ßßDRIVENßBY E910.26 Driving PowER LEDS AND STANDARD LEDS WITH PFM CONTROLLER Scope Features This application note provides information, hints and complete schematics for driving low and high power LED Applications with 910.24/.26 SMPS familiy. ÿSupply voltage range VS 3.0V to 60V ÿUp to 90% efficiency ÿ40µA standby current ÿ 180µA circuit operating current ÿAdjustable output voltage ≥ 1,22V ÿUp to 300kHz switching frequency ÿ Improved current-limited PFM control scheme ÿ High current driver for external MOSFET ÿUnder-voltage lockout and thermal shutdown ÿ-40°C to +125°C operating temperature ÿSO8 package General Description The PFM controller family 910.24/.25/.26 are flexible, easy to use switched mode power supplies. Low standby current, very wide input voltage range make them suitable for applications in automotive and industrial environment. An advanced PFM control scheme gives these devices the benefits of PWM converters with high efficiency for heavy loads, while using very low operating current for light loads to maintain excellent behaviour with output load variation. Applications ÿ L ED driving applications ÿ 14V, 28V or 42V automotive systems ÿ Minimum component DC-DC converters VINP = 4V ... 60V L1 C5 LED Cluster D1 C1 VIN ON MDRV R4 M1 L2 C2 E910.26 C3 PGND VFB VSM AGND ISEN R1 C4 R3 R2 ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 Package Pin Out PGND 1 8 AGND 2 7 ISEN 3 6 VFB 4 5 MDRV VSM VS ON Pin Description Pin-No. Name Typ 1) Description 1 PGND S Driver power ground pin. Connect pin to the current sense resistor, the (-) terminal of the input capacitor and the (-) terminal of the output capacitor. Due to high currents, and high frequency operation of the IC, a low impedance circuit ground plane is highly recommended 2 AGND S 3 ISEN AI Analog ground pin. This pin provides a clean ground for the controller circuitry: The output voltage sensing resistors should be connected to this ground pin. This pin is connected to the IC substrate. Connect to the (-) terminal of the output capacitor 4 VFB AI 5 ON DI 6 VS S 7 VSM A 8 MDRV AO 1) Current sense input pin. Voltage generated across an external sense resistor is fed into this pin. Filters extensive high-frequency noise Positive feedback pin. Connect to SMPS output via external resistor divider to set output voltage and is referenced to 1.22V. For best stability, keep VFB lead as short as possible and VFB stray capacitance as small as possible Switch ON input. Tie this pin to ground to force the IC into idle mode. A voltage of VSM or higher switches the controller in operating mode Main supply input. Filters out high-frequency noise with a 100nF ceramic capacitor placed close to the pin to PGND Internal 5V regulator output. The driver and all control circuits are powered from this voltage. Decouple this pin to PGND with a minimum of 4.7µF tantalum and 100nF ceramic capacitors Drive output. Drives the gate of the external MOSFET between PGND and VSM. Connect the external MOSFET via a damping resistor to this pin D = digital, A = Analog, S = Supply, I = Input, O = Output, HV = High Voltage (max. 40V) ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 In this application note three schematics will be described driving Power LED‘s and furthermore one schematic for driving standard LED‘s. Overview of discussed schematics Circuit 1: ÿ 5 white power LED with IF = 350mA ÿ 9V to 20V input voltage range ÿ SEPIC transformer ÿ -40°C to +85°C Circuit 2: ÿ 5 white power LED with IF = 350mA ÿ 6V to 20V input voltage range ÿ separate SEPIC chokes ÿ -40°C to +85°C Circuit 3: ÿ 4 white power LED with IF = 700mA ÿ 6V to 20V input voltage range ÿ separate SEPIC chokes ÿ -40°C to +85°C Circuit 3b: ÿ 4 white power LED with IF = 700mA ÿ as above ÿ dimming capability 10% to 100% Circuit 4: ÿ 24 coloured standard LED with IF = 60mA ÿ 9V to 36V input voltage range ÿ Step Up topology ÿ -40°C to +85°C Disclaimer The components used in our simulations are especially designed to deliver meaningful results during development of switched mode power supplies. They are the basis for fast calculation of the circuits behaviour and give a good view to functionality and dependencies of component changes - in values or quality. Nevertheless the model based simulation does not show exactly the natural behaviour of a circuit board. Therefore the user of all ELMOS products is in charge for a save module and product development including among other things prototyping, measurements and qualification procedures. Additionally the customer is in charge for observing all security and protection standards and laws. ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 Circuit 1 The converter shown in figure one supplies the power for five white power LED‘s in series connection driven with a constant current of 350mA. VBAT L0=47μH RDC=0.10 L_EMC_1 D_reserve 9V to 20V ES2D L1 22µH * C_filter_1 C_bat 100n 470µF ZL, 25V C_input 470μF ZL, 25V C_filter_2 C_filter_3 100n 10n C_sepic 330µF ZL, 25V R_snubber 270 * Operating Frequency approx. 120kHz FB1 ES1D SMFBEMC Simple Bead L2 22µH * C_snubber 820p * 100n VIN MDRV E910.26 VSM R_damping M_power SUD40N06-25L 4.7 C_out_1 220μF ZL, 35V LED Cluster VOUT C_out_2 C_filter_4 150μF 220n ZL, 35V D1 D2 D3 P1N970A D_safety 24V, 50mW D4 D5 ISEN ON PGND 100n AGND 4µ7 D_rec VFB R_sense 0.047 R_pullup 10k 350mA R_safety Fault 1k BC547B Q_Fault 1k R_LED_Current 3.6 5x18R (parallel) Both SEPIC chokes are build on one ferrite core, EF12.6, as described below. Therewith a compact, electrical advantageous and cheap solution can be realised. In the working range of 9V to 20V the output current through the LED string is controlled and regulated to 350mA. With a battery voltage below about 8V the LED current starts decreasing as shown in figure 1.1. The working frequency of the PFM converter will be about 120kHz at an input voltage of 12V. In case of a broken LED string, the zener diode will clamp the output voltage to an unperilous level. The fault signal is true (high) when the feedback voltage is too low. ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 Description The converter uses a SEPIC topology. The current loaded into the choke is determined by the resistor R_sense. The snubber network is used to remove HF noise generated during switching the FET. Two safety parts, D_safety and R_safety are needed to protect the system against open load faults. Because the feedback path VFB controls the output current which in case of a broken wire is zero, the converter will try to increase Vout to infinity what will cause overvoltage at the C_out capacitors. The fault detection uses Q_fault as a simple voltage comparator. In case VFB is higher than Vth of Q_fault its output is low signalling „pass“. With an open load the current through R_LED_current will be zero and Q_fault will close, signalling high which is fault at the diagnostic line. Components All electrolytic capacitors used in the schematic are of the ZL-series of Rubicon. For inductances see table below. The snubber network strongly depends on components and layout. The given values are suitable for an example application and must be adapted to the final module. Also the R_damping depends on the used FET type and the layout. It might be necessary to modify or remove it. Inductivity Technical specifications L_EMC_1 47µH FB1 U_choke_1 Name Producer Ms85 Neosid 742 792 411 Würth 2x22µH EF12.6 The SEPIC choke consists of four windings on the same standard core of ferrite material. Below you find the specification suitable for building such a choke. Of course choke suppliers can build the transformer based on this specification. ELMOS Semiconductor AG N22 L2 N21 N12 N11 L1 SEPIC - Choke L1 = L2 = 22μH +/- 15% Core: EE13/7/4 (EF12.6) Material: N27 or N87 (EPCOS) Central Air Gap: 0.30mm Coil Former with 8 Pins N11=N12=N21=N22= 19 Turns Wire: 0.35mm Cul Application Note /28 QM-No.: 03AN0201E.00 E910.26 Simulation results figure 1.1 figure 1.2 Figure 1.1 shows the system behaviour in the moment of first battery contact and the following startup behaviour. The LED voltage and the the fault signal indicating the current being roughly in specification is shown. In figure 1.2 the LED current is plotted and within about 15ms it reaches the target level. figure 1.3 ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 Figure 1.3 shows the current through the chokes. In the first few ms the current reaches nearly 12A which may not cause the core to go into saturation. After the startup is finished the following curves can be found: figure 1.4 Here you see the LED current which has a small ripple and some noise resulting from parasitic components in the chokes, caps, and the FET. They can be eliminated by using appropriate filter elements at input and output side such as mentioned in the schematic. figure 1.5 This figure shows the current through the SEPIC chokes. Continuous current mode is used leading to lower EMI and better efficiency of the system. The battery current is about 650mA DC at 12V into the filter elements. The following figures will give important information about the power dissipation in the FET, the output diode and the reverse polarity diode, followed by graphs about the RMS current stress in the FET, the chokes and the capacitors. ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 figure 1.6 figure 1.7 figure 1.8 There is a safe failure behaviour which can be adapted to the users needs by changing just one component: the value of the zener diode. This is a very easy way to detect a fault and protect the system against damage in case of an open load condition. The other fault mechanism, a shorted LED, cannot be detected so easy. It would be necessary to measure the output voltage in a kind of learning phase where the Vout vs. temperature as well as versus LED device variations if Vf must be taken into account and must be separated from an error condition. Tolerances in the sum of all LEDs Vf over temperature are very big compared to the voltage change caused by one failing LED. For that reason there is currently no planning for a detection system for that failure. ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 The next graphs are to explain the system behaviour in case of an open load failure. figure 1.9 The error occurs figure 1.10 The fault signal is activated figure 1.11 The output voltage increases up to zener voltage of D_safety figure 1.13 The FET stopps switching ELMOS Semiconductor AG Application Note /28 QM-No.: 03AN0201E.00 E910.26 To give an impression of what happens during ignition phase of the vehicles engine as well as a principle view to the behaviour in the input voltage range, the next graphs will illustrate this scenario. The battery voltage, plotted green in figure 1.14 drops down to 6V. The converters input voltage follows with a delay due to the input caps. figure 1.14 As mentioned above the LED current starts decreasing with an input voltage below about 9V which can be seen in the following plot. But current only decreases by about 10% which in many cases is not very critical due to the logarithmic light sensitivity of human eyes. figure 1.15 An important fact is that current through the chokes and Csepic as well as from the battery increases significantly with decreasing input voltage. That is of course due to the converters natural behaviour as being a power converter delivering constant output-power and showing a negative input impedance to the supply system. figure 1.16 ELMOS Semiconductor AG Application Note 10 /28 QM-No.: 03AN0201E.00 E910.26 Finally an impression of the noise spectrum to be expected is given. The conducted disturbances fulfill the CISPR25 requirements. These are simulation results and therefore may vary from the final results which are depending on the quality of all the components on the pcb as well as on the layout. figure 1.17 ELMOS Semiconductor AG Application Note 11 /28 QM-No.: 03AN0201E.00 E910.26 Circuit 2 This converter shown in figure two also supplies the power for five white power LED‘s in series connection driven with a constant current of 350mA but in contrast to the first one it is designed to work with lower input voltage: 6V to 20V. VBAT 6V to 20V L0=47μH RDC=0.10 L_EMC_1 D_reserve L1 ES2D C_filter_1 C_bat 100n 470µF ZL, 25V 47µH RDC=0.12 C_input 470μF ZL, 25V C_filter_2 C_filter_3 100n 10n C_sepic 330µF ZL, 25V C_snubber 820p * 100n VIN MDRV E910.26 VSM ES1D SMFBEMC Simple Bead R_damping M_power SUD40N06-25L 4.7 LED Cluster VOUT C_out_2 C_filter_4 150μF 220n ZL, 35V D1 D2 D3 P1N970A D_safety 24V, 50mW D4 D5 ISEN ON PGND 100n AGND 4µ7 FB1 47µH C_out_1 RDC=0.12 220μF ZL, 35V L2 R_snubber 270 * Operating Frequency approx. 120kHz D_rec VFB R_sense 0.039 350mA R_pullup 10k R_safety Fault 1k BC547B Q_Fault 1k R_LED_Current 3.6 5x18R (parallel) The SEPIC chokes are realised as two standard parts for easy purchase and developing purpose. In the working range of 6V to 20V the output current through the LED string is controlled and regulated to 350mA. With a battery voltage below about 6V the LED current starts decreasing as shown in figure 2.1. The working frequency of the PFM converter will be about 80kHz at an input voltage of 12V. Description The converter is similar to the one used in circuit 1. The component values have changed to match the requirements of lower input voltage. ELMOS Semiconductor AG Application Note 12 /28 QM-No.: 03AN0201E.00 E910.26 Components All electrolytic capacitors used in the schematic are of the ZL-series of Rubicon. For inductances see table below. Inductivity Technical specifications Name Producer L_EMC_1 47µH Ms85 Neosid L1 47µH Ms95a Neosid L2 47µH Ms95a Neosid 742 792 411 Würth FB1 In the following figures will illustrate the output current and choke currents during ignition phase. figure 2.1 As mentioned above the LED current starts decreasing with an input voltage below about6V which can be seen in the following plot. But current only decreases a few percent which in many cases may not be very critical. figure 2.2 ELMOS Semiconductor AG Application Note 13/28 QM-No.: 03AN0201E.00 E910.26 An important fact is that current through the chokes and Csepic as well as from the battery increases significantly