QUAD 5V RAIL-TO-RAIL PRECISION OPERATIONAL AMPLIFIER

Transcription

1 ADVANCED LINEAR DEVICES, INC. ALD472A/ALD472B ALD472 QUAD 5V RAILTORAIL PRECISION OPERATIONAL AMPLIFIER GENERAL DESCRIPTION The ALD472 is a quad monolithic precision CMOS railtorail operational amplifier intended for a broad range of analog applications using ±2.5V to ±6V dual power supply systems, as well as 4V to 12V battery operated systems. All device characteristics are specified for 5V single supply or ±2.5V dual supply systems. Total supply current for four operational amplifiers is 6mA maximum at 5V supply voltage. It is manufactured with Advanced Linear Devices' enhanced ACMOS silicon gate CMOS process. The ALD472 is designed to offer a tradeoff of performance parameters providing a wide range of desired specifications. It offers the popular industry pin configuration of LM324 and ICL7641 types. The ALD472 has been developed specifically with the 5V single supply or ±2.5V dual supply user. Several important characteristics of the device make many applications easy to implement for these supply voltages. First, the operational amplifier can operate with rail to rail input and output voltages. This feature allows numerous analog serial stages to be implemented without losing operating voltage margin. Secondly, the device was designed to accommodate mixed applications where digital and analog circuits may work off the same 5V power supply. Thirdly, the output stage can drive up to 4pF capacitive and 5KΩ resistive loads in noninverting unity gain connection and double the capacitance in the inverting unity gain mode. These features, coupled with extremely low input currents, high voltage gain, useful bandwidth of 1.5MHz, a slew rate of 2.1V/µs, low power dissipation, low offset voltage and temperature drift, make the ALD472 a truly versatile, user friendly, operational amplifier. The ALD472 is designed and fabricated with silicon gate CMOS technology, and offers 1pA typical input bias current. Onchip offset voltage trimming allows the device to be used without nulling in most applications. The device offers typical offset drift of less than 7µV/ C which eliminates many trim or temperature compensation circuits. For precision applications, the ALD472 is designed to settle to.1% in 8µs. FEATURES Railtorail input and output voltage ranges Symmetrical pushpull class AB output drivers All parameters specified for 5V single supply or ±2.5V dual supply systems Inputs can extend beyond supply rails by 3mV Outputs settle to 2mV of supply rails High load capacitance capability up to 4pF No frequency compensation required unity gain stable Extremely low input bias currents 1.pA typical Ideal for high source impedance applications Dual power supply ±2.5V to ±5.V operation Single power supply 5V to 12V operation High voltage gaintypically ±2.5V and ±5.V Drive as low as 2KΩ load with 5mA drive current Output short circuit protected Unity gain bandwidth of 1.5MHz Slew rate of 1.9V/µs Low power dissipation APPLICATIONS Voltage amplifier Voltage follower/buffer Charge integrator Photodiode amplifier Data acquisition systems High performance portable instruments Signal conditioning circuits Sensor and transducer amplifiers Low leakage amplifiers Active filters Sample/Hold amplifier Picoammeter Current to voltage convert Coaxial cable driver PIN CONFIGURATION ORDERING INFORMATION OUT A 1 14 OUT D Operating Temperature Range* 55 C to 125 C C to 7 C C to 7 C 14Pin 14Pin 14Pin CERDIP Small Outline Plastic Dip Package Package (SOIC) Package ALD472A DB ALD472A SB ALD472A PB ALD472B DB ALD472B SB ALD472B PB ALD472 DB ALD472 SB ALD472 PB IN A IN A V IN B IN B OUT B IN D IN D V IN C IN C OUT C * Contact factory for industrial temperature range DB, PB, SB Package 1998 Advanced Linear Devices, Inc. 415 Tasman Drive, Sunnyvale, California Tel: (48) Fax: (48)

