LMH6642EP

LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers July 2004 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers General Description The LMH664XEP 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 LMH664XEP family is offered in single (LMH6642EP), dual (LMH6643EP), and quad (LMH6644EP) options. See ordering information for packages offered. ENHANCED PLASTIC • Extended Temperature Performance of −40˚C to +85˚C • • • • • Baseline Control - Single Fab & Assembly Site Process Change Notification (PCN) Qualification & Reliability Data Solder (PbSn) Lead Finish is standard Enhanced Diminishing Manufacturing Sources (DMS) Support Features (VS = ± 5V, TA = 25˚C, RL = 2kΩ, AV = +1. Typical values unless specified). n −3dB BW (AV = +1) 130MHz n Supply voltage range 2.7V to 12.8V n Slew rate (Note 11), (AV = −1) 130V/µs n Supply current (no load) 2.7mA/amp n Output short circuit current +115mA/−145mA ± 75mA n Linear output current n Input common mode volt. 0.5V beyond V−, 1V from V+ n Output voltage swing 40mV from rails n Input voltage noise (100kHz) 17nV/ n Input current noise (100kHz) 0.9pA/ n THD (5MHz, RL = 2kΩ, VO = 2VPP, AV = +2) −62dBc n Settling time 68ns n Fully characterized for 3V, 5V, and ± 5V n Overdrive recovery 100ns n Output short circuit protected (Note 14) n No output phase reversal with CMVR exceeded Applications n Selected Military Applications n Selected Avionics Applications Ordering Information PART NUMBER LMH6642MFXEP LMH6643MAXEP LMH6644MAXEP (Notes 1, 2) VID PART NUMBER V62/04625-01 V62/04625-02 V62/04625-03 TBD NS PACKAGE NUMBER (Note 3) MF05A M08A M14A TBD Note 1: For the following (Enhanced Plastic) versions, check for availability: LMH6642MAEP, LMH6642MAXEP, LMH6642MFEP, LMH6643MAEP, LMH6643MMEP, LMH6643MMXEP, LMH6644MAEP, LMH6644MTEP, LMH6644MTXEP. Parts listed with an "X" are provided in Tape & Reel and parts without an "X" are in Rails. Note 2: FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/ mil Note 3: Refer to package details under Physical Dimensions © 2004 National Semiconductor Corporation DS200894 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Absolute Maximum Ratings (Note 4) If Military/Aerospace specified devices are required, please contact the National Semiconductor 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 Storage Temperature Range Junction Temperature (Note 7) Soldering Information + − Infrared or Convection Reflow(20 sec) Wave Soldering Lead Temp.(10 sec) 235˚C 260˚C 2KV (Note 5) 200V (Note 12) Operating Ratings (Note 4) Supply Voltage (V+ – V−) Junction Temperature Range (Note 7) Package Thermal Resistance (Note 7) (θJA) SOT23-5 SOIC-8 MSOP-8 SOIC-14 TSSOP-14 265˚C/W 190˚C/W 235˚C/W 145˚C/W 155˚C/W 2.7V to 12.8V −40˚C to +85˚C ± 2.5V (Note 6), (Note 14) 13.5V V+ +0.8V, V− −0.8V ± 10mA −65˚C to +150˚C +150˚C 3V Electrical Characteristics Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 3V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol BW BW0.1dB PBW en in THD DG −3dB BW 0.1dB Gain Flatness Full Power Bandwidth Input-Referred Voltage Noise Input-Referred Current Noise Total Harmonic Distortion Differential Gain Parameter Conditions AV = +1, VOUT = 200mVPP AV = +2, −1, VOUT = 200mVPP AV = +2, RL = 150Ω to V+/2, RL = 402Ω, VOUT = 200mVPP AV = +1, −1dB, VOUT = 1VPP f = 100kHz f = 1kHz f = 100kHz f = 1kHz f = 5MHz, VO = 2VPP, AV = −1, RL = 100Ω to V+/2 VCM = 1V, NTSC, AV = +2 RL =150Ω to V+/2 RL =1kΩ to V /2 + Min (Note 9) 80 Typ (Note 8) 115 46 19 40 17 48 0.90 3.3 −48 0.17 Max (Note 9) Units MHz MHz MHz nV/ pA/ dBc % 0.03 0.05 deg 0.03 47 68 90 120 dB ns V/µs DP Differential Phase VCM = 1V, NTSC, AV = +2 RL =150Ω to V+/2 RL =1kΩ to V+/2 f = 5MHz, Receiver: Rf = Rg = 510Ω, AV = +2 VO = 2VPP, ± 0.1%, 8pF Load, VS = 5V AV = −1, VI = 2VPP CT Rej. TS SR VOS TC VOS IB IOS RIN CIN Cross-Talk Rejection Settling Time Slew Rate (Note 11) Input Offset Voltage Input Offset Average Drift Input Bias Current Input Offset Current Common Mode Input Resistance Common Mode Input Capacitance ±1 (Note 15) (Note 10) ±5 ±7 −2.60 −3.25 800 1000 mV µV/˚C µA nA MΩ pF ±5 −1.50 20 3 2 www.national.com 2 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic 3V Electrical Characteristics Symbol CMVR Parameter Input