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EL2270
Data Sheet July 13, 2004 FN7053.1
70MHz/1mA Current Mode Feedback Amplifiers
The EL2270 is a dual current-feedback operational amplifiers which achieves a -3dB bandwidth of 70MHz at a gain of +1 while consuming only 1mA of supply current per amplifier. It will operate with dual supplies ranging from 1.5V to 6V, or from single supplies ranging from +3V to +12V. In spite of its low supply current, the EL2270 can output 55mA while swinging to 4V on 5V supplies. These attributes make the EL2270 an excellent choice for low power and/or low voltage cable-driver, HDSL, or RGB applications. For applications where board space is extremely critical. The EL2270 is available in industry standard pinouts in SO package. For single and dual applications with disable, consider the EL2176 (8-pin single) or EL2276 (14-pin dual). For higher speed applications where power is still a concern, consider the EL2180/EL2186 family which also comes in similar single, dual, triple and quad configurations. The EL2180/EL2186 family provides a -3dB bandwidth of 250MHz while consuming 3mA of supply current per amplifier.
Features
* Dual topologies * 1mA supply current (per amplifier) * 70MHz -3dB bandwidth * Low cost * Single- and dual-supply operation down to 1.5V * 0.15%/0.15 diff. gain/diff. phase into 150 * 800V/s slew rate * Large output drive current - 55mA * Also available with disable in single (EL2176) & dual (EL2276) * Higher speed EL2180/EL2186 family available (3mA/250MHz) in single, dual, and quad * Pb-free available
Applications
* Low power/battery applications * HDSL amplifiers * Video amplifiers * Cable drivers * RGB amplifiers * Test equipment amplifiers
Ordering Information
PART NUMBER EL2270CS EL2270CS-T7 EL2270CS-T13 EL2270CSZ (See Note) EL2270CSZ-T7 (See Note) EL2270CSZT13 (See Note) PACKAGE 8-Pin SO 8-Pin SO 8-Pin SO 8-Pin SO (Pb-free) 8-Pin SO (Pb-free) 8-Pin SO (Pb-free) TAPE & REEL PKG. DWG. # 7" 13" 7" 13" MDP0027 MDP0027 MDP0027 MDP0027 MDP0027 MDP0027
* Current to voltage converters
Pinout
EL2270 (8-PIN SO) TOP VIEW
NOTE: Intersil Pb-free products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which is compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J Std-020B.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright (c) 2002 Elantec Semiconductor, Inc. 2002-2004 Intersil Americas Inc. All Rights Reserved. Elantec is a registered trademark of Elantec Semiconductor, Inc. All other trademarks mentioned are the property of their respective owners.
1
EL2270
Absolute Maximum Ratings (TA = 25C)
Voltage between VS+ and VS- . . . . . . . . . . . . . . . . . . . . . . . . +12.6V Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . . VS- to VS+ Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6V Current into +IN or -IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.5mA Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . See Curves Operating Ambient Temperature Range . . . . . . . . . .-40C to +85C Operating Junction Temperature Plastic Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150C Output Current (EL2270) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60mA Storage Temperature Range . . . . . . . . . . . . . . . . . .-65C to +150C
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
DC Electrical Specifications
PARAMETER VOS TCVOS dVOS +IIN d+IIN -IIN d-IIN CMRR -ICMR PSRR -IPSR ROL +RIN +CIN CMIR VO
VS = 5V, RL = 150, TA = 25C unless otherwise specified. CONDITIONS MIN TYP 2.5 Measured from TMIN to TMAX 5 0.5 0.5 20 4 1.5 VCM = 3.5V VCM = 3.5V VS is moved from 4V to 6V VS is moved from 4V to 6V VOUT = 2.5V VCM = 3.5V 150 1 60 45 50 4 70 0.5 400 4 1.2 3.5 VS = 5 VS = 5 single-supply, high VS = 5 single-supply, low 3.5 4.0 4.0 4.0 0.3 50 55 1 2 5 10 15 5 MAX 15 UNIT mV V/C mV A nA A A dB A/V dB A/V k M pF V V V V mA mA
DESCRIPTION Input Offset Voltage Average Input Offset Voltage Drift VOS Matching +Input Current +IIN Matching -Input Current -IIN Matching Common Mode Rejection Ratio -Input Current Common Mode Rejection Power Supply Rejection Ratio -Input Current Power Supply Rejection Transimpedance +Input Resistance +Input Capacitance Common Mode Input Range Output Voltage Swing
IO IS
Output Current Supply Current