with decreasing input voltage. That is of course due to the converters natural behaviour as being a power converter delivering constant output-power and showing a negative input impedance to the supply system. figure 2.3 ELMOS Semiconductor AG Application Note 14 /28 QM-No.: 03AN0201E.00 E910.26 Finally an impression of the noise spectrum to be expected is given. The conducted disturbances fulfill the CISPR25 requirements. These are simulation results and therefore may vary from the final results which are depending on the quality of all the components on the pcb as well as on the layout. figure 2.4 ELMOS Semiconductor AG Application Note 15 /28 QM-No.: 03AN0201E.00 E910.26 Circuit 3 This converter shown in figure three supplies the power for four white power LED‘s in series connection driven with a constant current of 700mA. Also this one is designed to work with lower input voltage: 6V to 20V. VBAT 6V to 20V L0=10μH RDC=0.10 L_EMC_1 D_reserve L1 ES3D C_filter_1 C_bat 100n 470µF ZL, 25V L0=22µH RDC=0.10 C_input 470μF ZL, 25V C_filter_2 C_filter_3 100n 10n C_sepic 470µF ZL, 25V C_snubber 820p * VIN MDRV E910.26 VSM L0=10µH RDC=0.15 R_damping VOUT LED Cluster C_out_2 C_filter_4 220μF 220n ZL, 25V D1 D2 D3 P1N968A D_safety 20V, 50mW M_power SUD40N06-25L 4.7 D4 ISEN ON PGND 100n AGND 4µ7 L_EMC_2 ES2D L0=22µH C_out_1 RDC=0.12 470μF ZL, 25V L2 R_snubber 270 * 100n D_rec R_sense 0.022 VFB 700mA R_pullup 10k R_spike_filter Fault C_spike_filter BC547B Q_Fault * R_safety 1k * 1k R_LED_Current 1.743 (10x18R+1x56R) The SEPIC chokes are realised as two standard parts for easy purchase and developing purpose. In the working range of 6V to 20V the output current through the LED string is controlled and regulated to 350mA. With a battery voltage below about 6V the LED current starts decreasing as shown in figure 2.1. The working frequency of the PFM converter will be about 110kHz at an input voltage of 12V. Description The converter is similar to the one used in circuit 1. The component values have changed to match the requirements of lower input voltage. Components All electrolytic capacitors used in the schematic are of the ZL-series of Rubicon. For inductances see table below. Inductivity Technical specifications Name Producer L_EMC_1 10µH Ms85 Neosid L1 22µH Ms95a Neosid L2 22µH Ms95a Neosid L_EMC_2 10µH Ms85 Neosid ELMOS Semiconductor AG Application Note 16 /28 QM-No.: 03AN0201E.00 E910.26 The following graphs will illustrate the component requirements regarding current stress during ignition phase. The RMS currents will be L1= 1.6A, L2= 1.1A, Cinput= 800mA, Csepic= 1.3A, Coutput= 1.4A figure 3.2 As mentioned above the LED current starts decreasing with an input voltage below about 6V which can be seen in the following plot. But current only decreases a few percent which in many cases may not be very critical. figure 3.3 An important fact is that current through the chokes and Csepic as well as from the battery increases significantly with decreasing input voltage. That is of course due to the converters natural behaviour as being a power converter delivering constant output-power and showing a negative input impedance to the supply system. figure 3.4 ELMOS Semiconductor AG Application Note 17/28 QM-No.: 03AN0201E.00 E910.26 Finally an impression of the noise spectrum to be expected is given. The conducted disturbances fulfill the CISPR25 requirements. These are simulation results and therefore may vary from the final results which are depending on the quality of all the components on the pcb as well as on the layout. figure 3.5 ELMOS Semiconductor AG Application Note 18 /28 QM-No.: 03AN0201E.00 E910.26 Circuit 3b This converter is exactly the same as circuit 3 with a dimming capability is beeing added. D_reserve L1 ES3D C_filter_1 C_bat 100n 470µF ZL, 25V 22µH RDC=0.10 C_input 470μF ZL, 25V C_filter_2 C_filter_3 100n 10n C_sepic 470µF ZL, 25V C_snubber 820p * VIN VSM L0=10µH RDC=0.15 C_out_2 C_filter_4 220μF 220n ZL, 25V D2 D3 P1N968A D_safety 20V, 50mW PGND ON D4 R_sense 0.022 VFB 700mA R1 39k R_spike_filter C_spike_filter GND * R_safety 1k * 2 R2 3 IC2a 1 R5 5 100k 6 GND R6 C2 1µ 39k 10k R4 4 100k + 8 10k R3 1N4148 D2 VSM PWM Input D1 ISEN AGND D1 GND LED Cluster 100n 1N4148 C1 1µ VOUT 4.7 E910.26 4µ7 ES2D M_power SUD40N06-25L R_damping MDRV L_EMC_2 22µH C_out_1 RDC=0.10 470μF ZL, 25V L2 R_snubber 270 * 100n D_rec 10k VBAT 10μH RDC=0.10 L_EMC_1 C3 1µ + - R_LED_Current 1.743 (10x18R+1x56R) IC2b 7 D3 1N4148 The PWM signal is used in two ways. First it is used as the ON signal to start the converter. In the main path the signal is converted into an analog voltage which is added to the current signal of the shunt resistor. The circuit can be used for dimming in the range of