Common-Mode Voltage Range (Continued) Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 3V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2. Boldface limits apply at the temperature extremes. Conditions CMRR ≥ 50dB 1.8 1.6 Min (Note 9) Typ (Note 8) −0.5 2.0 95 96 82 2.98 2.93 25 75 50 35 55 40 75 95 110 mA 75 150 dB Max (Note 9) −0.2 −0.1 Units V CMRR AVOL Common Mode Rejection Ratio Large Signal Voltage Gain VCM Stepped from 0V to 1.5V VO = 0.5V to 2.5V RL = 2kΩ to V+/2 VO = 0.5V to 2.5V RL = 150Ω to V+/2 72 80 75 74 70 2.90 2.80 dB VO Output Swing High Output Swing Low RL = 2kΩ to V+/2, VID = 200mV RL = 150Ω to V+/2, VID = 200mV RL = 2kΩ to V+/2, VID = −200mV RL = 150Ω to V /2, VID = −200mV + V mV ISC Output Short Circuit Current Sourcing to V+/2 VID = 200mV (Note 13) Sinking to V+/2 VID = −200mV (Note 13) IOUT +PSRR IS Output Current Positive Power Supply Rejection Ratio Supply Current (per channel) VOUT = 0.5V from either supply V+ = 3.0V to 3.5V, VCM = 1.5V No Load ± 65 85 2.70 4.00 4.50 mA dB mA 5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol BW BW0.1dB PBW en in THD DG Parameter −3dB BW 0.1dB Gain Flatness Full Power Bandwidth Input-Referred Voltage Noise Input-Referred Current Noise Total Harmonic Distortion Differential Gain Conditions AV = +1, VOUT = 200mVPP AV = +2, −1, VOUT = 200mVPP AV = +2, RL = 150Ω to V+/2, Rf = 402Ω, VOUT = 200mVPP AV = +1, −1dB, VOUT = 2VPP f = 100kHz f = 1kHz f = 100kHz f = 1kHz f = 5MHz, VO = 2VPP, AV = +2 NTSC, AV = +2 RL =150Ω to V+/2 RL =1kΩ to V+/2 DP Differential Phase NTSC, AV = +2 RL =150Ω to V+/2 RL =1kΩ to V /2 + Min (Note 9) 90 Typ (Note 8) 120 46 15 22 17 48 0.90 3.3 −60 0.16 0.05 0.05 0.01 47 68 Max (Note 9) Units MHz MHz MHz nV/ pA/ dBc % deg CT Rej. TS Cross-Talk Rejection Settling Time f = 5MHz, Receiver: Rf = Rg = 510Ω, AV = +2 VO = 2VPP, ± 0.1%, 8pF Load dB ns 3 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic 5V Electrical Characteristics Symbol SR VOS TC VOS IB IOS RIN CIN CMVR Parameter Slew Rate (Note 11) Input Offset Voltage Input Offset Average Drift Input Bias Current Input Offset Current Common Mode Input Resistance Common Mode Input Capacitance Input Common-Mode Voltage Range (Continued) Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2. Boldface limits apply at the temperature extremes. Conditions AV = −1, VI = 2VPP Min (Note 9) 95 Typ (Note 8) 125 Max (Note 9) Units V/µs ±1 (Note 15) (Note 10) ±5 ±7 −2.60 −3.25 800 1000 mV µV/˚C µA nA MΩ pF ±5 −1.70 20 3 2 CMRR ≥ 50dB 3.8 3.6 −0.5 4.0 95 98 −0.2 −0.1 V CMRR AVOL Common Mode Rejection Ratio Large Signal Voltage Gain VCM Stepped from 0V to 3.5V VO = 0.5V to 4.50V RL = 2kΩ to V+/2 VO = 0.5V to 4.25V RL = 150Ω to V+/2 72 86 82 76 72 4.90 4.65 dB dB 82 4.98 4.90 25 100 100 150 V mV VO Output Swing High Output Swing Low RL = 2kΩ to V+/2, VID = 200mV RL = 150Ω to V+/2, VID = 200mV RL = 2kΩ to V+/2, VID = −200mV RL = 150Ω to V /2, VID = −200mV + ISC Output Short Circuit Current Sourcing to V+/2 VID = 200mV (Note 13) Sinking to V+/2 VID = −200mV (Note 13) 55 40 70 55 115 mA 140 IOUT +PSRR IS Output Current Positive Power Supply Rejection Ratio Supply Current (per channel) VO = 0.5V from either supply V+ = 4.0V to 6V No Load 79 ± 70 90 2.70 4.25 5.00 mA dB mA ± 5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = −5V, VCM = VO = 0V and RL = 2kΩ to ground. Boldface limits apply at the temperature extremes. Symbol BW BW0.1dB PBW en Parameter −3dB BW 0.1dB Gain Flatness Full Power Bandwidth Input-Referred Voltage Noise Conditions AV = +1, VOUT = 200mVPP AV = +2, −1, VOUT = 200mVPP AV = +2, RL = 150Ω to V+/2, Rf = 806Ω, VOUT = 200mVPP AV = +1, −1dB, VOUT = 2VPP f = 100kHz f = 1kHz Min (Note 9) 95 Typ (Note 8) 130 46 12 24 17 48 Max (Note 9) Units MHz MHz MHz nV/ www.national.com 4 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic ± 5V Electrical Characteristics Symbol in THD DG Parameter Input-Referred Current Noise Total Harmonic Distortion Differential Gain (Continued) Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = −5V, VCM = VO = 0V and RL = 2kΩ to ground. Boldface limits apply at the temperature extremes. Conditions f = 100kHz f = 1kHz f = 5MHz, VO = 2VPP, AV = +2 NTSC, AV = +2 RL =150Ω to V+/2 RL =1kΩ to V /2 + Min (Note 9) Typ (Note 