OPA4344UA/2K5

OPA344 OPA2344 OPA4344 OPA 434 4 OPA 344 OPA345 OPA 345 OPA 342 OPA2345 OPA4345 ® www.ti.com SBOS107A – APRIL 2000 – REVISED AUGUST 2008 LOW POWER, SINGLE-SUPPLY, RAIL-TO-RAIL OPERATIONAL AMPLIFIERS MicroAmplifier ™ Series FEATURES DESCRIPTION ● ● ● ● The OPA344 and OPA345 series rail-to-rail CMOS operational amplifiers are designed for precision, low-power, miniature applications. The OPA344 is unity gain stable, while the OPA345 is optimized for gains greater than or equal to five, and has a gain-bandwidth product of 3MHz. The OPA344 and OPA345 are optimized to operate on a single supply from 2.5V and up to 5.5V with an input common-mode voltage range that extends 300mV beyond the supplies. Quiescent current is only 250µA (max). Rail-to-rail input and output make them ideal for driving sampling analog-to-digital converters. They are also well suited for general purpose and audio applications and providing I/V conversion at the output of D/A converters. Single, dual and quad versions have identical specs for design flexibility. A variety of packages are available. All are specified for operation from –40ºC to 85ºC. A SPICE macromodel for design analysis is available for download from www.ti.com. RAIL-TO-RAIL INPUT RAIL-TO-RAIL OUTPUT (within 1mV) LOW QUIESCENT CURRENT: 150µA typ MicroSIZE PACKAGES SOT23-5 MSOP-8 TSSOP-14 ● GAIN-BANDWIDTH OPA344: 1MHz, G ≥ 1 OPA345: 3MHz, G ≥ 5 ● SLEW RATE OPA344: 0.8V/µs OPA345: 2V/µs ● THD + NOISE: 0.006% APPLICATIONS ● ● ● ● ● ● ● PCMCIA CARDS DATA ACQUISITION PROCESS CONTROL AUDIO PROCESSING COMMUNICATIONS ACTIVE FILTERS TEST EQUIPMENT OPA344, OPA345 Out 1 V– 2 +In 3 1 –In A 2 +In A 3 V– 4 A B V+ 4 –In OPA4344, OPA4345 Out A 1 –In A 2 14 Out D 13 –In D SOT23-5 OPA2344, OPA2345 Out A 5 A OPA344, OPA345 8 V+ 7 Out B 6 –In B 5 +In B NC –In 1 2 +In A 3 12 +In D 8 NC +V 4 11 –V 7 V+ +In B 5 10 +In C 6 Out –In B 6 9 –In C 5 NC Out B 7 8 Out C B SO-8, MSOP-8, 8-Pin DIP (OPA2344 Only) +In V– 3 4 D SO-8, 8-Pin DIP (OPA344 Only) C TSSOP-14, SO-14, 14-PIn DIP (OPA4344 Only) Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. Copyright © 2000-2008, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. www.ti.com SPECIFICATIONS: VS = 2.7V to 5.5V At TA = +25°C, RL = 10kΩ connected to VS /2 and VOUT = VS /2, unless otherwise noted. Boldface limits apply over the temperature range, TA = –40°C to +85°C. OPA344NA, UA, PA OPA2344EA, UA, PA OPA4344EA, UA, PA PARAMETER OFFSET VOLTAGE Input Offset Voltage Over Temperature vs Temperature vs Power Supply Over Temperature Channel Separation, dc f = 1kHz INPUT BIAS CURRENT Input Bias Current Over Temperature Input Offset Current NOISE Input Voltage Noise Input Voltage Noise Density Current Noise Density INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection Ratio Over Temperature Common-Mode Rejection Over Temperature Common-Mode Rejection Over Temperature CONDITION VS = 2.7V to 5.5V, VCM < (V+) -1.8V VS = 2.7V to 5.5V, VCM < (V+) -1.8V IOS f = 0.1 to 50kHz f = 10kHz f = 10kHz en in VCM CMRR CMRR CMRR AOL TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance SOT23-5 Surface Mount MSOP-8 Surface Mount 8-Pin DIP SO-8 Surface Mount TSSOP-14 Surface Mount 14-Pin DIP SO-14 Surface Mount mV mV µV/°C µV/V µV/V µV/V dB 200 250 VS = +5.5V, –0.3V < VCM < (V+)-1.8 