Per amplifier Per amplifier
AC Electrical Specifications
PARAMETER -3dB BW -3dB BW SR tR, tF tPD OS
VS = 5V, RF = RG = 1k, RL = 150, TA = 25C unless otherwise specified CONDITIONS AV = 1 AV = 2 VOUT = 2.5V, AV = 2 VOUT = 500mV VOUT = 500mV VOUT = 500mV 400 MIN TYP 70 60 800 4.5 4.5 3.0 MAX UNIT MHz MHz V/s ns ns %
DESCRIPTION -3dB Bandwidth -3dB Bandwidth Slew Rate Rise and Fall Time Propagation Delay Overshoot
2
EL2270
AC Electrical Specifications
PARAMETER tS dG dP dG dP CS NOTE: 1. DC offset from 0V to 0.714V, AC amplitude 286mVP-P, f = 3.58MHz. 0.1% Settling Differential Gain Differential Phase Differential Gain Differential Phase Channel Separation VS = 5V, RF = RG = 1k, RL = 150, TA = 25C unless otherwise specified (Continued) CONDITIONS VOUT = 2.5V, AV = -1 AV = 2, RL = 150 (Note 1) AV = 2, RL = 150 (Note 1) AV = 1, RL = 500 (Note 1) AV = 1, RL = 500 (Note 1) EL2270 only, f = 5MHz MIN TYP 40 0.15 0.15 0.02 0.01 85 MAX UNIT ns % % dB
DESCRIPTION
Test Circuit (per Amplifier)
Simplified Schematic (per Amplifier)
3
EL2270 Typical Performance Curves
Non-Inverting Frequency Response (Gain) Non-Inverting Frequency Response (Phase) Frequency Response for Various RF and RG
Inverting Frequency Response (Gain)
Inverting Frequency Response (Phase)
Frequency Response for Various RL and CL
Transimpedance (ROL)
PSRR and CMRR
Frequency Response for Various CIN-
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EL2270 Typical Performance Curves (Continued)
Voltage and Current Noise vs Frequency
2nd and 3rd Harmonic Distortion vs Frequency
FOutput Voltage vs Frequency
-3dB Bandwidth and Peaking vs Supply Voltage for Various Non-Inverting Gains
-3dB Bandwidth and Peaking vs Supply Voltage for Various Inverting Gains
Output Voltage Swing vs Supply Voltage
Supply Current vs Supply Voltage
Common-Mode Input Range vs Supply Voltage
Slew Rate vs Supply Voltage
5
EL2270 Typical Performance Curves (Continued)
Input Bias Current vs Die Temperature
Short-Circuit Current vs Die Temperature
Transimpedance (ROL) vs Die Temperature
-3dB Bandwidth and Peaking vs Die Temperature for Various Non-Inverting Gains
-3dB Bandwidth and Peaking vs Die Temperature for Various Inverting Gains
Input Offset Voltage vs Die Temperature
Supply Current vs Die Temperature
Input Voltage Range vs Die Temperature
Slew Rate vs Die Temperature
6
EL2270 Typical Performance Curves (Continued)
Differential Gain and Phase vs DC Input Voltage at 3.58MHz/AV = +2
Differential Gain and Phase vs DC Input Offset at 3.58MHz/AV = +1
Settling Time vs Settling Accuracy
Small-Signal Step Response
Large-Signal Step Response
Channel Separation vs Frequency
Package Power Dissipation vs Ambient Temperature JEDEC JESD51-7 High Effective Thermal Conductivity Test Board 2 1.8 Power Dissipation (W) Power Dissipation (W) 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 25 50 75 85 100 125 150 Ambient Temperature (C) 1.136W SO8 JA=110C/W
Package Power Dissipation vs Ambient Temperature JEDEC JESD51-3 Low Effective Thermal Conductivity Test Board 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 25 50 75 85 100 125 150 Ambient Temperature (C) 781mW SO8 JA=160C/W
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EL2270 Applications Information
Product Description
The EL2270 is a current-feedback operational amplifier that offers a wide -3dB bandwidth of 70MHz and a low supply current of 1mA per amplifier. This product also features high output current drive. The EL2270 can output 55mA per amplifier and works with supply voltages ranging from a single 3V to 6V, and is also capable of swinging to within 1V of either supply on the input and the output. Because of its current-feedback topology, the EL2270 does not have the normal gain-bandwidth product associated with voltagefeedback operational amplifiers. This allows its -3dB bandwidth to remain relatively constant as closed-loop gain is increased. This combination of high bandwidth and low power, together with aggressive pricing make the EL2270 the ideal choice for many low-power/high-bandwidth applications such as portable computing, HDSL, and video processing. For applications where board space is extremely critical. The EL2270 is available in industry standard pinouts in SO package. For single and dual applications with