LMV821 Single/ LMV822 Dual/ LMV824 Quad Low Voltage, Low Power, R-to-R Output, 5 MHz Op Amps General Description The LMV821/LMV822/LMV824 bring performance and economy to low voltage / low power systems. With a 5 MHz unity-gain frequency and a guaranteed 1.4 V/µs slew rate, the quiescent current is only 220 µA/amplifier (2.7 V). They provide rail-to-rail (R-to-R) output swing into heavy loads (600 Ω Guarantees). The input common-mode voltage range includes ground, and the maximum input offset voltage is 3.5mV (Guaranteed). They are also capable of comfortably driving large capacitive loads (refer to the application notes section). The LMV821 (single) is available in the ultra tiny SC70-5 package, which is about half the size of the previous title holder, the SOT23-5. Overall, the LMV821/LMV822/LMV824 (Single/Dual/Quad) are low voltage, low power, performance op amps, that can be designed into a wide range of applications, at an economical price. Features (For Typical, 5 V Supply Values; Unless Otherwise Noted) n Ultra Tiny, SC70-5 Package 2.0 x 2.0 x 1.0 mm Guaranteed 2.5 V, 2.7 V and 5 V Performance Maximum VOS 3.5 mV (Guaranteed) VOS Temp. Drift 1 uV/˚ C GBW product @ 2.7 V 5 MHz ISupply @ 2.7 V 220 µA/Amplifier Minimum SR 1.4 V/us (Guaranteed) CMRR 90 dB PSRR 85 dB Rail-to-Rail (R-to-R) Output Swing — @600 Ω Load 160 mV from rail — @10 kΩ Load 55 mV from rail n VCM @ 5 V -0.3 V to 4.3 V n Stable with High Capacitive Loads (Refer to Application Section) n n n n n n n n n Applications n n n n n Cordless Phones Cellular Phones Laptops PDAs PCMCIA Connection Diagrams 5-Pin SC70-5/SOT23-5 14-Pin SO/TSSOP DS100128-84 Top View 8-Pin SO/MSOP DS100128-85 Top View DS100128-63 Top View © 1999 National Semiconductor Corporation DS100128 www.national.com LMV821 Single/ LMV822 Dual/ LMV824 Quad Low Voltage, Low Power, RRO, 5 MHz Op Amps August 1999 Ordering Information Temperature Range Package Industrial Packaging Marking Transport Media NSC Drawing MAA05 −40˚C to +85˚C 5-Pin SC-70-5 5-Pin SOT23-5 8-Pin SO 8-Pin MSOP 14-Pin SO 14-Pin TSSOP www.national.com LMV821M7 A15 1k Units Tape and Reel LMV821M7X A15 3k Units Tape and Reel LMV821M5 A14 1k UnitsTape and Reel LMV821M5X A14 3k Units Tape and Reel LMV822M LMV822M Rails LMV822MX LMV822M 2.5k Units Tape and Reel LMV822MM LMV822 1k Units Tape and Reel LMV822MMX LMV822 3.5k Units Tape and Reel LMV824M LMV824M Rails LMV824MX LMV824M 2.5k Units Tape and Reel LMV824MT LMV824MT Rails LMV824MTX LMV824MT 2.5k Units Tape and Reel 2 MA05B M08A MUA08A M14A MTC14 Absolute Maximum Ratings (Note 1) Operating Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage 2.5V to 5.5V Temperature Range −40˚C ≤T LMV821, LMV822, LMV824 ESD Tolerance (Note 2) Machine Model Thermal Resistance (θ 100V Ultra Tiny SC70-5 Package 5-Pin Surface Mount Human Body Model LMV822/824 2000V LMV821 1500V Differential Input Voltage ± Supply Voltage Supply Voltage (V+–V −) 5.5V Tiny SOT23-5 Package Surface Mount Output Short Circuit to V+ (Note 3) Output Short Circuit to V− (Note 3) Storage Temperature Range Junction Temperature (Note 4) ≤85˚C 440 ˚C/W 5-Pin 265 ˚C/W SO Package, 8-Pin Surface Mount 190 ˚C/W MSOP Package, 8-Pin Mini Surface Mount 235 ˚C/W Soldering Information Infrared or Convection (20 sec) J JA) 235˚C −65˚C to 150˚C SO Package, 14-Pin Surface Mount 145 ˚C/W TSSOP Package, 14-Pin 155 ˚C/W 150˚C 2.7V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V Boldface limits apply at the temperature extremes. Symbol VOS Parameter Condition Input Offset Voltage − = 0V, VCM = 1.0V, VO = 1.35V and R