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| EL2150C EL2157C EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Features Specified for a 3V a 5V or g 5V Applications Power Down to 0 mA (EL2157C) Output Voltage Clamp (EL2157C) Large Input Comon Mode Range 0V k VCM k Vs - 1 2V Output Swings to Ground Without Saturating b 3 dB Bandwidth e 125 MHz g 0 1 dB Bandwidth e 30 MHz Low Supply Current e 5 mA Slew Rate e 275V ms Low Offset Voltage e 2 mV max (PDIP and SO Packages) Output Current e g100 mA High Open Loop Gain e 80 dB Differential Gain e 0 05% Differential Phase e 0 05 General Description The EL2150C EL2157C are the electronics industry's fastest single supply op amps available Prior single supply op amps have generally been limited to bandwidths and slew rates that of the EL2150C EL2157C The 125 MHz bandwidth 275 V ms slew rate and 0 05% 0 05 differential gain differential phase makes this part ideal for single or dual supply video speed applications With its voltage feedback architecture this amplifier can accept reactive feedback networks allowing them to be used in analog filtering applications The inputs can sense signals below the bottom supply rail and as high as 1 2V below the top rail Connecting the load resistor to ground and operating from a single supply the outputs swing completely to ground without saturating The outputs can also drive to within 1 2V of the top rail The EL2150C EL2157C will output g100 mA and will operate with single supply voltages as low as 2 7V making it ideal for portable low power applications The EL2157C has a high speed disable feature Applying a low logic level to this pin reduces the supply current to 0 mA within 50 ns This is useful for both multiplexing and reducing power consumption The EL2157C also has an output voltage clamp feature This clamp is a fast recovery ( k 7 ns) output clamp that prevents the output voltage from going above the preset clamp voltage This feature is desirable for A D applications as A D converters can require long times to recover if overdriven For applications where board space is critical the EL2150C is available in the tiny 5 lead SOT23 package which has a footprint 28% the size of an 8 lead SOIC The EL2150C EL2157C are also both available in 8 pin plastic DIP and SOIC packages All parts operate over the industrial temperature range of b 40 C to a 85 C For dual triple or quad applications contact the factory Applications Video Amplifier PCMCIA Applications A D Driver Line Driver Portable Computers High Speed Communications RGB Applications Broadcast Equipment Active Filtering Ordering Information Part No Temp Range Package Outline MDP0031 MDP0027 MDP0038 MDP0031 MDP0027 Connection Diagrams EL2150C SO P-DIP EL2157C SO P-DIP EL2150C SOT23-5 EL2150CN b 40 C to a 85 C 8 Pin PDIP EL2150CS b 40 C to a 85 C 8 Pin SOIC EL2150CW b 40 C to a 85 C 5 Pin SOT23 EL2157CN b 40 C to a 85 C 8 Pin PDIP EL2157CS b 40 C to a 85 C 8 Pin SOIC June 1996 Rev B See Ordering databook Information section of 2150 - 1 2150 - 2 2150 - 3 Top View Top View Top View Note All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication however this data sheet cannot be a ``controlled document'' Current revisions if any to these specifications are maintained at the factory and are available upon your request We recommend checking the revision level before finalization of your design documentation 1995 Elantec Inc EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Absolute Maximum Ratings (TA e 25 C) a 12 6V Supply Voltage between VS a and GND Input Voltage (IN a INb ENABLE CLAMP) GNDb0 3V VS a 0 3V g6V Differential Input Voltage Maximum Output Current 90 mA Output Short Circuit Duration (note 1) Power Dissipation Storage Temperature Range Ambient Operating Temperature Range Operating Junction Temperature See Curves b 65 C to a 150 C b 40 C to a 85 C 150 C Important Note All parameters having Min Max