LMV7271/LMV7275/LMV7272 Single & Dual, 1.8V Low Power Comparators with Rail-to-Rail Input General Description Features The LMV727X are rail-to-rail input low power comparators, which are characterized at supply voltage 1.8V, 2.7V and 5.0V. They consume only 9uA supply current per channel while achieving a 800ns propagation delay. The LMV7271/LMV7275 (single) are available in SC70 and SOT23 packages. The LMV7272 (dual) is available in micro SMD package. With these tiny packages, the PC board area can be significantly reduced. They are ideal for low voltage, low power and space critical designs. The LMV7271/LMV7272 both feature a push-pull output stage which allows operation with minimum power consumption when driving a load. The LMV7275 features an open drain output stage that allows for wired-OR configurations. The open drain output also offers the advantage of allowing the output to be pulled to any voltage up to 5V, regardless of the supply voltage of the LMV7275. (VS = 1.8V, TA = 25˚C, Typical values unless specified). n Single or Dual Supplies n Ultra low supply current 9µA per channel n Low input bias current 10nA n Low input offset current 200pA n Low guaranteed VOS 4mV n Propagation delay 880ns (20mV overdrive) n Input common mode voltage range 0.1V beyond rails n LMV7272 is available in micro SMD package Applications n n n n Mobile communications Laptops and PDA’s Battery powered electronics General purpose low voltage applications The LMV727X are built with National Semiconductor’s advance submicron silicon-gate BiCMOS process. They all have bipolar inputs for improved noise performance and CMOS outputs for rail-to-rail output swing. Typical Circuit Part Number Single/Dual Package Output Single SC70, SOT23 Push/Pull LMV7272 Dual micro SMD Push/Pull LMV7275 Single SC70, SOT23 Open Drain LMV7271 20064024 FIGURE 1. Threshold Detector © 2003 National Semiconductor Corporation DS200640 www.national.com LMV7271/LMV7275/LMV7272 Single & Dual, 1.8V Low Power Comparators with Rail-to-Rail Input September 2003 LMV7271/LMV7275/ LMV7272 Absolute Maximum Ratings Storage Temperature Range (Note 1) Junction Temperature (Note 4) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance 2KV (Note 2) ± Supply Voltage Supply Voltage (V+ - V−) Voltage at Input/Output pins 5.5V Operating Temperature Range (Note 3) Soldering Information 235˚C Wave Soldering (10 sec.) 260˚C −40˚C to +85˚C Package Thermal Resistance (Note 3) V+ +0.1V, V− −0.1V Infrared or Convection (20 sec.) +150˚C Operating Ratings (Note 1) 200V (Note 6) VIN Differential −65˚C to +150˚C SOT23-5 325˚C/W SC-70 265˚C/W 8-Bump Thin micro SMD 220˚C/W 1.8V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 1.8V, V− = 0V. Boldface limits apply at the temperature extremes. Symbol Parameter VOS Input Offset Voltage TC VOS Input Offset Temperature Drift IB IOS IS Supply Current ISC Condition VOL VCM Typ (Note 4) Max (Note 5) Units 0.3 4 6 mV 20 uV/˚C Input Bias Current 10 nA Input Offset Current 200 Output Short Circuit Current VCM = 0.9V (Note 7) pA LMV7271/LMV7275 9 12 14 LMV7272 18 25 28 Sourcing, VO = 0.9V (LMV7271/LMV7272 only) Sinking, VO = 0.9V VOH Min (Note 5) 3.5 6 4 6 µA mA Output Voltage High (LMV7271/LMV7272 only) IO = 0.5mA 1.7 1.74 IO = 1.5mA 1.47 1.63 Output Voltage Low IO = −0.5mA 52 100 IO = −1.5mA 166 220 Input Common Mode Voltage Range µA CMRR > 45 dB V 1.9 −0.1 mV V V CMRR Common Mode Rejection Ratio 0 < VCM < 1.8V 46 78 dB PSRR Power Supply Rejection Ratio V+ = 1.8V to 5V 55 80 dB ILEAKAGE Output Leakage Current VO = 1.8V (LMV7275 only) 2 pA 1.8V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 1.8V, V− = 0V, VCM = 0.5V, VO = V+/2 and RL > 1MΩ to V−. Boldface limits apply at the temperature extremes. Symbol tPHL tPLH Parameter Propagation Delay (High to Low) Propagation Delay (Low to High) www.national.com Condition Min (Note 6) Typ (Note 5) Max (Note 6) Units Input Overdrive = 20mV Load = 50pF//5kΩ 880 ns Input Overdrive = 50mV Load = 50pF//5kΩ 570 ns Input Overdrive = 20mV Load = 50pF//5kΩ 1100 ns Input Overdrive = 50mV Load = 50pF//5kΩ 800 ns 2 Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.7V, V− = 0V. Boldface limits apply at the temperature extremes. Symbol Parameter VOS Input Offset Voltage TC VOS Input Offset Temperature Drift IB Input Bias Current IOS Input offset Current IS Supply Current ISC VOH VOL Output Short Circuit Current Conditions