125 MHz Single Supply, Clamping Op Amps Features General Description # 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 g 100 mA # High Open Loop Gain e 80 dB # Differential Gain e 0.05% # Differential Phase e 0.05§ 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 (/4 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 g 100 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. Applications # # # # # # # # # EL2150C/EL2157C EL2150C/EL2157C Video Amplifier PCMCIA Applications A/D Driver Line Driver Portable Computers High Speed Communications RGB Applications Broadcast Equipment Active Filtering 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. Ordering Information Part No. Temp. Range Package Outline Ý EL2150CN b 40§ C to a 85§ C 8 Pin PDIP MDP0031 EL2150CS b 40§ C to a 85§ C 8 Pin SOIC MDP0027 EL2157CN b 40§ C to a 85§ C 8 Pin PDIP EL2157CS b 40§ C to a 85§ C 8 Pin SOIC *See Ordering databook. Information EL2150C SO, P-DIP EL2157C SO, P-DIP EL2150C SOT23-5 MDP0031 MDP0027 section of Top View 2150 – 3 2150 – 2 2150 – 1 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. June 1996 Rev B EL2150CW b 40§ C to a 85§ C 5 Pin SOT23* MDP0038 Connection Diagrams EL2150C/EL2157C 125 MHz Single Supply, Clamping Op Amps Absolute Maximum Ratings (TA e 25§ C) Power Dissipation Storage Temperature Range Ambient Operating Temperature Range Operating Junction Temperature a 12.6V Supply Voltage between VS a and GND Input Voltage (IN a , INb, ENABLE, CLAMP) GNDb0.3V, VS a 0.3V g 6V Differential Input Voltage Maximum Output Current 90 mA Output Short Circuit Duration (note 1) 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. 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 Description Offset Voltage Conditions PDIP and SOIC Packages b2 SOT23-5 Package b3 TCVOS Offset Voltage Temperature Coefficient Measured from Tmin to Tmax IB Input Bias Current VIN e 0V IOS Input Offset Current VIN e 0V TCIOS Input Bias Current Temperature Coefficient Measured from Tmin to Tmax PSRR Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio CMIR Common Mode Input Range RIN Input Resistance CIN Input Capacitance Min Typ Max 2 3 10 b 5.5 b 10 b 750 150 750 Test Units Level I mV I mV V mV/§ C I mA I nA 50 V nA/§ C VS e VENABLE e a 2.7V to a 12V, VCLAMP e OPEN 55 70 I dB VCM e 0V to a 3.8V 55 65 I dB VCM e 0V to a 3.0V 55 70 I dB Common Mode 1 0 VSb1.2 2 I V I MX SOIC Package 1 V pF PDIP Package 1.5 V pF Output Resistance Av e a 1 40 V mX IS,ON Supply CurrentÐEnabled VS e VCLAMP e a 12V, VENABLE e a 12V 5 6.5 I mA IS,OFF Supply CurrentÐShut Down VS e VCLAMP e a 10V, VENABLE e a 0.5V 0 50 I mA VS e VCLAMP e a 12V, VENABLE e a 0.5V 5 V mA I v ROUT PSOR Power Supply Operating Range 2.7 2 12.0 TAB WIDE 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. TD is 3.8in Test Level I II EL2150C/EL2157C 125 MHz Single Supply, Clamping Op Amps DC Electrical Characteristics Ð 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 Description PSOR Power Supply Operating Range AVOL Open Loop Gain VOP Positive Output Voltage Swing Conditions Min Typ Max 2.7 I V 80 I dB VOUT e a 1.5V to a 3.5V, RL e 1 kX to GND 70 V dB VOUT e a 1.5V to a 3.5V, RL e 150X to GND 60 V dB 10.8 V V 10.0 I V 4.0 V V I V VS e VCLAMP e a 12V, VOUT e a 2V to a 9V, RL e 1 kX to GND 65 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 9.6 VS e g 5V, AV e a 1, RL e 1 kX to 0V VON Negative Output Voltage Swing VS e g 5V, AV e a 1, RL e 150X to 0V 3.4 3.8 VS e a 3V, AV e a 1, RL e 150X to 0V 1.8 1.95 VS e a 12V, AV e a 1, RL e 150X to 0V VS e g 5V, AV e a 1, RL e 150X to 0V Output Current (Note 1) I V I mV b 4.0 V V b 3.7 b 3.4 5.5 VS e g 5V, AV e a 1, RL e 1 kX to 0V IOUT 12.0 Test Units Level 8 I V VS e g 5V, AV e a 1, RL e 10X to 0V g 75 g 100 I mA VS e g 5V, AV e a 1, RL e 50X to 0V g 60 V mA I mA I V IOUT,OFF Output Current, Disabled VENABLE e a 0.5V VIH-EN ENABLE pin Voltage for Power Up Relative to GND pin VIL-EN ENABLE pin Voltage for Shut Down Relative to GND pin 0.5 I V IIH-EN ENABLE pin Input Current-High (Note 3) VS e VCLAMP e