specifications are guaranteed The Test Level column indicates the specific device testing actually performed during production and Quality inspection Elantec performs most electrical tests using modern high-speed automatic test equipment specifically the LTX77 Series system Unless otherwise noted all tests are pulsed tests therefore TJ e TC e TA Test Level I II III IV V Test Procedure 100% production tested and QA sample tested per QA test plan QCX0002 100% production tested at TA e 25 C and QA sample tested at TA e 25 C TMAX and TMIN per QA test plan QCX0002 QA sample tested per QA test plan QCX0002 Parameter is guaranteed (but not tested) by Design and Characterization Data Parameter is typical value at TA e 25 C for information purposes only TAB WIDE DC Electrical Characteristics (Note 2) VS e a 5V GND e 0V TA e 25 C VCM e 1 5V VOUT e 1 5V VCLAMP e a 5V VENABLE e a 5V unless otherwise specified Parameter VOS Offset Voltage Description Conditions PDIP and SOIC Packages SOT23-5 Package TCVOS IB IOS TCIOS PSRR CMRR Offset Voltage Temperature Coefficient Input Bias Current Input Offset Current Measured from Tmin to Tmax VIN e 0V VIN e 0V Min Typ Max b2 b3 Test Units Level I I V I I V I I I mV mV mV C mA nA nA C dB dB dB V MX pF pF mX mA TD is 3 8in mA mA v 2 3 10 b 5 5 b 10 b 750 150 750 Input Bias Current Temperature Coefficient Measured from Tmin to Tmax Power Supply Rejection Ratio Common Mode Rejection Ratio VS e VENABLE e a 2 7V to a 12V VCLAMP e OPEN VCM e 0V to a 3 8V VCM e 0V to a 3 0V 55 55 55 0 Common Mode SOIC Package PDIP Package 1 50 70 65 70 VSb1 2 2 1 15 40 5 0 5 27 12 0 65 50 CMIR RIN CIN Common Mode Input Range Input Resistance Input Capacitance I I V V V I I V I ROUT IS ON IS OFF Output Resistance Supply Current Supply Current Enabled Shut Down Av e a 1 VS e VCLAMP e a 12V VENABLE e a 12V VS e VCLAMP e a 10V VENABLE e a 0 5V VS e VCLAMP e a 12V VENABLE e a 0 5V PSOR Power Supply Operating Range 2 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps DC Electrical Characteristics Contd (Note 2) VS e a 5V GND e 0V TA e 25 C VCM e a 1 5V VOUT e a 1 5V VCLAMP e a 5V VENABLE e a 5V unless otherwise specified Parameter PSOR AVOL Description Power Supply Operating Range Open Loop Gain VS e VCLAMP e a 12V VOUT e a 2V to a 9V RL e 1 kX to GND VOUT e a 1 5V to a 3 5V RL e 1 kX to GND VOUT e a 1 5V to a 3 5V RL e 150X to GND VOP Positive Output Voltage Swing VS e a 12V AV e a 1 RL e 1 kX to 0V VS e a 12V AV e a 1 RL e 150X to 0V VS e g5V AV e a 1 RL e 1 kX to 0V VS e g5V AV e a 1 RL e 150X to 0V VS e a 3V AV e a 1 RL e 150X to 0V VON Negative Output Voltage Swing VS e a 12V AV e a 1 RL e 150X to 0V VS e g5V AV e a 1 RL e 1 kX to 0V VS e g5V AV e a 1 RL e 150X to 0V IOUT Output Current (Note 1) VS e g5V AV e a 1 RL e 10X to 0V VS e g5V AV e a 1 RL e 50X to 0V IOUT OFF VIH-EN VIL-EN IIH-EN IIL-EN VOR-CL VACC-CL IIH-CL IIL-CL Output Current Disabled ENABLE pin Voltage for Power Up ENABLE pin Voltage for Shut Down VENABLE e a 0 5V Relative to GND pin Relative to GND pin 340 0 12 b 250 100 Conditions Min Typ Max 27 65 80 70 60 10 8 96 10 0 40 34 18 38 1 95 55 b4 0 b3 7 b3 4 g75 g100 g60 Test Units Level I I V V V I V I I V dB dB dB V V V V V mV V V mA mA mA V V mA mA V mV mA mA TD is 5 2in 12 0 8 I V I I V 0 20 20 I I 05 410 1 VOP 250 25 I I I I I I I ENABLE pin Input Current-High (Note 3) VS e VCLAMP e a 12V VENABLE e a 12V ENABLE pin Input Current-Low (Note 3) VS e VCLAMP e a 12V VENABLE e a 0 5V Voltage Clamp Operating Range (Note 4) CLAMP Accuracy (Note 5) CLAMP pin Input Current CLAMP pin Input Current High Low Relative to GND pin VIN e a 4V RL e 1 kX to GND VCLAMP e a 1 5V and a 3 5V VS e VCLAMP e a 12V VS e a 12V VCLAMP e a 1 2V 12 b 20 b 15 3 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Closed Loop AC Electrical Characteristics (Notes 2 6) VS e a 5V GND e 0V TA e 25 C VCM e a 1 5V VOUT e a 1 5V VCLAMP e a 5V VENABLE e a 5V AV e a 1 RF e 0X