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Selecting the right op amp – Understanding the specifications and navigating through the minefield of products Bob Lee,

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**Where to look for op amps ??**

Op amps are the fundamental analog building block and are most commonly found between the analog input or sensor and the ADC and between the DAC and the analog output or actuator

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**What are op amps used for?**

Some of the uses for op amps Providing gain to small signals Filtering Level shifting ADC driver DAC buffer Current to voltage converter(transimpedance amplifier) Current source(transconductance amplifier) Common mode noise rejection Peak voltage detection Sample and hold Absolute value circuit

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**So what’s so difficult about op amp selection ?**

Selecting the right op amp for your customers application, just how hard can that be ? The first problem is that all op amps basically look the same, with 5 pins + - +Vcc -Vcc All that differentiates one from another are the specifications – normally many pages of these

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Op Amp specifications A typical op amp specification table is long and complicated. All op amp specifications are a tradeoff, improving one specification means relaxing another Generally an op amp is not chosen on any one specification but a combination of them The ‘perfect op amp’ doesn’t exist ! In order to be able to effectively support these products and help customers with product selection we need to be able to identify which parameters are most important and to have at least a basic understanding of these

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**Ideal Operational Amplifier**

Using our derived concepts of how an op amp operates and assuming an ideal op amp we can derive the theoretical gain equation for Vout/Vin for an inverting op amp configuration. With infinite Aol and an external feedback network the op amp +input and –input are forced to equal each other. In the inverting gain configuration the +input is ground and therefore the +input is forced to zero volts or to “virtual ground”. From nodal analysis we easily derive the standard inverting gain equation for an op amp of Vout/Vin = - RF/RI.

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**Ideal Operational Amplifier**

Using our derived concepts of how an op amp operates and assuming an ideal op amp we can derive the theoretical gain equation for Vout/Vin for a non-inverting op amp configuration. With infinite Aol and an external feedback network the op amp +input and –input are forced to equal each other. From nodal analysis we easily derive the standard non-inverting gain equation for an op amp of Vout/Vin = 1 + RF/RI.

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**Limitation of the exercise**

In order to keep things simpler we will limit this discussion to general purpose op amps(‘precision’ op amps) This covers to majority of op amp applications The class we are not discussing is high speed op amps (> 100MHz bandwidth) Much of what follows also applies to high speed op amps as well However, high speed op amps also have many other important factors to consider

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**Keeping it simple Op amp specifications fall into two classes**

DC parameters AC parameters Generally speaking, customer applications require good DC performance or good AC performance but not both. Appreciating which of these classes of specifications are going to be important is a good first step Very often it will be obvious which is going to be most important from the application, but if in doubt, then just ask the customer !

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DC or AC performance ? Applications that will requires good DC performance generally have small amplitude, low bandwidth signals. These include:- Most temperature measurement, thermocouple, RTD, PT100, thermistor Pressure measurement/strain gauge ECG/EEG etc Voltage/current Applications that require good AC performance have wide bandwidth signals and generally care more about peak to peak amplitude rather than about absolute voltage levels. Examples include:- Audio – you can’t hear DC Any waveform analysis Vibration monitoring Cable detection

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**DC Specifications The main DC specifications are :-**

Offset voltage (Vos) and drift (dVos/dt) These tend to be related, parts with a low offset also have a low offset drift Input bias current (Ib) A key careabout in some applications, such as photodiodes but generally not a major concern for most customers Noise For low frequency applications its likely to be low frequency, 1/f noise that’s of most concern Lets looks at each of these in more detail

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**Input Offset Voltage (Vos) Vout Error**

25C Specs in Table Often Histograms show distribution of Vos Polarity is + or – Input Offset Voltage is the inherent offset voltage due to non-ideal devices and mis-matches inside of the real op amp. The effect of this can be see with the op amp in inverting configuration and the +input grounded. Ideally Vout would be zero volts. For the real op amp Vout becomes Vos times closed loop gain. The input offset voltage can be either positive or negative. Often the data sheet will include an Offset Voltage Distribution histogram to indicate how the Offset Voltage typically varies over a wide number of units.

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**Input Offset Voltage (Vos) Drift Vout Error**

Vos Drift Specs in Table Often Histograms show distribution of Vos Drift Polarity is + or - Offset Voltage Drift is an additional input offset voltage which is added to Vos depending upon the operating temperature of the op amp relative to 25C. A distribution of the Vos Drift may be shown in histogram form to indicate how Vos Drift will typically be different over a wide number of parts.

