LMH6642Q / LMH6643Q Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers General Description Features The LMH664X family true single supply voltage feedback amplifiers offer high speed (130MHz), low distortion (−62dBc), and exceptionally high output current (approximately 75mA) at low cost and with reduced power consumption when compared against existing devices with similar performance. Input common mode voltage range extends to 0.5V below V − and 1V from V+. Output voltage range extends to within 40mV of either supply rail, allowing wide dynamic range especially desirable in low voltage applications. The output stage is capable of approximately 75mA in order to drive heavy loads. Fast output Slew Rate (130V/µs) ensures large peak-to-peak output swings can be maintained even at higher speeds, resulting in exceptional full power bandwidth of 40MHz with a 3V supply. These characteristics, along with low cost, are ideal features for a multitude of industrial and commercial applications. Careful attention has been paid to ensure device stability under all operating voltages and modes. The result is a very well behaved frequency response characteristic (0.1dB gain flatness up the 12MHz under 150Ω load and AV = +2) with minimal peaking (typically 2dB maximum) for any gain setting and under both heavy and light loads. This along with fast settling time (68ns) and low distortion allows the device to operate well in ADC buffer, and high frequency filter applications as well as other applications. This device family offers professional quality video performance with low DG (0.01%) and DP (0.01°) characteristics. Differential Gain and Differential Phase characteristics are also well maintained under heavy loads (150Ω) and throughout the output voltage range. The LMH664X family is offered in single (LMH6642), dual (LMH6643). See ordering information for packages offered. (VS = ±5V, TA = 25°C, RL = 2kΩ, AV = +1. Typical values unless specified). 130MHz ■ −3dB BW (AV = +1) 2.7V to 10V ■ Supply voltage range 130V/µs ■ Slew rate (Note 8), (AV = −1) 2.7mA/amp ■ Supply current (no load) +115mA/−145mA ■ Output short circuit current ±75mA ■ Linear output current ■ Input common mode volt. 0.5V beyond V−, 1V from V+ 40mV from rails ■ Output voltage swing 17nV/ ■ Input voltage noise (100kHz) 0.9pA/ ■ Input current noise (100kHz) −62dBc ■ THD (5MHz, RL = 2kΩ, VO = 2VPP, AV = +2) 68ns ■ Settling time ■ Fully characterized for 3V, 5V, and ±5V 100ns ■ Overdrive recovery ■ Output short circuit protected (Note 11) ■ No output phase reversal with CMVR exceeded ■ LMH6643QMM and LMH6642QMF are AEC-Q100 grade 3 qualified and are manufactured on an automotive grade flow Closed Loop Gain vs. Frequency for Various Gain 30158335 © 2012 Texas Instruments Incorporated 301583 SNOSC61A Applications ■ ■ ■ ■ ■ ■ Active filters CD/DVD ROM ADC buffer amp Portable video Current sense buffer Automotive Large Signal Frequency Response 30158347 www.ti.com LMH6642Q / LMH6643Q Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers January 18, 2012 LMH6642Q / LMH6643Q Storage Temperature Range Junction Temperature (Note 4) Soldering Information Infrared or Convection Reflow(20 sec) Wave Soldering Lead Temp.(10 sec) Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. ESD Tolerance VIN Differential Output Short Circuit Duration Supply Voltage (V+ - V−) Voltage at Input/Output pins Input Current 2KV (Note 2) 200V (Note 9) 1000V (Note 13) ±2.5V (Note 3), (Note 11) 13.5V V+ +0.8V, V− −0.8V ±10mA Operating Ratings −65°C to +150°C +150°C 235°C 260°C (Note 1) Supply Voltage (V+ – V−) Junction Temperature Range (Note 4) 2.7V to 10V −40°C to +85°C Package Thermal Resistance (Note 4) (θJA) 5-Pin SOT-23 8-Pin MSOP 265°C/W 235°C/W 3V Electrical Characteristics Unless otherwise specified, all limits guaranteed for at TJ = 25°C, V+ = 3V, V− = 0V, VCM = VO = V+/2, VID (input differential voltage) as noted (where applicable) and RL = 2kΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol