Precision Low-Voltage Micropower Operational Amplifier OP90

Transcription

1 a FEATURES Single/Dual Supply Operation:. V to V,.8 V to 8 V True Single-Supply Operation; Input and Output Voltage Ranges Include Ground Low Supply Current: A Max High Output Drive: ma Min Low Input Offset Voltage: V Max High Open-Loop Gain: V/mV Min Outstanding PSRR:. V/V Max Standard Pinout with Nulling to V GENERAL DESCRIPTION The OP9 is a high performance, micropower op amp that operates from a single supply of. V to V or from dual supplies of ±.8 V to ±8 V. The input voltage range includes the negative rail allowing the OP9 to accommodate input signals down to ground in a single-supply operation. The OP9 s output swing also includes a ground when operating from a single-supply, enabling zero-in, zero-out operation. The OP9 draws less than µa of quiescent supply current, while able to deliver over ma of output current to a load. The input offset voltage is below µv eliminating the need for Precision Low-Voltage Micropower Operational Amplifier OP9 PIN CONNECTIONS 8-Lead Hermetic DIP (Z-Suffix) 8-Lead Epoxy Mini-DIP (P-Suffix) 8-Lead SO (S-Suffix) V OS NULL IN +IN V NC = NO CONNECT 8 NC V+ OUT V OS NULL external nulling. Gain exceeds, and common-mode rejection is better than db. The power supply rejection ratio of under. µv/v minimizes offset voltage changes experienced in battery-powered systems. The low offset voltage and high gain offered by the OP9 bring precision performance to micropower applications. The minimal voltage and current requirements of the OP9 suit it for battery and solar powered applications, such as portable instruments, remote sensors, and satellites. V+ +IN OUTPUT IN * * NULL NULL V *ELECTRONICALLY ADJUSTED ON CHIP FOR MINIMUM OFFSET VOLTAGE Figure. Simplied Schematic Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9, Norwood, MA -9, U.S.A. Tel: 8/9- Fax: 8/-8 Analog Devices, Inc.,

2 SPECIFICATIONS ELECTRICAL CHARACTERISTICS (V S =. V to V, T A = C, unless otherwise noted.) OP9A/E OP9G Parameter Symbol Conditions Min Typ Max Min Typ Max Unit INPUT OFFSET VOLTAGE V OS µv INPUT OFFSET CURRENT I OS V CM = V.. na INPUT BIAS CURRENT I B V CM = V.. na LARGE-SIGNAL V S = ± V, V O = ± V VOLTAGE GAIN A VO R L = kω 8 V/mV A VO R L = kω V/mV A VO R L = kω V/mV V+ = V, V = V, V < V O < V A VO R L = kω V/mV A VO R L = kω 8 V/mV INPUT VOLTAGE RANGE IVR V+ = V, V = V / / V V S = ± V /. /. V OUTPUT VOLTAGE SWING V O V S = ± V R L = kω ± ±. ± ±. V R L = kω ± ± ± ± V V OH V+ = V, V = V R L = kω.... V V OL V+ = V, V = V R L = kω µv COMMON-MODE CMR V+ = V, V = V, REJECTION V < V CM < V 9 8 db CMR V S = ± V, V < V CM <. V 9 db POWER SUPPLY REJECTION RATIO PSRR... µv/v SLEW RATE SR V S = ± V V/ms SUPPLY CURRENT I SY V S = ±. V 9 9 µa I SY V S = ± V µa CAPACITIVE LOAD A V = STABILITY No Oscillations pf INPUT NOISE VOLTAGE e n p-p f O =. Hz to Hz V S = ± V µv p-p INPUT RESISTANCE DIFFERENTIAL MODE R IN V S = ± V MΩ INPUT RESISTANCE COMMON-MODE R INCM V S = ± V GΩ NOTES Guaranteed by CMR test. Guaranteed but not % tested. Specifications subject to change without notice.