RL e 150X to GND pin unless otherwise specified Parameter BW Description b 3 dB Bandwidth (VOUT e 400 mVp-p) Conditions VS e a 5V AV e a 1 RF e 0X VS e a 5V AV eb1 RF e 500X VS e a 5V AV e a 2 RF e 500X VS e a 5V AV e a 10 RF e 500X VS e a 12V AV e a 1 RF e 0X VS e a 3V AV e a 1 RF e 0X Min Typ Max 125 60 60 6 150 100 25 30 20 60 55 200 275 300 28 10 32 40 75 0 05 0 05 48 1 25 50 25 7 Test Units Level V V V V V V V V V V V I V V V V V V V V V V V V V nV0Hz pA0Hz TD is 5 1in ns ns ns V ms V ms ns % ns ns ns % MHz MHz MHz MHz MHz MHz MHz MHz MHz MHz BW g0 1 dB Bandwidth (VOUT e 400 mVp-p) VS e a 12V AV e a 1 RF e 0X VS e a 5V AV e a 1 RF e 0X VS e a 3V AV e a 1 RF e 0X GBWP PM SR Gain Bandwidth Product Phase Margin Slew Rate VS e a 12V AV e a 10 RL e 1 kX CL e 6 pF VS e a 10V RL e 150X Vout e 0V to a 6V VS e a 5V RL e 150X VOUT e 0V to a 3V tR tF OS tPD tS Rise Time Fall Time Overshoot Propagation Delay 0 1% Settling Time 0 01% Settling Time g0 1V step g0 1V step g0 1V step VS e g5V RL e 500X AV e a 1 VOUT e g3V VS e g5V RL e 500X AV e a 1 VOUT e g3V AV e a 2 RF e 1 kX AV e a 2 RF e 1 kX f e 10 kHz f e 10 kHz dG dP eN iN tDIS tEN tCL Note Note Note Note 1 2 3 4 Differential Gain (Note 7) Differential Phase (Note 7) Input Noise Voltage Input Noise Current Disable Time (Note 8) Enable Time (Note 8) Clamp Overload Recovery Note Note Note Note 5 6 7 8 Internal short circuit protection circuitry has been built into the EL2150C EL2157C See the Applications section CLAMP pin and ENABLE pin specifications apply only to the EL2157C If the disable feature is not desired tie the ENABLE pin to the VS pin or apply a logic high level to the ENABLE pin The maximum output voltage that can be clamped is limited to the maximum positive output Voltage or VOP Applying a Voltage higher than VOP inactivates the clamp If the clamp feature is not desired either tie the CLAMP pin to the VS pin or simply let the CLAMP pin float The clamp accuracy is affected by VIN and RL See the Typical Curves Section and the Clamp Accuracy vs VIN RL curve All AC tests are performed on a ``warmed up'' part except slew rate which is pulse tested Standard NTSC signal e 286 mVp-p f e 3 58MHz as VIN is swept from 0 6V to 1 314V RL is DC coupled Disable Enable time is defined as the time from when the logic signal is applied to the ENABLE pin to when the supply current has reached half its final value 4 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves Non-Inverting Frequency Response (Gain) Non-Inverting Frequency Response (Phase) 3 dB Bandwidth vs Temperature for Non-Inverting Gains Inverting Frequency Response (Gain) Inverting Frequency Response (Phase) 3 dB Bandwidth vs Temperature for Inverting Gains Frequency Response for Various RL Frequency Response for Various CL Non-Inverting Frequency Response vs Common Mode Voltage 2150 - 74 5 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves 3 dB Bandwidth vs Supply Voltage for Non-Inverting Gains Contd Frequency Response for Various Supply Voltages AV e a 1 PSSR and CMRR vs Frequency 3 dB Bandwith vs Supply Voltage for Inverting Gains Frequency Response for Various Supply Voltages AV e a 2 PSRR and CMRR vs Die Temperature Open Loop Gain and Phase vs Frequency Open Loop Voltage Gain vs Die Temperature Closed Loop Output Impedance vs Frequency 2150 - 75 6 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves Large Signal Step Response VS e a 3V Contd Large Signal Step Response VS e a 12V Large Signal Step Response VS e a 5V Small Signal Step Response Large Signal Step Response VS e g5V Slew Rate vs Temperature Settling Time vs Settling Accuracy Voltage and Current Noise vs Frequency 2150 - 76 7 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves Differential Gain for Single Supply Operation Contd Differential Gain and Phase for Dual Supply Operation Differential Phase for Single Supply Operation 2nd and 3rd Harmonic Distortion vs Frequency 