a 12V, VENABLE e a 12V 340 410 I mA IIL-EN ENABLE pin Input Current-Low (Note 3) VS e VCLAMP e a 12V, VENABLE e a 0.5V 0 1 I mA VOR-CL Voltage Clamp Operating Range (Note 4) Relative to GND pin VACC-CL CLAMP Accuracy (Note 5) VIN e a 4V, RL e 1 kX to GND VCLAMP e a 1.5V and a 3.5V IIH-CL CLAMP pin Input CurrentÐHigh VS e VCLAMP e a 12V IIL-CL CLAMP pin Input CurrentÐLow VS e a 12V, VCLAMP e a 1.2V 3 0 20 2.0 VOP I V b 250 100 1.2 250 I mV 12 25 b 20 b 15 I mA I mA TD is 5.2in Parameter 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 BW Description b 3 dB Bandwidth (VOUT e 400 mVp-p) Conditions 125 V MHz VS e a 5V, AV eb1, RF e 500X 60 V MHz VS e a 5V, AV e a 2, RF e 500X 60 V MHz 6 V MHz VS e a 12V, AV e a 1, RF e 0X 150 V MHz VS e a 3V, AV e a 1, RF e 0X 100 V MHz g 0.1 dB Bandwidth (VOUT e 400 mVp-p) VS e a 12V, AV e a 1, RF e 0X 25 V MHz VS e a 5V, AV e a 1, RF e 0X 30 V MHz VS e a 3V, AV e a 1, RF e 0X 20 V MHz 60 V MHz 55 V § @ GBWP Gain Bandwidth Product VS e a 12V, PM Phase Margin RL e 1 kX, CL e 6 pF Slew Rate VS e a 10V, RL e 150X, Vout e 0V to a 6V SR Test Units Level VS e a 5V, AV e a 1, RF e 0X VS e a 5V, AV e a 10, RF e 500X BW Min Typ Max AV e a 10 200 275 I V/ms VS e a 5V, RL e 150X, VOUT e 0V to a 3V 300 V V/ms 2.8 V ns tR,tF Rise Time, Fall Time g 0.1V step OS Overshoot g 0.1V step 10 V % tPD Propagation Delay g 0.1V step 3.2 V ns tS 0.1% Settling Time VS e g 5V, RL e 500X, AV e a 1, VOUT e g 3V 40 V ns 0.01% Settling Time VS e g 5V, RL e 500X, AV e a 1, VOUT e g 3V 75 V ns dG Differential Gain (Note 7) AV e a 2, RF e 1 kX 0.05 V % dP Differential Phase (Note 7) AV e a 2, RF e 1 kX 0.05 V § eN Input Noise Voltage f e 10 kHz 48 V nV0Hz iN Input Noise Current f e 10 kHz 1.25 V pA0Hz tDIS Disable Time (Note 8) 50 V ns tEN Enable Time (Note 8) 25 V ns tCL Clamp Overload Recovery 7 V ns Note Note Note Note Note Note Note Note 1: Internal short circuit protection circuitry has been built into the EL2150C/EL2157C. See the Applications section. 2: CLAMP pin and ENABLE pin specifications apply only to the EL2157C. 3: 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. 4: 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. 5: The clamp accuracy is affected by VIN and RL. See the Typical Curves Section and the Clamp Accuracy vs. VIN & RL curve. 6: All AC tests are performed on a ‘‘warmed up’’ part, except slew rate, which is pulse tested. 7: 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. 8: 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 TD is 5.1in Parameter 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 Ð Contd. 3 dB Bandwidth vs Supply Voltage for Non-Inverting Gains 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 Ð Contd. Large Signal Step Response, VS e a 3V Large Signal Step Response, VS e a 5V Large Signal Step Response, VS e g 5V Small Signal Step Response Slew Rate vs Temperature Large Signal Step Response, VS e a 12V 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 Ð Contd. Differential Gain for Single Supply Operation Differential Phase for Single Supply Operation Differential Gain and Phase for Dual 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 Ð Contd. Supply Current vs Supply Voltage Supply Current vs Die Temperature Input Resistance 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 Ð Contd. Clamp Accuracy RL e 150X Clamp Accuracy RL e 1 kX 2150 – 48 Clamp Accuracy RL e 10 kX 2150 – 49 Enable Response for a Family of DC Inputs 2150 – 50 Disable Response for a Family of DC Inputs 2150 – 52 2150 – 51 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 Ð Contd. 5-Lead Plastic SOT23 Maximum Power Dissipation vs Ambient Temperature 8-Lead Plastic DIP Maximum Power Dissipation vs Ambient Temperature 8-Lead Plastic SO Maximum Power Dissipation vs Ambient Temperature 2150 – 55 2150 – 54 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 Applications Information Product Description 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 g 1.35V to g 6V. 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. 