8) 0.90 3.3 −62 0.15 0.01 0.04 0.01 47 68 Max (Note 9) Units pA/ dBc % DP Differential Phase NTSC, AV = +2 RL =150Ω to V+/2 RL =1kΩ to V+/2 f = 5MHz, Receiver: Rf = Rg = 510Ω, AV = +2 VO = 2VPP, ± 0.1%, 8pF Load, VS = 5V AV = −1, VI = 2VPP 100 deg CT Rej. TS SR VOS TC VOS IB IOS RIN CIN CMVR Cross-Talk Rejection Settling Time Slew Rate (Note 11) Input Offset Voltage Input Offset Average Drift Input Bias Current Input Offset Current Common Mode Input Resistance Common Mode Input Capacitance Input Common-Mode Voltage Range dB ns V/µs 135 ±1 (Note 15) (Note 10) ±5 ±7 −2.60 −3.25 800 1000 mV µV/˚C µA nA MΩ pF ±5 −1.60 20 3 2 CMRR ≥ 50dB 3.8 3.6 −5.5 4.0 95 96 −5.2 −5.1 V CMRR AVOL Common Mode Rejection Ratio Large Signal Voltage Gain VCM Stepped from −5V to 3.5V VO = −4.5V to 4.5V, RL = 2kΩ VO = −4.0V to 4.0V, RL = 150Ω 74 88 84 78 74 4.90 4.65 dB dB 82 4.96 4.80 −4.96 −4.80 −4.90 −4.65 V V VO Output Swing High Output Swing Low RL = 2kΩ, VID = 200mV RL = 150Ω, VID = 200mV RL = 2kΩ, VID = −200mV RL = 150Ω, VID = −200mV Sourcing to Ground VID = 200mV (Note 13) Sinking to Ground VID = −200mV (Note 13) ISC Output Short Circuit Current 60 35 85 65 115 mA 145 mA 90 2.70 4.50 5.50 dB IOUT PSRR IS Output Current Power Supply Rejection Ratio Supply Current (per channel) VO = 0.5V from either supply (V , V ) = (4.5V, −4.5V) to (5.5V, −5.5V) No Load + − ± 75 78 mA 5 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic ± 5V Electrical Characteristics Note 5: Human body model, 1.5kΩ in series with 100pF. (Continued) Note 4: 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 6: 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 7: 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 8: Typical values represent the most likely parametric norm. Note 9: All limits are guaranteed by testing or statistical analysis. Note 10: Positive current corresponds to current flowing into the device. Note 11: Slew rate is the average of the rising and falling slew rates. Note 12: Machine Model, 0Ω in series with 200pF. Note 13: Short circuit test is a momentary test. See Note 14. Note 14: 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 15: Offset voltage average drift determined by dividing the change in VOS at temperature extremes by the total temperature change. Connection Diagrams SOIC-8 and MSOP-8 (LMH6643) SOT23-5 (LMH6642) SOIC-8 (LMH6642) 20089461 20089462 Top View Top View Top View SOIC-14 and TSSOP-14 (LMH6644) 20089463 20089468 Top View www.national.com 6 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics erwise specified. Closed Loop Frequency Response for Various Supplies At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless othClosed Loop Gain vs. Frequency for Various Gain 20089457 20089451 Closed Loop Gain vs. Frequency for Various Gain Closed Loop Frequency Response for Various Temperature 20089450 20089435 Closed Loop Gain vs. Frequency for Various Supplies Closed Loop Frequency Response for Various Temperature 20089448 20089434 7 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) Closed Loop Small Signal Frequency Response for Various Supplies Large Signal Frequency Response 20089447 20089446 Closed Loop Frequency Response for Various Supplies ± 0.1dB Gain Flatness for Various Supplies 20089444 20089445 VOUT (VPP) for THD < 0.5% VOUT (VPP) for THD < 0.5% 20089409 20089408 www.national.com 8 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) VOUT (VPP) for THD < 0.5% Open Loop Gain/Phase for Various Temperature 20089410 20089432 Open Loop Gain/Phase for Various Temperature HD2 (dBc) vs. Output Swing 20089433 20089414 HD3 (dBc) vs. Output Swing HD2 vs. Output Swing 20089415 20089404 9 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) HD3 vs. Output Swing THD (dBc) vs. Output Swing 20089405 20089406 Settling Time vs. Input Step Amplitude (Output Slew and Settle Time) Input Noise vs. Frequency 20089413 20089412 VOUT from V vs. ISOURCE + VOUT from V vs. ISINK − 20089418 20089419 www.national.com 10 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) VOUT from V+ vs. ISOURCE VOUT from V− vs. ISINK 20089416 20089417 Swing vs. VS Short Circuit Current (to VS/2) vs. VS 20089429 20089431 Output Sinking Saturation Voltage vs. IOUT Output Sourcing Saturation Voltage