2nd and 3rd Harmonic Distortion vs Frequency 2nd and 3rd Harmonic Distortion vs Frequency Output Voltage Swing vs Frequency for THD k 0 1% Output Voltage Swing vs Frequency for Unlimited Distortion Output Current vs Die Temperature 2150 - 77 8 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves Supply Current vs Supply Voltage Contd Input Resistance vs Die Temperature Supply Current vs Die Temperature Offset Voltage vs Die Temperature (4 Samples) Input Bias Current vs Input Voltage Input Offset Current and Input Bias Current vs Die Temperature Positive Output Voltage Swing vs Die Temperature RL e 150X to GND Negative Output Voltage Swing vs Die Temperature RL e 150X to GND Clamp Accuracy vs Die Temperature 2150 - 78 9 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves Clamp Accuracy RL e 150X Contd Clamp Accuracy RL e 1 kX Clamp Accuracy RL e 10 kX 2150 - 48 2150 - 49 2150 - 50 Enable Response for a Family of DC Inputs Disable Response for a Family of DC Inputs 2150 - 51 2150 - 52 Disable Enable Response for a Family of Sine Waves OFF Isolation 2150 - 53 2150 - 72 10 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Typical Performance Curves 5-Lead Plastic SOT23 Maximum Power Dissipation vs Ambient Temperature Contd 8-Lead Plastic DIP Maximum Power Dissipation vs Ambient Temperature 8-Lead Plastic SO Maximum Power Dissipation vs Ambient Temperature 2150 - 54 2150 - 55 2150 - 56 Burn-In Circuit 2150 - 57 Simplified Schematic 2150 - 58 11 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Supply Voltage Range and Single-Supply Operation The EL2150C EL2157C have been designed to operate with supply voltages having a span of greater than 2 7V and less than 12V In practical terms this means that the EL2150C EL2157C will operate on dual supplies ranging from g1 35V to g6V With a single-supply the EL2150C EL2157C will operate from a 2 7V to a 12V Performance has been optimized for a single a 5V supply Pins 7 and 4 are the power supply pins The positive power supply is connected to pin 7 When used in single supply mode pin 4 is connected to ground When used in dual supply mode the negative power supply is connected to pin 4 As supply voltages continue to decrease it becomes necessary to provide input and output voltage ranges that can get as close as possible to the supply voltages The EL2150C EL2157C have an input voltage range that includes the negative supply and extends to within 1 2V of the positive supply So for example on a single a 5V supply the EL2150C EL2157C have an input range which spans from 0V to 3 8V The output range of the EL2150C EL2157C is also quite large It includes the negative rail and extends to within 1V of the top supply rail On a a 5V supply the output is therefore capable of swinging from 0V to a 4V On split supplies the output will swing g4V If the load resistor is tied to the negative rail and split supplies are used the output range is extended to the negative rail Applications Information Product Description The EL2150C EL2157C are the industry's fastest single supply operational amplifiers Connected in voltage follower mode their b 3dB bandwidth is 125 MHz while maintaining a 275 V ms slew rate With an input and output common mode range that includes ground these amplifiers were optimized for single supply operation but will also accept dual supplies They operate on a total supply voltage range as low as a 2 7V or up to a 12V This makes them ideal for a 3V applications especially portable computers While many amplifiers claim to operate on a single supply and some can sense ground at their inputs most fail to truly drive their outputs to ground If they do succeed in driving to ground the amplifier often saturates causing distortion and recovery delays However special circuitry built into the EL2150C EL2157C allows the output to follow the input signal to ground without recovery delays Power Supply Bypassing And