AN682 Using Single Supply Operational Amplifiers in Embedded Systems Author: Bonnie Baker Microchip Technology Inc. INTRODUCTION Beyond the primitive transistor, the operational amplifier (op amp) is the most basic building block for analog applications. Fundamental functions such as gain, load isolation, signal inversion, level shifting, adding and/or subtracting signals are easily implemented with an op amp. More complex circuits can also be implemented, such as the instrumentation amplifier, a current-to-voltage converter, and filters, to name only a few. Regardless of the level of complexity of the op amp circuit, knowing the fundamental operation and behavior of an op amp will save a considerable amount of up-front design time. Formal classes on this subject can be very comprehensive and useful. However, many times they fall short in terms of experience or common sense. For instance, a common mistake that is made when designing with op amps is neglecting to include bypass capacitors in the circuit. Op amp theory often overlooks this practical detail. If the bypass capacitor is missing, the amplifier circuit can oscillate at a frequency that “theoretically” doesn’t make sense. If textbook solutions are used, this can be a difficult problem to solve. This application note is divided into three sections. The first section lists fundamental amplifier applications, including design equations. These amplifier circuits were selected with embedded system integration in mind. The second section uses these fundamental circuits to build useful amplifier functions in embedded control applications. The third section identifies the most common singlesupply op amp circuit design mistakes. This list of mistakes has been gathered over many years of troubleshooting circuits with numerous designers in the industry. The most common design pitfalls can easily be avoided if the suggestions in this application note are used. 1998-2011 Microchip Technology Inc. FUNDAMENTAL OP AMP CIRCUITS The op amp is the analog building block that is analogous to the digital gate. By using the op amp in the design, circuits can be configured to modify the signal in the same fundamental way that the inverter and the AND and OR gates do in digital circuits. In this section, fundamental building blocks such as the voltage follower, non-inverting gain and inverting gain circuits are discussed, followed by a rail splitter, difference amplifier, summing amplifier and the current-to-voltage converter. Voltage Follower Amplifier Starting with the most basic op amp circuit, the buffer amplifier (shown in Figure 1) is used to drive heavy loads, solve impedance matching problems, or isolate high power circuits from sensitive, precise circuitry. VDD 2 VIN – 7 * MCP601 3 + VOUT 6 4 VOUT = VIN *Bypass Capacitor, 1 µF FIGURE 1: voltage follower. Buffer amplifier; also called a The buffer amplifier shown in Figure 1 can be implemented with any single-supply, unity-gain, stable amplifier. In this circuit, as with all amplifier circuits, the op amp must be bypassed with a capacitor. For singlesupply amplifiers that operate in bandwidths from DC to megahertz, a 1 µF capacitor is usually appropriate. Sometimes a smaller bypass capacitor is required, for amplifiers that have bandwidths up to the 10s of megahertz. In these cases, a 0.1 µF capacitor would be appropriate. If the op amp does not have a bypass capacitor or the wrong value is selected, it may oscillate. DS00682D-page 1 AN682 The analog gain of the circuit in Figure 1 is +1 V/V. Notice that this circuit has a positive overall gain, but the feedback loop is tied from the output of the amplifier to the inverting input. An all too common error is to assume that an op amp circuit that has a positive gain requires positive feedback. If positive feedback is used, the amplifier will most likely drive to either rail at the output. This amplifier circuit will give good linear performance across the bandwidth of the amplifier. The only restrictions on the signal will occur as a result of a violation of the input common-mode and output swing limits. These limitations are discussed in the third section of this application note, Amplifier Design Pitfalls. If this circuit is used to drive heavy loads, the amplifier that is actually selected must be specified to provide the required output