disable, consider the EL2176 (8-pin single) and EL2276 (14-pin dual). If higher speed is required, refer to the EL2180/EL2186 family which provides singles, duals, triples, and quads with 250MHz of bandwidth while consuming 3mA of supply current per amplifier. inverting input. For inverting gains this parasitic capacitance has little effect because the inverting input is a virtual ground, but for non-inverting gains this capacitance (in conjunction with the feedback and gain resistors) creates a pole in the feedback path of the amplifier. This pole, if low enough in frequency, has the same destabilizing effect as a zero in the forward open-loop response. The use of large value feedback and gain resistors further exacerbates the problem by further lowering the pole frequency. The experienced user with a large amount of PC board layout experience may find in rare cases that the EL2270 has less bandwidth than expected. The reduction of feedback resistor values (or the addition of a very small amount of external capacitance at the inverting input, e.g. 0.5pF) will increase bandwidth as desired. Please see the curves for Frequency Response for Various RF and RG, and Frequency Response for Various CIN-.
Feedback Resistor Values
The EL2270 has been designed and specified at gains of +1 and +2 with RF = 1k. This value of feedback resistor gives 70MHz of -3dB bandwidth at AV = +1 with about 1.5dB of peaking, and 60MHz of -3dB bandwidth at AV = +2 with about 0.5dB of peaking. Since the EL2270 is a currentfeedback amplifier, it is also possible to change the value of RF to get more bandwidth. As seen in the curve of Frequency Response For Various RF and RG, bandwidth and peaking can be easily modified by varying the value of the feedback resistor. Because the EL2270 is a current-feedback amplifier, its gainbandwidth product is not a constant for different closed-loop gains. This feature actually allows the EL2270 to maintain about the same -3dB bandwidth, regardless of closed-loop gain. However, as closed-loop gain is increased, bandwidth decreases slightly while stability increases. Since the loop stability is improving with higher closed-loop gains, it becomes possible to reduce the value of RF below the specified 1k and still retain stability, resulting in only a slight loss of bandwidth with increased closed-loop gain.
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 4.7F tantalum capacitor in parallel with a 0.1F capacitor has been shown to work well when placed at each supply pin. For good AC performance, parasitic capacitance should be kept to a minimum especially at the inverting input (see the Capacitance at the Inverting Input section). Ground plane construction should be used, but it should be removed from the area near the inverting input to minimize any stray capacitance at that node. 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.
Supply Voltage Range and Single-Supply Operation
The EL2270 has been designed to operate with supply voltages having a span of greater than 3V, and less than 12V. In practical terms, this means that the EL2270 will operate on dual supplies ranging from 1.5V to 6V. With a single-supply, the EL2270 will operate from +3V to +12V. 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 EL2270 has an input voltage range that extends to within 1V of either supply. So, for example, on a single +5V supply, the EL2270 has an input range which spans from 1V to 4V. The output range of the EL2270 is also quite large, extending to within 1V of the supply rail. On a 5V supply, the output is
Capacitance at the Inverting Input
Any manufacturer's high-speed voltage- or current-feedback amplifier can be affected by stray capacitance at the 8
EL2270
therefore capable of swinging from -4V to +4V. Single-supply output range is even larger because of the increased negative swing due to the external pull-down resistor to ground. On a single +5V supply, output voltage range is about 0.3V to 4V.
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 decouple the EL2270 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 5 and 50) 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. In many cases it is also possible to simply increase the value of the feedback resistor (RF) to reduce the peaking.