VS = +5.5V, –0.3V < VCM < (V+)-1.8 VS = +5.5V, –0.3V < VCM < 5.8V VS = +5.5V, –0.3V < VCM < 5.8V VS = +2.7V, –0.3V < VCM < 3V VS = +2.7V, –0.3V < VCM < 3V –0.3 76 74 70 68 66 64 RL RL RL RL = 100kΩ, 10mV < VO < (V+) –10mV = 100kΩ, 10mV < VO < (V+) –10mV = 5kΩ, 400mV < VO < (V+) –400mV = 5kΩ, 400mV < VO < (V+) –400mV 104 100 96 90 pA pA pA µVrms nV/√Hz fA/√Hz (V+) + 0.3 92 84 80 V dB dB dB dB dB dB 1013 || 3 1013 || 6 Ω || pF Ω || pF 122 dB dB dB dB 120 CL = 100pF THD+N 1 0.8 5 8 2.5 0.006 VS = 5.5V, 2V Step VS = 5.5V, 2V Step VIN • G = VS VS = 5.5V, VO = 3Vp-p, G = 1, f = 1kHz RL = 100kΩ, AOL ≥ 96dB RL = 100kΩ, AOL ≥ 104dB RL = 100kΩ, AOL ≥ 100dB RL = 5kΩ, AOL ≥ 96dB RL = 5kΩ, AOL ≥ 90dB Over Temperature POWER SUPPLY Specified Voltage Range Operating Voltage Range Quiescent Current (per amplifier) Over Temperature ±1 ±1.2 8 30 0.5 GBW SR OUTPUT Voltage Output Swing from Rail(1) Over Temperature Short-Circuit Current Capacitive Load Drive UNITS ±0.2 ±10 See Typical Curve ±0.2 ±10 IB Over Temperature FREQUENCY RESPONSE Gain-Bandwidth Product Slew Rate Settling Time, 0.1% 0.01% Overload Recovery Time Total Harmonic Distortion + Noise MAX 0.2 130 INPUT IMPEDANCE Differential Common-Mode OPEN-LOOP GAIN Open-Loop Voltage Gain Over Temperature TYP ±0.2 ±0.8 ±3 30 VS = +5.5V, VCM = VS/2 VOS dVOS/dT PSRR MIN 1 3 40 IQ 10 10 400 400 ±15 See Typical Curve ISC CLOAD VS MHz V/µs µs µs µs % 2.7 5.5 2.5 to 5.5 150 VS = 5.5V, IO = 0 –40 –55 –65 θJA 200 150 100 150 100 80 100 mV mV mV mV mV mA 250 300 V V µA µA 85 125 150 °C °C °C °C/W °C/W °C/W °C/W °C/W °C/W °C/W NOTE: (1) Output voltage swings are measured between the output and power-supply rails. OPA344, 2344, 4344 OPA345, 2345, 4345 2 www.ti.com SBOS107A SPECIFICATIONS: VS = 2.7V to 5.5V At TA = +25°C, RL = 10kΩ connected to VS /2 and VOUT = VS /2, unless otherwise noted. Boldface limits apply over the temperature range, TA = –40°C to +85°C. OPA345NA, UA OPA2345EA, UA OPA4345EA, UA PARAMETER OFFSET VOLTAGE Input Offset Voltage Over Temperature vs Temperature vs Power Supply Over Temperature Channel Separation, dc f = 1kHz INPUT BIAS CURRENT Input Bias Current Over Temperature Input Offset Current NOISE Input Voltage Noise Input Voltage Noise Density Current Noise Density INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection Ratio Over Temperature Common-Mode Rejection Ratio Over Temperature Common-Mode Rejection Ratio Over Temperature CONDITION VOS dVOS/dT PSRR MIN ±0.2 ±0.8 ±3 30 VS = +5.5V, VCM = VS/2 VS = 2.7V to 5.5V, VCM < (V+) -1.8V VS = 2.7V to 5.5V, VCM < (V+) -1.8V IOS f = 0.1 to 50kHz f = 10kHz f = 10kHz en in VCM CMRR CMRR CMRR AOL TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance SOT23-5 Surface Mount MSOP-8 Surface Mount SO-8 Surface Mount TSSOP-14 Surface Mount SO-14 Surface Mount mV mV µV/°C µV/V µV/V µV/V dB 200 250 VS = +5.5V, –0.3V < VCM < (V+)-1.8 VS = +5.5V, –0.3V < VCM < (V+)-1.8 VS = +5.5V, –0.3V < VCM < 5.8V VS = +5.5V, –0.3V < VCM < 5.8V VS = +2.7V, –0.3V < VCM < 3V VS = +2.7V, –0.3V < VCM < 3V –0.3 76 74 70 68 66 64 RL RL RL RL = 100kΩ, 10mV < VO < (V+) –10mV = 100kΩ, 10mV < VO < (V+) –10mV = 5kΩ, 400mV < VO < (V+) –400mV = 5kΩ, 400mV < VO < (V+) –400mV 104 100 96 90 pA pA pA µVrms nV/√Hz fA/√Hz (V+) + 0.3 92 84 80 V dB dB dB dB dB dB 1013 || 3 1013 || 6 Ω || pF Ω || pF 122 dB dB dB dB 120 CL = 100pF THD+N 3 2 1.5 1.6 2.5 0.006 G = 5, 2V Output Step G = 5, 2V Output Step VIN • G = VS VS = 5.5V, VO = 2.5Vp-p, G = 5, f = 1kHz RL = 100kΩ, AOL ≥ 96dB RL = 100kΩ, AOL ≥ 104dB RL = 100kΩ, AOL ≥ 100dB RL = 5kΩ, AOL ≥ 96dB RL = 5kΩ, AOL ≥ 90dB Over Temperature POWER SUPPLY Specified Voltage Range Operating Voltage Range Quiescent Current (per amplifier) Over Temperature ±1 ±1.2 8 30 0.5 GBW SR OUTPUT Voltage Output Swing from Rail(1) Over Temperature Short-Circuit Current Capacitive Load Drive UNITS ±0.2 ±10 See Typical Curve ±0.2 ±10 IB Over Temperature FREQUENCY RESPONSE Gain-Bandwidth Product Slew Rate Settling Time, 0.1% 0.01% Overload Recovery Time Total Harmonic Distortion + Noise MAX 0.2 130 INPUT IMPEDANCE Differential Common-Mode OPEN-LOOP GAIN Open-Loop Voltage Gain Over Temperature TYP 1 3 40 IQ 10 10 400 400 ±15 See Typical Curve ISC CLOAD VS MHz V/µs µs µs µs % 2.7 5.5 2.5 to 5.5 150 VS = 5.5V, IO = 0 –40 –55 –65 θJA 200 150 150 100 100 mV mV mV mV mV mA 250 300 V V µA µA 85 125 150 °C °C °C °C/W °C/W °C/W °C/W °C/W NOTE: (1) Output voltage swings are measured between the output and power-supply rails. OPA344, 2344, 4344 OPA345, 2345, 4345 SBOS107A 3 www.ti.com ABSOLUTE MAXIMUM RATINGS(1) ELECTROSTATIC DISCHARGE SENSITIVITY Supply Voltage, V+ to V- ................................................................... 7.5V Signal Input Terminals, Voltage(2) ..................... (V–) –0.5V to (V+) +0.5V Current(2) .................................................... 10mA Output Short-Circuit(3) .............................................................. Continuous Operating Temperature .................................................. –55°C to +125°C Storage Temperature ..................................................... –65°C to +150°C Junction Temperature ...................................................................... 150°C Lead Temperature (soldering, 10s) ................................................. 300°C ESD Tolerance (Human Body Model) ............................................ 4000V This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. NOTES: (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only. Functional operation of the device at these conditions, or beyond the specified operating conditions, is not implied. (2) Input terminals are diode-clamped to the power supply rails. Input signals that can swing more than 0.5V beyond the supply rails should be current-limited to 10mA or less. (3) Short-circuit to ground, one amplifier per package. PACKAGE/ORDERING INFORMATION(1) SPECIFIED TEMPERATURE RANGE PACKAGE MARKING ORDERING NUMBER(2) TRANSPORT MEDIA OPA344NA/250 OPA344NA /3K OPA344UA OPA344UA /2K5 OPA344PA Tape and Reel Tape and Reel Rails Tape and Reel Rails OPA2344EA /250 OPA2344EA /2K5 OPA2344UA OPA2344UA /2K5 OPA2344PA Tape and Reel Tape and Reel Rails Tape and Reel Rails Rails Tape and Reel Rails Tape and Reel Rails PRODUCT PACKAGE PACKAGE DESIGNATOR OPA344NA SOT23-5 DBV –40°C to +85°C B44 " " " " SO-8 D –40°C to +85°C OPA344UA " " " " OPA344PA 8-Pin Dip P –40° C to +85°C OPA344PA OPA2344EA MSOP-8 DGK –40°C to +85°C C44 " " " " " OPA2344UA SO-8 D –40°C to +85°C OPA2344UA " " " " " OPA2344PA 8-Pin DIP P –40°C to +85°C OPA2344PA OPA4344EA TSSOP-14 PW –40°C to +85°C