BW Parameter −3dB BW Conditions AV = +1, VOUT = 200mVPP Min (Note 6) Typ (Note 5) 80 115 Max (Note 6) Units MHz AV = +2, −1, VOUT = 200mVPP 46 19 MHz MHz BW0.1dB 0.1dB Gain Flatness AV = +2, RL = 150Ω to V+/2, PBW Full Power Bandwidth AV = +1, −1dB, VOUT = 1VPP 40 en Input-Referred Voltage Noise f = 100kHz 17 f = 1kHz 48 RL = 402Ω, VOUT = 200mVPP in THD Input-Referred Current Noise Total Harmonic Distortion f = 100kHz 0.90 f = 1kHz 3.3 f = 5MHz, VO = 2VPP, AV = −1, −48 nV/ pA/ dBc RL = 100Ω to V+/2 DG Differential Gain VCM = 1V, NTSC, AV = +2 0.17 RL =150Ω to V+/2 DP Differential Phase % RL =1kΩ to V+/2 0.03 VCM = 1V, NTSC, AV = +2 0.05 RL =150Ω to V+/2 deg 0.03 RL =1kΩ to V+/2 CT Rej. Cross-Talk Rejection f = 5MHz, Receiver: Rf = Rg = 510Ω, AV = +2 47 dB TS Settling Time VO = 2VPP, ±0.1%, 8pF Load, VS = 5V 68 ns SR Slew Rate (Note 8) AV = −1, VI = 2VPP 120 V/µs VOS Input Offset Voltage For LMH6642 ±1 ±5 ±7 For LMH6643 ±1 ±3.4 ±7 90 mV TC VOS Input Offset Average Drift (Note 12) ±5 IB Input Bias Current (Note 7) −1.50 −2.60 −3.25 µA IOS Input Offset Current 20 800 1000 nA RIN Common Mode Input Resistance 3 MΩ CIN Common Mode Input Capacitance 2 pF www.ti.com 2 µV/°C CMVR Parameter Input Common-Mode Voltage Range Conditions Min (Note 6) CMRR ≥ 50dB Typ (Note 5) Max (Note 6) −0.5 −0.2 −0.1 1.8 1.6 2.0 CMRR Common Mode Rejection Ratio VCM Stepped from 0V to 1.5V 72 95 AVOL Large Signal Voltage Gain VO = 0.5V to 2.5V 80 75 96 74 70 82 RL = 2kΩ to V+/2 VO = 0.5V to 2.5V RL = 150Ω to V+/2 VO ISC dB RL = 2kΩ to V+/2, VID = 200mV 2.90 2.98 RL = 150Ω to 2.80 2.93 Output Swing Low RL = 2kΩ to V+/2, VID = −200mV 25 75 RL = 150Ω to V+/2, VID = −200mV 75 150 Output Short Circuit Current Sourcing to V+/2 VID = 200mV (Note 10) 50 35 95 Sinking to V+/2 VID = −200mV (Note 10) 55 40 110 VID = 200mV IOUT Output Current +PSRR Positive Power Supply Rejection V+ = 3.0V to 3.5V, VCM = 1.5V Ratio VOUT = 0.5V from either supply IS Supply Current (per channel) 75 No Load V dB Output Swing High V+/2, Units V mV mA ±65 mA 85 dB 2.70 4.00 4.50 mA 5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for at TJ = 25°C, V+ = 5V, V− = 0V, VCM = VO = V+/2, VID (input differential voltage) as noted (where applicable) and RL = 2kΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions BW −3dB BW AV = +1, VOUT = 200mVPP Min (Note 6) Typ (Note 5) 90 120 Max (Note 6) Units MHz AV = +2, −1, VOUT = 200mVPP 46 15 MHz MHz BW0.1dB 0.1dB Gain Flatness AV = +2, RL = 150Ω to V+/2, PBW Full Power Bandwidth AV = +1, −1dB, VOUT = 2VPP 22 en Input-Referred Voltage Noise f = 100kHz 17 f = 1kHz 48 Rf = 402Ω, VOUT = 200mVPP in Input-Referred Current Noise f = 100kHz 0.90 f = 1kHz 3.3 THD Total Harmonic Distortion f = 5MHz, VO = 2VPP, AV = +2 −60 DG Differential Gain NTSC, AV = +2 0.16 RL =150Ω to V+/2 DP Differential Phase pA/ dBc % RL = 1kΩ to V+/2 0.05 NTSC, AV = +2 0.05 RL = 150Ω to V+/2 RL = 1kΩ to nV/ deg 0.01 V+/2 CT Rej. Cross-Talk Rejection f = 5MHz, Receiver: Rf = Rg = 510Ω, AV = +2 TS Settling Time VO = 2VPP, ±0.1%, 8pF Load SR Slew Rate (Note 8) AV = −1, VI = 2VPP 47 95 3 dB 68 ns 125 V/µs www.ti.com LMH6642Q / LMH6643Q Symbol LMH6642Q / LMH6643Q Typ (Note 5) Max (Note 6) For LMH6642 ±1 ±5 ±7 For LMH6643 ±1 ±3.4 ±7 Symbol Parameter Conditions VOS Input Offset Voltage Min (Note 6) Units mV TC VOS Input Offset Average Drift (Note 12) ±5 IB Input Bias Current (Note 7) −1.70 −2.60 −3.25 µA IOS Input Offset Current 20 800 1000 nA RIN Common Mode Input Resistance 3 MΩ CIN Common Mode Input Capacitance 2 pF CMVR Input Common-Mode Voltage Range CMRR ≥ 50dB −0.5 3.8 3.6 4.0 CMRR Common Mode Rejection Ratio VCM Stepped from 0V to 3.5V 72 95 AVOL Large Signal Voltage Gain VO = 0.5V to 4.50V 86 82 98 76 72 82 RL = 2kΩ to V+/2 VO = 0.5V to 4.25V RL = 150Ω to V+/2 VO ISC µV/°C −0.2 −0.1 dB dB Output Swing High RL = 2kΩ to V+/2, VID = 200mV 4.90 4.98 RL = 150Ω to 4.65 4.90 Output Swing Low RL = 2kΩ to V+/2, VID = −200mV 25 100 RL = 150Ω to V+/2, VID = −200mV 100 150 Output Short Circuit Current Sourcing to V+/2 VID = 200mV (Note 10) 55 40 115 Sinking to V+/2 VID = −200mV (Note 10) 70 55 140 V+/2, IOUT Output Current +PSRR Positive Power Supply Rejection V+ = 4.0V to 6V Ratio IS Supply Current (per channel) VID = 200mV VO = 0.5V from either supply 79 No Load V V mV mA ±70 mA 90 dB 2.70 4.25 5.00 mA ±5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for at TJ = 25°C, V+ = 5V, V− = −5V, VCM = VO = 0V, VID (input differential voltage) as noted (where applicable) and RL = 2kΩ to ground. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions BW −3dB BW AV = +1, VOUT = 200mVPP Min (Note 6) Typ (Note 5) 95 130 Max (Note 6) Units MHz AV = +2, −1, VOUT = 200mVPP 46 12 MHz MHz BW0.1dB 0.1dB Gain Flatness AV = +2, RL = 150Ω to V+/2, PBW Full Power Bandwidth AV = +1, −1dB, VOUT = 2VPP 24 en Input-Referred Voltage Noise f = 100kHz 17 f = 1kHz 48 Rf = 806Ω, VOUT = 200mVPP in www.ti.com Input-Referred Current Noise f = 100kHz 0.90 f = 1kHz 3.3 4 nV/ pA/ Typ (Note 5) Parameter Conditions THD Total Harmonic Distortion f = 5MHz, VO = 2VPP, AV = +2 −62 DG Differential Gain NTSC, AV = +2 0.15 Max (Note 6) dBc RL = 150Ω to V+/2 DP Differential Phase % RL = 1kΩ to V+/2 0.01 NTSC, AV = +2 0.04 RL = 150Ω to V+/2 RL = 1kΩ to Units deg 0.01 V+/2 CT Rej. Cross-Talk Rejection f = 5MHz, Receiver: Rf = Rg = 510Ω, AV = +2 47 TS Settling Time VO = 2VPP, ±0.1%, 8pF Load, VS = 5V 68 ns SR Slew Rate (Note 8) AV = −1, VI = 2VPP 135 V/µs VOS Input Offset Voltage For LMH6642 ±1 ±5 ±7 For LMH6643 ±1 ±3.4 ±7 100 dB mV TC VOS Input Offset Average Drift (Note 12) ±5 IB Input Bias Current (Note 7) −1.60 −2.60 −3.25 µA IOS Input Offset Current 20 800 1000 nA RIN Common Mode Input Resistance 3 MΩ CIN Common Mode Input Capacitance 2 pF CMVR Input Common-Mode Voltage Range CMRR ≥ 50dB −5.5 3.8 3.6 4.0 CMRR Common Mode Rejection Ratio VCM Stepped from −5V to 3.5V 74 95 AVOL Large Signal Voltage Gain VO = −4.5V to 4.5V, 88 84 96 78 74 82 RL = 2kΩ VO = −4.0V to 4.0V, RL = 150Ω VO ISC µV/°C −5.2 −5.1 dB dB Output Swing High RL = 2kΩ, VID = 200mV 4.90 4.96 RL = 150Ω, VID = 200mV 4.65 4.80 Output Swing Low RL = 2kΩ, VID = −200mV −4.96 −4.90 RL = 150Ω, VID = −200mV −4.80 −4.65 Output Short Circuit Current Sourcing to Ground VID = 200mV (Note 10) 60 35 115 Sinking to Ground VID = −200mV (Note 10) 85 65 145 IOUT Output Current VO = 0.5V from either supply ±75 PSRR Power Supply Rejection Ratio (V+, V−) = (4.5V, −4.5V) to (5.5V, −5.5V) 78 IS Supply Current (per channel) No Load V V mA mA 90 2.70 5 V dB 4.50 5.50 mA www.ti.com LMH6642Q / LMH6643Q Min (Note 6) Symbol LMH6642Q / LMH6643Q Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. Note 2: Human body model, 1.5kΩ in series with 100pF. Note 3: 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. 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 = (TJ(MAX) - TA)/ θJA . All numbers apply for packages soldered directly onto a PC board. Note 5: Typical values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or statistical analysis. Note 7: Positive current corresponds to current flowing into the device. Note 8: Slew rate is the average of the rising and falling slew rates. Note 9: Machine Model, 0Ω in series with 200pF. Note 10: Short circuit test is a momentary test. See Note 11. Note 11: Output short circuit duration is infinite for VS < 6V at room temperature and below. For VS > 6V, allowable short circuit duration is 1.5ms. Note 12: Offset voltage average drift determined by dividing the change in VOS at temperature extremes by the total temperature change. Note 13: CDM: Charge Device Model Connection Diagrams 5-Pin SOT23 (LMH6642) 8-Pin MSOP (LMH6643) 30158361 Top View 30158363 Top View www.ti.com 6 At TJ = 25°C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. Closed Loop Frequency Response for Various Supplies Closed Loop Gain vs. Frequency for Various Gain 30158357 30158351 Closed Loop Gain vs. Frequency for Various Gain Closed Loop Frequency Response