currents. Another application where this circuit may be used is to drive capacitive loads. Not every amplifier is capable of driving capacitors without becoming unstable. If an amplifier can drive capacitive loads, the product data sheet will highlight this feature. However, if an amplifier cannot drive capacitive loads, the product data sheets will not explicitly say. Another use for the buffer amplifier is to solve impedance matching problems. This would be applicable in a circuit where the analog signal source has a relatively high impedance, as compared to the impedance of the following circuitry. If this occurs, there will be a voltage loss with the signal, as a consequence of the voltage divider between the source’s impedance and the following circuitry’s impedance. The buffer amplifier is a perfect solution to the problem. The input impedance of the non-inverting input of an amplifier can be as high as 1013 for CMOS amplifiers. In addition, the output impedance of this amplifier configuration is usually less than 10. VDD VDD – MCP601 VIN Gaining Analog Signals The buffer solves a lot of analog signal problems; however, there are instances in circuits where a signal needs to be gained. Two fundamental types of amplifier circuits can be used. With the first type, the signal is not inverted, as shown in Figure 3. This type of circuit is useful in single-supply(1) amplifier applications, where negative voltages are usually not possible. R1 R2 VDD – * VOUT MCP601 VIN + *Bypass Capacitor, 1 µF FIGURE 3: Op amp configured in a noninverting gain circuit. The input signal to this circuit is presented to the highimpedance, non-inverting input of the op amp. The gain applied by the amplifier circuit to the signal is equal to: R2 R1 This type of amplification is difficult to do with any level of accuracy in the best of situations. This precision measurement can easily be disrupted by changing the output current drive of the device that is doing the amplification work. An increase in current drive will cause self heating of the chip, which induces an offset change. An analog buffer can be used to perform the function of driving heavy loads, while the front-end circuitry can be used to make precision measurements. – EQUATION 1: R2 VOUT = 1 + ------ VIN R1 * * VOUT + + Buffer Precision Amplifier Typical values for these resistors in single supply circuits are above 2 k for R2. The resistor (R1) restrictions are dependent on the amount of gain desired versus the amount of amplifier noise and input offset voltage, as specified in the product data sheet of the op amp. *Bypass Capacitor, 1 µF FIGURE 2: Load isolation is achieved by using a buffer amplifier. Yet another use of this configuration is to separate a heat source from the sensitive precision circuitry, as shown in Figure 2. Imagine that the input circuitry to this buffer amplifier is amplifying a 100 µV signal. DS00682D-page 2 1. For this discussion, single supply implies that the negative supply pin of the operational amplifier is tied to ground and the positive supply pin is tied to +5V. All discussion in this application note can be extrapolated to other supply voltages where the single supply exceeds 5V or dual supplies are used. 1998-2011 Microchip Technology Inc. AN682 Once again, this circuit has some restrictions in terms of the input and output range. The non-inverting input is restricted by the common-mode range of the amplifier. The output swing of the amplifier is also restricted, as stated in the product data sheet of the individual amplifier. Most typically, the larger signal at the output of the amplifier causes more signal clipping errors than the smaller signal at the input. If undesirable clipping occurs at the output of the amplifier, the gain should be reduced. An inverting amplifier configuration is shown in Figure 4. With this circuit, the signal at the input resistor (R1) is gained and inverted to the output of the amplifier. The gain equation for this circuit is: EQUATION 2: Single Supply Circuits and Supply Splitters As was shown in the inverting gain circuit (Figure 4), single supply circuits often need a level shift to keep the signal between negative (usually ground) and positive supply pins. This level shift can be designed with a single amplifier and a combination of resistors and capacitors, as shown