LMX324

19-2103; Rev 0; 8/01 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps General Description The LMX321/LMX358/LMX324 are single/dual/quad, low-cost, low-voltage, pin-to-pin compatible upgrades to the LMV321/LMV358/LMV324 family of general purpose op amps. These devices offer Rail-to-Rail® outputs and an input common-mode range that extends below ground. These op amps draw only 105µA of quiescent current per amplifier, operate from a single +2.3V to +7V supply, and drive 2kΩ resistive loads to within 40mV of either rail. The LMX321/LMX358/LMX324 are unity-gain stable with a 1.3MHz gain-bandwidth product capable of driving capacitive loads up to 400pF. The combination of low voltage, low cost, and small package size makes these amplifiers ideal for portable/battery-powered equipment. The LMX321 single op amp is available in ultra-small 5pin SC70 and space-saving 5-pin SOT23 packages. The LMX358 dual op amp is available in the tiny 8-pin SOT23 package. The LMX324 quad op amp is available in 14-pin TSSOP and SO packages. Features o Upgrade to LMV321/LMV358/LMV324 Family o Single +2.3V to +7V Supply Voltage Range o Available in Space-Saving Packages 5-Pin SC70 (LMX321) 8-Pin SOT23 (LMX358) 14-Pin TSSOP (LMX324) o 1.3MHz Gain-Bandwidth Product o 105µA Quiescent Current per Amplifier (VCC = +2.7V) o No Phase Reversal for Overdriven Inputs o No Crossover Distortion o Rail-to-Rail Output Swing o Input Common-Mode Voltage Range: VEE - 0.2V to VCC - 0.8V o Drives 2kΩ Resistive Loads LMX321/LMX358/LMX324 Applications Cellular Phones Laptops Low-Power, Low-Voltage Applications Portable/Battery-Powered Equipment Cordless Phones Active Filters PART LMX321AXK-T LMX321AUK-T LMX358AKA-T LMX358ASA LMX358AUA LMX324ASD LMX324AUD Ordering Information TEMP. RANGE -40°C to +125°C -40°C to +125°C -40°C to +125°C -40°C to +125°C -40°C to +125°C -40°C to +125°C -40°C to +125°C PIN-PACKAGE 5 SC70-5 5 SOT23-5 8 SOT23-8 8 SO 8 µMAX 14 SO 14 TSSOP Selector Guide appears at end of data sheet. Pin Configurations TOP VIEW OUT1 1 IN1- 2 OUT1 1 IN+ 1 VEE 2 IN1+ 3 IN- 3 4 OUT VEE 4 5 IN2+ 6 IN28 VCC 7 OUT2 IN1+ 3 VCC 4 IN2+ 5 IN2- 6 OUT2 7 14 OUT4 13 IN412 IN4+ 11 VEE 10 IN3+ 9 IN38 OUT3 LMX321 5 VCC IN1- 2 LMX358 LMX324 SC70-5/SOT23-5 SOT23-8/SO/µMAX TSSOP/SO Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC to VEE) ....................................-0.3V to +8V Differential Input Voltage (VIN+ - VIN-) ........................VEE to VCC OUT_ to VEE ...............................................-0.3V to (VCC + 0.3V) Output Short-Circuit Duration OUT_ Shorted to VCC or VEE ..................................Continuous Continuous Power Dissipation (TA = +70°C) 5-Pin SC70-5 (derate 3.1mW/°C above +70°C)...........247mW 5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) ........571mW 8-Pin SOT23-8 (derate 7.52mW/°C above +70°C) ......602mW 8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW 8-Pin µMAX (derate 4.5mW/°C above +70°C) .............362mW 14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW 14-Pin SO (derate 8.3mW/°C above +70°C)................667mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +2.7V, VEE = 0, VOUT = VCC/2, VCM = 1V, RL > 1MΩ, TA = +25°C, unless otherwise noted.) PARAMETER DC Characteristics Input Offset Voltage Input Offset Voltage Average Drift Input Bias Current Input Offset Current Common-Mode Rejection Ratio Power-Supply Rejection Ratio Input Common-Mode Voltage Range Large-Signal Voltage Gain VOS TCVOS IB IOS CMRR PSRR VCM AVOL -0.2V < VCM < 1.8V 2.3V < VCC < 7V, VOUT = 1V For CMRR > 72dB Limit Typ VCC - VOH VOL VCC - VOH VOL 72 82 -0.2 -0.2 20 120 12 10 40 25 105 210 420 1 1.3 64 24 f = 1kHz f = 1kHz 66 0.13 50 40 110 60 150 300 600 V/µs MHz degrees dB nV/√Hz pA/√Hz µA mV 1 6 18 1 92 96 1.8 1.9 50 8 6 mV µV/oC nA nA dB dB V V/mV SYMBOL CONDITIONS MIN TYP MAX UNITS RL = 2kΩ to VEE, 0.3V < VOUT < 2.4V RL = 10kΩ to 1.35V Output Voltage Swing VOUT RL = 2kΩ to 1.35V LMX321 (Single) Supply Current AC Characteristics Slew Rate Gain-Bandwidth Product Phase Margin Gain Margin Input Noise Voltage Density Input Current Noise Density ICC LMX358 (Dual) LMX324 (Quad) SR GBW φM GM en in 1V step Input CL = 200pF 2 _______________________________________________________________________________________ Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps ELECTRICAL CHARACTERISTICS (VCC = +2.7V, VEE = 0, VOUT = VCC/2, VCM = 1V, RL > 1MΩ, TA = -40°C to +125°C, unless otherwise noted.) (Note 1) PARAMETER DC Characteristics Input Offset Voltage Input Bias Current Input Offset Current Common-Mode Rejection Ratio Power-Supply Rejection Ratio Input Common-Mode Voltage Range Large-Signal Voltage Gain VOS IB IOS CMRR PSRR VCM AVOL -0.1 < VCM < 1.7V 2.3V < VCC < 7V, VOUT = 1V For CMRR > 60dB Limit Typ VCC - VOH VOL VCC - VOH VOL 60 75 -0.1 -0.1 10 130 50 150 70 180 360 720 µA mV 1.7 1.8 9 70 15 mV nA nA dB dB V V/mV SYMBOL CONDITIONS MIN TYP MAX UNITS LMX321/LMX358/LMX324 RL = 2kΩ to VEE, 0.3V < VOUT < 2.4V RL = 10kΩ to 1.55V Output Voltage Swing VOUT RL = 2kΩ to 1.35V LMX321 (Single) Supply Current ICC LMX358 (Dual) LMX324 (Quad) ELECTRICAL CHARACTERISTICS (VCC = +5V, VEE = 0, VOUT = VCC/2, VCM = 2V, RL > 1MΩ, TA = +25°C, unless otherwise noted.) PARAMETER DC Characteristics Input Offset Voltage Input Offset Voltage Average Drift Input Bias Current Input Offset Current Common-Mode Rejection Ratio Power-Supply Rejection Ratio Input Common-Mode Voltage Range Large-Signal Voltage Gain VOS TCVOS IB IOS CMRR PSRR VCM AVOL -0.2 < VCM < 4.1V 2.3V < VCC < 7V, VOUT = 1V, VCM = 1V For CMRR > 72dB RL = 2kΩ to VEE, 0.3V < VOUT < 4.7V Limit Typ 72 82 -0.2 -0.2 40 200 1 6 18 1 92 96 4.1 4.2 50 8 6 mV µV/oC nA nA dB dB V V/mV SYMBOL CONDITIONS MIN TYP MAX UNITS _______________________________________________________________________________________ 3 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 ELECTRICAL CHARACTERISTICS (continued) (VCC = +5V, VEE = 0, VOUT = VCC/2, VCM = 2V, RL > 1MΩ, TA = +25°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS RL = 10kΩ to 2.5V Output Voltage Swing VOUT RL = 2kΩ to 2.5V Output Short-Circuit Current ISC Sourcing, VOUT = 0 Sinking, VOUT = 5V LMX321 (Single) Supply Current AC Characteristics Slew