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**Input offset voltage reduction**

Remember this ? The untrimmed offset on the LM741 is 6mV and the drift is 15uV/C ! Hence the need for the trim pot Laser trimming replaces the offset trim pot with internal laser trimmed resistors and enables an offset of 20uV and drift of 0.1uV/C(OPA277) – but at a cost E-trim replaces the laser trimmed resistors with trim fuses, blown once at the factory during test to produce cost effective parts with an offset of 25uV and drift of 0.26uV/C (OPA376) Auto zero and chopping techniques reduce this to 5uV and 0.001uV/C (LMP2021)

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**Input Bias Current (Ib), Input Offset Current (Ios)**

Input bias current is the input current into or out of the +input and –input of the op amp required for the input stages of the op amp to function properly. Unless specified the current could be either into or out of the op amp inputs. Industry standard definition of input bias current is the average of current into the +input and –input. Input offset current is defined as the difference between the input bias current of the +input and the input bias current of the –input. Ib = 5pA Ios = 4pA Polarity is + or – Current into or out of inputs

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**Input Bias Current (Ib), Input Offset Current (Ios)**

25C Specs in Table Often Curves for Temperature Specs Polarity is + or – Input Bias Current and Input Offset Current are usually specified in the Electrical Characteristics Table for 25C operation. Often the change in input bias current over temperature is shown as a curve in the Typical Characteristics

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**Input Bias Current (Ib) Vout Error**

2 1 3 4 Input bias current flows through any resistance on the +input or –input of the op amp. This current flow creates an offset voltage on the input to the op amp and will be multiplied by the op amp closed loop gain as an error voltage at the output. To analyze this additional offset voltage set all voltage sources in the circuit to zero volts. Set the op amp output to zero volts since it is viewed as low impedance at DC. For the non-inverting op amp configuration this results in the Ib- flowing through the parallel combination of RF and RI. Ib+ flows through the input source resistance, Rs. Two offset voltages, Vb+ and Vb-, on the op amp inputs can be created. The equivalent offset voltage error due to Ib can be lumped into Vb = Vb+ - Vb- and this lumped offset voltage is gained up as an error on Vout by the closed loop gain of the op amp.

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Op Amp noise Calculating the total noise generated by an op amp and the associated resistors is a complex subject and outside of the scope of this presentation. However there are some things we can do to make it easier In the same way that most customers are more concerned about offset voltage rather than input bias current, most customers are more concerned about voltage noise than they are current noise Its important to realise that op amps have two voltage noise specs The broadband noise – that’s the one that headlines in the datasheets. Given in nV/rt Hz The 1/f noise – probably more important in the low frequency applications where DC accuracy is the main careabout. Given as an rms or peak to peak voltage, 0.1 – 10Hz The left hand curve is the voltage spectral density curve. It has a 1/f and broadband region. The right hand curve is the open loop gain (Aol) curve. The bandwidth of the circuit is determined by the Aol curve because there is no other filter. The calculation shows that the bandwidth is 158kHz; this can also be seen graphically.

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**Op Amp noise spectrum 50nV/rt-Hz 5nV/rt-Hz The 1/f noise**

The broadband noise 1/f noise corner, the point at which the 1/f noise starts to dominate

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Good 1/f noise example

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**AC Specifications The main AC specifications of on op amp are:-**

Gain Bandwith Product - determines the small signal bandwidth Slew Rate - determines the large signal bandwidth Noise, now it’s the broadband noise that will dominate rather than the 1/f noise

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**Gain-Bandwidth Product = UGBW (Unity Gain Bandwidth)**

Open Loop Gain & Phase Open-Loop Voltage Gain at DC Linear operation conditions NOT the same as Voltage Output Swing to Rail Open Loop Gain & Phase will be used to compute gain accuracy at any frequency of interest as well as how stable the op amp is when the loop is closed with feedback for a resistive load. Open Loop Gain is usually measured with Vout a specified drop away from the power supply rails. The op amp may be capable of swinging closer to the rails than where the Open Loop Gain is specified but the op amp will not have as high of open loop gain and other non-linearities may occur. Gain-Bandwidth Product = UGBW (Unity Gain Bandwidth) G=1 Stable Op Amps 5.5MHz

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**Bandwidth, Small Signal, Bw**

Op-Amp small signal bandwidth is shown on Bode Plot. The -3 dB point for closed loop gain of 10 can be determined using the Bode Plot.

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**The importance of loop gain**

Loop gain is the difference between the desired closed loop gain (i.e. that set by the feedback resistors) and the op amps open loop gain (its gain in the absence of feedback)

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**The importance of loop gain**

For the part shown on the previous slide, the gain bandwidth product was 5.5Mhz. At a gain of 20db(x10) this implies a small signal bandwidth of 550kHz However, at 550kHz, the loop gain has fallen to zero, it’s the point at which the open loop gain and closed loop gain curves cross Its loop gain that enables an op amp to do its job and for AC applications this primarily means reduce distortion. No loop gain = no distortion reduction In order to have some loop gain always in hand we need to use an op amp with much more bandwidth than is implied by multiplying gain by required bandwidth, to get to a gain bandwidth figure(GBW) 10 x GBW gives 20 dB loop gain in hand – still not very much ` 100 x GBW gives 40 dB – that's more like it