3 ELECTRICAL CHARACTERISTICS (V S =. V to V, C T A + C, unless otherwise noted.) Parameter Symbol Conditions Min Typ Max Unit INPUT OFFSET VOLTAGE V OS 8 µv AVERAGE INPUT OFFSET VOLTAGE DRIFT TCV OS.. µv/ C INPUT OFFSET CURRENT I OS V CM = V. na INPUT BIAS CURRENT I B V CM = V. na LARGE-SIGNAL VOLTAGE GAIN A VO V S = ± V, V O = ± V R L = kω V/mV R L = kω V/mV R L = kω V/mV A VO V+ = V, V = V, V < V O < V R L = kω V/mV R L = kω V/mV INPUT VOLTAGE RANGE* IVR V+ = V, V = V /. V V S = ± V / V OUTPUT VOLTAGE SWING V O V S = ± V R L = kω ±. ±. V R L = kω ±. ±. V V OH V+ = V, V = V R L = kω.9. V V OL V+ = V, V = V R L = kω µv COMMON-MODE REJECTION CMR V+ = V, V = V, V < V CM <. V 8 db V S = ± V, V < V CM <. V 9 db POWER SUPPLY REJECTION RATIO PSRR. µv/v SUPPLY CURRENT I SY V S = ±. V µa V S = ± V 9 µa NOTE *Guaranteed by CMR test. OP9

4 ELECTRICAL CHARACTERISTICS (V S =. V to V, C T A +8 C for OP9E/F, C T A +8 C for OP9G, unless otherwise noted.) OP9OE OP9OG Parameter Symbol Conditions Min Typ Max Min Typ Max Unit INPUT OFFSET VOLTAGE V OS 8 µv AVERAGE INPUT OFFSET VOLTAGE DRIFT TCV OS.. µv/ C INPUT OFFSET CURRENT I OS VCM = V.8. na INPUT BIAS CURRENT I B VCM = V.. na LARGE-SIGNAL A VO V S = ± V, V O = ± V VOLTAGE GAIN R L = kω 8 V/mV R L = kω V/mV R L = kω V/mV A VO V+ = V, V = V, V < V O < V R L = kω 8 8 V/mV R L = kω 9 V/mV INPUT VOLTAGE RANGE* IVR V+ = V, V = V /. /. V V S = ± V /. /. V OUTPUT VOLTAGE SWING V O V S = ± V R L = kω ±. ± ±. ± V R L = kω ±. ±.8 ±. ±.8 V V OH V+ = V, V = V R L = kω V V OL V+ = V, V = V R L = kω µv COMMON-MODE CMR V+ = V, V = V, REJECTION V < V CM <. V 8 8 db V S = ± V, V < V CM <. V 9 db POWER SUPPLY REJECTION RATIO PSRR...8 µv/v SUPPLY CURRENT I SY V S = ±. V µa V S = ± V µa NOTE *Guaranteed by CMR test.

5 ABSOLUTE MAXIMUM RATINGS Supply Voltage ± 8 V Differential Input Voltage.... [(V ) V] to [(V+) + V] Common-Mode Input Voltage [(V ) V] to [(V+) + V] Output Short-Circuit Duration Indefinite Storage Temperature Range Z Package C to + C P Package C to + C Operating Temperature Range OP9A C to + C OP9E C to +8 C OP9G C to +8 C Junction Temperature (T J ) C to + C Lead Temperature (Soldering sec) C ORDERING GUIDE Package Options T A = C Operating V OS Max CERDIP Plastic Temperature (mv) 8-Lead 8-Lead Range OP9AZ/88* MIL OP9EZ* IND OP9GP XIND OP9GS XIND *Not for new design, obsolete April. Package Type JA JC Unit 8-Lead Hermetic DIP (Z) 8 C/W 8-Lead Plastic DIP (P) C/W 8-Lead SO (S) 8 C/W NOTES Absolute Maximum Ratings apply to packaged parts, unless otherwise noted. JA is specified for worst-case mounting conditions; i.e., JA is specified for device in socket for CerDIP, and P-DIP; JA is specified for devices soldered to printed circuit board for SO package. CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as V readily accumulate on the human body and test equipment and can discharge without detection. Although the OP9 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. WARNING! ESD SENSITIVE DEVICE