about 10% to 100%. Below 10% the converter starts discontinuous mode which can be seen as blinking of the LEDs. With the same principle a temperature control unit can be build up using an NTC. ELMOS Semiconductor AG Application Note 19 /28 QM-No.: 03AN0201E.00 E910.26 Circuit 4 This converter shown in figure four supplies the power for 24 coloured standard LED‘s in series connection driven with a constant current of 60mA. VBAT 9V to 36V WE-PD4S L0=10μH RDC=0.20 L_EMC_1 D_reserve ES1D C_filter_1 100n C_filter_2 C_filter_3 100n 10n C_bat 100µF ZL, 50V C_input 100μF ZL, 50V WE-PD4L L_StepUp L0=100μH RDC=0.33 D_rec FB1 ES1D Ferrite Bead C_out_1 82μF ZL, 63V R_snubber 330 * VOUT (42V to 59V) C_out_2 C_filter_4 82μF 220n ZL, 63V C_snubber 1n * VIN MDRV E910.24 4.7µF PGND VSM 4.7 ISEN AGND ON R_damping M_power BUK9875-100A VFB R_sense 150m 50mW 68V LED1 LED9 LED17 LED2 LED10 LED18 LED3 LED11 LED19 LED4 LED12 LED20 LED5 LED13 LED21 LED6 LED14 LED22 LED7 LED15 LED23 LED8 LED16 LED24 60mA R_safety 100n 1k R_LED_Current 20.76 33E//56E The Step Up converter serves up to about 59V at the cluster output. It uses a standard choke many suppliers offer. In the working range of 9V to 36V the output current through the LED string is controlled and regulated to 60mA. With a battery voltage below about 9V the LED current starts decreasing as shown in figure 2.1. The working frequency of the PFM converter will be about 29kHz at an input voltage of 9V and 60kHz at 27V. To make use of smaller chokes the 910.24 is used which offers an extended maximum ON time for the gate driver. That ensures that with lower battery voltage the choke can be loaded with the required amount of energy. ELMOS Semiconductor AG Application Note 20 /28 QM-No.: 03AN0201E.00 E910.26 Components All electrolytic capacitors used in the schematic are of the ZL-series of Rubicon. For inductances see table below. Name Technical specifications Comment C_filter_1 100nF, 50V, 10%, X7R 1206, SMD C_bat 100µF, 50V. 74mOhm, 0,72Arms ZL-Series, 105°C C_filter_2 100nF, 50V, 10%, X7R 1206, SMD Epcos C_filter_3 10nF, 50V, 10%, X7R 1206, SMD Epcos C_input 100μF, 50V, 74mOhm, 0,72Arms ZL-Series, 105°C C_snubber 1nF, 1000V, 10%, NP0 1206, SMD Kemet C_VSM_2 4.7μF,25V (Low ESR) Tantal, SMD Epcos C_VSM_1 100nF, 50V, 10%, X7R 1206, SMD Epcos C_output_1 82μF, 63V, 150mOhm, 0.68Arms ZL-Series, 105°C Rubycon C_output_2 82μF, 63V, 150mOhm, 0.68Arms ZL-Series, 105°C Rubycon C_filter_4 220nF, 25V, 10%, X7R 1206, SMD Epcos L_EMC_1 10μH, 35MHz, 1.2A, 160mOhm WE-PD4S Würth L_EMC_2 100μH, 8MHz, 1.2A, 330mOhm WE-PD4L Würth 742792411 Würth Logic Level Philips Semi L_FB1 R_snubber 330Ohm R_damping 4.7Ohm R_LED_Current 33 Ohm // 56 Ohm R_sense 150mOhm R_safety 1k D_reverse ES1D D_rec_1 ES1D M_power BUK9875-100A U_E91024 E91024A ELMOS Semiconductor AG Producer Epcos Rubycon Rubycon ELMOS Application Note 21 /28 QM-No.: 03AN0201E.00 E910.26 Simulation results In the following figures the output current and some interesting values can be seen with respect to input voltage variations. figure 4.1 behariour at VBAT = 9V ELMOS Semiconductor AG Application Note 22 /28 QM-No.: 03AN0201E.00 E910.26 figure 4.2 behariour at VBAT = 27V ELMOS Semiconductor AG Application Note 23/28 QM-No.: 03AN0201E.00 E910.26 figure 4.3 behariour at VBAT = 36V ELMOS Semiconductor AG Application Note 24 /28 QM-No.: 03AN0201E.00 E910.26 Record of Revisions Chapter Rev. 1 Change and Reason for Change Initial Revision ELMOS Semiconductor AG Application Note 25/28 Date Released 12.02.2007 TZIE/RL QM-No.: 03AN0201E.00 E910.26 Contents Scope........................................................................................................................................................� 1 General Description................................................................................................................................� 1 Features...................................................................................................................................................� 1 Applications.............................................................................................................................................� 1 Package Pin Out...................................................................................................................................... 2 Pin Description........................................................................................................................................ 2 Overview of discussed schematics.......................................................................................................�3 Disclaimer................................................................................................................................................