LMV821/822/824 Limit (Note 6) 1 3.5 mV 4 max Input Offset Voltage Average Drift 1 IB Input Bias Current 30 CMRR +PSRR −PSRR VCM Input Offset Current Common Mode Rejection Ratio 0.5 0V ≤ VCM ≤ 1.7V > 1 MΩ. Typ (Note 5) TCVOS IOS L 85 Positive Power Supply Rejection Ratio 1.7V ≤ V+ ≤ 4V, V- = 1V, VO = 0V, VCM = 0V 85 Negative Power Supply Rejection Ratio -1.0V ≤ V- ≤ -3.3V, V+ =1.7V, VO= 0V, VCM = 0V 85 Input Common-Mode Voltage Range For CMRR ≥ 50dB -0.3 Units µV/˚C 90 nA 140 max 30 nA 50 max 70 dB 68 min 75 dB 70 min 73 dB 70 min -0.2 V max 2.0 1.9 V min AV Large Signal Voltage Gain Sourcing, RL=600Ω to 1.35V, VO=1.35V to 2.2V 100 Sinking, RL=600Ω to 1.35V, VO=1.35V to 0.5V 90 Sourcing, RL=2kΩ to 1.35V, VO=1.35V to 2.2V 100 Sinking, RL=2kΩ to 1.35, VO=1.35 to 0.5V 95 3 90 dB 85 min 85 dB 80 min 95 dB 90 min 90 dB 85 min www.national.com 2.7V DC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V Boldface limits apply at the temperature extremes. Symbol VO Parameter Output Swing − Condition + V =2.7V, RL= 600Ω to 1.35V = 0V, VCM = 1.0V, VO = 1.35V and R LMV821/822/824 Limit (Note 6) 2.58 2.50 V 2.40 min 2.66 0.08 IO Output Current Sourcing, VO=0V > 1 MΩ. Typ (Note 5) 0.13 V+=2.7V, RL= 2kΩ to 1.35V L 16 Units 0.20 V 0.30 max 2.60 V 2.50 min 0.120 V 0.200 max 12 mA min Sinking, VO=2.7V 26 12 mA min IS Supply Current LMV821 (Single) 0.22 LMV822 (Dual) 0.45 LMV824 (Quad) 0.72 0.3 mA 0.5 max 0.6 mA 0.8 max 1.0 mA 1.2 max 2.5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.5V, V Boldface limits apply at the temperature extremes. Symbol VOS VO Parameter − Condition Input Offset Voltage Output Swing V+=2.5V, RL= 600Ω to 1.25V = 0V, VCM = 1.0V, VO = 1.25V and R > 1 MΩ. Typ (Note 5) LMV821/822/824 Limit (Note 6) 1 3.5 mV 4 max 2.37 0.13 V+=2.5V, RL= 2kΩ to 1.25V L 2.46 0.08 Units 2.30 V 2.20 min 0.20 V 0.30 max 2.40 V 2.30 min 0.12 V 0.20 max 2.7V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V Boldface limits apply at the temperature extremes. Symbol Parameter SR Slew Rate GBW Conditions = 0V, VCM = 1.0V, VO = 1.35V and R Typ (Note 5) L LMV821/822/824 Limit (Note 6) > 1 MΩ. Units 1.5 V/µs Gain-Bandwdth Product 5 MHz Φm Phase Margin 61 Deg. Gm Gain Margin 10 dB dB en (Note 7) − Amp-to-Amp Isolation (Note 8) 135 Input-Related Voltage Noise f = 1 kHz, VCM = 1V 28 www.national.com 4 2.7V AC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V Boldface limits apply at the temperature extremes. Symbol Parameter − = 0V, VCM = 1.0V, VO = 1.35V and R Typ (Note 5) Conditions in Input-Referred Current Noise f = 1 kHz 0.1 THD Total Harmonic Distortion f = 1 kHz, AV = −2, RL = 10 kΩ, VO = 4.1 VPP 0.01 L LMV821/822/824 Limit (Note 6) > 1 MΩ. Units % 5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V Boldface limits apply at the temperature extremes. Symbol VOS Parameter − Condition Input Offset Voltage = 0V, VCM = 2.0V, VO = 2.5V and R LMV821/822/824 Limit (Note 6) 1 3.5 mV 4.0 max Input Offset Voltage Average Drift 1 IB Input Bias Current 40 CMRR +PSRR −PSRR VCM Input Offset Current Common Mode Rejection Ratio 0.5 0V ≤ VCM ≤ 4.0V > 1 MΩ. Typ (Note 5) TCVOS IOS L 90 Positive Power Supply Rejection Ratio 1.7V ≤ V+ ≤ 4V, V- = 1V, VO = 0V, VCM = 0V 85 Negative Power Supply Rejection Ratio -1.0V ≤ V- ≤ -3.3V, V+ =1.7V, VO = 0V, VCM = 0V 85 Input Common-Mode Voltage Range For CMRR ≥ 50dB -0.3 Units µV/˚C 100 nA 150 max 30 nA 50 max 72 dB 70 min 75 dB 70 min 73 dB 70 min -0.2 V max 4.3 4.2 V min AV VO Large Signal Voltage Gain Output Swing Sourcing, RL=600Ω to 2.5V, VO=2.5 to 4.5V 105 Sinking, RL=600Ω to 2.5V, VO=2.5 