Min (Note 6) VCM = 1.35V (Note 7) Typ (Note 5) Max (Note 6) Units 0.3 4 6 mV 20 µV/˚C 10 nA 200 pA LMV7271/LMV7275 9 13 15 LMV7272 18 25 28 Sourcing, VO = 1.35V (LMV7271/LMV7272 only) 12 15 Sinking, VO = 1.35V 12 15 µA µA mA Output Voltage High (LMV7271/LMV7272 only) IO = 0.5mA 2.63 2.66 IO = 2.0mA 2.48 2.55 Output Voltage Low IO = −0.5mA 50 70 IO = −2mA 155 220 V mV VCM Input Common Voltage Range CMRR > 45dB CMRR Common Mode Rejection Ratio 0 < VCM < 2.7V 46 78 PSRR Power Supply Rejection Ratio V+ = 1.8V to 5V 55 80 dB ILEAKAGE Output Leakage Current VO = 2.7V (LMV7275 only) 2 pA 2.8 −0.1 V V dB 2.7V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.7V, V− = 0V, VCM = 0.5V, VO = V+/2 and RL > 1MΩ to V−. Boldface limits apply at the temperature extremes. Symbol tPHL tPLH Parameter Propagation Delay (High to Low) Propagation Delay (Low to High) Condition Min (Note 6) Typ (Note 5) Max (Note 6) Units Input Overdrive = 20mV Load = 50pF//5kΩ 1200 ns Input Overdrive = 50mV Load = 50pF//5kΩ 810 ns Input Overdrive = 20mV Load = 50pF//5kΩ 1300 ns Input Overdrive = 50mV Load = 50pF//5kΩ 860 ns 5.0V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V. Boldface limits apply at the temperature extremes. Symbol Parameter VOS Input Offset Voltage TC VOS Input Offset Temperature Drift IB IOS Conditions VCM = 2.5V (Note 7) Min (Note 6) Typ (Note 5) Max (Note 6) Units 0.3 4 6 mV 20 µV/˚C Input Bias Current 10 nA Input Offset Current 200 pA 3 www.national.com LMV7271/LMV7275/ LMV7272 2.7V Electrical Characteristics LMV7271/LMV7275/ LMV7272 5.0V Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V. Boldface limits apply at the temperature extremes. Symbol Parameter Supply Current IS ISC VOH VOL VCM Output Short Circuit Current Conditions Min (Note 6) Typ (Note 5) Max (Note 6) LMV7271/LMV7275 10 14 16 LMV7272 20 27 30 Sourcing, VO = 2.5V (LMV7271/LMV7272 only) 28 34 Sinking, VO = 2.5V 28 34 IO = 0.5mA 4.93 4.96 IO = 4.0mA 4.70 4.77 Output Voltage Low IO = −0.5mA 27 70 IO = −4.0mA 225 300 Common Mode Rejection Ratio CMRR > 45dB 0 < VCM < 5.0V + PRSS Power Supply Rejection Ratio V = 1.8V to 5V ILEAKAGE Output Leakage Current VO = 5V (LMV7275 only) µA V 5.1 −0.1 CMRR µA mA Output Voltage High (LMV7271/LMV7272 only) Input Common Voltage Range Units mV V 46 78 dB 55 80 dB 2 pA 5.0V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5.0V, V− = 0V, VCM = 0.5V, VO = V+/2 and RL > 1MΩ to V−. Boldface limits apply at the temperature extremes. Symbol tPHL tPLH Parameter Propagation Delay (High to Low) Propagation Delay (Low to High) Condition Min (Note 6) Typ (Note 5) Max (Note 6) Units Input Overdrive = 20mV Load = 50pF//5kΩ 2100 ns Input Overdrive = 50mV Load = 50pF//5kΩ 1380 ns Input Overdrive = 20mV Load = 50pF//5kΩ 1800 ns Input Overdrive = 50mV Load = 50pF//5kΩ 1100 ns Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. Note 2: Human body model, 1.5kΩ in series with 100pF. Note 3: The maximum power dissipation is a function of TJ(MAX), θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) - TA)/θJA. All numbers apply for packages soldered directly into a PC board. Note 4: Typical values represent the most likely parametric norm. Note 5: All limits are guaranteed by testing or statistical analysis. Note 6: Machine Model, 0Ω in series with 200pF. Note 7: Offset Voltage average drift determined by dividing the change in VOS at temperature extremes into the total temperature change. Note 8: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self heating where TJ > TA. Absolute Maximum Ratings indicate junction temperature limits beyond which the device may be permanently degraded, either mechanically or electrically. www.national.com 4 LMV7271/LMV7275/ LMV7272 Connection Diagrams 5-Pin SOT23/SC70 (LMV7271/LMV7275) 8-Bump micro SMD (LMV7272) 20064023 Top View 20064041 Top View (bump side down) Ordering Information Package 5-Pin SOT23 Part Number Package Marking Transport Media NSC Drawing LMV7271MF C25A 1k Units Tape and Reel MF05A LMV7271MFX LMV7275MF 3k Units Tape and Reel C26A 1k Units Tape and Reel C34 1k Units Tape and Reel LMV7275MFX 5-Pin SC70 LMV7271MG 3k Units Tape and Reel LMV7271MGX LMV7275MG C35 1k Units Tape and Reel LMV7275MGX 8-Bump micro SMD LMV7272TL MAA05A 3k Units Tape and Reel 3k Units Tape and Reel I 01 250 Units Tape and Reel LMV7272TLX TLA08AAA 3k Units Tape and Reel 5 www.national.com LMV7271/LMV7275/ LMV7272 Typical