OPA4344EA " " " " " OPA4344UA SO-14 D –40°C to +85°C OPA4344UA " " " " " OPA4344PA 14-Pin DIP N –40°C to +85°C OPA4344PA OPA4344EA /250 OPA4344EA /2K5 OPA4344UA OPA4344UA /2K5 OPA4344PA OPA345NA " OPA345UA " SOT23-5 " SO-8 " DBV " D " –40°C to +85°C " –40°C to +85°C " A45 " OPA345UA " OPA345NA/250 OPA345NA/3K OPA345UA OPA345UA/2K5 Tape and Reel Tape and Reel Rails Tape and Reel OPA2345EA MSOP-8 DGK –40°C to +85°C B45 " " " " " OPA2345UA SO-8 D –40°C to +85°C OPA2345UA " " " " " OPA2345EA/250 OPA2345EA /2K5 OPA2345UA OPA2345UA /2K5 Tape and Reel Tape and Reel Rails Tape and Reel OPA4345EA TSSOP-14 PW –40°C to +85°C OPA4345EA " " " " " OPA4345UA SO-14 D –40°C to +85°C OPA4345UA " " " " " OPA4345EA/250 OPA4345EA /2K5 OPA4345UA OPA4345UA /2K5 Tape and Reel Tape and Reel Rails Tape and Reel " OPA344UA " NOTES: (1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. (2) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of “OPA344UA/2K5” will get a single 2500-piece Tape and Reel. OPA344, 2344, 4344 OPA345, 2345, 4345 4 www.ti.com SBOS107A TYPICAL PERFORMANCE CURVES At TA = +25°C, VS = +5V, and RL = 10kΩ connected to VS/2, unless otherwise noted. OPEN-LOOP GAIN/PHASE vs FREQUENCY OPEN-LOOP GAIN/PHASE vs FREQUENCY 100 OPA344 120 30 100 0 30 OPA345 Phase 80 90 40 120 Gain (dB) 60 60 60 90 40 120 Gain Gain 20 0 0.1 10 1 100 1k 10k 100k 1M 150 20 180 10M 0 150 0.1 10 1 100 Frequency (Hz) 6 Maximum Output Voltage (VPP) 1M 180 10M CMRR –PSRR 40 20 VS = +5V 5 4 OPA344 OPA345 3 VS = +2.7V 2 1 0 10 10 100 1k 10k 100k 10k 100k 1M 10M Frequency (Hz) Frequency (Hz) CHANNEL SEPARATION vs FREQUENCY VOLTAGE AND CURRENT NOISE SPECTRAL DENSITY vs FREQUENCY 10000 Voltage Noise (nV/√Hz) 140 120 100 Dual and quad devices. G = 1, all channels. Quad measured channel A to D or B to C—other combinations yield improved rejection. 80 100 IN 1000 10 VN 100 1 10 60 100 1k 10k 100k 1 1M 100 1k 10k 100k 1M 0.1 10M Frequency (Hz) Frequency (Hz) OPA344, 2344, 4344 OPA345, 2345, 4345 SBOS107A 10 Current Noise (fA/√Hz) Rejection Ratio (dB) 100k VS = +5.5V +PSRR Channel Separation (dB) 10k MAXIMUM OUTPUT VOLTAGE vs FREQUENCY 100 80 1k Frequency (Hz) POWER SUPPLY AND COMMON-MODE REJECTION RATIO vs FREQUENCY 60 Phase 80 60 Phase (°) Gain (dB) 0 Phase (°) 120 5 www.ti.com TYPICAL PERFORMANCE CURVES (Cont.) At TA = +25°C, VS = +5V, and RL = 10kΩ connected to VS/2, unless otherwise noted. TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY OPEN-LOOP GAIN, COMMON-MODE REJECTION RATIO, AND POWER-SUPPLY REJECTION vs TEMPERATURE 1 140 AOL OPA344: G = 1 120 AOL, CMRR, PSRR (dB) OPA345: G = 5 THD+N (%) 0.1 0.010 100 CMRR 80 PSRR 60 40 20 0.001 0 100 1k 10k 20k –75 –50 –25 0 25 100 INPUT BIAS CURRENT vs TEMPERATURE QUIESCENT CURRENT AND SHORT-CIRCUIT CURRENT vs TEMPERATURE 125 200 40 175 1000 Quiescent Current (µA) Input Bias Current (pA) 75 Temperature (°C) 10000 100 10 1 0.1 35 IQ 150 30 135 25 +ISC 100 20 –ISC 75 15 50 10 25 5 0 –75 –50 –25 0 25 50 75 100 –75 125 –50 25 0 –25 50 75 Temperature (°C) Temperature (°C) SLEW RATE vs TEMPERATURE INPUT BIAS CURRENT vs COMMON-MODE VOLTAGE 100 0 125 5 6 6 3.0 SR– SR+ OPA345 2.0 1.5 SR– OPA344 1.0 SR+ 4 Input Bias Current (pA) 2.5 Slew Rate (V/µs) 50 Frequency (Hz) V– Supply 2 0 –2 Input voltage ≤ –0.3V can cause op amp output to lock up. See text. –4 