�3 Circuit 1..................................................................................................................................................... 4 Description..............................................................................................................................................�5 Components............................................................................................................................................�5 Simulation results................................................................................................................................... 6 Circuit 2....................................................................................................................................................12 Description .............................................................................................................................................12 Components............................................................................................................................................13 Circuit 3....................................................................................................................................................16 Description..............................................................................................................................................16 Components............................................................................................................................................16 Circuit 3b..................................................................................................................................................19 Circuit 4�������������������������������������������������������������������������������������������������������������������������������������������������� 20 Components............................................................................................................................................21 Simulation results...................................................................................................................................22 Record of Revisions.................................................................................................................................25 ELMOS Semiconductor AG Application Note 26 /28 QM-No.: 03AN0201E.00 E910.26 WARNING – Life Support Applications Policy ELMOS Semiconductor AG is continually working to improve the quality and reliability of its products. Nevertheless, semiconductor devices in general can malfunction or fail due to their inherent electrical sensitivity and vulnerability to physical stress. It is the responsibility of the buyer, when utilizing ELMOS Semiconductor AG products, to observe standards of safety, and to avoid situations in which malfunction or failure of an ELMOS Semiconductor AG Product could cause loss of human life, body injury or damage to property. In development your designs, please ensure that ELMOS Semiconductor AG products are used within specified operating ranges as set forth in the most recent product specifications. General Disclaimer Information furnished by ELMOS Semiconductor AG is believed to be accurate and reliable. However, no responsibility is assumed by ELMOS Semiconductor AG for its use, nor for any infringements of patents or other rights of third parties, which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of ELMOS Semiconductor AG. ELMOS Semiconductor AG reserves the right to make changes to this document or the products contained therein without prior notice, to improve performance, reliability, or manufacturability . Application Disclaimer Circuit diagrams may contain components not manufactured by ELMOS Semiconductor AG, which are included as means of illustrating typical applications. Consequently, complete information sufficient for construction purposes is not necessarily given. The information in the application examples has been carefully checked and is believed to be entirely reliable. However, no responsibility is assumed for inaccuracies. Furthermore, such information does not convey to the purchaser of the semiconductor devices described any license under the patent rights of ELMOS Semiconductor AG or others. Copyright © 2006 ELMOS Semiconductor AG Reproduction, in part or whole, without the prior written consent of ELMOS Semiconductor AG, is prohibited. ELMOS Semiconductor AG Application Note 27/28 QM-No.: 03AN0201E.00 ELMOS Semiconductor AG – Headquarters Heinrich-Hertz-Str. 1 | 44227 Dortmund | Germany Phone + 49 (0) 231 - 75 49 - 0 | Fax + 49 (0) 231 - 75 49 - 149 [email protected] | www.elmos.de 28/28