Printed Circuit Board Layout As with any high-frequency device good printed circuit board layout is necessary for optimum performance Ground plane construction is highly recommended Lead lengths should be as short as possible The power supply pins must be well bypassed to reduce the risk of oscillation The combination of a 4 7 mF tantalum capacitor in parallel with a 0 1 mF ceramic capacitor has been shown to work well when placed at each supply pin For single supply operation where pin 4 (VS b ) is connected to the ground plane a single 4 7 mF tantalum capacitor in parallel with a 0 1 mF ceramic capacitor across pins 7 and 4 will suffice For good AC performance parasitic capacitance should be kept to a minimum Ground plane construction should be used Carbon or Metal-Film resistors are acceptable with the Metal-Film resistors giving slightly less peaking and bandwidth because of their additional series inductance Use of sockets particularly for the SO package should be avoided if possible Sockets add parasitic inductance and capacitance which will result in some additional peaking and overshoot 12 Choice Of Feedback Resistor RF The feedback resistor forms a pole with the input capacitance As this pole becomes larger phase margin is reduced This increases ringing in the time domain and peaking in the frequency domain Therefore RF has some maximum value which should not be exceeded for optimum performance If a large value of RF must be used a small capacitor in the few picofarad range in parallel with RF can help to reduce this ringing and peaking at the expense of reducing the bandwidth EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps For other biasing conditions see the Differential Gain and Differential Phase vs Input Voltage curves Contd As far as the output stage of the amplifier is concerned RF a RG appear in parallel with RL for gains other than a 1 As this combination gets smaller the bandwidth falls off Consequently RF has a minimum value that should not be exceeded for optimum performance For AV e a 1 RF e 0X is optimum For Av e b 1 or a 2 (noise gain of 2) optimum response is obtained with RF between 500X and 1 kX For Av e b 4 or a 5 (noise gain of 5) keep RF between 2 kX and 10 kX Applications Information Output Drive Capability In spite of their moderately low 5 mA of supply current the EL2150C EL2157C are capable of providing g100 mA of output current into a 10X load or g60 mA into 50X With this large output current capability a 50X load can be driven to g3V with VS e g5V making it an excellent choice for driving isolation transformers in telecommunications applications Video Performance For good video performance an amplifier is required to maintain the same output impedance and the same frequency response as DC levels are changed at the output This can be difficult when driving a standard video load of 150X because of the change in output current with DC level Differential Gain and Differential Phase for the EL2150C EL2157C are specified with the black level of the output video signal set to a 1 2V This allows ample room for the sync pulse even in a gain of a 2 configuration This results in dG and dP specifications of 0 05% and 0 05 while driving 150X at a gain of a 2 Setting the black level to other values although acceptable will compromise peak performance For example looking at the single supply dG and dP curves for RL e 150 X if the output black level clamp is reduced from 1 2V to 0 6V dG dP will increase from 0 05% 0 05 to 0 08% 0 25 Note that in a gain of a 2 configuration this is the lowest black level allowed such that the sync tip doesn't go below 0V If your application requires that the output goes to ground then the output stage of the EL2150C EL2157C like all other single supply op amps requires an external pull down resistor tied to ground As mentioned above the current flowing through this resistor becomes the DC bias current