in Figure 5. Many times a simple buffer amplifier without compensation capacitors will accomplish this task. In other cases the level shift circuit will see dynamic or transient load changes, like the reference to an Analog-to-Digital (A/D) converter. In these applications, the level shift circuit must hold its voltage constant. If it does change, a conversion error might be observed. R2 R2 VOUT = – ------ VIN + 1 + ------ V BIAS R1 R1 VDD The ranges for R1 and R2 are the same as in the non-inverting circuit shown in Figure 3. R1 C2 T R3 R2 R1 * – VIN VDD – VS R2 VOUT C1 + VREF * VOUT MCP601 VBIAS * MCP601 R4 VIN ADC + *Bypass Capacitor, 1 µF FIGURE 4: Op amp configured in an inverting gain circuit. in single supply environments, a VBIAS is required to insure the output stays above ground. In single supply applications, this circuit can easily be misused. For example, let R2 equal 10 k R1 equal 1 k, VBIAS equal 0V, and the voltage at the input resistor R1 equal to 100 mV. With this configuration, the output voltage would be 1V. This would violate the output swing range of the op amp. In reality, the output of the amplifier would go as near to the ground as possible. The inclusion of a DC voltage at VBIAS in this circuit solves this problem. In the previous example, a voltage of 225 mV applied to VBIAS would level shift the output signal up 2.475V. This would make the output signal equal to (2.475V 1V) or 1.475V at the output of the amplifier. Typically, the average output voltage should be designed to be equal to VDD/2. 1998-2011 Microchip Technology Inc. *Bypass Capacitor, 1 µF R1 = 10 to 100 R2 = 10 to 100 FIGURE 5: A supply splitter is constructed using one op amp. This type of function is particularly useful in single supply circuits. A solid level shift voltage can easily be implemented using a voltage divider (R3 and R4), or a reference voltage source buffered by the amplifier. The transfer function for this circuit is: EQUATION 3: R4 VOUT = V DD ------------------- R3 + R 4 The circuit in Figure 5 has an elaborate compensation scheme, to allow for the heavy capacitive load C1. The benefit of this big capacitor is that it presents a very low AC resistance to the reference pin of the A/D converter. In the AC domain, the capacitor serves as a charge reservoir that absorbs any momentary current surges which are characteristic of sampling A/D converter reference pins. DS00682D-page 3 AN682 The Difference Amplifier Summing Amplifier The difference amplifier combines the non-inverting amplifier and inverting amplifier circuits of Figure 3 and Figure 4 into a signal block that subtracts two signals. The implementation of this circuit is shown in Figure 6. Summing amplifiers are used when multiple signals need to be combined by addition or subtraction. Since the difference amplifier can only process two signals, it is a subset of the summing amplifier. R1 R1 R2 V2 V4 VDD – R1 VDD R1 R1 * MCP601 V1 R2 V3 VOUT + R2 – V1 V2 * MCP601 VOUT + R1 R2 VREF *Bypass Capacitor, 1 µF *Bypass Capacitor, 1 µF FIGURE 6: Op amp configured in a difference amplifier circuit. FIGURE 7: Op amp configured in a summing amplifier circuit. The transfer function for this amplifier circuit is: The transfer function of this circuit is: EQUATION 4: EQUATION 5: R2 VOUT = V1 – V2 -------- + VR E F R1 R2 VOUT = V 1 + V 2 – V3 – V 4 ------ R1 This circuit configuration will reliably take the difference of two signals as long as the signal source impedances are low. If the signal source impedances are high with respect to R1, there will be a signal loss due to the voltage divider action between the source and the input resistors to the difference amplifier. Additionally, errors can occur if the two signal source impedances are mismatched. With this circuit, it is possible to have gains equal to, or higher than one. Any number of inputs can be used on either the inverting or non-inverting input sides, as long as there are an equal number of both with equivalent resistors. DS00682D-page 4 1998-2011 Microchip Technology Inc. AN682 Current-to-Voltage Conversion An op amp can be used to easily convert the signal from a sensor that produces an output current, such as a photodetector, into a voltage. This is implemented with a single resistor and an optional capacitor in the feedback loop of the amplifier, as shown in