to 0.5V 105 Sourcing, RL=2kΩ to 2.5V, VO=2.5 to 4.5V 105 Sinking, RL=2kΩ to 2.5, VO=2.5 to 0.5V 105 V+=5V,RL= 600Ω to 2.5V 4.84 0.17 V+=5V, RL=2kΩ to 2.5V 4.90 0.10 5 95 dB 90 min 95 dB 90 min 95 dB 90 min 95 dB 90 min 4.75 V 4.70 min 0.250 V .30 max 4.85 V 4.80 min 0.15 V 0.20 max www.national.com 5V DC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V Boldface limits apply at the temperature extremes. Symbol IO Parameter Output Current − = 0V, VCM = 2.0V, VO = 2.5V and R Typ (Note 5) Condition Sourcing, VO=0V IS Supply Current 40 LMV821 (Single) 0.30 LMV822 (Dual) 0.5 LMV824 (Quad) > 1 MΩ. LMV821/822/824 Limit (Note 6) 45 Sinking, VO=5V L 1.0 Units 20 mA 15 min 20 mA 15 min 0.4 mA 0.6 max 0.7 mA 0.9 max 1.3 mA 1.5 max 5V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V Boldface limits apply at the temperature extremes. Symbol Parameter Conditions − = 0V, VCM = 2V, VO = 2.5V and R L > 1 MΩ. Typ (Note 5) LMV821/822/824 Limit (Note 6) 2.0 1.4 (Note 7) Units SR Slew Rate V/µs min GBW Gain-Bandwdth Product 5.6 MHz Φm Phase Margin 67 Deg. Gm Gain Margin 15 dB Amp-to-Amp Isolation (Note 8) 135 dB en Input-Related Voltage Noise f = 1 kHz, VCM = 1V 24 in Input-Referred Current Noise f = 1 kHz 0.25 THD Total Harmonic Distortion f = 1 kHz, AV = −2, RL = 10 kΩ, VO = 4.1 VPP 0.01 % 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, 1.5 kΩ in series wth 100 pF. Machine model, 200Ω in series with 100 pF. Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150˚C. Output currents in excess of 45 mA over long term may adversely affect reliability. Note 4: The maximum power dissipation is a function of TJ(max) , θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJAll numbers apply for packages soldered directly into a PC board. (max)–T A)/θJA. Note 5: Typical Values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or statistical analysis. Note 7: V+ = 5V. Connected as voltage follower with 3V step input. Number specified is the slower of the positive and negative slew rates. Note 8: Input referred, V+ = 5V and RL = 100 kΩ connected to 2.5V. Each amp excited in turn with 1 kHz to produce V O = 3 VPP. www.national.com 6 5V AC Electrical Characteristics (Continued) Typical Performance Characteristics Supply Current vs Supply Voltage (LMV821) Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. Input Current vs Temperature Sourcing Current vs Output Voltage (VS=2.7V) DS100128-2 DS100128-1 Sourcing Current vs Output Voltage (VS=5V) DS100128-3 Sinking Current vs Output Voltage (VS=2.7V) DS100128-4 Output Voltage Swing vs Supply Voltage (RL=10kΩ) DS100128-5 Output Voltage Swing vs Supply Voltage (RL=2kΩ) DS100128-7 DS100128-86 7 Sinking Current vs Output Voltage (VS=5V) DS100128-6 Output Voltage Swing vs Supply Voltage (RL=600Ω) DS100128-8 www.national.com Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) Output Voltage Swing vs Load Resistance Input Voltage Noise vs Frequency Input Current Noise vs Frequency DS100128-18 DS100128-17 DS100128-87 Crosstalk Rejection vs Frequency +PSRR vs Frequency DS100128-93 CMRR vs Frequency -PSRR vs Frequency DS100128-9 Input Voltage vs Output Voltage DS100128-10 Gain and Phase Margin vs Frequency (RL=100kΩ, 2kΩ, 600Ω) 2.7V DS100128-88 DS100128-47 DS100128-11 www.national.com 8 Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) Gain and Phase Margin vs Frequency (RL=100kΩ, 2kΩ, 600Ω) 5V Gain and Phase Margin vs Frequency (Temp.=25, -40, 85˚C, RL= 10kΩ) 2.7V Gain and Phase Margin vs Frequency (Temp.