for the output stage NPN transistor As this current approaches zero the NPN turns off and dG and dP will increase This becomes more critical as the load resistor is increased in value While driving a light load such as 1 kX if the input black level is kept above 1 25V dG and dP are a respectable 0 03% and 0 03 13 Driving Cables and Capacitive Loads When used as a cable driver double termination is always recommended for reflection-free performance For those applications the back-termination series resistor will de-couple the EL2150C EL2157C from the cable and allow extensive capacitive drive However other applications may have high capacitive loads without a back-termination resistor In these applications a small series resistor (usually between 5X and 50X) can be placed in series with the output to eliminate most peaking The gain resistor (RG) can then be chosen to make up for any gain loss which may be created by this additional resistor at the output Disable Power-Down The EL2157C amplifier can be disabled placing its output in a high-impedance state The disable or enable action takes only about 40 nsec When disabled the amplifier's supply current is reduced to 0 mA thereby eliminating all power consumption by the EL2157C The EL2157C amplifier's power down can be controlled by standard CMOS signal levels at the ENABLE pin The applied CMOS signal is relative to the GND pin For example if a single a 5V supply is used the logic voltage levels will be a 0 5V and a 2 0V If using dual g5V supplies the logic levels will be b 4 5V and b 3 0V Letting the ENABLE pin float will disable the EL2157C If the powerdown feature is not desired connect the ENABLE pin to the VS a pin The guaranteed logic levels of a 0 5V and a 2 0V are not standard TTL levels of a 0 8V and a 2 0V so care must be taken if standard TTL will be used to drive the ENABLE pin EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Figure 3 shows the output of the same circuit being driven by a 0 5V to 2 75V square wave as the clamp voltage is varied from 1 0V to 2 5V as well as the unclamped output signal The rising edge of the signal is clamped to the voltage applied to the CLAMP pin almost instantaneously The output recovers from the clamped mode within 5 - 7 ns depending on the clamp voltage Even when the CLAMP pin is taken 0 2V below the minimum 1 2V specified the output is still clamped and recovers in about 11 ns Applications Information Output Voltage Clamp Contd The EL2157C amplifier has an output voltage clamp This clamping action is fast being activated almost instantaneously and being deactivated in k 7 ns and prevents the output voltage from going above the preset clamp voltage This can be very helpful when the EL2157C is used to drive an A D converter as some converters can require long times to recover if overdriven The output voltage remains at the clamp voltage level as long as the product of the input voltage and the gain setting exceeds the clamp voltage If the EL2157C is connected in a gain of 2 for example and a 3V DC is applied to the CLAMP pin any voltage higher than a 1 5V at the inputs will be clamped and a 3V will be seen at the output Figure 1 below is a unity gain connected EL2157C being driven by a 3Vp-p sinewave with 2 25V applied to the CLAMP pin The resulting output waveform with its output being clamped to 2 25V is shown in Figure 2 2150 - 61 Figure 3 2150 - 59 The clamp accuracy is affected by 1) the CLAMP pin voltage 2) the input voltage and 3) the load resistor Depending upon the application the accuracy may be as little as a few tens of millivolts to a few hundred millivolts Be sure to allow for these inaccuracies when choosing the clamp voltage Curves of Clamp Accuracy vs VCLAMP and VIN for 3 values of RL are included in the Typical Performance Curves Section Unlike amplifiers that clamp at the input and are therefore limited to non-inverting applications