6 Typical Performance Characteristics INPUT OFFSET VOLTAGE V 8 TEMPERATURE C TPC. Input Offset Voltage vs. Temperature INPUT OFFSET CURRENT na TEMPERATURE C TPC. Input Offset Current vs. Temperature INPUT BIAS CURRENT na TEMPERATURE C TPC. Input Bias Current vs. Temperature SUPPLY CURRENT A 8 8 NO LOAD V S =.V OPEN-LOOP GAIN V/mV R L = k T A = C T A = 8 C T A = C OPEN-LOOP GAIN db 8 GAIN T A = C R L = k 9 8 PHASE SHIFT DEG TEMPERATURE C TPC. Supply Current vs. Temperature SINGLE-SUPPLY VOLTAGE V TPC. Open-Loop Gain vs. Single-Supply Voltage. k k k FREQUENCY Hz TPC. Open-Loop Gain and Phase Shift vs. Frequency CLOSED-LOOP GAIN db T A = C OUTPUT VOLTAGE SWING V V+ = V, V = V T A = C OUTPUT SWING V 8 POSITIVE NEGATIVE T A = C k k k FREQUENCY Hz TPC. Closed-Loop Gain vs. Frequency k k k LOAD RESISTANCE TPC 8. Output Voltage Swing vs. Load Resistance k k k LOAD RESISTANCE TPC 9. Output Voltage Swing vs. Load Resistance

7 POWER SUPPLY REJECTION db 8 T A = C NEGATIVE SUPPLY POSITIVE SUPPLY COMMON-MODE REJECTION db 8 T A = C NOISE VOLTAGE DENSITY nv/ Hz T A = C k FREQUENCY Hz TPC. Power Supply Rejection vs. Frequency k FREQUENCY Hz TPC. Common-Mode Rejection vs. Frequency. k FREQUENCY Hz TPC. Noise Voltage Density vs. Frequency CURRENT NOISE DENSITY pa/ Hz T A = C.. k FREQUENCY Hz TPC. Current Noise Density vs. Frequency T A = C A V = + R L = k C L = pf TPC. Small-Signal Transient Response T A = C A V = + R L = k C L = pf TPC. Large-Signal Transient Response +8V OP9 8V Figure. Burn-In Circuit APPLICATION INFORMATION Battery-Powered Applications The OP9 can be operated on a minimum supply voltage of. V, or with dual supplies ±.8 V, and draws only pa of supply current. In many battery-powered circuits, the OP9 can be continuously operated for thousands of hours before requiring battery replacement, reducing equipment down time and operating cost. High-performance portable equipment and instruments frequently use lithium cells because of their long shelf-life, light weight, and high-energy density relative to older primary cells. Most lithium cells have a nominal output voltage of V and are noted for a flat discharge characteristic. The low-supply voltage requirement of the OP9, combined with the flat discharge characteristic of the lithium cell, indicates that the OP9 can be operated over the entire useful life of the cell. Figure shows the typical discharge characteristic of a Ah lithium cell powering an OP9 which, in turn, is driving full output swing into a kω load.