=25, -40, 85 ˚C, RL=10kΩ) 5V DS100128-12 DS100128-13 DS100128-14 Gain and Phase Margin vs Frequency (CL=100pF, 200pF, 0pF, RL=10kΩ)2.7V Gain and Phase Margin vs Frequency (CL=100pF,200pF,0pF RL=10kΩ)5V Gain and Phase Margin vs Frequency (CL=100pF,200pF,0pF RL=600Ω)2.7V DS100128-15 DS100128-16 DS100128-19 Gain and Phase Margin vs Frequency (CL=100pF,200pF,0pF RL=600Ω)5V Slew Rate vs Supply Voltage DS100128-62 Non-Inverting Large Signal Pulse Response DS100128-21 DS100128-20 9 www.national.com Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) Non-Inverting Small Signal Pulse Response Inverting Large Signal Pulse Response DS100128-24 DS100128-27 THD vs Frequency DS100128-82 www.national.com 10 Inverting Small Signal Pulse Response DS100128-30 APPLICATION NOTE This application note is divided into two sections: design considerations and Application Circuits. 1.0 Design Considerations This section covers the following design considerations: 1. Frequency and Phase Response Considerations 2. Unity-Gain Pulse Response Considerations 3. Input Bias Current Considerations 1.1 Frequency and Phase Response Considerations The relationship between open-loop frequency response and open-loop phase response determines the closed-loop stability performance (negative feedback). The open-loop phase response causes the feedback signal to shift towards becoming positive feedback, thus becoming unstable. The further the output phase angle is from the input phase angle, the more stable the negative feedback will operate. Phase Margin (φm) specifies this output-to-input phase relationship at the unity-gain crossover point. Zero degrees of phasemargin means that the input and output are completely in phase with each other and will sustain oscillation at the unitygain frequency. The AC tables show φm for a no load condition. But φm changes with load. The Gain and Phase margin vs Frequency plots in the curve section can be used to graphically determine the φm for various loaded conditions. To do this, examine the phase angle portion of the plot, find the phase margin point at the unity-gain frequency, and determine how far this point is from zero degree of phase-margin. The larger the phase-margin, the more stable the circuit operation. The bandwidth is also affected by load. The graphs of Figure 1 and Figure 2 provide a quick look at how various loads affect the φm and the bandwidth of the LMV821/822/824 family. These graphs show capacitive loads reducing both φm and bandwidth, while resistive loads reduce the bandwidth but increase the φm. Notice how a 600Ω resistor can be added in parallel with 220 picofarads capacitance, to increase the φm 20˚(approx.), but at the price of about a 100 kHz of bandwidth. Overall, the LMV821/822/824 family provides good stability for loaded condition. DS100128-61 FIGURE 2. Unity-Gain Frequency vs Common Mode Voltage for Various Loads 1.2 Unity Gain Pulse Response Considerations A pull-up resistor is well suited for increasing unity-gain, pulse response stability. For example, a 600 Ω pull-up resistor reduces the overshoot voltage by about 50%, when driving a 220 pF load. Figure 3 shows how to implement the pull-up resistor for more pulse response stability. DS100128-41 FIGURE 3. Using a Pull-up Resistor at the Output for Stabilizing Capacitive Loads Higher capacitances can be driven by decreasing the value of the pull-up resistor, but its value shouldn’t be reduced beyond the sinking capability of the part. An alternate approach is to use an isolation resistor as illustrated in Figure 4 . Figure 5 shows the resulting pulse response from a LMV824, while driving a 