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 is especially difficult when driving a standard video load of 150, because of the change in output current with DC level. Until the EL2270, good Differential Gain could only be achieved by running high idle currents through the output transistors (to reduce variations in output impedance). These currents were typically more than the entire 1mA supply current of each EL2270 amplifier! Special circuitry has been incorporated in the EL2270 to reduce the variation of output impedance with current output. This results in dG and dP specifications of 0.15% and 0.15 while driving 150 at a gain of +2. Video performance has also been measured with a 500 load at a gain of +1. Under these conditions, the EL2270 has dG and dP specifications of 0.01% and 0.02 respectively while driving 500 at AV = +1.
Current Limiting
The EL2270 has no internal current-limiting circuitry. If any output is shorted, it is possible to exceed the Absolute Maximum Ratings for output current or power dissipation, potentially resulting in the destruction of the device.
Power Dissipation
With the high output drive capability of the EL2270, it is possible to exceed the 150C Absolute Maximum junction temperature under certain very high load current conditions. Generally speaking, when RL falls below about 25, it is important to calculate the maximum junction temperature (TJMAX) for the application to determine if power-supply voltages, load conditions, or package type need to be modified for the EL2270 to remain in the safe operating area. These parameters are calculated as follows [1]:
T JMAX = T MAX + ( JA x n x PD MAX )
Output Drive Capability
In spite of its low 1mA of supply current, each amplifier of the EL2270 is capable of providing a minimum of 50mA. These output drive levels are unprecedented in amplifiers running at these supply currents. With a minimum 80mA of output drive, the 50mA minimum output drive of each EL2270 amplifier allows swings of 2.5V into 50 loads.
where: TMAX = Maximum ambient temperature JA = Thermal resistance of the package n = Number of amplifiers in the package PDMAX = Maximum power dissipation of each amplifier in the package PDMAX for each amplifier can be calculated as follows [2]:
V OUTMAX PD MAX = ( 2 x V S x I SMAX ) + ( V S - V OUTMAX ) x --------------------------R
L
where: VS = Supply voltage ISMAX = Maximum supply current of 1 amplifier VOUTMAX = Maximum output voltage of the application RL = Load resistance
9
EL2270 Typical Application Circuits
INVERTING 200mA OUTPUT CURRENT DISTRIBUTION AMPLIFIER
FAST-SETTLING PRECISION AMPLIFIER
DIFFERENTIAL LINE-DRIVER/RECEIVER
10
EL2270 EL2270 Macromodel
* Revision A, March 1995 * AC characteristics used Rf=Rg=1K,RL=150 * Connections: +input * | -input * | | +Vsupply * | | | -Vsupply * | | | | output * | | | | | .subckt EL2170/el 3 2 7 4 6 * * Input Stage * e1 10 0 3 0 1.0 vis 10 9 0V h2 9 12 vxx 1.0 r1 2 11 165 l1 11 12 25nH* iinp 3 0 0.5uA iinm 2 0 4uA* r12 3 0 4Meg * * Slew Rate Limiting * h1 13 0 vis 600 r2 13 14 1K d1 14 0 dclamp d2 0 14 dclamp * * High Frequency Pole * e2 30 0 14 0 0.00166666666 l3 30 17 0.5uH c5 17 0 0.69pF r5 17 0 300 * * Transimpedance Stage * g1 0 18 17 0 1.0 rol 18 0 400K cdp 18 0 1.9pF * * Output Stage * q1 4 18 19 qp q2 7 18 20 qn q3 7 19 21 qn q4 4 20 22 qp r7 21 6 4 r8 22 6 4 ios1 7 19 0.4mA ios2 20 4 0.4mA * Supply Current ips 7 4 1nA * * Error Terms * ivos 0 23 2mA vxx 23 0 0V e4 24 0 3 0 1.0
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EL2270
e5 25 0 7 0 1.0 e6 26 0 4 0 -1.0 r9 24 23 0.316K r10 25 23 3.2K r11 26 23 3.2K * * Models * .model qn npn(is=5e-15 bf=200 tf=0.01nS) .model qp pnp(is=5e-15 bf=200 tf=0.01nS) .model dclamp d(is=1e-30 ibv=0.266 + bv=1.3v n=4) .ends
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