Figure 8. C2 R2 D1 VDD ID1 – Light * MCP601 VOUT + VBIAS Two circuits are shown in Figure 8. The top circuit is designed to provide precision sensing from the photodetector. In this circuit the voltage across the detector is nearly zero and equal to the offset voltage of the amplifier. With this configuration, current that appears across the resistor R2 is primarily a result of the light excitation on the photodetector. The photosensing circuit on the bottom of Figure 8 is designed for higher speed sensing. This is done by reverse biasing the photodetector, which reduces the parasitic capacitance of the diode. There is more leakage through the diode, which causes a higher DC error. R2 D1 Light As light impinges on the photo diode, charge is generated, causing a current to flow in the reverse bias direction of the photodetector. If a CMOS op amp is used, the high input impedance of the op amp causes the current from the detector (ID1) to go through the path of lower resistance R2. Additionally, the op amp input bias current error is low because it is CMOS (typically < 200 pA). The non-inverting input of the op amp is referenced to ground, which keeps the entire circuit biased to ground. These circuits will only work if the common mode range of the amplifier includes zero. VDD ID1 – * MCP601 VOUT + VOUT = R2 ID1 *Bypass Capacitor, 1 µF FIGURE 8: Current-to-voltage converter using an amplifier and one resistor. The top lightscanning circuit is appropriate for precision applications. The bottom circuit is appropriate for high-speed applications. 1998-2011 Microchip Technology Inc. DS00682D-page 5 AN682 USING THE FUNDAMENTALS Instrumentation Amplifier Instrumentation amplifiers are found in a large variety of applications, from medical instrumentation to process control. The instrumentation amplifier is similar to the difference amplifier in that it subtracts one analog signal from another, but it differs in terms of the quality of the input stage. A classic, three op amp instrumentation amplifier is illustrated in Figure 9. VDD V2 + ½ MCP602 * R3 EQUATION 6: 2R2 R 4 VOUT = V1 –V2 1 + --------- ------ + VREF RG R3 A second instrumentation amplifier is shown in Figure 10. In this circuit, the two amplifiers serve the functions of load isolation, and signal gain. The second amplifier also differentiates the two signals. R4 – RG VDD R2 R2 RG –½ MCP602 R3 + – ½ V1 The reference voltage of the difference stage of this instrumentation amplifier is capable of spanning a wide range. Most typically this node is referenced to half of the supply voltage in a signal supply application. A supply splitter, such as the circuit in Figure 5, can be used for this purpose. The transfer function of this circuit is: R1 VOUT – ½ MCP602 R4 VREF VDD VREF MCP602 + R2 * V2 R1 * R2 + –½ MCP602 *Bypass Capacitor, 1 µF FIGURE 9: An instrumentation amplifier can be designed using three amplifiers. The input op amps provide signal gain. The output op amp converts the signal from two inputs to a singleended output with a difference amplifier. With this circuit, the two input signals are presented to the high-impedance non-inverting inputs of the amplifiers. This is a distinct advantage over the difference amplifier configuration, when source impedances are high or mismatched. The first stage also gains the two incoming signals. This gain is simply adjusted with one resistor, RG. Following the first stage of this circuit is a difference amplifier. The function of this portion of the circuit is to reject the common mode voltage of the two input signals, as well as to differentiate them. The source impedances of the signals into the input of the difference amplifier are low, equivalent and well controlled. DS00682D-page 6 V1 + VOUT *Bypass Capacitor, 1 µF FIGURE 10: An instrumentation amplifier can be designed using two amplifiers. This configuration is best suited for higher gains (gain > 3 V/V). The circuit reference voltage is supplied to the first op amp in the signal chain. Typically, this voltage is half of the supply voltage in a single supply environment. The transfer function of this circuit is: EQUATION 7: R1 2R1 V OUT = V1 –V 2 1 + ------ + ---------- + V REF R2 R G 1998-2011 Microchip Technology Inc. AN682 Floating Current Source Filters A floating current source can come in handy when driving a variable