0.5 V+ Supply –6 0 –75 –50 –25 0 25 50 75 100 –1 125 0 1 2 3 4 Common-Mode Voltage (V) Temperature (°C) OPA344, 2344, 4344 OPA345, 2345, 4345 6 www.ti.com SBOS107A Short-Circuit Current (mA) 20 TYPICAL PERFORMANCE CURVES (Cont.) At TA = +25°C, VS = +5V, and RL = 10kΩ connected to VS/2, unless otherwise noted. QUIESCENT CURRENT AND SHORT-CIRCUIT CURRENT vs SUPPLY VOLTAGE OUTPUT VOLTAGE SWING vs OUTPUT CURRENT 160 V+ 20 15 –ISC 150 10 IQ 145 5 140 (V+) – 1 Output Voltage (V) 155 Short-Circuit Current (mA) Quiescent Current (µA) +ISC 3 4 5 (V+) – 2 2 85°C 25°C ≈ ≈ 25°C –40°C 1 85°C 0 0 2 –40°C 5 0 6 10 15 Supply Voltage (V) Output Current (mA) OPEN-LOOP GAIN vs OUTPUT VOLTAGE SWING OFFSET VOLTAGE PRODUCTION DISTRIBUTION 20 130 RL = 100kΩ 120 RL = 5kΩ Population Open-Loop Gain (dB) 140 110 800 1000 235 250 600 400 0 200 20 0 40 –200 60 –400 80 Output Voltage Swing from Rail (mV) –600 100 –1000 120 –800 100 Offset Voltage (µV) OFFSET VOLTAGE DRIFT PRODUCTION DISTRIBUTION Offset Voltage Drift (µV/°C) 220 205 190 175 160 145 130 Quiescent Current (µA) OPA344, 2344, 4344 OPA345, 2345, 4345 SBOS107A 115 100 10 8 6 4 2 0 –2 –4 –6 –8 –10 Population Population QUIESCENT CURRENT PRODUCTION DISTRIBUTION 7 www.ti.com TYPICAL PERFORMANCE CURVES (Cont.) At TA = +25°C, VS = +5V, and RL = 10kΩ connected to VS/2, unless otherwise noted. SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE 50 70 Small-Signal Overshoot (%) Small-Signal Overshoot (%) OPA345 OPA344 45 40 35 G = +1 30 G = +5 25 G = –1 20 15 10 G = –5 5 0 60 G = +5 50 G = –5 40 30 G = –10, +10 20 10 0 1 10 100 1k 10 10k 100 1k 10k Load Capacitance (pF) Load Capacitance (pF) LARGE-SIGNAL STEP RESPONSE: OPA344 G = +1, RL = 10kΩ, CL = 100pF LARGE-SIGNAL STEP RESPONSE: OPA345 G = +5, RL = 10kΩ, CL = 100pF OPA345 1V/div 1V/div OPA344 5µs/div 5µs/div SMALL-SIGNAL STEP RESPONSE: OPA344 G = +1, RL = 10kΩ, CL = 100pF SMALL-SIGNAL STEP RESPONSE: OPA345 G = +5, RL = 10kΩ, CL = 100pF OPA344 20mV/div 20mV/div OPA345 5µs/div 5µs/div OPA344, 2344, 4344 OPA345, 2345, 4345 8 www.ti.com SBOS107A APPLICATIONS INFORMATION OPA344 series op amps are unity gain stable and can operate on a single supply, making them highly versatile and easy to use. OPA345 series op amps are optimized for applications requiring higher speeds with gains of 5 or greater. Rail-to-rail input and output swing significantly increases dynamic range, especially in low supply applications. Figure 1 shows the input and output waveforms for the OPA344 in unity-gain configuration. Operation is from VS = +5V with a 10kΩ load connected to VS/2. The input is a 5Vp-p sinusoid. Output voltage is approximately 4.997Vp-p. Power supply pins should be bypassed with 0.01µF ceramic capacitors. G = +1, VS = +5V Input 1V/div 5V 0V Output (inverted on scope) 5µs/div OPERATING VOLTAGE OPA344 and OPA345 series op amps are fully specified and ensured from +2.7V to +5.5V. In addition, many specifications apply from –40ºC to +85ºC. Parameters that vary significantly with operating voltages or temperature are shown in the Typical Performance Curves. RAIL-TO-RAIL INPUT The input common-mode voltage range of the OPA344 and OPA345 series extends 300mV beyond the supply rails. This is achieved with a complementary input stage—an Nchannel input differential pair in parallel with