8 LITHIUM SULPHUR DIOXIDE CELL VOLTAGE V HOURS Figure. Lithium Sulphur Dioxide Cell Discharge Characteristic with OP9 and kω Load Input Voltage Protection The OP9 uses a PNP input stage with protection resistors in series with the inverting and noninverting inputs. The high breakdown of the PNP transistors coupled with the protection resistors provides a large amount of input protection, allowing the inputs to be taken V beyond either supply without damaging the amplifier. Offset Nulling The offset null circuit of Figure provides mv of offset adjustment range. A kω resistor placed in a series with the wiper of the offset null potentiometer, as shown in Figure, reduces the offset adjustment range to µv and is recommended for applications requiring high null resolution. Offset nulling does not affect TCV OS performance. TEST CIRCUITS V+ Single-Supply Output Voltage Range In single-supply operation, the OP9 s input and output ranges include ground. This allows true zero-in, zero-out operation. The output stage provides an active pull-down to around.8 V above ground. Below this level, a load resistance of up to MΩ to ground is required to pull the output down to zero. In the region from ground to.8 V, the OP9 has voltage gain equal to the data sheet specification. Output current source capatibility is maintained over the entire voltage range including ground. APPLICATIONS Battery-Powered Voltage Reference The circuit of Figure is a battery-powered voltage reference that draws only µa of supply current. At this level, two AA cells can power this reference over 8 months. At an output voltage of. C, drift of the reference is only at. µv/ C over the industrial temperature range. Load regulation is 8 µv/ma with line regulation at µv/v. Design of the reference is based on the bandgap technique. Scaling of resistors R and R produces unequal currents in Q and Q. The resulting V BE mismatch creates a temperature proportional voltage across R which, in turn, produces a larger temperature-proportional voltage across R and R. This voltage appears at the output added to the V BE of Q, which has an opposite temperature coefficient. Adjusting the output to l. V at C produces minimum drift over temperature. Bandgap references can have start-up problems. With no current in R and R, the OP9 is beyond its positive input range limit and has an undefined output state. Shorting Pin (an offset adjust pin) to ground, forces the output high under these conditions and ensures reliable start-up without significantly degrading the OP9 s offset drift. OP9 k V C pf R k R.M OP9 V+ (.V TO V) V OUT C) Figure. Offset Nulling Circuit V+ MAT-AH OP9 k k V R 8k R k R k OUTPUT ADJUST Figure. High Resolution Offset Nulling Circuit Figure. Battery-Powered Voltage Reference 8

9 Single Op Amp Full-Wave Rectifier Figure shows a full-wave rectifier circuit that provides the absolute value of input signals up to ±. V even though operated from a single V supply. For negative inputs, the amplifier acts as a unity-gain inverter. Positive signals force the op amp output to ground. The N9 diode becomes reversed-biased and the signal passes through R and R to the output. Since output impedance is dependent on input polarity, load impedances cause an asymmetric output. For constant load impedances, this can be corrected by reducing R. Varying or heavy loads can be buffered by a second OP9. Figure 8 shows the output of the full-wave rectifier with a V p-p, Hz input signal. V IN R k HP8-8 OP9FZ R k N9 R k Figure. Single Op Amp Full-Wave Rectifier V OUT -WIRE ma TO ma CURRENT TRANSMITTER The current transmitter of Figure 9 provides an output of ma to ma that is linearly proportional to the input voltage. Linearity of the transmitter exceeds.% and line rejection is.%/volt. Biasing for the current transmitter is provided by the REF-EZ. The OP9EZ regulates the output current to satisfy the current summation at the noninverting node: I OUT For the values shown in Figure 9, VIN R VR = + R R R IOUT = VIN ma + Ω giving a full-scale output of ma with a mv input. Adjustment of R will provide an offset trim and adjustment of R will provide a gain trim. These trims do not interact since the noninverting input of the OP9 is at virtual ground. The Schottky diode, D, prevents input voltage spikes from pulling the noninverting input more than mv below the inverting input. Without the diode, such spikes could cause phase reversal of the OP9 and possible latch-up of the transmitter. Compliance of this circuit is from V to V. The voltage reference output can provide up to ma for transducer excitation. Figure 8. Output of Full-Wave Rectifier with V p-p, Hz Input REFERENCE ma MAX + V IN R k R M D HP 8-8 OP9EZ R.k R k REF-EZ N V+ (V TO V) R R 8k I OUT I OUT = V IN + ma R L Figure 9. -Wire ma to ma Transmitter 9