vs. IOUT 20089420 20089401 11 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) Closed Loop Output Impedance vs. Frequency AV = +1 PSRR vs. Frequency 20089402 20089403 CMRR vs. Frequency Crosstalk Rejection vs. Frequency (Output to Output) 20089407 20089411 VOS vs. VOUT (Typical Unit) VOS vs. VCM (Typical Unit) 20089430 20089427 www.national.com 12 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) VOS vs. VS (for 3 Representative Units) VOS vs. VS (for 3 Representative Units) 20089422 20089423 VOS vs. VS (for 3 Representative Units) IB vs. VS 20089424 20089425 IOS vs. VS IS vs. VCM 20089426 20089428 13 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) IS vs. VS Small Signal Step Response 20089453 20089421 Large Signal Step Response Large Signal Step Response 20089441 20089439 Small Signal Step Response Small Signal Step Response 20089456 20089436 www.national.com 14 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless otherwise specified. (Continued) Small Signal Step Response Small Signal Step Response 20089452 20089438 Large Signal Step Response Large Signal Step Response 20089437 20089454 Large Signal Step Response 20089460 15 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Application Notes CIRCUIT DESCRIPTION The LMH664XEP 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 millivolts of either supply rail. • Consistent performance from any supply voltage (3V10V) with little variation with supply voltage 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. 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 LMH664XEP 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 LMH664XEP 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 LMH664XEP 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 LMH664XEP output current capability (∼75mA) is enhanced compared to AD805X. This enhancement, increases the output load range, adding to the LMH664XEP’s versatility. Because of the LMH664XEP’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: 20089442 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: 20089443 FIGURE 2. Overload Recovery Waveform www.national.com 16 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Application Notes (Continued) SINGLE SUPPLY, LOW POWER PHOTODIODE AMPLIFIER The circuit shown in Figure 3 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 LMH664XEP 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 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. (1) 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, LMH6642EP/6643EP family GBWP is approximately 57MHz. Therefore, with Rf = 1k, from Equation 1 and 2 above. Cf = ∼4.1pF, and fp = 39MHz 20089464 FIGURE 3. Single Supply Photodiode I-V Converter 17 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Application Notes (Continued) For this example, optimum Cf was empirically determined to be around 5pF. This time domain response is shown in Figure 4 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. 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 LMH6642MF LMH6642MF LMH6643MA LMH6643MA LMH6644MA LMH6644MA Package SOT23-5 8-Pin SOIC 8-Pin SOIC 8-Pin MSOP 14-Pin SOIC 14-Pin TSSOP Evaluation Board PN CLC730068 CLC730027 CLC730036 CLC730123 CLC730031 CLC730131 These free evaluation boards are shipped when a device sample request is placed with National Semiconductor. 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 byproduct 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. 20089465 FIGURE 4. Converter Step Response (1VPP, 20 ns/DIV) PRINTED CIRCUIT BOARD LAYOUT AND COMPONENT VALUES SECTIONS Generally, a good high frequency layout will keep power supply and ground traces away from the inverting input and www.national.com 18 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23 NS Package Number MF05A 8-Pin SOIC NS Package Number M08A 19 www.national.com LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin MSOP NS Package Number MUA08A 14-Pin SOIC NS Package Number M14A www.national.com 20 LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 14-Pin TSSOP 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. BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. National Semiconductor Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.