19-1612; Rev 3; 4/02 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps The MAX4291/MAX4292/MAX4294 family of micropower operational amplifiers operates from a 1.8V to 5.5V single supply or ±0.9V to ±2.75V dual supplies and has Rail-to-Rail® input/output capabilities. These amplifiers provide a 500kHz gain-bandwidth product and 120dB open-loop voltage gain while using only 100µA of supply current per amplifier. The combination of low input offset voltage (±200µV) and high open-loop gain makes them ideal for low-power/low-voltage, high-precision portable applications. The MAX4291/MAX4292/MAX4294 have an input common-mode range that extends to each supply rail, and their outputs swing to within 46mV of the rails with a 2kΩ load. Although the minimum operating voltage is specified at 1.8V, these devices typically operate down to 1.5V. The combination of ultra-low-voltage operation, railto-rail inputs/output, and low-power consumption makes these devices ideal for any portable/two-cell battery-powered system. The single MAX4291 is offered in an ultra-small 5-pin SC70 package. The dual MAX4292 is offered in a space-saving 8-bump, 1.5mm X 1.5mm footprint, ultra chip-scale package (UCSP™). Features ♦ Ultra-Low Voltage Operation—Guaranteed Down to 1.8V ♦ 100µA Supply Current per Amplifier ♦ 500kHz Gain-Bandwidth Product ♦ 120dB Open-Loop Voltage Gain (RL = 100kΩ) ♦ 0.017% Total Harmonic Distortion Plus Noise (THD + N) at 1kHz ♦ Rail-to-Rail Input Common-Mode Range ♦ Rail-to-Rail Output Drives 2kΩ Load ♦ No Phase Reversal for Overdriven Inputs ♦ Unity-Gain Stable for Capacitive Loads up to 100pF ♦ 200µV Input Offset Voltage (MAX4292/MAX4294) ♦ Single in Small 5-Pin SC70 ♦ Available in Ultra-Small Packages: 5-Pin SC70 (MAX4291) 8-Bump UCSP (MAX4292) Ordering Information Applications MAX4291EXK-T -40°C to +85°C PINPACKAGE 5 SC70-5 Battery-Powered Instrumentation MAX4291EUK-T -40°C to +85°C 5 SOT23-5 ADML Digital Scales MAX4292EBL-T* -40°C to +85°C 8 UCSP-8 AAJ Strain Gauges MAX4292EUA -40°C to +85°C 8 µMAX — — 2-Cell Battery-Operated Systems Portable Electronic Equipment PART TEMP RANGE TOP MARK AAD Sensor Amplifiers MAX4292ESA -40°C to +85°C 8 SO Cellular Phones MAX4294ESD -40°C to +85°C 14 SO — MAX4294EUD -40°C to +85°C 14 TSSOP — Pin Configurations TOP VIEW (BUMPS ON BOTTOM) OUTA VCC OUTB INA- MAX4292 INB- *UCSP reliability is integrally linked to the user’s assembly methods, circuit board material, and environment. Refer to the UCSP Reliability Notice in the UCSP Reliability section of this data sheet for more information. Selector Guide PART INA+ VEE INB+ AMPLIFIERS PIN-PACKAGE MAX4291 1 5-pin SC70/SOT23 MAX4292 2 8-pin µMAX/SO/UCSP MAX4294 4 14-pin SO/TSSOP UCSP Pin Configurations continued at end of data sheet. Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. UCSP is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX4291/MAX4292/MAX4294 General Description MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC to VEE) ....................................................6V All Other Pins ...................................(VCC + 0.3V) to (VEE - 0.3V) Current into IN_+, IN_- .....................................................