Performance Characteristics (TA = 25˚C, Unless otherwise specified). VOS vs. VCM VOS vs. VCM 20064028 20064029 VOS vs. VCM Short Circuit vs. Supply Voltage 20064030 20064001 Supply Current vs. Supply Voltage (LMV7271) Supply Current vs. Supply Voltage (LMV7272) 20064002 www.national.com 20064031 6 Supply Current vs. Supply Voltage (LMV7272) (Continued) Output Positive Swing vs. VSUPPLY 20064032 20064033 Output Negative Swing vs. VSUPPLY Output Positive Swing vs. ISOURCE 20064035 20064034 Output Negative Swing vs. ISINK Output Positive Swing vs. ISOURCE 20064036 20064037 7 www.national.com LMV7271/LMV7275/ LMV7272 Typical Performance Characteristics (TA = 25˚C, Unless otherwise specified). LMV7271/LMV7275/ LMV7272 Typical Performance Characteristics (TA = 25˚C, Unless otherwise specified). Output Negative Swing vs. ISINK (Continued) Output Negative Swing vs. ISINK 20064039 20064038 Output Positive Swing vs. ISOURCE Propagation Delay (tPLH) 20064014 20064040 Propagation Delay (tPHL) Propagation Delay (tPLH) 20064018 www.national.com 20064015 8 Propagation Delay (tPHL) (Continued) Propagation Delay (tPLH) 20064020 20064016 Propagation Delay (tPHL) tPHL vs. Overdrive 20064022 20064050 tPLH vs. Overdrive 20064049 9 www.national.com LMV7271/LMV7275/ LMV7272 Typical Performance Characteristics (TA = 25˚C, Unless otherwise specified). LMV7271/LMV7275/ LMV7272 Application Notes BASIC COMPARATOR VIN is less than VREF, the output (VO) is low. However, if VIN is greater than VREF, the output voltage (VO) is high. A comparator is often used to convert an analog signal to a digital signal. As shown in Figure 2, the comparator compares an input voltage (VIN) to a reference voltage (VREF). If LMV7271 20064025 20064017 FIGURE 2. LMV7271 Basic Comparator HYSTERESIS RAIL-TO-RAIL INPUT STAGE The LMV727X has an input common mode voltage range (VCM) of −0.1V below the V− to 0.1V above V+. This is achieved by using paralleled PNP and NPN differential input pairs. When the VCM is near V+, the NPN pair is on and the PNP pair is off. When the VCM is near V−, the NPN pair is off and the PNP pair is on. The crossover point between the NPN and PNP input stages is around 950mV from V+. Since each input stage has its own offset voltage (VOS), the VOS of the comparator becomes a function of the VCM. See curves for VOS vs. VCM in Typical Performance Characteristics section. In application design, it is recommended to keep the VCM away from the crossover point to avoid problems. The wide input voltage range makes LMV727X ideal in power supply monitoring circuits, where the comparators are used to sense signals close to ground and power supplies. It is a standard procedure to use hysteresis (positive feedback) around a comparator, to prevent oscillation, and to avoid excessive noise on the output because the comparator is a good amplifier of its own noise. Inverting Comparator with Hysteresis The inverting comparator with hysteresis requires a three resistor network that is referenced to the supply voltage VCC of the comparator (Figure 3). When VIN at the inverting input is less than VA, the voltage at the non-inverting node of the comparator (VIN < VA), the output voltage is high (for simplicity assume VO switches as high as VCC). The three network resistors can be represented as R1||R3 in series with R2. The lower input trip voltage VA1 is defined as OUTPUT STAGE The LMV7271 and LMV7272 have a push-pull output stage. This output stage keeps the total system power consumption to the absolute minimum. The only current consumed is the low supply current and the current going directly into the load. When the output switches, both PMOS and NMOS at the output stage are on at the same time for a very short time. This allows current to flow directly between V+ and V− through output transistors. The result is a short spike of current (shoot-through current) drawn from the supply and glitches in the supply voltages. The glitches can spread to other parts of the board as noise. To prevent the glitches in supply lines, power supply bypass capacitors must be installed. See section for supply bypassing in the Application Notes for details. When VIN is greater than VA (VIN > VA), the output voltage is low and very close to ground. In this case the three network resistors can be presented as R2//R3 in series with R1. The upper trip voltage VA2 is defined as The total