10,000pF load through a 20 Ω isolation resistor. DS100128-43 FIGURE 4. Using an Isolation Resistor to Drive Heavy Capacitive Loads DS100128-60 FIGURE 1. Phase Margin vs Common Mode Voltage for Various Loads 11 www.national.com 2.1 Telephone-Line Transceiver The telephone-line transceiver of Figure 7 provides a fullduplexed connection through a PCMCIA, miniature transformer. The differential configuration of receiver portion (UR), cancels reception from the transmitter portion (UT). Note that the input signals for the differential configuration of UR, are the transmit voltage (Vt) and Vt/2. This is because Rmatch is chosen to match the coupled telephone-line impedance; therefore dividing Vt by two (assuming R1 >> Rmatch). The differential configuration of UR has its resistors chosen to cancel the Vt and Vt/2 inputs according to the following equation: DS100128-54 FIGURE 5. Pulse Response per Figure 4 1.3 Input Bias Current Consideration Input bias current (IB) can develop a somewhat significant offset voltage. This offset is primarily due to IB flowing through the negative feedback resistor, RF. For example, if IB is 90nA (max room) and RF is 100 kΩ, then an offset of 9 mV will be developed (VOS=IBx RF).Using a compensation resistor (RC), as shown in Figure 6, cancels out this affect. But the input offset current (IOS) will still contribute to an offset voltage in the same manner - typically 0.05 mV at room temp. DS100128-33 FIGURE 7. Telephone-line Transceiver for a PCMCIA Modem Card Note that Cr is included for canceling out the inadequacies of the lossy, miniature transformer. Refer to application note AN-397 for detailed explanation. 2.2“Simple” Mixer (Amplitude Modulator) The mixer of Figure 8 is simple and provides a unique form of amplitude modulation. Vi is the modulation frequency (FM), while a +3V square-wave at the gate of Q1, induces a carrier frequency (FC). Q1 switches (toggles) U1 between inverting and non-inverting unity gain configurations. Offsetting a sine wave above ground at Vi results in the oscilloscope photo of Figure 9. The simple mixer can be applied to applications that utilize the Doppler Effect to measure the velocity of an object. The difference frequency is one of its output frequency components. This difference frequency magnitude (/FM-FC/) is the key factor for determining an object’s velocity per the Doppler Effect. If a signal is transmitted to a moving object, the reflected frequency will be a different frequency. This difference in transmit and receive frequency is directly proportional to an object’s velocity. DS100128-59 FIGURE 6. Canceling the Voltage Offset Effect of Input Bias Current 2.0 APPLICATION CIRCUITS This section covers the following application circuits: 1. Telephone-Line Transceiver 2. “Simple” Mixer (Amplitude Modulator) 3. Dual Amplifier Active Filters (DAAFs) a. Low-Pass Filter (LPF) • b. High-Pass Filter (HPF) • 5. Tri-level Voltage Detector www.national.com 12 DS100128-39 FIGURE 8. Amplitude Modulator Circuit DS100128-36 FIGURE 10. Dual Amplifier, 3 kHz Low-Pass Active Filter with a Butterworth Response and a Pass Band Gain of Times Two f mod f carrier DS100128-40 FIGURE 9. Output signal per the Circuit of Figure 8 2.4 Dual Amplifier Active Filters (DAAFs) The LMV822/24 bring economy and performance to DAAFs. The low-pass and the high-pass filters of Figure 10 and Figure 11 (respectively), offer one key feature: excellent sensitivity performance. Good sensitivity is when deviations in component values cause relatively small deviations in a filter’s