resistance, like a Resistive Temperature Device (RTD). This particular configuration produces an appropriate 1 mA source for an RTD-type sensor; however, it can be tuned to any current. Band-pass and low-pass filters are very useful in eliminating unwanted signals prior to the input of an A/D converter. The low-pass filter shown in Figure 12 has two poles that can be configured for a Butterworth filter response. Butterworth filters have a flat magnitude response in the pass-band with good all-around performance. R1 R1 VDD – ½ MCP602 * 2 (VREF - 2VR1) R3 R4 100 k 909 k + VDD RL = 2.5 k – – ½ VREF = 2.5V + VR1 MCP602 R1 R1 + IOUT R1 VREF - 2VR1 RTD R1 = 25 k *Bypass Capacitor, 1 µF FIGURE 11: A floating current source can be constructed using two op amps and a precision voltage reference. With this configuration, the voltage of VREF is reduced via the first resistor (R1) by the voltage VR1. The voltage applied to the non-inverting input of the top op amp is VREF VR1. This voltage is gained to the amplifier’s output by two to equal 2(VREF VR1). Meanwhile, the output for the bottom op amp is presented with the voltage VREF 2VR1. Subtracting the voltage at the output of the top amplifier from the non-inverting input of the bottom amplifier gives: 2(VREF VR1) (VREF 2VR1), which equals VREF. The transfer function of the circuit is: EQUATION 8: V REF I OUT = ------------RL VIN R2 * MCP601 VOUT + 54.9 k 97.6 k C1 470 pF C2 100 pF Second Order: 10 kHz, Low-Pass Sallen Key Filter *Bypass Capacitor, 1 µF FIGURE 12: Low-pass, two-pole, active filters are easily designed with one op amp. The resistors and capacitors can be adjusted to implement other filter types, such as Bessel and Chebyshev. On the down side, there is some overshoot and ringing with a step response through this filter. This may or may not be an issue, depending on the application circuit requirements. The gain of this filter is adjustable with R3 and R4. Notice the similarities in this gain equation and the non-inverting amplifier shown in Figure 3. This type of filter is also referred to as an anti-aliasing filter, which is used to eliminate circuit noise in the frequency band above half of Nyquist of the sampling system. In this manner, these high-frequency noises, that would typically alias back into the signal path, are removed. The DC gain of the circuit in Figure 12 is: EQUATION 9: V OUT R4 ------------- = 1 + ------ V IN R3 1998-2011 Microchip Technology Inc. DS00682D-page 7 AN682 The band-pass filter shown in Figure 13 is configured with a zero and two poles, to accommodate speech applications. The single zero high-pass filter portion of this circuit is constructed with C1 and R1 in parallel with R2. Notice that R1 and R2 also create a supply splitter voltage at the non-inverting inputs of both of the amplifiers. This insures that both op amps operate in their linear region. The second amplifier, U2, in conjunction with the components R3, R4, C3 and C4 set a two pole corner frequency. This filter eliminates high-frequency noise that may be aliased back into the signal path. The signal gain of this circuit is: EQUATION 10: R3 R2 V OUT = V IN ------ -------------------- R 4 R1 + R2 For more information about low-pass filters, refer to AN699 – “Anti-Aliasing Analog Filters for Data Acquisitions Systems”. VDD R3 VDD C3 R1 C1 VIN – ½ MCP602 * + R4 REF R5 – ½ MCP602 C4 IN+ ADC IN– + R2 PIC12C509 *Bypass Capacitor, 1 µF FIGURE 13: Band-pass filters can be implemented with one op amp designed to perform the highpass function, and a second amplifier to perform the low-pass function. 24.9 k 24.9 k ¼ – MCP604 + 1 mA 2.49 k – ¼ MCP604 100 + 100 k REF 10 k ¼ MCP604 – ¼ 4.7 µF PIC12C509 – 100 k +IN ADC + MCP604 + VREF = 2.5 V 24.9 k 24.9 k 2.67 k 13 k 3.3 µF Pt100 2.2 µF Lead Compensation FIGURE 14: DS00682D-page 8 Gain = 6V/V Complete single supply temperature measurement circuit. 