for Various Temperature 30158350 30158335 Closed Loop Gain vs. Frequency for Various Supplies Closed Loop Frequency Response for Various Temperature 30158348 30158334 7 www.ti.com LMH6642Q / LMH6643Q Typical Performance Characteristics LMH6642Q / LMH6643Q Large Signal Frequency Response Closed Loop Small Signal Frequency Response for Various Supplies 30158347 30158346 Closed Loop Frequency Response for Various Supplies ±0.1dB Gain Flatness for Various Supplies 30158344 30158345 VOUT (VPP) for THD < 0.5% VOUT (VPP) for THD < 0.5% 30158309 www.ti.com 30158308 8 Open Loop Gain/Phase for Various Temperature 30158332 30158310 Open Loop Gain/Phase for Various Temperature HD2 (dBc) vs. Output Swing 30158333 30158314 HD3 (dBc) vs. Output Swing HD2 vs. Output Swing 30158304 30158315 9 www.ti.com LMH6642Q / LMH6643Q VOUT (VPP) for THD < 0.5% LMH6642Q / LMH6643Q HD3 vs. Output Swing THD (dBc) vs. Output Swing 30158305 30158306 Settling Time vs. Input Step Amplitude (Output Slew and Settle Time) Input Noise vs. Frequency 30158312 30158313 VOUT from V+ vs. ISOURCE VOUT from V− vs. ISINK 30158318 www.ti.com 30158319 10 LMH6642Q / LMH6643Q VOUT from V+ vs. ISOURCE VOUT from V− vs. ISINK 30158316 30158317 Swing vs. VS Short Circuit Current (to VS/2) vs. VS 30158329 30158331 Output Sinking Saturation Voltage vs. IOUT Output Sourcing Saturation Voltage vs. IOUT 30158320 30158301 11 www.ti.com LMH6642Q / LMH6643Q Closed Loop Output Impedance vs. Frequency AV = +1 PSRR vs. Frequency 30158303 30158302 CMRR vs. Frequency Crosstalk Rejection vs. Frequency (Output to Output) 30158307 30158311 VOS vs. VOUT (Typical Unit) VOS vs. VCM (Typical Unit) 30158327 30158330 www.ti.com 12 LMH6642Q / LMH6643Q VOS vs. VS (for 3 Representative Units) VOS vs. VS (for 3 Representative Units) 30158322 30158323 VOS vs. VS (for 3 Representative Units) IB vs. VS 30158325 30158324 IOS vs. VS IS vs. VCM 30158328 30158326 13 www.ti.com LMH6642Q / LMH6643Q IS vs. VS Small Signal Step Response 30158353 30158321 Large Signal Step Response Large Signal Step Response 30158341 30158339 Small Signal Step Response Small Signal Step Response 30158356 www.ti.com 30158336 14 LMH6642Q / LMH6643Q Small Signal Step Response Small Signal Step Response 30158352 30158338 Large Signal Step Response Large Signal Step Response 30158337 30158354 Large Signal Step Response 30158360 15 www.ti.com LMH6642Q / LMH6643Q Application Information CIRCUIT DESCRIPTION The LMH664X family is based on National Semiconductor’s proprietary VIP10 dielectrically isolated bipolar process. This device family architecture features the following: • Complimentary bipolar devices with exceptionally high ft (∼8GHz) even under low supply voltage (2.7V) and low bias current. • A class A-B “turn-around” stage with improved noise, offset, and reduced power dissipation compared to similar speed devices (patent pending). • Common Emitter push-push output stage capable of 75mA output current (at 0.5V from the supply rails) while consuming only 2.7mA of total supply current per channel. This architecture allows output to reach within milli-volts of either supply rail. • Consistent performance over the entire operating supply voltage range with little variation for the most important specifications (e.g. BW, SR, IOUT, etc.) • Significant power saving (∼40%) compared to competitive devices on the market with similar performance. 