±25mA Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70°C) 5-Pin SC70 (derate 2.5mW/°C above +70°C) ................200mW 5-Pin SOT23 (derate 7.1mW/°C above +70°C)................571mW 8-Bump UCSP (derate 4.7mW/°C above +70°C) ...........379mW 8-Pin µMAX (derate 4.10mW/°C above +70°C)..............330mW 8-Pin SO (derate 5.88mW/°C above +70°C) ..................471mW 14-Pin SO (derate 8.33mW/°C above +70°C) ................667mW 14-Pin TSSOP (derate 6.3mW/°C above +70°C) ............500mW Operating Temperature Range............................-40°C to +85°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 = 1.8V to 5.5V, VEE = VCM = 0, VOUT = VCC/2, RL = 100kΩ connected to VCC/2, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER TYP MAX UNITS 5.5 V VCC = 1.8V 100 210 VCC = 5.0V 100 255 MAX4291 ±400 ±2500 MAX4292/MAX4294 ±200 ±1200 IB VCC = 5.0V, 0 ≤ VCM ≤ 5.0V ±15 ±60 Input Offset Current IOS VCC = 5.0V, 0 ≤ VCM ≤ 5.0V ±1 ±7 Differential Input Resistance RIN |VIN+ - VIN-| < 10mV Input Common-Mode Voltage Range VCM Inferred from CMRR test 0 Tested for 0 ≤ VCM ≤ 1.8V; VCC = 1.8V MAX4291 50 80 MAX4292/MAX4294 57 80 MAX4291 60 90 Supply Voltage Range Quiescent Supply Current (Per Amplifier) Input Offset Voltage Input Bias Current Common-Mode Rejection Ratio SYMBOL VCC IQ VOS 2 Inferred from PSRR test MIN 1.8 0.75 µA µV nA nA MΩ VCC V dB CMRR Tested for 0 ≤ VCM ≤ 5.0V, VCC = 5.0V Common-Mode Rejection Ratio Power-Supply Rejection Ratio CONDITIONS PSRR dB MAX4292/MAX4294 66 90 77 100 _______________________________________________________________________________________ dB Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps (VCC = 1.8V to 5.5V, VEE = VCM = 0, VOUT = VCC/2, RL = 100kΩ connected to VCC/2, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP RL = 100kΩ, 0.02V ≤ VOUT ≤ VCC - 0.02V 80 120 RL = 2kΩ, 0.1V ≤ VOUT ≤ VCC - 0.1V 80 110 MAX UNITS VCC = 1.8V Large-Signal Voltage Gain AV dB RL = 100kΩ, 0.02V ≤ VOUT ≤ VCC - 0.02V 80 130 RL = 2kΩ, 0.1V ≤ VOUT ≤ VCC - 0.1V 80 120 VCC = 5.0V Output-Voltage Swing High VOH Specified as |VCC - VOH| RL = 100kΩ to VCC/2 2 20 RL = 2kΩ to VCC/2 15 40 Output-Voltage Swing Low VOL Specified as |VEE - VOL| RL = 100kΩ to VCC/2 25 80 RL = 2kΩ to VCC/2 46 120 Output Short-Circuit Current IOUT(SC) Channel-to-Channel Isolation CHISO Gain-Bandwidth Product mV mV Sourcing or sinking 20 Specified at f = 10kHz (MAX4292/MAX4294 only) 83 dB GBWP 500 kHz Phase Margin φM 65 degrees Gain Margin GM 12 dB Slew Rate SR 0.2 V/µs Input Voltage-Noise Density en f = 10kHz 70 nV/√Hz Input Current-Noise Density in f = 10kHz 0.05 pA/√Hz AVCL = 1V/V, no sustained oscillations 100 pF Capacitive-Load Stability mA ELECTRICAL CHARACTERISTICS (VCC = 1.8V to 5.5V, VEE = VCM = 0, VOUT = VCC/2, RL = 100kΩ connected to VCC/2, TA = TMIN to TMAX, unless otherwise noted.) (Note 1) PARAMETER Supply-Voltage Range Quiescent Supply Current (Per Amplifier) Input Offset Voltage SYMBOL VCC IQ VOS CONDITIONS Inferred from PSRR test MIN 1.8 TYP MAX UNITS 5.5 V VCC = 1.8V 240 VCC = 5.0V 270 MAX4291 ±3000 MAX4292/MAX4294 ±2000 µA µV _______________________________________________________________________________________ 