parameter such as cutoff frequency (Fc). Single amplifier active filters like the Sallen-Key provide relatively poor sensitivity performance that sometimes cause problems for high production runs; their parameters are much more likely to deviate out of specification than a DAAF would. The DAAFs of Figure 10 and Figure 11 are well suited for high volume production. DS100128-37 FIGURE 11. Dual Amplifier, 300 Hz High-Pass Active Filter with a Butterworth Response and a Pass Band Gain of Times Two Table 1 provides sensitivity measurements for a 10 MΩ load condition. The left column shows the passive components for the 3 kHz low-pass DAAF. The third column shows the components for the 300 Hz high-pass DAAF. Their respective sensitivity measurements are shown to the right of each component column. Their values consists of the percent change in cutoff frequency (Fc) divided by the percent change in component value. The lower the sensitivity value, the better the performance. Each resistor value was changed by about 10 percent, and this measured change was divided into the measured change in Fc. A positive or negative sign in front of the measured value, represents the direction Fc changes relative to components’ direction of change. For example, a sensitivity value of negative 1.2, means that for a 1 percent increase in component value, Fc decreases by 1.2 percent. Note that this information provides insight on how to fine tune the cutoff frequency, if necessary. It should be also noted that R4 and R5 of each circuit also caused variations in 13 www.national.com the pass band gain. Increasing R4 by ten percent, increased the gain by 0.4 dB, while increasing R5 by ten percent, decreased the gain by 0.4 dB. TABLE 1. Component (LPF) Sensitivity (LPF) Component (HPF) Sensitivity (HPF) Ra -1.2 Ca -0.7 C1 -0.1 Rb -1.0 R2 -1.1 R1 +0.1 R3 +0.7 C2 -0.1 C3 -1.5 R3 +0.1 R4 -0.6 R4 -0.1 R5 +0.6 R5 +0.1 Active filters are also sensitive to an op amp’s parameters -Gain and Bandwidth, in particular. The LMV822/24 provide a large gain and wide bandwidth. And DAAFs make excellent use of these feature specifications. Single Amplifier versions require a large open-loop to closed-loop gain ratio - approximately 50 to 1, at the Fc of the filter response. Figure 12 shows an impressive photograph of a network analyzer measurement (hp3577A). The measurement was taken from a 300kHz version of Figure 10. At 300 kHz, the open-loop to closed-loop gain ratio @ Fc is about 5 to 1. This is 10 times lower than the 50 to 1 “rule of thumb” for Single Amplifier Active Filters. To simplify the design process, certain components are set equal to each other. Refer to Figure 10 and Figure 11. These equal component values help to simplify the design equations as follows: To illustrate the design process/implementation, a 3 kHz, Butterworth response, low-pass filter DAAF (Figure 10) is designed as follows: 1. Choose C1 = C3 = C = 1 nF 2. Choose R4 = R5 = 1 kΩ 3. Calculate Ra and R2 for the desired Fc as follows: DS100128-92 FIGURE 12. 