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Loop gain example The customer has an audio application and requires a 20kHz bandwidth. He also requires a gain of 20dB(x10) The minimum gain bandwidth required is therefore 200kHz, however as we have just seen, this would leave no loop gain at 20kHz To retain 20dB of loop gain at 20kHz, we therefore need a gain bandwidth of 2Mhz – this should be considered the medium Better would be to go for 40dB of loop bandwidth, this implies a gain bandwidth of 20MHz. Notice, the difference between the customers system bandwidth (20kHz) and the gain bandwidth of the op amp required (20MHz)

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**Small signal and large signal requirements**

The previous discussion on loop gain and bandwidth assumes small signal swings The means that we are assuming that the op amps output stage can actually swing (slew) fast enough to support a sine wave of that frequency. Keeping the signals small ensures this Slew rate may well limit the output peak to peak voltage swing at high frequencies. We need to check this next

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**Slew Rate Slew Rate Measurement: 10% to 90% of Vout**

Slew Rate is a large signal transfer function of an op amp. It is a rate-of-change of the output for a large step voltage on the input. The accepted measurement points for delta Vout are 10% and 90%. The delta t (time) it takes to transition between these two voltage points is used to compute slew rate.

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Full Power Bandwidth Remember that figure given above is the minimum slew rate required. For low distortion, expect to need x5 to x10 this figure Slew Rate is also used to determine the frequency and magnitude limitations of passing a large signal sinewave through an op amp. Maximum Output Voltage vs Frequency plot shows these frequency-amplitude limitations. This curve is also know as Power Bandwidth or Full Power Bandwidth curve.

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**Broadband noise 50nV/rt-Hz The broadband noise 5nV/rt-Hz**

Its now the broadband noise that care about, the number on the first page of the datasheet Measured in nV/rt Hz Still not as simple as it seems since we have to understand what is meant by the bandwidth(depends on the filter order of the system) and may in any case be dominated by resistor noise

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**Resistor Noise – Thermal Noise**

Noise Spectral Density vs. Resistance en density = √ (4kTKR) Noise Spectral Density vs. Resistance nV/rt-Hz Peak to Peak noise, such as that as seen on an oscilloscope can be estimated by applying a scale factor to RMS noise calculations. This chart was generated using the equation given in the last slide. Note that the equation was divided by the square root of bandwidth to give a spectral density. This chart is useful because it gives you a quick way of comparing resistor noise to op-amp noise. Most op-amps specify noise in nV/rtHz. So, for example a very low noise amplifier may have a 1nV/rtHz noise. This corresponds to approximately 70ohms on the curve above. Thus, for this example, op-amp you should try to keep resistance below 70ohms. Resistance (Ohms) Low noise circuits need low value resistors !

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**Selecting the right part**

The main DC and AC specifications are the first step to selecting the right op amp for the job. But its not the end of the story ! We now have to consider the power supplies and the input and output voltage swings with respect to the rails We need to know the supply voltage(s) the customer intends to use and his expectation on output voltage swing and input voltage range

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**Power Supplies +Vcc + - -Vcc**

An op amp doesn’t have a ground pin, it has no knowledge of where ground is An op amp only cares about the total voltage across the supply pins As far as an op amp is concerned, +/15V is the same as 0-30V and +/-5V is the same as 0 -10V We do have to take care that the inputs operate within the allowed voltage range which will be with respect to –Vcc for the lower limit and with respect to +Vcc for the upper limit. Not with respect to ground Likewise we have to ensure that the op amp can provide the required output swing which will be with respect to it’s supply rails

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Rail to Rail I/0 ‘Rail to rail inputs’ and ‘Rail to Rail outputs’ are terms much beloved by marketing and customers often ask for these features The problem is that ‘rail to rail’ means different things to different people, so always ask the customer to be very specific :- What supply voltage(s) is the op amp operating from ? How close to the –ve rail do the inputs need to operate ? How close to the +ve rail do the inputs need to operate ? What’s the load and where is it connected ? Then :- How close to the –ve rail does the output have to swing ? How close to the +ve rail does the output have to swing ?

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**Output Voltage Swing - Rail-to-Rail Output**

Output Swing refers to how close the amplifier can swing to the power supplies (rails). It depends on the type of Op-Amp... OPA376 + - V+ V- Rload Vin Vout Positive Rail Negative Rail and the size of the load.

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**Voltage Output Swing From Rail**

Loaded Vout swing from Rail Higher Current Load Further from Rail Note, its with respect to the rail Voltage Output Swing from Rail is an indication of output voltage swing capability of the op amp as it has to provide current into a load. The larger current required for the load the further away from the rails the op amp will swing. This curve is based on saturating the output transistors to get as close to the rails as possible. If one is trying to operate on a point directly on top of one of these curves then there is potential for higher gain errors as this is in anon-linear region of the output stage of the op and Aol is degraded.