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. 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. 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. 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. 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. 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 g 4V. If the load resistor is tied to the negative rail and split supplies are used, the output range is extended to the negative rail. 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. 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 EL2150C/EL2157C 125 MHz Single Supply, Clamping Op Amps For other biasing conditions see the Differential Gain and Differential Phase vs. Input Voltage curves. Applications Information Ð 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. Output Drive Capability 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. In spite of their moderately low 5 mA of supply current, the EL2150C/EL2157C are capable of providing g 100 mA of output current into a 10X load, or g 60 mA into 50X. With this large output current capability, a 50X load can be driven to g 3V with VS e g 5V, making it an excellent choice for driving isolation transformers in telecommunications applications. Video Performance 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. 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. 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 g 5V 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. 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 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 Ð Contd. Output Voltage Clamp 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 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 2150 – 59 Figure 1 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. 2150 – 60 Figure 2 14 EL2150C/EL2157C 125 MHz Single Supply, Clamping Op Amps Applications Information Ð Contd. Propagation Delay vs Overdrive EL2157 as a Comparator 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. 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 g 1V, 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 Ð Contd. 2150 – 68 2150 – 66 Figure 10 Figure 8 Short Circuit Current Limit Multiplexing with the EL2157C 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 g 90 mA. A heat sink may be required to keep the junction temperature below absolute maximum when an output is shorted indefinitely. 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. 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 Ð Contd. Single Supply Voltage vs RLOAD for Various VOUT (PDIP Package) The maximum power dissipation allowed in a package is determined according to  : PDMAX e TJMAX – TAMAX iJA  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 Figure 11 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  Single Supply Voltage vs RLOAD for Various VOUT (SO Package) VOUT  PDMAX e VS*ISMAX a (VS – VOUT) * RL 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,  &  , equal to each other, and solve for VS, we can get a family of curves for various loads and output voltages according to  : RL * (TJMAX b TAMAX) a (VOUT)2 iJA VS e (IS * RL) a VOUT 2150 – 70 Figure 12 Single Supply Voltage vs RLOAD for Various VOUT (SOT23-5 Package)  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 Ð Contd. * 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 * l l l l l l .subckt EL2157/el 3 2 7 4 6 1 * * 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 * * Second Stage & Compensation * 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 * * Output Stage & Clamp * 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 * .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 18 TD is 3.8in EL2157C Macromodel EL2150C/EL2157C 125 MHz Single Supply, Clamping Op Amps EL2157C Macromodel Ð 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. June 1996 Rev B WARNING Ð Life Support Policy 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. 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 Printed in U.S.A.