2 ABSOLUTE MAXIMUM RATINGS Supply voltage, V referenced to V.3V to V13.2V Supply voltage, V S referenced to V ±6.6V Differential input voltage range.3v to V.3V Power dissipation 6 mw Operating temperature range PB, SB package C to 7 C DB package 55 C to 125 C Storage temperature range 65 C to 15 C Lead temperature, 1 seconds 26 C OPERATING ELECTRICAL CHARACTERISTICS unless otherwise specified 472A 472B 472 Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions Supply V S ±2. ±6. ±2. ±6. ±2. ±6. V Dual Supply Voltage V V Single Supply Input Offset V OS mv R S 1KΩ Voltage mv C T A 7 C Input Offset I OS pa Current pa C T A 7 C Input Bias I B pa Current pa C T A 7 C Input Voltage V IR V V = 5V Range V Input R IN Ω Resistance Input Offset TCV OS µv/ C R S 1KΩ Voltage Drift Power Supply PSRR db R S 1KΩ C T A 7 C Common Mode CMRR db R S 1KΩ C T A 7 C Large Signal A V V/mV R L = 1KΩ Voltage Gain V/mV R L 1MΩ Output V O low V R L = 1MΩ Single supply Voltage V O high C T A 7 C Range V O low V R L = 1KΩ Dual supply V O high C T A 7 C Output Short I SC ma Circuit Current Supply I S ma V IN = V No Load Current Power P D mw Dissipation All four amplifiers Input C IN pf Capacitance Bandwidth B W MHz Slew Rate S R V/µs A V = 1 R L = 1KΩ Rise time t r µs R L = 1KΩ Overshoot % R L = 1KΩ C L = 1pF Factor ALD472A/ALD472B Advanced Linear Devices 2 ALD472

3 OPERATING ELECTRICAL CHARACTERISTICS (cont'd) TA = 25 C VS = ±2.5V unless otherwise specified 472A 472B 472 Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Uni Test Conditions Maximum Load C L pf Gain = 1 Capacitance pf Gain = 5 Input Noise e n nv/ Hz f = 1KHz Voltage Input Current Noise i n fa/ Hz f = 1Hz Settling t s µs.1% Time µs.1% A V = 1 R L = 5KΩ C L = 5pF V S = ±5.V unless otherwise specified 472A 472B 472 Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions Power Supply PSRR db R S 1KΩ Common Mode CMRR db R S 1KΩ Large Signal A V V/mV R L = 1KΩ Voltage Gain Output Voltage V O low V R L = 1KΩ Range V O high Bandwidth B W MHz Slew Rate S R V/µs A V = 1 C L = 5pF V S = 5.V 55 C T A 125 C unless otherwise specified 472A DA 472B DA 472 DA Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions Input Offset V OS mv R S 1KΩ Voltage Input Offset I OS na Current Input Bias I B na Current Power Supply PSRR db R S 1KΩ Common Mode CMRR db R S 1KΩ Large Signal A V V/mV A V = 1 Voltage Gain R L 1KΩ Output Voltage V O low V R L 1KΩ Range V O high ALD472A/ALD472B Advanced Linear Devices 3 ALD472

4 Design & Operating Notes: 1. The ALD472 CMOS operational amplifier uses a 3 gain stage architecture and an improved frequency compensation scheme to achieve large voltage gain, high output driving capability, and better frequency stability. The ALD472 is internally compensated for unity gain stability using a novel scheme. This design produces a clean single pole roll off in the gain characteristics while providing for more than 7 degrees of phase margin at the unity gain frequency. A unity gain buffer using the ALD472 will typically drive 4pF of external load capacitance without stability problems. In the inverting unity gain configuration, it can drive up to 8pF of load capacitance. Compared to other CMOS operational amplifiers, the ALD472 is much more resistant to parasitic oscillations. 2. The ALD472 has complementary pchannel and nchannel input differential stages connected in parallel to accomplish railtorail input common mode voltage range. With the common mode input voltage close to the power supplies, one of the two differential stages is switched off internally. To maintain compatibility with other operational amplifiers, this switching point has been selected to be about 1.5V above the negative supply voltage. As offset voltage trimming on the ALD472 is made when the input voltage is symmetrical to the supply voltages, this internal switching does not affect a large variety of applications such as an inverting amplifier or noninverting amplifier with a gain greater than 2.5 (5V operation), where the common mode voltage does not make excursions below this switching point. 3. The input bias and offset currents are essentially input protection diode reverse bias leakage currents, and are typically less than 1pA at room temperature. This low input bias current assures that the analog signal from the source will not be distorted by input bias currents. For applications where source impedance is very high, it may be necessary to limit noise and hum pickup through proper shielding. 4. The output stage consists of class AB complementary output drivers, capable of driving a low resistance load. The output voltage swing is limited by the drain to source onresistance of the output transistors as determined by the bias circuitry, and the value of the load resistor when connected. In the voltage follower configuration, the oscillation resistant feature, combined with the rail to rail input and output feature, makes the ALD472 an effective analog signal buffer for medium to high source impedance sensors, transducers, and other circuit networks. 5. The ALD472 operational amplifier has been designed with static discharge protection. Internally, the design has been carefully implemented to minimize latch up. However, care must be exercised when handling the device to avoid strong static fields. In using the operational amplifier, the user is advised to power up the circuit before, or simultaneously with, any input voltages applied and to limit input voltages to not exceed.3v of the power supply voltage levels. Alternatively, a 1KΩ or higher value resistor at the input terminals will limit input currents to acceptable levels while causing very small or negligible accuracy effects. TYPICAL PERFORMANCE CHARACTERISTICS ±7 ±6 COMMON MODE INPUT VOLTAGE RANGE AS A FUNCTION OF SUPPLY VOLTAGE OPEN LOOP VOLTAGE GAIN AS A FUNCTION OF SUPPLY VOLTAGE AND TEMPERATURE 1 } 55 C COMMON MODE INPUT VOLTAGE ) RANGE (V ±5 ±4 ±3 ±2 ±1 ±1 ±2 ±3 ±4 ±5 ±6 ±7 OPEN LOOP VOLTAGE GAIN (V/mV) ±2 ±4 ±6 } 25 C } 125 C R L = 1KΩ R L = 5KΩ ±8 INPUT BIAS CURRENT (pa) INPUT BIAS CURRENT AS A FUNCTION OF AMBIENT TEMPERATURE V S = ± 2.5V AMBIENT TEMPERATURE ( C) SUPPLY CURRENT (ma) SUPPLY CURRENT AS A FUNCTION OF SUPPLY VOLTAGE ±1 ±2 INPUTS GROUNDED S UNLOADED T A = 55 C 25 C 25 C 8 C 125 C ±3 ±4 ±5 ±6 ALD472A/ALD472B Advanced Linear Devices 4 ALD472