300 kHz, Low-Pass Filter, Butterworth Response as Measured by the HP3577A Network Analyzer 4. Calculate R3 for the desired Q. The desired Q for a Butterworth (Maximally Flat) response is 0.707 (45 degrees into the s-plane). R3 calculates as follows: In addition to performance, DAAFs are relatively easy to design and implement. The design equations for the low-pass and high-pass DAAFs are shown below. The first two equation calculate the Fc and the circuit Quality Factor (Q) for the LPF (Figure 10). The second two equations calculate the Fc and Q for the HPF (Figure 11). Notice that R3 could also be calculated as 0.707 of Ra or R2. The circuit was implemented and its cutoff frequency measured. The cutoff frequency measured at 2.92 kHz. The circuit also showed good repeatability. Ten different LMV822 samples were placed in the circuit. The corresponding change in the cutoff frequency was less than a percent. www.national.com 14 stops and the op amp responds open loop. The design equation directly preceding Figure 14, shows how to determine the clamping range. The equation solves for the input voltage band on each side GND. The mid-range is twice this voltage band. 2.5 Tri-level Voltage Detector The tri-level voltage detector of Figure 13 provides a type of window comparator function. It detects three different input voltage ranges: Min-range, Mid-range, and Max-range. The output voltage (VO) is at VCC for the Min-range. VO is clamped at GND for the Mid-range. For the Max-range, VO is at Vee. Figure 14 shows a VO vs. VI oscilloscope photo per the circuit of Figure 13. Its operation is as follows: VI deviating from GND, causes the diode bridge to absorb IIN to maintain a clamped condition (VO= 0V). Eventually, IIN reaches the bias limit of the diode bridge. When this limit is reached, the clamping effect DS100128-89 ∆v | ∆v | +Vo | -Vo OV -VIN OV +VIN DS100128-35 FIGURE 14. X, Y Oscilloscope Trace showing VOUT vs VIN per the Circuit of Figure 13 DS100128-34 FIGURE 13. Tri-level Voltage Detector 15 www.national.com SC70-5 Tape and Reel Specification DS100128-96 SOT-23-5 Tape and Reel Specification Tape Format www.national.com Tape Section # Cavities Cavity Status Cover Tape Status Leader 0 (min) Empty Sealed (Start End) 75 (min) Empty Sealed Carrier 3000 Filled Sealed 250 Filled Sealed Trailer 125 (min) Empty Sealed (Hub End) 0 (min) Empty Sealed 16 Tape Dimensions DS100128-97 8 mm Tape Size 0.130 0.124 0.130 0.126 0.138 ± 0.002 0.055 ± 0.004 0.157 0.315 ± 0.012 (3.3) (3.15) (3.3) (3.2) (3.5 ± 0.05) (1.4 ± 0.11) (4) (8 ± 0.3) DIM A DIM Ao DIM B DIM Bo DIM F DIM Ko DIM P1 DIM W 17 www.national.com Reel Dimensions DS100128-98 8 mm Tape Size www.national.com 7.00 0.059 0.512 0.795 2.165 330.00 1.50 A B 13.00 20.20 55.00 C D N 18 0.331 + 0.059/−0.000 0.567 W1+ 0.078/−0.039 8.40 + 1.50/−0.00 14.40 W1 + 2.00/−1.00 W1 W2 W3 Physical Dimensions inches (millimeters) unless otherwise noted SC70-5 Order Number LMV821M7 or LMV821M7X NS Package Number MAA05 19 www.national.com Physical Dimensions inches (millimeters) unless otherwise noted (Continued) SOT 23-5 Order Number LMV821M5 or LMV821M5X NS Package Number MA05B www.national.com 20 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin Small Outline Order Number LMV822M or LMV822MX NS Package Number M08A 21 www.national.com Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin MSOP Order Number LMV822MM or LMV822MMX NS Package Number MUA08A www.national.com 22 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 14-Pin Small Outline Order Number LMV824M or LMV824MX NS Package Number M14A 23 www.national.com LMV821 Single/ LMV822 Dual/ LMV824 Quad Low Voltage, Low Power, RRO, 5 MHz Op Amps Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 14-Pin TSSOP Order Number LMV824MTC or LMV824MTCX NS Package Number MTC14 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 Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Français Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 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. 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