Rate Gain-Bandwidth Product Phase Margin Gain Margin Input Noise Voltage Density Input Noise Current Density SR GBW φM GM en in f = 1kHz f = 1kHz 3V step input CL = 200pF 1 1.3 65 25 65 0.13 V/µs MHz degrees dB nV/√Hz pA/√Hz ICC LMX358 (Dual) LMX324 (Quad) VCC - VOH VOL VCC - VOH VOL 5 10 MIN TYP 20 12 65 40 25 28 120 240 480 170 340 680 µA MAX 60 40 130 80 mA mV UNITS ELECTRICAL CHARACTERISTICS (VCC = +5V, VEE = 0, VOUT = VCC/2, VCM = 2V, RL > 1MΩ, TA = -40°C to +125°C, unless otherwise noted.) (Note 1) PARAMETER DC Characteristics Input Offset Voltage Input Bias Current Input Offset Current Common-Mode Rejection Ratio Power-Supply Rejection Ratio Input Common-Mode Voltage Range Large-Signal Voltage Gain VOS IB IOS CMRR PSRR VCM AVOL -0.1 < VCM < 4.0V 2.3V < VCC < 7V, VOUT = 1V, VCM = 1V For CMRR > 63dB Limit Typ VCC - VOH VOL VCC - VOH VOL 63 75 -0.1 -0.1 20 170 70 190 90 210 420 840 µA mV 4.0 4.1 9 70 15 mV nA nA dB dB V V/mV SYMBOL CONDITIONS MIN TYP MAX UNITS RL = 2kΩ to VEE, 0.3V < VOUT < 4.7V RL = 10kΩ to 2.5V Output Voltage Swing VOUT RL = 2kΩ to 2.5V LMX321 (Single) Supply Current ICC LMX358 (Dual) LMX324 (Quad) Note 1: Specifications are 100% tested at TA = +25°C (exceptions noted). All temperature limits are guaranteed by design. 4 _______________________________________________________________________________________ Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps Typical Operating Characteristics (TA = +25°C, VEE = 0, unless otherwise noted.) LMX321/LMX358/LMX324 SUPPLY CURRENT PER AMPLIFIER vs. SUPPLY VOLTAGE LMX321 toc01 INPUT BIAS CURRENT vs. TEMPERATURE LMX321 toc02 SOURCE CURRENT vs. OUTPUT VOLTAGE VCC = 2.7V LMX321 toc03 160 SUPPLY CURRENT PER AMPLIFIER (µA) 140 120 100 80 60 40 20 0 0 1 2 3 4 5 6 TA = +25°C TA = -40°C TA = +85°C TA = +125°C -10 -11 INPUT BIAS CURRENT (nA) -12 -13 -14 -15 -16 -17 -18 -19 -20 VCC = +5V, VIN = VCC/2 100 SOURCE CURRENT (mA) 10 1 0.1 0.01 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 0.01 0.1 1 10 OUTPUT VOLTAGE REFERENCED TO VCC (V) 7 SUPPLY VOLTAGE (V) SOURCE CURRENT vs. OUTPUT VOLTAGE LMX321 toc04 SINK CURRENT vs. OUTPUT VOLTAGE LMX321 toc05 SINK CURRENT vs. OUTPUT VOLTAGE VCC = 5V LMX321 toc06 100 VCC = 5V 10 100 VCC = 2.7V 100 SOURCE CURRENT (mA) SINK CURRENT (mA) 1 1 SINK CURRENT (mA) 0.01 0.1 1 10 10 10 1 0.1 0.1 0.1 0.01 0.01 0.1 1 10 OUTPUT VOLTAGE REFERENCED TO VCC (V) 0.01 0.001 0.01 0.001 0.01 0.1 1 10 OUTPUT VOLTAGE REFERENCED TO VEE (V) OUTPUT VOLTAGE REFERENCED TO VEE (V) OUTPUT VOLTAGE SWING vs. SUPPLY VOLTAGE LMX321 toc07 OUTPUT VOLTAGE SWING vs. SUPPLY VOLTAGE LMX321 toc08 INPUT VOLTAGE NOISE vs. FREQUENCY 600 550 500 450 400 350 300 250 200 150 100 50 0 1 10 VCC = 2.7V TO 5V, VCM = VCC/2 LMX321 toc09 100 90 OUTPUT VOLTAGE SWING (mV) 80 70 60 50 40 30 20 2 RL = 2 k Ω 35 OUTPUT VOLTAGE SWING (mV) 30 25 20 15 10 RL = 10kΩ POSITIVE SWING (VCC - VOH) POSITIVE SWING (VCC - VOH) NEGATIVE SWING (VOL) 3 4 5 6 7 NEGATIVE SWING (VOL) 5 2 3 4 5 6 7 INPUT VOLTAGE NOISE (nV/√Hz) 100 1k 10k 100k SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) FREQUENCY (Hz) _______________________________________________________________________________________ 5 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 Typical Operating Characteristics (continued) (TA = +25°C, VEE = 0, unless otherwise noted.) INPUT CURRENT NOISE vs. FREQUENCY LMX321 toc10 CROSSTALK REJECTION vs. FREQUENCY LMX321 toc11 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY VCC = 2.7V TO 5V -20 -40 PSRRLMX321 toc12 4.0 INPUT CURRENT NOISE (pA/√Hz) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 1 10 VCC = 2.7V TO 5V, VCM = VCC/2 -50 CROSSTALK REJECTION (dB) -70 -90 -110 -130 -150 VCC = 5V, RL = 5kΩ 0 PSRR (dB) -60 -80 -100 -120 PSRR+ 100 1k 10k 100k 100 1k 10k 100k 1M 10M 100M 100 1k 10k FREQUENCY (Hz) 100k 1M FREQUENCY (Hz) FREQUENCY (Hz) INPUT OFFSET VOLTAGE vs. COMMON-MODE VOLTAGE LMX321 toc13 INPUT OFFSET VOLTAGE vs. COMMON-MODE VOLTAGE LMX321 toc14 INPUT OFFSET VOLTAGE vs. OUTPUT VOLTAGE VCC = 2.5V, VEE = -2.5V RL = 600Ω RL = 2kΩ 75 INPUT OFFSET VOLTAGE (µV) 50 25 0 -25 -50 -75 -100 RL = 10kΩ LMX321 toc15 0.10 VCC = 1.35V, VEE = -1.35V 0.05 0 ∆VOS (mV) -0.05 -0.10 -0.15 -0.20 -1.7 -1.2 -0.7 -0.2 0.3 0.15 0.10 0.05 ∆VOS (mV) 0 -0.05 -0.10 -0.15 -0.20 VCC = 2.5V, VEE = -2.5V 100 0.8 -2.8 -2.3 -1.8 -1.3 -0.8 -0.3 0.2 0.7 1.2 1.7 2.2 COMMON-MODE VOLTAGE (V) -3 -2 -1 0 1 2 3 COMMON-MODE VOLTAGE (V) OUTPUT VOLTAGE (V) INPUT OFFSET VOLTAGE vs. OUTPUT VOLTAGE VCC = 1.35V, VEE = -1.35V RL = 600Ω LMX321 toc16 GAIN AND PHASE vs. FREQUENCY and RESISTIVE LOAD 50 40 30 GAIN (dB) LMX321 toc17 GAIN AND PHASE vs. FREQUENCY AND RESISTIVE LOAD 100 80 PHASE MARGIN (degrees) 50 40 30 GAIN (dB) 20 10 0 -10 -20 VCC = 1.35V, VEE = -1.35V CL = 0, RL TO VEE AVCL = 60dB, VOUT = 0 RL = 100kΩ 10k 100k 1M 10M RL = 600Ω RL = 100kΩ LMX321 toc18 100 75 INPUT OFFSET VOLTAGE (mV) 50 25 0 -25 -50 -75 100 -1.5 -1.0 -0.5 RL = 10kΩ 100 80 60 40 20 0 -20 -40 RL = 600Ω RL = 100kΩ RL = 2kΩ 20 10 0 RL = 600kΩ 40 20 0 VCC = 2.5V, VEE = -2.5V CL = 0, RL TO VEE AVCL = 60dB, VOUT = 0 RL = 100kΩ 10k 100k 1M 10M -20 -40 FREQUENCY (Hz) -10 -20 0 0.5 1.0 1.5 OUTPUT VOLTAGE (V) FREQUENCY (Hz) 6 _______________________________________________________________________________________ PHASE (degrees) 60 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 Typical Operating Characteristics (continued) (TA = +25°C, VEE = 0, unless otherwise noted.) GAIN AND PHASE vs. FREQUENCY AND CAPACTIVE LOAD 50 40 30 GAIN (dB) 20 10 0 -10 -20 10k 100k 1M 10M FREQUENCY (Hz) VCC = 2.5V, VEE = -2.5V RL = 600Ω TO VEE AVCL = 60dB, VOUT = 0 CL = 0 CL = 500pF CL = 1nF 20 0 -20 -40 LMX321 toc19 GAIN AND PHASE vs. FREQUENCY AND CAPACITIVE LOAD 100 80 60 40 50 40 PHASE (degrees) 30 GAIN (dB) 20 10 0 -10 -20 CL = 1nF CL = 500pF CL = 100pF VCC = 2.5V, VEE = -2.5V RL = 100kΩ TO VEE AVCL = 60dB, VOUT = 0 10k 100k 0 -20 CL = 0 1M -40 10M LMX321 toc20 100 80 60 40 20 CL = 0 CL = 100pF CL = 500pF CL = 1nF FREQUENCY (Hz) GAIN AND PHASE vs. FREQUENCY AND TEMPERATURE 50 40 TA = -40°C 30 GAIN (dB) 20 10 0 -10 -20 VCC = 2.5V, VEE = -2.5V RL = 2kΩ TO VEE AVCL = 60dB, VOUT = 0 10k 100k 1M 10M FREQUENCY (Hz) TA = +85°C TA = +125°C TA = +25°C TA = +85°C TA = -25°C LMX321 toc21 