10 Micropower Voltage-Controlled Oscillator Two OP9s in combination with an inexpensive quad CMOS switch comprise the precision VCO of Figure. This circuit provides triangle and square wave outputs and draws only µa from a single V supply. A acts as an integrator; S switches the charging current symmetrically to yield positive and negative ramps. The integrator is bounded by A which acts as a Schmitt trigger with a precise hysteresis of. V, set by resistors R, R, and R, and associated CMOS switches. The resulting output of A is a triangular wave with upper and lower levels of. V and. V. The output of A is a square wave with almost rail-to-rail swing. With the components shown, frequency of operation is given by the equation: f = V ( V) Hz/ V OUT CONTROL but this is easily changed by varying C. The circuit operates well up to a few hundred hertz. Micropower Single-Supply Instrumentation Amplifier The simple instrumentation amplifier of Figure provides over db of common-mode rejection and draws only µa of supply current. Feedback is to the trim pins rather than to the inverting input. This enables a single amplifier to provide differential to single-ended conversion with excellent common-mode rejection. Distortion of the instrumentation amplifier is that of a differential pair, so the circuit is restricted to high gain applica- C tions. Nonlinearity is less than.% for gains of to over a. V output range. Resistors R and R set the voltage gain and, with the values shown, yield a gain of. Gain tempco of the instrumentation amplifier is only ppm/ C. Offset voltage is under µv with drift below µv/ C. The OP9 s input and output voltage ranges include the negative rail which allows the instrumentation amplifier to provide true zero-in, zero-out operation. IN +IN OP9EZ R.M. F R.9M R M R k GAIN ADJUST V OUT Figure. Micropower Single-Supply Instrumentation Amplifier V CONTROL R k R k R k OP9EZ A R k nf TRIANGLE OUT R k OP9EZ A SQUARE OUT IN/OUT CD S V DD R8 k R k R k OUT/IN CONT OUT/IN S CONT IN/OUT IN/OUT CONT S OUT/IN CONT OUT/IN 9 S V SS IN/OUT 8 Figure. Micropower Voltage Controlled Oscillator

11 Single-Supply Current Monitor Current monitoring essentially consists of amplifying the voltage drop across a resistor placed in a series with the current to be measured. The difficulty is that only small voltage drops can be tolerated and with low precision op amps this greatly limits the overall resolution. The single supply current monitor of Figure has a resolution of µa and is capable of monitoring ma of current. This range can be adjusted by changing the current sense resistor R. When measuring total system current, it may be necessary to include the supply current of the current monitor, which bypasses the current sense resistor, in the final result. This current can be measured and calibrated (together with the residual offset) by adjustment of the offset trim potentiometer, R. This produces a deliberate offset that is temperature dependent. However, the supply current of the OP9 is also proportional to temperature and the two effects tend to track. Current in R and R, which also bypasses R, can be accounted for by a gain trim. + TO CIRCUIT UNDER TEST OP9EZ V OUT = mv/ma (I TEST ) I TEST R R R k R k V+ R 9.9k Figure. Single-Supply Current Monitor

12 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 8-Lead PDIP Package (N-8) 8-Lead Hermetic Package (Q-8) PIN. (.) MAX. (.). (.9). (.9).8 (8.8) 8. (.8). (.). (.) BSC. (.). (.).8 (.). (.). (.). (.8). (.) MIN SEATING PLANE. (8.). (.).9 (.9). (.9). (.8).8 (.) PIN. (.8) MAX. (.8). (.8). (.) MIN 8. (.) MAX. (.) BSC. (.9) MAX. (.8). (.9). (.). (.8). (.8) MIN SEATING. (.8). (.8) PLANE. (.). (.). (8.).9 (.). (.8).8 (.) C /(A) 8-Lead Soic Package (R-8).98 (.).89 (.8). (.).9 (.8) 8. (.).8 (.8) PIN.98 (.). (.) SEATING PLANE. (.) BSC.9 (.9).8 (.). (.9).9 (.9).98 (.). (.9) 8.9 (.).99 (.). (.). (.) Revision History Location Page 9/ Data Sheet changed from REV. to. Edits to PIN CONNECTIONS Edits to ELECTRICAL CHARACTERISTICS ,, Edits to ORDERING INFORMATION Edits to ABSOLUTE MAXIMUM RATINGS Edits to PACKAGE TYPE DELETED OP9 DICE CHARACTERISTICS DELETED WAFER TEST LIMITS PRINTED IN U.S.A.