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Output stage trends CMOS op amps, intended for singe supply operation(typically 5V or less) have always had good output swing to the rails Bipolar and FET input op amps, intended for supplies of up to +/15V, have in the past had very poor output swing to the rails Normally these parts don’t get closer than 2-3V from the rails This restricts the use of these parts for lower voltage applications More modern parts are much better in this respect and this enables the parts to be used for both high and low supply voltage applications

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**Wide supply voltage range, OPA171**

For a high voltage (36V) op amp, these are very good figures and allow its use over a wide supply voltage range. The part is useful on +/-15V and single 3.3V rails This actually confuses the selection process since for a low voltage application, you may well have to check out some of the new high voltage parts as well ! The OPAx171 is a very versatile, cost effective op amp, happy on single 5V as well as +/- 15V

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**Input Voltage Range - Rail-to-Rail Input**

Input Voltage Range refers to how close the input is allowed to get to the rails. Positive Rail Rail to rail op amps can exceed both rails by 300 mV. OPA376 + - V+ V- Most Bipolar and JFET Op-Amps can not get to the rails, some can get to one. Vout Vin Negative Rail

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**Input voltage range With respect to the rails again**

This is the OPA171 who’s output voltage range we looked at earlier. Although its output voltage swing will allow a wide supply voltage range, we would still have to be careful about the input voltage range Remember that in the inverting configuration, the op amp inputs stay at the same voltage irrespective of the input signal This makes the inverting configuration the low distortion option The non-inverting configuration is much more difficult since the op amp inputs move with the signal, more so at low gains, the worst case being a unity gain buffer

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**Unity gain buffer, the problem**

+ - +Vcc -Vcc Vin Vout For the unity gain buffer, the swing on Vout is the same as the swing on Vin and both op amp inputs need to be able to accommodate this. If Vout has a large swing (‘rail to rail’), then the inputs need to be able to swing rail to rail

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**Inputs outside of the rails**

Most op amps can operate with inputs slightly outside of the rails. Going further outside of the rails, will turn on the internal ESD cells. With no current limiting this will damage the cells and damage the part Provided however that the current is limited to few mA(<10mA), input signals outside of the rails are acceptable. The part won’t operate correctly but it won’t sustain damage or latch up Sometimes arises as a power on sequencing issue Sometimes a voltage spikes issue

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**How about the current consumpsion ?**

What we are concerned with here is current drawn by the op amp from the supplies Early in this presentation we said that all op amp specifications are a compromise, playing off one spec against another This is very true of quiescent current. Don’t expect low current op amps to have the best performance in other aspects, in particular bandwidth and noise Remember that the load will also draw a current from the supply as well

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So what’s left Almost home a dry on op amp selection, what’s left to think about ? Other features ? EMI/RFI hardening. Many of the HPA and SVA op amps now have this feature. This can make life much easier for your customer and be a key selling point Package type All modern op amps are available in miniature packages but standard SO-8 packages may still be required when second sourcing Price Pricing is outside of the scope of this presentation but many new op amps are available as two part numbers, one being a lower cost option (typically relaxed offset spec)

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**OP Amps and EMI EMI/RFI may cause Vos shifts, noise**

Most dominant if seen by OPA inputs Remedy: External Rs and Cs to Band-limit New OPA designs series Rs internally sized to have defined High-f roll-off Improved and predicable EMI rejection

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**Newer Op-amps have built-in EMI filtering(EMIRR)**

Reducing an operational-amplifier’s EMI susceptibility now may include an integrated input filter. A low-pass filter is created by using the input differential pair junction capacitances, and a small series resistances in the input paths. Since the differential pair exhibits both differential and common-mode capacitances the filter is effective for filtering both types of EMI. An equivalent filter is shown having total differential and common-mode capacitances of 2.5pF and 5.0pF, respectively, and 1kΩ series input resistors. The filter response plot reveals a first-order, low-pass response, and a -3dB cutoff frequency of 32MHz. Both differential and common-mode cutoff frequencies are the same for the capacitance and resistance values used. The actual unity-gain bandwidth of the operational-amplifier is commonly be a few Megahertz, so the low-pass filter cutoff frequency is well above it. That prevents the EMI filter from becoming a factor in the operational-amplifier’s normal AC response. However, the cutoff frequency is low enough to be effective in filtering of 100MHz and higher. The series resistances are selected to set the filter’s cutoff frequency, yet must be keep low in value so as not to degrade the amplifier’s low noise performance.

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**HPA LV Op Amps with internal EMI filtering**

OPA376/377 Family This Low-Noise, Precision, 5.5MHz device Input filtering with the corner at approximately 75 MHz OPA378 Family Lowest noise, Zero-Drift Op Amps with a GBW of 900KHz EMI input filter with a corner frequency of 25MHz OPA369 Family This nano-Power Op Amp has superb DC performance EMI input filtering with a corner frequency of 25MHz. Great for low power, EMI sensitive applications! OPA333, OPA330 and INA333 Zero-Drift devices with outstanding DC precision. EMI inputs filters have a corner frequency of 8MHz. OPA334/335 Zero-Drift models with great DC performance with 2MHz GBW EMI filtering with fc =30MHz EMI

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**HPA 36V Op Amps with EMI Filtering**