CAPACITIVE-LOAD STABILITY LMX321 toc22 SLEW RATE vs. SUPPLY VOLTAGE RL = 10kΩ VIN = 1V STEP, AVCL = +1V/V LMX321 toc23 TA = -40°C TA = +25°C 100 80 LOAD CAPACITANCE (pF) 60 PHASE (degrees) 40 20 0 -20 -40 4000 3500 UNSTABLE 3000 1.10 1.08 SLEW RATE (V/µS) 1.06 2500 2000 1500 1000 STABLE 500 0 100 1k 10k 100k LOAD RESISTANCE (Ω) RISING EDGE 1.04 1.02 1.00 0.98 0.96 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE FALLING EDGE NONINVERTING LARGE-SIGNAL RESPONSE LMX321 toc24 NONINVERTING SMALL-SIGNAL RESPONSE LMX321 toc25 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY LMX321 toc26 RL = 2kΩ VCC = 5V VIN 1V/div VIN 100mV/div RL = 2kΩ VCC = 5V 10 1 THD + NOISE (%) VCC = 2.7V, AV = +10, VOUT = 1Vp-p VCC = 5V, AV = +10, VOUT = 2.5Vp-p 0.1 VOUT 1V/div VOUT 100mV/div 0.01 VCC = 2.7V, AV = +1, VOUT = 1Vp-p VCC = 5V, AV = +1, VOUT = 2.5Vp-p 1µs/div 1µs/div 0.001 10 100 1k FREQUENCY (Hz) 10k 100k _______________________________________________________________________________________ PHASE (degrees) 7 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 Typical Operating Characteristics (continued) (TA = +25°C, VEE = 0, unless otherwise noted.) SHORT-CIRCUIT CURRENT vs. TEMPERATURE (SINKING) LMX321 toc27 SHORT-CIRCUIT CURRENT vs. TEMPERATURE (SOURCING) LMX321 toc28 OUTPUT IMPEDANCE vs. FREQUENCY VCC = 2.7V TO 5V AVCL = +1V/V LMX321 toc29 40 SHORT-CIRCUIT CURRENT (mA) 35 30 25 20 15 10 5 0 VCC = 5V 40 SHORT-CIRCUIT CURRENT (mA) 35 30 25 20 15 10 5 0 VCC = 2.7V VCC = 5V 1000 OUTPUT IMPEDANCE (Ω) 100 VCC = 2.7V 10 1 0.01 0.001 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 100 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) Pin Description PIN NAME LMX321 1 2 3 4 5 — — — — — — — — — — — — LMX358 — 4 — — 8 1 2 3 7 6 5 — — — — — — LMX324 — 11 — — 4 1 2 3 7 6 5 8 9 10 14 13 12 IN+ VEE INOUT VCC OUT1 IN1IN1+ OUT2 IN2IN2+ OUT3 IN3IN3+ OUT4 IN4IN4+ Noninverting Amplifier Input Negative Supply. Connect to ground for single-supply operation. Inverting Amplifier Input Output Positive Supply Output for Amplifier 1 Inverting Input for Amplifier 1 Noninverting Input for Amplifier 1 Output for Amplifier 2 Inverting Input for Amplifier 2 Noninverting Input for Amplifier 2 Output for Amplifier 3 Inverting Input for Amplifier 3 Noninverting Input for Amplifier 3 Output for Amplifier 4 Inverting Input for Amplifier 4 Noninverting Input for Amplifier 4 FUNCTION 8 _______________________________________________________________________________________ Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 3.5kΩ RL CL 3.5kΩ LMX321 LMX358 LMX324 Figure 1. Input Protection Circuit VIN 2V/div 2.5V Figure 3. Capacitive-Load-Driving Circuit VCC = 5V, VEE = 0, CL = 2.2nF RL = 2kΩ VIN 100mV/div 2.6V 2.4V VOUT 1V/div VOUT 100mV/div 2.6V 2.4V -2.5V 200µs/div VCC = 2.5V, VEE = -2.5V, AVCL = 2V/V 4µs/div Figure 2. Rail-to-Rail Output Swing Figure 4. Output With Excessive Capacitive Load Detailed Description Input Protection Circuit The LMX321/LMX358/LMX324’s inputs are protected from large differential input voltages by internal 3.5kΩ series resistors and back-to-back triple diode stacks across