hysteresis provided by the network is defined as ∆VA = VA1 - VA2 A good typical value of ∆VA would be in the range of 5 to 50mV. This is easily obtained by choosing R3 as 1000 to 100 times (R1||R2) for 5V operation, or as 300 to 30 times (R1||R2) for 1.8V operation. www.national.com 10 LMV7271/LMV7275/ LMV7272 Application Notes (Continued) 20064042 FIGURE 3. Inverting Comparator with Hysteresis When VIN is high, the output is also high. To make the comparator switch back to its low state, VIN must equal VREF before VA will again equal VREF. VIN can be calculated by: Non-Inverting Comparator with Hysteresis A non-inverting comparator with hysteresis requires a two resistor network, and a voltage reference (VREF) at the inverting input (Figure 4). When VIN is low, the output is also low. For the output to switch from low to high, VIN must rise up to VIN1, where VIN1 is calculated by The hysteresis of this circuit is the difference between VIN1 and VIN2. ∆VIN = VCCR1/R2 11 www.national.com LMV7271/LMV7275/ LMV7272 Application Notes low inductive ground connection. Make sure ground paths are low-impedance where heavier currents are flowing to avoid ground level shift. Preferably there should be a ground plane under the component. (Continued) 4. The output trace should be routed away from inputs. The ground plane should extend between the output and inputs to act as a guard. This can be achieved by running a topside ground plane between the output and inputs. A typical PCB layout is shown in Figure 5. 20064044 20064051 FIGURE 5. Typical PCB Layout 5. When the signal source is applied through a resistive network to one input of the comparator, it is usually advantageous to connect the other input with a resistor with the same value, for both DC and AC consideration. Input traces should be laid out symmetrically if possible. 6. All pins of any unused comparators should be tied to the negative supply. 20064043 micro SMD LIGHT SENSITIVITY Exposing the micro SMD device to direct sunlight will cause mis-operation of the device. Light sources such as Halogen lamps can also affect electrical performance if brought near to the device. The wavelengths, which have the most detrimental effect, are reds and infrareds. FIGURE 4. Non-Inverting Comparator with Hysteresis CIRCUIT TECHNIQUES FOR AVOIDING OSCILLATIONS IN COMPARATOR APPLICATIONS Feedback to almost any pin of a comparator can result in oscillation. In addition, when the input signal is a slow voltage ramp or sine wave, the comparator may also burst into oscillation near the crossing point. To avoid oscillation or instability, PCB layout should be engineered thoughtfully. Several precautions are recommended: 1. Power supply bypassing is critical, and will improve stability and transient response. Resistance and inductance from power supply wires and board traces increase power supply line impedance. When supply current changes, the power supply line will move due to its impedance. Large enough supply line shift will cause the comparator to mis-operate. To avoid problems, a small bypass capacitor, such as 0.1uF ceramic, should be placed immediately adjacent to the supply pins. An additional 6.8µF or greater tantalum capacitor should be placed at the point where the power supply for the comparator is introduced onto the board. These capacitors act as an energy reservoir and keep the supply impedance low. In dual supply application, a 0.1µF capacitor is recommended to be placed across V+ and V− pins. 2. Keep all leads short to reduce stray capacitance and lead inductance. It will also minimize any unwanted coupling from any high-level signals (such as the output). The comparators can easily oscillate if the output lead is inadvertently allowed to capacitively couple to the inputs via stray capacitance. This shows up only during the output voltage transition intervals as the comparator changes states. Try to avoid a long loop which could act as an inductor (coil). 3. It is a good practice to use an unbroken ground plane on a printed circuit board to provide all components with a www.national.com micro SMD MOUNTING The micro SMD package requires specific mounting techniques, which are detailed in National Semiconductor Application Note AN-1112. LMV7272 micro SMD to DIP Conversion Board To facilitate characterization and testing, a micro SMD to DIP conversion board, LMV7272TLCONV, is available. It is a 2-layer board, with the LMV7272 mounted on the bottom layer, and a capacitor (C1, between the positive and negative supplies) added to the top layer. 