OPA170, OPA2170 & OPA4170 (RTM 2Q11) Low 110µA with 1.2MHz bandwidth EMI input filter with a corner frequency of 75 MHz OPA171, OPA2171 & OPA4171 (Available Now) Medium 475µA with 3MHz bandwidth EMI input filter with a corner frequency of 25MHz OPA188, OPA2188 & OPA4188 (RTM 3Q11) Precision Zero-Drift Amplifier 25µV Offset Voltage & 0.1µV/°C EMI input filter with a corner frequency of 25MHz. EMI

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**SVA EMIRR Application Note**

AN-1698 "A specification for EMI Hardened Op Amps" A

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**Smaller packages, OPAx171 Packaging options:**

Single: SO-8, SOT23-5, SOT553 Dual: SO-8, MSOP-8, VSSOP-8 Quad: SO-14, TSSOP-14 SOT23-5 3 x 3 x 1.45 VSSOP 3.1 x 2 x 0.9 SOT553 1.6 x 1.6 x 0.6

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Lower cost options Some parts are now offered with one part number for the high performance option and a different part number for a more cost effective option. Normally the main difference is in DC specifications such as offset voltage Examples High performance Cost effective OPAx OPAx141 OPAx OPAx330 OPAx OPAx377 OPAx OPAx322

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**? TLC OPA TLV TL Where to start TLE LMV THS LM LMP LME LPV TPA**

The op amp minefield ! TLC OPA TLV TL ? Where to start TLE LMV THS LM LMP LME LPV TPA

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**Operational Amplifier Naming**

OPA x 333 Channel count 0: No character 2: dual 3: triple 4: quad 1xx : JFET Input 2xx: Bipolar 3xx: CMOS 4xx: High Voltage 5xx: High Outputcurrent 6xx: High Speed 7xx: High Voltage CMOS (12V) 8xx: High Speed (different process than 6xx) OPA Operational Amplifier INA Instrumentation Amplifier and Difference Amplifier LOG Logarithmic Amplifier XTR Current Loop Driver PGA Programable Gain Amplifier (digital) VCA Voltage Controlled Variable Gain Amplifier IVC Current to Voltage Converter

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**Operational Amplifier Naming**

TLV Low Voltage CMOS TLC CMOS TLE Bipolar / BiFET TL Bipolar THS High Speed TPA Audio Power Amps LM LMV NE MC Or could be an SVA part ! Commodity Second Sources

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**Operational Amplifier Naming**

THS xy 01 Amplifier Type 30 = Current Feedback 31 = Current Feedback 40 = Voltage Feedback 41 = Fully Differential 42 = Voltage Feedback 43 = Fast Voltage Feedback 45 = Fully Differential 46 = Transimpedance 60 = Line Receiver 61 = Line Driver 73 = Programmable Filters THS=High Speed

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**Operational Amplifier Naming**

TL x 278 y Amp Class V = Low Supply Voltage C = 5V CMOS E = Wide Supply Voltage Channels and Shutdown Options 0 = Single with Shutdown 1 = Single 2 = Dual 3 = Dual with Shutdown 4 = Quad 5 = Quad with Shutdown

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**SVA Amplifier Families Prefixes**

High Precision Pure CMOS HiSpeed High Speed to Micro Power Micro Power Low Power up to 32VS The last digit indicated singe/dual/quad, i.e LMC6442 is a dual

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Where to start looking ? One starting point would be the applications block diagrams in ESP

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Block diagram example Click on the op amp symbol for initial suggestions of parts for this application

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**ESP Master Presentation**

While not the definitive way of selecting the right part, the majority of op amp selections can be done by using the XY charts highlighted in the Master Presentation slide above. These will at least give a starting point to be going from. The first step is to establish the supply voltage. 5V or less and look at the low voltage charts, above 5V and it’s the high voltage chart The next step is to establish if possible which of the five categories is most appropriate

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**Low Voltage - Low Offset Voltage**

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**Parametric search(ESP or web)**

These are the high speed op amps, Separate from the precision parts covered in this presentation Click here to see all precision op amps Or choose one of these subsets We also have op amps from the HVAL BU These are covered in a separate parametric search

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**The parametric search page**

Also other collateral here Remember that one option is to download the table to Excel and then sort and search it yourself.

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**Parametric Search – Excel download**

Add your own filters or sorting

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Some key op amps

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**Best in class products from the SVA portfolio**

The SVA portfolio introduces some parts with a performance that TI didn’t previously have. Some of the key parts here are :- Lowest offset voltage LMP2021 (5uV max) Lowest bias current LMP7721 (3 fA typical, 20fA max guaranteed) Lowest quiescent current LMP521(400nA max) Lowest noise LME49990(0.9nV/rt Hz)

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**LMP2021/2022 Low Noise Zero Drift Amplifier**

Features Benefits Lowest Noise Auto Zero Amplifier at Av>500 Ultra low drift at 0.004uV/deg C typ EMI Hardened Increased immunity to RFI/EMI disturbances Low Noise Density 11nV/rt Low Vos 5uV max Low Drift TcVos 0.02uV/deg C max EMI Hardened Applications Precision Instrumentations Amps Battery Powered Instrumentation Thermocouple Amplifiers Bridge Amplifiers EVM PART # LMP2021EVAL