only the EL2157C output clamp architecture works for both inverting and non-inverting gain applications There is also no maximum voltage difference limitation between VIN and VCLAMP which is common on input clamped architectures The voltage clamp operates for any voltage between a 1 2V above the GND pin and the minimum output voltage swing VOP Forcing the CLAMP pin much below a 1 2V can saturate transistors and should therefore be avoided 14 Figure 1 2150 - 60 Figure 2 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Applications Information Contd Forcing the CLAMP pin above VOP simply deactivates the CLAMP feature In other words one cannot expect to clamp any voltage higher than what the EL2157C can drive to in the first place If the clamp feature is not desired either let the CLAMP pin float or connect it to the VS a pin Propagation Delay vs Overdrive EL2157 as a Comparator EL2157C Comparator Application The EL2157C can be used as a very fast single supply comparator by utilizing the clamp feature Most op amps used as comparators allow only slow speed operation because of output saturation issues However by applying a DC voltage to the CLAMP pin of the EL2157C the maximum output voltage can be clamped thus preventing saturation Figure 4 below is the EL2157C implemented as a comparator 2 5V DC is applied to the CLAMP pin as well as the IN b pin A differential signal is then applied between the inputs Figure 5 shows the output square wave that results when a g1V 10 MHz triangular wave is applied while Figure 6 is a graph of propagation delay vs overdrive as a square wave is presented at the input 2150 - 64 Figure 6 Video Sync Pulse Remover Application All CMOS Analog to Digital Converters (A Ds) have a parasitic latch-up problem when subjected to negative input voltage levels Since the sync tip contains no useful video information and it is a negative going pulse we can chop it off Figure 7 shows a unity gain connected EL2150C EL2157C Figure 8 shows the complete input video signal applied at the input as well as the output signal with the negative going sync pulse removed 2150 - 62 Figure 4 2150 - 65 Figure 7 2150 - 63 Figure 5 15 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Applications Information Contd 2150 - 68 2150 - 66 Figure 8 Figure 10 Multiplexing with the EL2157C The ENABLE pin on the EL2157C allows for multiplexing applications Figure 9 shows two EL2157Cs with their outputs tied together driving a back terminated 75X video load A 2 Vp-p 10 MHz sinewave is applied at one input and a 1 Vp-p 5 MHz sinewave to the other Figure 10 shows the CLOCK signal which is applied and the resulting output waveform at VOUT Switching is complete in about 50 ns Notice the outputs are tied directly together Decoupling resistors at each output are not necessary In fact adding them approximately doubles the switching time to 100 nsec Short Circuit Current Limit The EL2150C EL2157C have internal short circuit protection circuitry that protect it in the event of its output being shorted to either supply rail This limit is set to around 100 mA nominally and reduces with increasing junction temperature It is intended to handle temporary shorts If an output is shorted indefinitely the power dissipation could easily increase such that the part will be destroyed Maximum reliability is maintained if the output current never exceeds g90 mA A heat sink may be required to keep the junction temperature below absolute maximum when an output is shorted indefinitely Power Dissipation With the high output drive capability of the EL2150C EL2157C it is possible to exceed the 150 C Absolute Maximum junction temperature under certain load current conditions Therefore it is important to calculate the maximum junction temperature for the application to determine if power-supply voltages load conditions or package type need to be modified for the EL2150C EL2157C to remain in the