a P-channel differential pair (see Figure 2). The N-channel pair is active for input voltages close to the positive rail, typically (V+) – 1.3V to 300mV above the positive supply, while the Pchannel pair is on for inputs from 300mV below the negative supply to approximately (V+) –1.3V. There is a small transition region, typically (V+) – 1.5V to (V+) – 1.1V, in which both pairs are on. This 400mV transition region can vary 300mV with process variation. Thus, the transition region (both stages on) can range from (V+) – 1.8V to (V+) – 1.4V on the low end, up to (V+) – 1.2V to (V+) – 0.8V on the high end. Within the 400mV transition region PSRR, CMRR, offset voltage, offset drift, and THD may be degraded compared to operation outside this region. For more information on designing with rail-to-rail input op amps, see Figure 3 “Design Optimization with Rail-to-Rail Input Op Amps.” FIGURE 1. Rail-to-Rail Input and Output. V+ Reference Current VIN+ VIN– VBIAS1 Class AB Control Circuitry VO VBIAS2 V– (Ground) FIGURE 2. Simplified Schematic. OPA344, 2344, 4344 OPA345, 2345, 4345 SBOS107A 9 www.ti.com DESIGN OPTIMIZATION WITH RAIL-TO-RAIL INPUT OP AMPS With a unity-gain buffer, for example, signals will traverse this transition at approximately 1.3V below V+ supply and may exhibit a small discontinuity at this point. The common-mode voltage of the non-inverting amplifier is equal to the input voltage. If the input signal always remains less than the transition voltage, no discontinuity will be created. The closed-loop gain of this configuration can still produce a rail-to-rail output. Inverting amplifiers have a constant common-mode voltage equal to VB. If this bias voltage is constant, no discontinuity will be created. The bias voltage can generally be chosen to avoid the transition region. Rail-to-rail op amps can be used in virtually any op amp configuration. To achieve optimum performance, however, applications using these special double-input-stage op amps may benefit from consideration of their special behavior. In many applications, operation remains within the common-mode range of only one differential input pair. However some applications exercise the amplifier through the transition region of both differential input stages. Although the two input stages are laser trimmed for excellent matching, a small discontinuity may occur in this transition. Careful selection of the circuit configuration, signal levels and biasing can often avoid this transition region. G = 1 Buffer Non-Inverting Gain V+ Inverting Amplifier V+ VB VO VIN V+ VIN VO VO VIN VB VCM = VIN = VO VCM = VIN VCM = VB FIGURE 3. Design Optimization with Rail-to-Rail Input Op Amps. COMMON-MODE REJECTION The CMRR for the OPA344 and OPA345 is specified in several ways so the best match for a given application may be used. First, the CMRR of the device in the common-mode range below the transition region (VCM < (V+) – 1.8V) is given. This specification is the best indicator of the capability of the device when the application requires use of one of the differential input pairs. Second, the CMRR at VS = 5.5V over the entire common-mode range is specified. Third, the CMRR at VS = 2.7V over the entire common-mode range is provided. These last two values include the variations seen through the