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**LMP7721 3 Femptoampere Input Bias Current Precision Op Amp Features**

Benefits Ultra ultra Low Input Bias Current 3 fA typical, 20fA max guaranteed Wide operating supply voltage 1.8 to 5.5V Low Supply Current 1.5mA max Low Vos only 180uV max Low Noise Density 7nV/rt Hz Offers precision performance at very low power Guaranteed tempco means precision over temperature CMOS inputs great for high impedance sources Applications Precision Instrumentation Amplifiers Battery Powered Medical Instruments High Impedance Sensors Electrometers EVM PART # LMP7721MAEVALMF/NOPB

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**LPV511/521/531 Micropower/Nanopower Operational Amplifiers**

Features Benefits LPV uA supply current, 2.7V to 12V operation Rail to Rail Input and Output SC-70 package LPV521 World’s Lowest supply current 400nA max Operates on 1.6V to 5.5V ( V) LPV531 Programmable Isupply 5uA to 435uA TSOT23-6 package Microwatt Power Consumption Long Battery Life in Portable Applications Programmable supply current (LPV531) Minimum board area Applications Battery powered systems Security systems Micropower thermostats Solar powered systems Portable instrumentation Micropower filter Remote sensor amplifier EVM PART /NOPB

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**LME49990 Ultra Low-Distortion, Low- Noise Audio Op Amp**

Voltage Noise Density Winning Features Extremely low 1/f noise enables flicker free operation Easily drives 600W loads PSRR and CMRR exceed 100dB Output short-circuit protection Winning Specs GBW 110MHz Slew Rate +22V/ms THD % Input Noise 0.9nV/rtHz Operating Voltage + 5V to + 18V PSRR 144dB CMRR 137dB LME49990 is the flagship high performance op amp in our portfolio. It is an industry leading device with lowest THDN of % and sub one nV noise density (best-in-class) and PSRR and CMRR well exceeding the 100dB. You can take a look at the specs on the datasheet but I’d like to point your attention towards its extremely low 1/f noise that is depicted in this graph and as you can see, unlike competitive devices, the noise level does not take a sharp upturn once it hits the corner frequency and as a result it will lead to flicker-free operation. You can take a look at the target applications including ultra high quality audio amplification, high fidelity filters, medical ultrasound preamps, and sigma-delta converter buffers. So really, this part can be employed anywhere within the signal chain that requires precise amplification or filtering, © 2010 National Semiconductor Corporation. Confidential. © 2010 National Semiconductor Corporation. Confidential. 73 73 73 73

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**Three new 36V OpAmp families High precision, ultra-low noise, industry’s smallest packages**

JFET input Ultra-low drift Lowest noise in class Rail-to-rail output For applications needing high accuracy and stability Ultra-low noise 2x gain bandwidth of closest competitor Rail-to-rail output For fast, high-precision data acquisition applications OPAx140 First in class with rail-to-rail output First in class with quad version Widest supply range in class Application examples: High-impedance sensor signal conditioning, medical instrumentation and interfacing with precision data converters Single: OPA140; Dual: OPA2140; Quad: OPA4140 Samples available now; production quantities of OPA2140 available now; production quantities of OPA140 and OPA4140 available in November OPAx209 Best-in-class settling time Application examples: Automated test equipment, medical instrumentation and professional audio pre-amplifiers Single: OPA209; Dual: OPA2209; Quad: OPA4209 Samples available now; production quantities of OPA2209 available now; production quantities of OPA209 and OPA4209 available in November OPAx171 Best combination of features to simplify general purpose op amp selection Up to 90% smaller than industry-standard packaging: First 36-V op amp offered in SOT553 (single) and VSSPO-8 (dual) Low-power for battery-powered operation Cost-effective Application examples: Tracking amplifiers in power modules, merchant power supplies, transducer amplifiers and battery-powered test equipment Single: OPA171; Dual: OPA2171; Quad: OPA4171 Samples available now; production quantities of OPA171 available November; production quantities of OPA2171 and OPA4171 available in December General purpose SOT553: 90% smaller than standard SOIC package Low power Rail-to-rail output For space-constrained industrial applications 74

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**much quiescent current ?**

Looking for… Low IBias OpAmp for your high impedance sensor ? OPA140 General purpose OpAmp in industries smallest package ? OPA171 Low noise OpAmp Without burning too much quiescent current ? OPA209 First HV Zero Drift OpAmp on the market ? OPA2188

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**OPA171 / OPA2171 / OPA4171 Industry’s smallest 36V Low Power RRO General Purpose Op Amp**