safe operating area 2150 - 67 Figure 9 16 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Applications Information Contd The maximum power dissipation allowed in a package is determined according to 1 PDMAX e where TJMAX e Maximum Junction Temperature TAMAX e Maximum Ambient Temperature iJA e Thermal Resistance of the Package PDMAX e Maximum Power Dissipation in the Package 2150 - 69 Single Supply Voltage vs RLOAD for Various VOUT (PDIP Package) TJMAX - TAMAX iJA 1 The maximum power dissipation actually produced by an IC is the total quiescent supply current times the total power supply voltage plus the power in the IC due to the load or 2 PDMAX e VS ISMAX a (VS - VOUT) where VS e Total Supply Voltage ISMAX e Maximum Supply Current VOUT e Maximum Output Voltage of the Application RL e Load Resistance tied to Ground If we set the two PDMAX equations 1 2 equal to each other and solve for VS we can get a family of curves for various loads and output voltages according to 3 RL (TJMAX b TAMAX) a (VOUT)2 iJA VS e (IS RL) a VOUT VOUT RL 2 Figure 11 Single Supply Voltage vs RLOAD for Various VOUT (SO Package) 2150 - 70 Figure 12 Single Supply Voltage vs RLOAD for Various VOUT (SOT23-5 Package) 3 Figures 11 through 13 show total single supply voltage VS vs RL for various output voltage swings for the PDIP and SOIC packages The curves assume WORST CASE conditions of TA e a 85 C and IS e 6 5 mA 2150 - 73 Figure 13 17 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps Applications Information EL2157C Macromodel Revision A July 1995 When not being used the clamp pin pin 1 should be connected to a Vsupply pin 7 a input Connections b input l a Vsupply l l b Vsupply l l l output l l l l clamp l l l l l Output Stage i3 20 4 1 0mA q3 7 23 20 qn q4 7 18 19 qn q5 7 18 21 qn q6 4 20 22 qp q7 7 23 18 qn d1 19 20 da d2 18 1 da r8 21 6 2 r9 22 6 2 r10 18 21 10k r11 7 23 100k d3 23 24 da d4 24 4 da d5 23 18 da Power Supply Current ips 7 4 3 2mA Models Second Stage Compensation model qn npn(is e 800e-18 bf e 150 tf e 0 02nS) model qpa pnp(is e 810e-18 bf e 50 tf e 0 02nS) model qp pnp(is e 800e-18 bf e 54 tf e 0 02nS) model da d(tt e 0nS) ends TD is 3 8in Clamp Contd l subckt EL2157 el Input Stage i1 7 10 250uA i2 7 11 250uA r1 10 11 4k q1 12 2 10 qp q2 13 3 11 qpa r2 12 4 100 r3 13 4 100 3 l 2 l 7 l 4 l 6 l 1 gm 15 4 13 12 4 6m r4 15 4 15Meg c1 15 4 0 36pF Poles e1 17 4 15 4 1 0 r6 17 25 400 c3 25 4 1pF r7 25 18 500 c4 18 4 1pF 18 EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps EL2157C Macromodel Contd 2150 - 71 19 EL2150C EL2157C EL2150C EL2157C 125 MHz Single Supply Clamping Op Amps General Disclaimer Specifications contained in this data sheet are in effect as of the publication date shown Elantec Inc reserves the right to make changes in the circuitry or specifications contained herein at any time without notice Elantec Inc assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement WARNING Life Support Policy June 1996 Rev B Elantec Inc 1996 Tarob Court Milpitas CA 95035 Telephone (408) 945-1323 (800) 333-6314 Fax (408) 945-9305 European Office 44-71-482-4596 20 Elantec Inc products are not authorized for and should not be used within Life Support Systems without the specific written consent of Elantec Inc Life Support systems are equipment intended to support or sustain life and whose failure to perform when properly used in accordance with instructions provided can be reasonably expected to result in significant personal injury or death Users contemplating application of Elantec Inc products in Life Support Systems are requested to contact Elantec Inc factory headquarters to establish suitable terms conditions for these applications Elantec Inc 's warranty is limited to replacement of defective components and does not cover injury to persons or property or other consequential damages Printed in U S A |
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