1998-2011 Microchip Technology Inc. AN682 Putting it Together AMPLIFIER DESIGN PITFALLS The circuit shown in Figure 14 utilizes four operational amplifiers along with a 12-bit A/D converter, to implement a complete single-supply temperature measurement circuit. The temperature sensor is an RTD that requires current excitation. The current excitation is supplied by the circuit described in Figure 11. The gain and anti-aliasing filter is implemented with the circuit shown in Figure 13. This section lists the common problems associated with using an op amp with a power supply and an input signal on a PC Board. It is divided into four categories: The voltage signal from the RTD is sensed by an amplifier, used in a combination of non-inverting and inverting configurations. Hopefully, the most common problems with op amp implementation have been addressed within this application note. The output of this amplifier is then sent to an amplifier configured as a two-pole, low-pass filter in a gain of +6 V/V. A gain of six was chosen in order to comply with the input range of the A/D converter. Assuming the sampling frequency of the A/D converter is 75 kHz, which is also know as the Nyquist frequency, the cut-off frequency of the anti-aliasing filter (U4) is set to 10 kHz. This allows plenty of bandwidth for the filter to attenuate the signal prior to half of Nyquist. The A/D converter is a 12-bit Successive Approximation Register (SAR) converter that is interfaced to the PIC12C509 microcontroller. • • • • General Suggestions 1. 2. 3. 4. 5. 6. 1998-2011 Microchip Technology Inc. General Suggestions Input Stage Problems Bandwidth Issues Single Supply Rail-to-Rail Be careful of the supply pins. Don’t make them too high per the amplifier specification sheet, and don’t make them too low. High supplies will damage the part. In contrast, low supplies will not bias the internal transistors and the amplifier won’t work or it may not operate properly. Make sure the negative supply (usually ground) is actually tied to a low-impedance potential. Additionally, make sure the positive supply is the voltage you expect when it is referenced to the negative supply pin of the op amp. Placing a voltmeter across the negative and positive supply pins verifies that you have the right relationship between the pins. Ground cannot be trusted, especially in digital circuits. Plan your grounding scheme carefully. If the circuit has a lot of digital circuitry, consider separate ground and power planes. It is very difficult, if not impossible, to remove digital switching noise from an analog signal. Decouple the amplifier power supplies with bypass capacitors as close to the amplifier as possible. For CMOS amplifiers, a 0.1 µF capacitor is usually recommended. Also decouple the power supply with a 10 µF capacitor. Use short lead lengths to the inputs of the amplifier. If you have a tendency to use the white perf boards for prototyping, be aware that they can cause noise and oscillation. There is a good chance that these problems won’t be a problem with the PCB implementation of the circuit. Amplifiers are static sensitive! If they are damaged, they may fail immediately or exhibit a soft error (like offset voltage or input bias current changes) that will get worse over time. DS00682D-page 9 AN682 Input Stage Problems REFERENCES 1. • Sergio Franco – “Design with Operational Amplifiers and Analog Integrated Circuits”, McGraw Hill, 2001 • Thomas Frederiksen – “Intuitive Operational Amplifiers: From Electron to Op Amp”, McGraw Hill, 1988 • Williams, Jim – “Analog Circuit Design”, Butterworth-Heinemann, 1991 • Bonnie Baker – “AN699 – Anti-aliasing Analog Filters for Data Acquisition Systems”, Microchip Technology Inc., DS00699, 1999 • Bonnie Baker – “AN722 – Operational Amplifier Topologies and DC Specifications”, Microchip Technology Inc., DS00722, 1999 • Bonnie Baker – “AN723 – Operational Amplifier AC Specifications and Applications”, Microchip Technology Inc., DS00723, 2000 2. 3. Know what input range is required from your amplifier. If either inputs of the amplifier go beyond the specified input range, the output will typically be driven to one of the power supply rails. If you have a high gain circuit, be aware of the offset voltage of the amplifier. That offset is gained with the rest of your signal, and it might dominate the results at the output of the amplifier. Do not use rail-to-rail input stage amplifiers, unless it is necessary. By the way, they are only needed when a buffer amplifier circuit is used or possibly an instrumentation amplifier configuration. Any circuit with gain will drive the output of the amplifier into the rail before the input has a problem. Bandwidth Issues 1. 