IO4 IO5 VCC Isw Temperature sensor SW0 SW1 SW3 SW4 SW5 SW6 SW7 IO0 IO1 IO2 IO3 LIN LIN GND GND Fig. 3 HS1 MLX81100 VCC Hall sensor M BRMID1 Ipu LS1 LS2 SW2 GND SHNT_L Shunt VBAT Reverse Polarity Protection CWD TI0 TI1 TO GND GND Sample application circuitry including current indicators MLX81100 application note Author: FJE Page 7 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation History record Rev. 1.0 No. 1 Change Creation MLX81100 application note Author: FJE Date 16/03/07 Page 8 of 9 Rev 1.0 / 16/03/07 Application Note MLX81100 Power Dissipation 4 Disclaimer Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. Melexis makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. Melexis reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with Melexis for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or lifesustaining equipment are specifically not recommended without additional processing by Melexis for each application. The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of Melexis’ rendering of technical or other services. © 2007 Melexis NV. All rights reserved. For the latest version of this document, go to our website at: www.melexis.com Or for additional information contact Melexis Direct: Europe and Japan: All other locations: Phone: +32 1367 0495 E-mail: [email protected] Phone: +1 603 223 2362 E-mail: [email protected] ISO/TS 16949 and ISO14001 Certified MLX81100 application note Author: FJE Page 9 of 9 Rev 1.0 / 16/03/07