Features Benefits Industry’s smallest 36V Packages: Single in SOT553, Dual in VSSOP-8 Micropackages use >50% less board space than the larger SOT23 and MSOP packages Rail to Rail Output +2.7V to +36V or ±1.35V to ±18V High CMRR: 104dB Low Noise: 14nV/√Hz at 1kHz Maximizes input voltage range for use with low voltage sensor outputs Versatility in design for ease of use with different supply rail systems Low Quiescent Current: 475μA/ch Enables battery powered operation DC Precision Offset Voltage: 1.8mV (max) Offset Voltage Drift: 0.3µV/°C Low Bias Current: 8pA Accuracy and stability over the entire industrial temperature range EMI/RFI Filtered Inputs Improved noise immunity from wireless interference GBW: 3 MHz Slew Rate: 1.5V/µs Wide Signal sources and fast response suitable to drive high performance ADCs Packaging options: Single: SO-8, SOT23-5, SOT553 Dual: SO-8, MSOP-8, VSSOP-8 Quad: SO-14, TSSOP-14 Applications Tracking Amplifiers in Power Modules Merchant Power Supplies Transducer Amplifiers Strain Gage Amplifier Precision Integrator Battery Powered Instruments SOT23-5 3 x 3 x 1.45 VSSOP 3.1 x 2 x 0.9 SOT553 1.6 x 1.6 x 0.6 (Already released / releasing in 3Q’11 )

77
**OPA140 / OPA2140 / OPA4140 11MHz, Precision, Low Noise, RRO, JFET Op Amp**

Features Benefits Very Low Offset and Drift Offset Voltage: 120μV (max) Offset Drift: 1µV/°C (max) Low Noise: 5.1nV/√Hz (1kHz) 1/f Noise: 250nVpp (0.1-10Hz) FET Input: Ib = 10pA (max) GBW: 11MHz Slew Rate: 20V/μs Wide Supply Range: + 4.5V to +36V or +2.25V to +18V Low power: 2.0mA/ch Guaranteed high accuracy and stability over the full industrial temperature range Allows for high sensitivity, high resolution systems across a wide frequency range Better matching to high impedance sources such as sensor outputs 60% lower IB than previous generation OPA132 High GBW and slew rate make it ideal for driving 16-bit ADC’s Enabling low power 5V supply systems 13% less power consumption per channel vs. competition Packaging options: Single: SO-8, MSOP-8, SOT-23 Dual: SO-8, MSOP-8 Quad: SO-14, TSSOP-14 OPAx141 as cost down versions of this part Applications Sensor Signal Conditioning Security Scanner Photodiode Measurement Active Filters Medical Instrumentation

78
**OPA209, OPA2209, & OPA4209 2.2nV/√Hz, 18MHz, Precision, RRO, 36V Op Amp**

Features Benefits Low Noise : 2.2nV/√Hz at 1kHz (max) 1/f Noise: 130nVpp (0.1Hz – 10Hz) Low Offset Voltage: 150µV (max) Gain Bandwidth: 18MHz Slew rate: 6.4V/ms Wide Supply Range: ±2.25 to ±18V, Single supply: 4.5 to 36V Low Supply Current: 2.5mA/ch max Provides a low noise solution across full operating frequency range Ideal for fast, high precision data acquisition applications and offering 50% wider bandwidth than the competition 50% lower minimum voltage supply with rail-to-rail output maximizes dynamic range and provide greater flexibility across designs as compared to the competition Packaging options: Single: SO-8, MSOP-8, SOT-23 Dual: SO-8, MSOP-8 Quad: TSSOP-14 Applications PLL Loop Filter Low Noise, Low Power Signal Processing High Performance ADC Driver High Performance DAC Output Amplifier. Active Filters Low Noise Instrumentation Amplifiers

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**OPA188 / OPA2188 / OPA4188 0.03µV/oC, 25µV Vos, 36V Zerø-DriftTM Operational Amplifier**

Features Benefits Very Low Offset and Drift Offset Voltage: 25µV (max) Offset Voltage Drift: 0.085µV/°C max Noise Voltage: 8.8nV/√Hz GBW : 2MHz Low Quiescent Current: 475μA (max) Low Bias Current: 850pA (max) Supply Range: +4.0V to +36V or ±2V to ±18V Rail to Rail Output EMI Filtered Inputs Improved high accuracy and stability over the previous generation OPA277 Offset drift 75% lower than the nearest competitor Allows for high sensitivity, high resolution systems across a wide frequency range Well suited for battery powered operation Minimizes errors on the output due to current noise Flexibility in design, enabling low power 5V supply systems Improved Noise Immunity Applications Packaging options: Single: SO-8, MSOP-8, SOT-23 Dual: SO-8, MSOP-8 Quad: SO-14, TSSOP-14 • Electronic Weigh Scales Bridge Amplifier Strain Gauge • Automated Test Equipment • Transducer amplifier • Medical Instrumentation • Resistor Thermal Detector (Preview / Already released / sampling, releasing in 3Q’11 )

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New Low voltage op amps

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**Looking for… Value Line OpAmp with best performance for price ?**

16-bit ADC driver that Combines wide bandwidth and low distortion with very low power ? OPA835/836 Cost effective, low power zero drift op amp OPA330