3 MAX4291/MAX4292/MAX4294 ELECTRICAL CHARACTERISTICS (continued) MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps ELECTRICAL CHARACTERISTICS (continued) (VCC = 1.8V to 5.5V, VEE = VCM = 0, VOUT = VCC/2, RL = 100kΩ connected to VCC/2, TA = TMIN to TMAX, unless otherwise noted.) (Note 1) PARAMETER Input Offset Voltage Drift SYMBOL CONDITIONS MIN TCVOS TYP MAX 1.2 UNITS µV/°C IB VCC = 5.0V, 0 ≤ VCM ≤ 5.0V ±90 nA Input Offset Current IOS VCC = 5.0V, 0 ≤ VCM ≤ 5.0V ±10 nA Input Common-Mode Voltage Range VCM Inferred from CMRR test 0 VCC V Tested for MAX4291 0 ≤ VCM ≤ 1.8V, MAX4292/MAX4294 VCC = 1.8V 50 Tested for MAX4291 0 ≤ VCM ≤ 5.0V, MAX4292/MAX4294 VCC = 5.0V 60 Input Bias Current Common-Mode Rejection Ratio Power-Supply Rejection Ratio CMRR PSRR VCC = 1.8V Large-Signal Voltage Gain dB 53 AV VCC = 5.0V Output-Voltage Swing High VOH Specified as |VCC - VOH| Output-Voltage Swing Low VOL Specified as |VEE - VOL| 62 dB dB 75 dB RL = 100kΩ, 0.02V ≤ VOUT ≤ VCC - 0.02V 80 RL = 2kΩ, 0.1V ≤ VOUT ≤ VCC - 0.1V 80 RL = 100kΩ, 0.02V ≤ VOUT ≤ VCC - 0.02V 80 RL = 2kΩ, 0.1V ≤ VOUT ≤ VCC - 0.1V 80 dB RL = 100kΩ to VCC/2 20 RL = 2kΩ to VCC/2 40 RL = 100kΩ to VCC/2 80 RL = 2kΩ to VCC/2 Note 1: All devices are 100% tested at TA = +25°C. All temperature limits are guaranteed by design. 4 _______________________________________________________________________________________ 120 mV mV Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps SUPPLY CURRENT PER AMPLIFIER vs. TEMPERATURE VCC = 5.5V 120 110 100 90 VCC = 1.8V 80 1.7 1.6 1.5 1.4 1.3 1.2 VCC = 5.5V -300 -450 VCC = 2.4V -600 VCC = 1.8V -900 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) INPUT BIAS CURRENT vs. TEMPERATURE INPUT BIAS CURRENT vs. COMMON-MODE VOLTAGE (VCC = 1.8V) INPUT BIAS CURRENT vs. COMMON-MODE VOLTAGE (VCC = 5.5V) VCC = 5.5V 15 VCC = 1.8V 5 20 10 0 -10 -20 10 0 -10 -20 -40 -40 -0.5 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 20 -30 -30 0 MAX4291 toc06 30 0 0.5 1.0 1.5 2.0 -0.5 2.5 0.5 1.5 2.5 3.5 4.5 5.5 TEMPERATURE (°C) COMMON-MODE VOLTAGE (V) COMMON-MODE VOLTAGE (V) OUTPUT VOLTAGE SWING vs. TEMPERATURE (RL = 100kΩ TO VCC/2) OUTPUT VOLTAGE SWING vs. TEMPERATURE (RL = 2kΩ TO VCC/2) COMMON-MODE REJECTION RATIO vs. TEMPERATURE 60 VOL (VCC = 5.5V) 20 15 10 VOH (VCC = 5.5V OR 1.8V) VOL (VCC = 1.8V) 5 VOH = VCC - VOUT VOL = VOUT - VEE 50 -75 40 30 VOH (VCC = 5.5V) VOL (VCC = 1.8V) -25 5 35 65 TEMPERATURE (°C) 95 125 VCC = 1.8V -80 -85 VCC = 5.5V -90 20 -95 10 -100 -105 0 -55 0 ≤ VCM ≤ VCC -70 VOL (VCC = 5.5V) VOH (VCC = 1.8V) 0 -65 CMRR (dB) 25 OUTPUT VOLTAGE SWING (mV) MAX4291-07 VOH = VCC - VOUT VOL = VOUT - VEE MAX4291 toc09 20 40 INPUT BIAS CURRENT (nA) 25 10 30 INPUT BIAS CURRENT (nA) 30 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 MAX4291 toc05 40 MAX4291 toc04 35 OUTPUT VOLTAGE SWING (mV) -150 -750 1.0 60 30 MAX4291 toc03 1.8 0 1.1 70 INPUT BIAS CURRENT (nA) 1.9 INPUT OFFSET VOLTAGE (µV) 130 2.0 MAX4291-08 SUPPLY CURRENT (µA) 140 INPUT OFFSET VOLTAGE vs. TEMPERATURE MAX4291 toc02 150 MINIMUM OPERATING VOLTAGE (V) MAX4291 toc01 160 MINIMUM OPERATING VOLTAGE vs. TEMPERATURE (PSRR ≥ 80dB) -55 -25 5 35 65 