30158342 FIGURE 1. Input and Output Shown with CMVR Exceeded However, if the input voltage range of −0.5V to 1V from V+ is exceeded by more than a diode drop, the internal ESD protection diodes will start to conduct. The current in the diodes should be kept at or below 10mA. Output overdrive recovery time is less than 100ns as can be seen from Figure 2 plot: Application Hints This Op Amp family is a drop-in replacement for the AD805X family of high speed Op Amps in most applications. In addition, the LMH664X will typically save about 40% on power dissipation, due to lower supply current, when compared to competition. All AD805X family’s guaranteed parameters are included in the list of LMH664X guaranteed specifications in order to ensure equal or better level of performance. However, as in most high performance parts, due to subtleties of applications, it is strongly recommended that the performance of the part to be evaluated is tested under actual operating conditions to ensure full compliance to all specifications. With 3V supplies and a common mode input voltage range that extends 0.5V below V−, the LMH664X find applications in low voltage/low power applications. Even with 3V supplies, the −3dB BW (@ AV = +1) is typically 115MHz with a tested limit of 80MHz. Production testing guarantees that process variations with not compromise speed. High frequency response is exceptionally stable confining the typical −3dB BW over the industrial temperature range to ±2.5%. As can be seen from the typical performance plots, the LMH664X output current capability (∼75mA) is enhanced compared to AD805X. This enhancement, increases the output load range, adding to the LMH664X’s versatility. Because of the LMH664X’s high output current capability attention should be given to device junction temperature in order not to exceed the Absolute Maximum Rating. This device family was designed to avoid output phase reversal. With input overdrive, the output is kept near supply rail (or as closed to it as mandated by the closed loop gain setting and the input voltage). See Figure 1: www.ti.com 30158343 FIGURE 2. Overload Recovery Waveform INPUT AND OUTPUT TOPOLOGY All input / output pins are protected against excessive voltages by ESD diodes connected to V+ and V- rails (see Figure 3). These diodes start conducting when the input / output pin voltage approaches 1Vbe beyond V+ or V- to protect against over voltage. These diodes are normally reverse biased. Further protection of the inputs is provided by the two resistors (R in Figure 3), in conjunction with the string of anti-parallel diodes connected between both bases of the input stage. The combination of these resistors and diodes reduces excessive differential input voltages approaching 2Vbe. The most common situation when this occurs is when the device is used as a comparator (or with little or no feedback) and the device inputs no longer follow each other. In such a case, the diodes may conduct. As a consequence, input current increases and the differential input voltage is clamped. It is important to make sure that the subsequent current flow through the device input pins does not violate the Absolute Maximum Ratings of the device. To limit the current through this protection circuit, extra series resistors can be placed. Together with the built-in series resistors of several hundred ohms, these ex16 30158369 FIGURE 3. Input Equivalent Circuit (1) SINGLE SUPPLY, LOW POWER PHOTODIODE AMPLIFIER The circuit shown in Figure 4 is used to amplify the current from a photo-diode into a voltage output. In this circuit, the emphasis is on achieving high bandwidth and the transimpedance gain setting is kept relatively low. Because of its high slew rate limit and high speed, the LMH664X family lends itself well to such an application. This circuit achieves approximately 1V/mA of transimpedance gain and capable of handling up to 1mApp from the photodiode. Q1, in a common base configuration, isolates the high capacitance of the photodiode (Cd) from the Op Amp input in order to maximize speed. Input is AC coupled through where GBWP is the Gain Bandwidth Product of the Op Amp Optimized as such, the I-V converter will have a theoretical pole, fp, at: (2) With Op Amp input capacitance of 3pF and an estimate for Q1 output capacitance of about 3pF as well, CIN = 6pF. From the typical performance plots, LMH6642/6643 family GBWP is approximately 57MHz. Therefore, with Rf = 1k, from Equation 1 and 2 above. Cf = ∼4.1pF, and fp = 39MHz 30158364 FIGURE 4. Single Supply Photodiode I-V Converter 