2. Account for the bandwidth of the amplifier when sending signals through the circuit. You may have designed an amplifier for a gain of 10 and find that the AC output signal is much lower than expected. If this is the case, you may have to look for an amplifier with a wider bandwidth. Instability problems can usually be solved by adding a capacitor in parallel with the feedback resistor around the amplifier. This does mean typically and not always. If an amplifier circuit is unstable, a quick stability analysis will show the problem and, probably, the solution. Single Supply Rail-to-Rail 1. 2. 3. Op amp output drivers are capable of driving a limited amount of current to the load. Capacitive loading an amplifier is risky business. Make sure the amplifier is specified to handle any loads that you may have. It is very rare that a single-supply amplifier will truly swing rail-to-rail. In reality, the output of most of these amplifiers can only come within 50 to 200 mV from each rail. Check the product data sheets of your amplifier. DS00682D-page 10 1998-2011 Microchip Technology Inc. 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Analog-for-the-Digital Age, Application Maestro, chipKIT, chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 1998-2011, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. ISBN: 978-1-61341-141-4 Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. 1998-2011 Microchip Technology Inc. DS00682D-page 11 Worldwide Sales and Service AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://www.microchip.com/ support Web Address: www.microchip.com Asia Pacific Office Suites 3707-14, 37th Floor Tower 6, The Gateway Harbour City, Kowloon Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 India - Bangalore Tel: 91-80-3090-4444 Fax: 91-80-3090-4123 India - New Delhi Tel: 91-11-4160-8631 Fax: 91-11-4160-8632 Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 India - Pune Tel: 91-20-2566-1512 Fax: 91-20-2566-1513 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Japan - Yokohama Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Atlanta Duluth, GA Tel: 678-957-9614 Fax: 678-957-1455 Boston Westborough, MA Tel: 774-760-0087 Fax: 774-760-0088 Chicago Itasca, IL Tel: 630-285-0071 Fax: 630-285-0075 Cleveland Independence, OH Tel: 216-447-0464 Fax: 216-447-0643 Dallas Addison, TX Tel: 972-818-7423 Fax: 972-818-2924 Detroit Farmington Hills, MI Tel: 248-538-2250 Fax: 248-538-2260 Indianapolis Noblesville, IN Tel: 317-773-8323 Fax: 317-773-5453 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 Santa Clara Santa Clara, CA Tel: 408-961-6444 Fax: 408-961-6445 Toronto Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509 Australia - Sydney Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 China - Beijing Tel: 86-10-8569-7000 Fax: 86-10-8528-2104 China - Chengdu Tel: 86-28-8665-5511 Fax: 86-28-8665-7889 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 China - Chongqing Tel: 86-23-8980-9588 Fax: 86-23-8980-9500 Korea - Seoul Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934 China - Hangzhou Tel: 86-571-2819-3180 Fax: 86-571-2819-3189 Malaysia - Kuala Lumpur Tel: 60-3-6201-9857 Fax: 60-3-6201-9859 China - Hong Kong SAR Tel: 852-2401-1200 Fax: 852-2401-3431 Malaysia - Penang Tel: 60-4-227-8870 Fax: 60-4-227-4068 China - Nanjing Tel: 86-25-8473-2460 Fax: 86-25-8473-2470 Philippines - Manila Tel: 63-2-634-9065 Fax: 63-2-634-9069 China - Qingdao Tel: 86-532-8502-7355 Fax: 86-532-8502-7205 Singapore Tel: 65-6334-8870 Fax: 65-6334-8850 China - Shanghai Tel: 86-21-5407-5533 Fax: 86-21-5407-5066 Taiwan - Hsin Chu Tel: 886-3-6578-300 Fax: 886-3-6578-370 China - Shenyang Tel: 86-24-2334-2829 Fax: 86-24-2334-2393 Taiwan - Kaohsiung Tel: 886-7-213-7830 Fax: 886-7-330-9305 China - Shenzhen Tel: 86-755-8203-2660 Fax: 86-755-8203-1760 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 China - Wuhan Tel: 86-27-5980-5300 Fax: 86-27-5980-5118 Thailand - Bangkok Tel: 66-2-694-1351 Fax: 66-2-694-1350 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 UK - Wokingham Tel: 44-118-921-5869 Fax: 44-118-921-5820 China - Xian Tel: 86-29-8833-7252 Fax: 86-29-8833-7256 China - Xiamen Tel: 86-592-2388138 Fax: 86-592-2388130 China - Zhuhai Tel: 86-756-3210040 Fax: 86-756-3210049 DS00682D-page 12 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Korea - Daegu Tel: 82-53-744-4301 Fax: 82-53-744-4302 05/02/11 1998-2011 Microchip Technology Inc.