transition region. INPUT VOLTAGE BEYOND THE RAILS If the input voltage can go more than 0.3V below the negative power supply rail (single-supply ground), special precautions are required. If the input voltage goes sufficiently negative, the op amp output may lock up in an inoperative state. A Schottky diode clamp circuit will prevent this—see Figure 4. The series resistor prevents excessive current (greater than 10mA) in the Schottky diode and in the internal ESD protection diode, if the input voltage can exceed the positive supply voltage. If the signal source is limited to less than 10mA, the input resistor is not required. RAIL-TO-RAIL OUTPUT A class AB output stage with common-source transistors is used to achieve rail-to-rail output. This output stage is capable of driving 600Ω loads connected to any potential between V+ and ground. For light resistive loads (> 50kΩ), the output voltage can typically swing to within 1mV from supply rail. With moderate resistive loads (2kΩ to 50kΩ), the output can swing to within a few tens of millivolts from the supply rails while maintaining high open-loop gain. See the typical performance curve “Output Voltage Swing vs Output Current.” V+ IOVERLOAD 10mA max OPA344 VOUT VIN 1kΩ IN5818 Schottky diode is required only if input voltage can go more than 0.3V below ground. FIGURE 4. Input Current Protection for Voltages Exceeding the Supply Voltage. CAPACITIVE LOAD AND STABILITY The OPA344 in a unity-gain configuration and the OPA345 in gains greater than 5 can directly drive up to 250pF pure capacitive load. Increasing the gain enhances the amplifier’s ability to drive greater capacitive loads. See the typical OPA344, 2344, 4344 OPA345, 2345, 4345 10 www.ti.com SBOS107A DRIVING A/D CONVERTERS The OPA344 and OPA345 series op amps are optimized for driving medium-speed sampling A/D converters. The OPA344 and OPA345 op amps buffer the A/D’s input capacitance and resulting charge injection while providing signal gain. performance curve “Small-Signal Overshoot vs Capacitive Load.” In unity-gain configurations, capacitive load drive can be improved by inserting a small (10Ω to 20Ω) resistor, RS, in series with the output, as shown in Figure 5. This significantly reduces ringing while maintaining dc performance for purely capacitive loads. However, if there is a resistive load in parallel with the capacitive load, a voltage divider is created, introducing a dc error at the output and slightly reducing the output swing. The error introduced is proportional to the ratio RS/RL, and is generally negligible. Figures 6 shows the OPA344 in a basic noninverting configuration driving the ADS7822. The ADS7822 is a 12-bit, micro-power sampling converter in the MSOP-8 package. When used with the low-power, miniature packages of the OPA344, the combination is ideal for space-limited, lowpower applications. In this configuration, an RC network at the A/D’s input can be used to filter charge injection. V+ Figure 7 shows the OPA2344 driving an ADS7822 in a speech bandpass filtered data acquisition system. This small, low-cost solution provides the necessary amplification and signal conditioning to interface directly with an electret microphone. This circuit will operate with VS = +2.7V to +5V with less than 500µA quiescent current. RS