20064060 LMV7272TLCONV Diagram 12 OR’ING THE OUTPUT Since the output is an unconnected NMOS drain, many drains can be tied together, pulled up to VDD by a single resistor to provide an output OR’ing function. If any of the comparator outputs is pulled low the output VO goes down. UNIVERSAL LOGIC LEVEL SHIFTER The output of LMV7275 is an unconnected drain of an NMOS device, which can be pulled up, through a resistor, to any desired output level within the permitted power supply range. Hence, the following simple circuit works as a universal logic level shifter, pulling up the signal to the desired level. 20064052 FIGURE 6. Logic Level Shifter POSITIVE PEAK DETECTOR A positive peak detect circuit is basically a comparator operated in a unity gain follower configuration, with a capacitor as a load to maintain the highest voltage. A diode is added at the output to prevent the capacitor from discharging through the pull-up resistor, and a 1MΩ resistor added in parallel to the capacitor to provide a high impedance discharge path. When the input VIN increases, the inverting input of the comparator follows it, thus charging the capacitor. When it decreases, the cap discharges through the 1MΩ resistor. The decay time can be modified by changing the resistor. The output should be accessed through a follower circuit to prevent loading. 20064053 FIGURE 8. OR’ing the Outputs 20064054 FIGURE 7. Positive Peak Detector 13 www.national.com LMV7271/LMV7275/ LMV7272 Typical Applications LMV7271/LMV7275/ LMV7272 Typical Applications (Continued) NEGATIVE PEAK DETECTOR For the negative detector, the output transistor of the comparator acts as a low impedance current sink. Since there is no pull-up resistor, the only discharge path will be the 1MΩ resistor and any load impedance used. Decay time is changed by varying the 1MΩ resistor. 20064055 20064056 FIGURE 9. Negative Peak Detector SQUARE WAVE GENERATOR A typical application for a comparator is as a square wave oscillator. The circuit below generates a square wave whose period is set by the RC time constant of the capacitor C1and resistor R4. The maximum frequency is limited by the large signal propagation delay of the comparator, and by the capacitive loading at the output, which limits the output slew rate. 20064057 FIGURE 10. Squarewave Oscillator To analyze the circuit, consider it when the output is high. That implies that the inverted input (VC) is lower than the non-inverting input (VA). This causes the C1 to get charged through R4, and the voltage VC increases till it is equal to the non-inverting input. The value of VA at this point is If R1 = R2 = R3 then VA1 = 2VCC/3 At this point the comparator switches pulling down the output to the negative rail. The value of VA at this point is If R1 = R2 = R3 then VA2 = VCC/3 The capacitor C1 now discharges through R4, and the voltage VC decreases till it is equal to VA2, at which point the comparator switches again, bringing it back to the initial stage. The time period is equal to twice the time it takes to discharge C1 from 2VCC/3 to VCC/3, which is given by R4C1.ln2. Hence the formula for the frequency is: F = 1/(2·R4·C1·ln2) www.national.com 14 LMV7271/LMV7275/ LMV7272 Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23-5 NS Package Number MF05A 5-Pin SC70-5 NS Package Number MAA05A 15 www.national.com LMV7271/LMV7275/LMV7272 Single & Dual, 1.8V Low Power Comparators with Rail-to-Rail Input Physical Dimensions inches (millimeters) unless otherwise noted (Continued) NOTE: UNLESS OTHERWISE SPECIFIED 1. EPOXY COATING 2. 63Sn/37Pb EUTECTIC BUMP 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION REMAINING PINS ARE NUMBERED COUNTERCLOCKWISE. 5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE HEIGHT. 6. REFERENCE JEDEC REGISTRATION MO-211, VARIATION BC. 8-Bump micro SMD NS Package Number TLA08AAA X1 = 1.514mm X2 = 1.514mm X3 = 0.600mm LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Americas Customer Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Asia Pacific Customer Support Center Email: [email protected] National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: [email protected] Tel: 81-3-5639-7560 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.