5 TYPICAL PERFORMANCE CHARACTERISTICS ±7 VOLTAGE SWING AS A FUNCTION OF SUPPLY VOLTAGE 12 OPEN LOOP VOLTAGE GAIN AS A FUNCTION OF FREQUENCY VOLTAGE SWING (V) ±6 ±5 ±4 ±3 ±2 ±25 C T A 125 C R L = 1KΩ R L = 1KΩ R L = 2KΩ OPEN LOOP VOLTAGE GAIN (db) PHASE SHIFT IN DEGREES ±1 ±2 ±3 ±4 ±5 ±6 ± K 1K 1K 1M 1M FREQUENCY (Hz) INPUT OFFSET VOLTAGE (mv) INPUT OFFSET VOLTAGE AS A FUNCTION OF AMBIENT TEMPERATURE REPRESENTATIVE UNITS AMBIENT TEMPERATURE ( C) INPUT OFFSET VOLTAGE (mv) INPUT OFFSET VOLTAGE AS A FUNCTION OF COMMON MODE INPUT VOLTAGE COMMON MODE INPUT VOLTAGE (V) OPEN LOOP VOLTAGE GAIN (V/mV) OPEN LOOP VOLTAGE GAIN AS A FUNCTION OF LOAD RESISTANCE 1 1K 1K 1K 1K LOAD RESISTANCE (Ω) VOLTAGE NOISE DENSITY (nv/ Hz) VOLTAGE NOISE DENSITY AS A FUNCTION OF FREQUENCY 1 1 1K 1K 1K FREQUENCY (Hz) 1K LARGE SIGNAL TRANSIENT RESPONSE SMALL SIGNAL TRANSIENT RESPONSE 5V/div R L = 1KΩ C L = 5pF 1 mv/div R L = 1KΩ C L = 5pF 1V/div 2µs/div 2 mv/div 2µs/div ALD472A/ALD472B Advanced Linear Devices 5 ALD472

6 TYPICAL APPLICATIONS RAILTORAIL VOLTAGE FOLLOWER/BUFFER RAILTORAIL WAVEFORM ~ Z IN = 1 12 Ω V IN 5V 4pF.1µF C L R L =1KΩ 5V INPUT V 5V V V IN 5V * See rail to rail waveform Performance waveforms. Upper trace is the output of a Wien Bridge Oscillator. Lower trace is the output of RailtoRail voltage follower. LOW OFFSET SUMMING AMPLIFIER PHOTO DETECTOR CURRENT TO VOLTAGE CONVERTER 5K R F = 5M 1K 2.5V INPUT 1 INPUT 2 1K GAIN = 5 * Circuit Drives Large Load Capacitance 4pF 2.5V.1µF.1µF C L = 4pF PHOTODIODE I 2.5V 2.5V V OUT = I x R F R L = 1K WIEN BRIDGE OSCILLATOR (RAILTO RAIL) SINE WAVE GENERATOR RAILTORAIL VOLTAGE COMPARATOR 2.5V 2.5V 1K V IN 5V 5V.1µF C =.1µF.1µF 1K R = 1K f = ~ 1 2πR C ~ 1.6KHz 1K 5K 1M * See rail to rail waveform ALD472A/ALD472B Advanced Linear Devices 6 ALD472