VOUT OPA344 10Ω to 20Ω VIN RL CL FIGURE 5. Series Resistor in Unity-Gain Configuration Improves Capacitive Load Drive. +5V 0.1µF 0.1µF 1 VREF 8 V+ DCLOCK 500Ω +In OPA344 ADS7822 12-Bit A/D 2 VIN DOUT –In CS/SHDN 3 3300pF 7 6 Serial Interface 5 GND 4 VIN = 0V to 5V for 0V to 5V output. NOTE: A/D Input = 0 to VREF RC network filters high frequency noise. FIGURE 6. OPA344 in Noninverting Configuration Driving ADS7822. V+ = +2.7V to 5V Passband 300Hz to 3kHz R9 510kΩ R1 1.5kΩ R2 1MΩ R4 20kΩ C3 33pF C1 1000pF 1/2 OPA2344 Electret Microphone(1) R3 1MΩ R6 100kΩ R7 51kΩ R8 150kΩ VREF 1 8 V+ 7 C2 1000pF 1/2 OPA2344 +IN ADS7822 6 12-Bit A/D 5 2 –IN DCLOCK DOUT CS/SHDN Serial Interface 3 4 NOTE: (1) Electret microphone powered by R1. R5 20kΩ G = 100 GND FIGURE 7. Speech Bandpass Filtered Data Acquisition System. OPA344, 2344, 4344 OPA345, 2345, 4345 SBOS107A 11 www.ti.com PACKAGE OPTION ADDENDUM www.ti.com 14-Oct-2022 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) OPA2344EA/250 ACTIVE VSSOP DGK 8 250 RoHS & Green Call TI | NIPDAUAG Level-2-260C-1 YEAR -40 to 85 C44 Samples OPA2344EA/2K5 ACTIVE VSSOP DGK 8 2500 RoHS & Green Call TI | NIPDAUAG Level-2-260C-1 YEAR -40 to 85 C44 Samples OPA2344UA ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 2344UA Samples OPA2344UA/2K5 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 2344UA Samples OPA2344UA/2K5G4 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 2344UA Samples OPA2345EA/250 ACTIVE VSSOP DGK 8 250 RoHS & Green Call TI | NIPDAUAG Level-2-260C-1 YEAR -40 to 85 B45 Samples OPA2345UA ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 2345UA Samples OPA2345UA/2K5 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 2345UA Samples OPA344NA/250 ACTIVE SOT-23 DBV 5 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 B44 Samples OPA344NA/250G4 ACTIVE SOT-23 DBV 5 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 B44 Samples OPA344NA/3K ACTIVE SOT-23 DBV 5 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 B44 Samples OPA344PA ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 OPA344PA Samples OPA344UA ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 344UA Samples OPA344UA/2K5 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 344UA Samples OPA344UAG4 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 344UA Samples OPA345NA/250 ACTIVE SOT-23 DBV 5 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 A45 Samples OPA345NA/3K ACTIVE SOT-23 DBV 5 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 A45 Samples OPA345UA ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA 345UA Samples Addendum-Page 1 PACKAGE OPTION ADDENDUM www.ti.com 14-Oct-2022 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) OPA4344EA/250 ACTIVE TSSOP PW 14 250 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 OPA 4344EA Samples OPA4344EA/2K5 ACTIVE TSSOP PW 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 OPA 4344EA Samples OPA4344UA ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA4344UA Samples OPA4344UA/2K5 ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA4344UA Samples OPA4344UAG4 ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA4344UA Samples OPA4345UA ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA4345UA Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of