the inputs (Figure 1). For differential input voltages (much less than 1.8V), input resistance is typically 3MΩ. For differential input voltages greater than 1.8V, input resistance is around 7kΩ, and the input bias current can be approximated by the following equation: IBIAS = (VDIFF - 1.8V) / 7kΩ In the region where the differential input voltage approaches 1.8V, input resistance decreases exponentially from 3MΩ to 7kΩ as the diode block begins conducting. Inversely, the bias current increases with the same curve. The LMX321/LMX358/LMX324 drive 2kΩ loads and still typically swing within 40mV of the supply rails. Figure 2 shows the output voltage swing of the LMX321 configured with AVCL = +2V/V. Driving Capacitive Loads Driving a capacitive load can cause instability in many op amps, especially those with low quiescent current. The LMX321/LMX358/LMX324 are unity-gain stable for a range of capacitive loads to above 400pF. Figure 4 shows the response of the LMX321 with an excessive capacitive load. Adding a series resistor between the output and the load capacitor (Figure 5) improves the circuit’s response by isolating the load capacitance from the op amp’s output. Applications Information Power-Up The LMX321/LMX358/LMX324 outputs typically settle within 10µs after power-up. Figure 6 shows the output voltage on power-up and power-down. Rail-to-Rail Output Stage _______________________________________________________________________________________ 9 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 Power Supplies and Layout The LMX321/LMX358/LMX324 operate from a single +2.3V to +7V power supply. Bypass the power supply with a 0.1µF capacitor to ground as close to VCC as possible. Good layout techniques optimize performance by minimizing the amount of stray capacitance at the op amp’s inputs and outputs. Place external components close to the op amp to minimize trace lengths and stray capacitance. RISO CL LMX321 LMX358 LMX324 Chip Information LMX321 TRANSISTOR COUNT: 88 LMX358 TRANSISTOR COUNT: 175 LMX324 TRANSISTOR COUNT: 349 PROCESS: Bipolar Figure 5. Capacitive-Load-Driving Circuit With Isolation Resistor VCC 2V/div VOUT 1V/div 4µs/div Figure 6. Power-Up/Power-Down Waveform Selector Guide PART LMX321AXK-T LMX321AUK-T LMX358AKA-T LMX358ASA LMX358AUA LMX324ASD LMX324AUD AMPLIFIERS PER PACKAGE 1 1 2 2 2 4 4 TOP MARK ACP ADSQ AAIR — — — — 10 ______________________________________________________________________________________ Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps Package Information SC70, 5L.EPS LMX321/LMX358/LMX324 ______________________________________________________________________________________ SOT5L.EPS 11 Single/Dual/Quad, General-Purpose, Low-Voltage, Rail-to-Rail Output Op Amps LMX321/LMX358/LMX324 Package Information (continued) SOT23, 8L.EPS 12 ______________________________________________________________________________________ 8LUMAXD.EPS Single/Dual/Quad, General Purpose, Low-Voltage, Rail-to-Rail Output Op Amps Package Information (continued) TSSOP,NO PADS.EPS LMX321/LMX358/LMX324 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.