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**OPA330, 2330, 4330 Single, Dual, Quad, Micro-Power, Zerø-Drift Operational Amplifier**

Economical alternative to OPA333 Low Quiescent Current: 25uA (typ), 35µA (max) Low Offset Voltage: 50µV (max) Offset Voltage Drift: 0.25µV/˚C (max) Low Noise: 1.1 µVP-P Flat 1/f Noise Bandwidth: 350kHz Rail-to-Rail Input and Output 1.8V to 5.5V Supply Voltage OPA330YFF: WCSP – 1.1mm x 0.9mm, 5-ball EMI Input Filtered Best performance/price offering on the market 30% lower 1k price than the competition Low Offset and Zero-Drift Removes need for Calibration No noise related errors especially for near DC and low frequency sensor signal applications. RRIO Increases Dynamic Range Tiny Chip-Scale Package Saves Board Space 60% Space Savings over an SC70 package Input filtering enables precision performance in a RF sensitive environment Battery-Powered Instruments Temperature Measurement Precision Strain Gages Precision Sensor Applications Handheld Test Equipment 82

83
**OPA835/ OPA2835 Ultra Low Power, RRO, Negative rail in, VFB**

Features Benefits Ultra Low Power Iq: 250µA/ch, Power-Down: <1uA +2.5V to +5V Single Supply Bandwidth: 56 MHz Slew Rate: 160 V/μs HD2: -105dBc &HD3: Input Voltage Noise: 9.3nV/rtHz RRO – Rail-to-Rail Output Negative Rail Input Power-Down Capability: <1μA Single and Dual Standard packaging Advanced packaging with integrated resistors for smallest footprint (≈ 2mm x 2mm) Flexible supply for power sensitive applications Exceptional performance at very low power Increased dynamic range / sensitivity Low signal distortion Larger outputs in low voltage applications Integrated gain setting resistors enables smallest footprint on PCB High Density Flexibility Gains of: +1, -1, +2, -3, +4, -4, +5, -7, +8 Non-integer Gains + Attenuation Applications Low Power Signal Conditioning Low Power SAR and ΔΣ ADC Driver Portable Systems Low Power Systems High Density Systems Packages available Single: SOT23-6 Single: WQFN -10 (RUN) Dual: SOIC-8 Dual: VSSOP-10 EVM OPA835 – SOT23 Samples Available EVMs Available OPA835 – RUN 83 83 83

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**OPA836/ OPA2836 Ultra Low Power, RRO, Negative rail in, VFB**

Singles RTM with Duals sampling! Features Benefits Very Low Power Iq: 1mA/ch, Power-Down: <1uA +2.5V to +5V Single Supply Bandwidth: 205 MHz Slew Rate: 560 V/μs HD2: -120dBc &HD3: Input Voltage Noise: 4.2nV/rtHz Vos : 1.08mV (max); Vos drift: 1.1uV/C (typ) RRO – Rail-to-Rail Output Negative Rail Input Single and Dual Standard packaging Advanced packaging with integrated resistors for smallest footprint (≈ 2mm x 2mm) Flexible supply for power sensitive applications Exceptional performance at very low power Increased dynamic range / sensitivity Low signal distortion Larger outputs in low voltage applications Integrated gain setting resistors enables smallest footprint on PCB High Density Flexibility Gains of: +1, -1, +2, -3, +4, -4, +5, -7, +8 Non-integer Gains + Attenuation Applications Low Power Signal Conditioning Low Power SAR and ΔΣ ADC Driver Portable Systems Low Power Systems High Density Systems Packages available Single: SOT23-6 Single: WQFN -10 (RUN) Dual: SOIC-8 Dual: VSSOP-10 EVM OPA836 – SOT23 Samples Available EVMs Available OPA836 – RUN 84 84 84

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**OPA314 / OPA2314 / OPA4314 Low Cost, 3MHz, 180uA, RRIO CMOS Amplifier**

Product Preview Features Benefits Best combination of Power and Performance Low quiescent current: 180µA/ch max Low Noise: 16nV/√Hz Input offset voltage: 2.5mV max. Rail-to-Rail I/O Supply voltage: 1.8V to 5.5V EMI/RFI Input Filter GBW: 3MHz Input bias current: 0.2pA Very low noise at low power is ideal for low-level signal amplifications while maintaining high Signal-to-Noise ratio RRIO maximizes input dynamic range with full use of single supply range High gain bandwidth for fast pulse response Low input bias current for high source impedance applications Applications Package Options: Single: SC70-5, SOT23-5 Dual: MSOP-8, SO-8, DFN-8 Quad: TSSOP-14 CO/Smoke detectors ▪ Photodiode Amplifier ▪ Sensor Signal Conditioning Low-Side Current Sense Portable Medical and Instrumentation (Preview / Already released / sampling, releasing in 3Q’11 )

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Chapter 10: Operational Amplifiers. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Electronic Devices.

Chapter 10: Operational Amplifiers. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Electronic Devices.

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