17 www.ti.com LMH6642Q / LMH6643Q C1 to ease biasing and allow single supply operation. With 5V single supply, the device input/output is shifted to near half supply using a voltage divider from VCC. Note that Q1 collector does not have any voltage swing and the Miller effect is minimized. D1, tied to Q1 base, is for temperature compensation of Q1’s bias point. Q1 collector current was set to be large enough to handle the peak-to-peak photodiode excitation and not too large to shift the U1 output too far from mid-supply. No matter how low an Rf is selected, there is a need for Cf in order to stabilize the circuit. The reason for this is that the Op Amp input capacitance and Q1 equivalent collector capacitance together (CIN) will cause additional phase shift to the signal fed back to the inverting node. Cf will function as a zero in the feedback path counter-acting the effect of the CIN and acting to stabilized the circuit. By proper selection of Cf such that the Op Amp open loop gain is equal to the inverse of the feedback factor at that frequency, the response is optimized with a theoretical 45° phase margin. ternal resistors can limit the input current to a safe number (i.e. < 10mA). Be aware that these input series resistors may impact the switching speed of the device and could slow down the device. LMH6642Q / LMH6643Q For this example, optimum Cf was empirically determined to be around 5pF. This time domain response is shown in Figure 5 below showing about 9ns rise/fall times, corresponding to about 39MHz for fp. The overall supply current from the +5V supply is around 5mA with no load. PRINTED CIRCUIT BOARD LAYOUT AND COMPONENT VALUES SECTION Generally, a good high frequency layout will keep power supply and ground traces away from the inverting input and output pins. Parasitic capacitances on these nodes to ground will cause frequency response peaking and possible circuit oscillations (see Application Note OA-15 for more information). National Semiconductor suggests the following evaluation boards as a guide for high frequency layout and as an aid in device testing and characterization: Device Package LMH6642QMF LMH6643QMM 5-Pin SOT-23 8-Pin MSOP Evaluation Board PN LMH730216 LMH730123 Another important parameter in working with high speed/high performance amplifiers, is the component values selection. Choosing external resistors that are large in value will effect the closed loop behavior of the stage because of the interaction of these resistors with parasitic capacitances. These capacitors could be inherent to the device or a by-product of the board layout and component placement. Either way, keeping the resistor values lower, will diminish this interaction to a large extent. On the other hand, choosing very low value resistors could load down nodes and will contribute to higher overall power dissipation. 30158365 FIGURE 5. Converter Step Response (1VPP, 20 ns/DIV) Ordering Information Package 5–Pin SOT23 8–Pin MSOP Part Number Package Marking Transport Media NSC Drawing Features LMH6642QMF 1k Units Tape and Reel MF05A LMH6642QMFX A64Q 3k Units Tape and Reel AEC-Q100 Grade 3 qualified. Automotive Grade Production Flow** LMH6643QMM 1k Units Tape and Reel LMH6643QMMX 643Q 3.5k Units Tape and Reel MUA08A AEC-Q100 Grade 3 qualified. Automotive Grade Production Flow** **Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. Reliability qualification is compliant with the requirements and temperature grades defined in the AEC-Q100 standard. Automotive grade products are identified with the letter Q. For more information go to http://www.national.com/ automotive. www.ti.com 18 LMH6642Q / LMH6643Q Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23 NS Package Number MF05A 8-Pin MSOP NS Package Number MUA08A 19 www.ti.com LMH6642Q / LMH6643Q Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers Notes www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. 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