TEMPERATURE (°C) 95 125 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX4291/MAX4292/MAX4294 Typical Operating Characteristics (VCC = 2.4V, VEE = VCM = 0, VOUT = VCC/2, no load, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = 2.4V, VEE = VCM = 0, VOUT = VCC/2, no load, TA = +25°C, unless otherwise noted.) OPEN-LOOP GAIN vs. OUTPUT SWING HIGH (VCC = 1.8V, RL CONNECTED TO VEE) RL = 1kΩ RL = 2kΩ 110 RL = 1kΩ 110 90 RL = 1kΩ GAIN (dB) 100 90 80 70 0 50 0 50 100 150 200 250 300 350 400 450 500 50 100 150 200 250 300 350 400 450 500 VOH (mV) VOL (mV) OPEN-LOOP GAIN vs. OUTPUT SWING HIGH (VCC = 5.5V, RL CONNECTED TO VEE) OPEN-LOOP GAIN vs. TEMPERATURE MAX4292/MAX4294 CROSSTALK vs. FREQUENCY RL = 1kΩ TO VCC 80 60 50 50 50 100 150 200 250 300 350 400 450 500 -80 VCC = 5.5V -90 MAX4291 toc17 144 40 108 40 108 30 72 30 72 20 36 20 36 10 0 10 0 0.1 1 10 100 FREQUENCY (kHz) 1000 AV = 1000V/V 180 0 -36 -10 -72 -108 -20 -108 -144 -30 -144 -180 -40 -20 -40 PHASE (DEGREES) GAIN (dB) 50 -30 -180 0.1 100 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 144 -72 10 GAIN AND PHASE vs. FREQUENCY (CL = 100pF) 50 -36 1 FREQUENCY (kHz) 60 0 0.1 TEMPERATURE (°C) 180 -10 0.01 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 GAIN AND PHASE vs. FREQUENCY (CL = 0) AV = 1000V/V -50 -60 -70 VOH (mV) 60 -30 -40 1 10 100 FREQUENCY (kHz) 1000 1 1000 MAX4291 toc18 70 60 MAX4291 toc16 RL = 1kΩ TO VEE RL = 2kΩ TO VEE 90 70 0 CROSSTALK (dB) 100 THD + NOISE (%) 80 -20 PHASE (DEGREES) 90 -10 110 RL = 2kΩ TO VCC MAX4291-15 120 OPEN-LOOP GAIN (dB) 100 0 MAX4291 toc14 RL = 1kΩ 110 130 MAX4191 toc13 RL = 2kΩ 120 6 0 50 100 150 200 250 300 350 400 450 500 VOL (mV) 130 GAIN (dB) 60 50 50 90 70 60 60 100 80 80 70 RL = 2kΩ 120 100 GAIN (dB) GAIN (dB) 110 130 MAX4291 toc11 RL = 2kΩ 120 120 MAX4291 toc10 130 OPEN-LOOP GAIN vs. OUTPUT SWING LOW (VCC = 5.5V, RL CONNECTED TO VCC) MAX4191 toc12 OPEN-LOOP GAIN vs. OUTPUT SWING LOW (VCC = 1.8V, RL CONNECTED TO VCC) GAIN (dB) MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps RL = 2kΩ Av = 1V/V (NONINVERTING CONFIGURATION) 0.1 VCC = 5.5V VCC = 1.8V 0.01 0.01 0.1 1 FREQUENCY (kHz) _______________________________________________________________________________________ 10 100 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps SMALL-SIGNAL TRANSIENT RESPONSE (NONINVERTING CONFIGURATION) LOAD RESISTOR vs. CAPACITIVE LOAD 10% OVERSHOOT AV = 1V/V (NONINVERTING CONFIGURATION) MAX4291 toc19 100 VCC = 2.5V VEE = -2.5V VCM = 0 MAX4291 toc21 VCC = 2.5V VEE = -2.5V VCM = 0 100mV 100mV 10 IN IN 0 0 100mV 100mV VCC = 5.5V 1 VCC = 2.4V 0.1 IOUT > 20mA VCC = 5.5V OUT IOUT > 20mA VCC = 2.4V OUT 0 0 0.01 3 4 5 6 7 8 9 10 1µs/div 1µs/div CAPACITIVE LOAD (nF) LARGE-SIGNAL TRANSIENT RESPONSE (INVERTING CONFIGURATION) LARGE-SIGNAL TRANSIENT RESPONSE (NONINVERTING CONFIGURATION) MAX4291 toc23 MAX4291 toc22 VCC = 2.5V VEE = -2.5V VCM = 0 VCC = 2.5V VEE = -2.5V VCM = 0 2V 2V IN IN -2V -2V 2V 2V OUT OUT -2V -2V 10µs/div 10µs/div SUPPLY CURRENT vs. SINK CURRENT 3000 2500 SUPPLY CURRENT vs. SOURCE CURRENT 150 VCC = 5.5V 2000 1500 VCC = 2.4V 1000 MAX4291/2/4-25 2 135 120 SUPPLY CURRENT (µA) 1 MAX4291/2/4-24 0 SUPPLY CURRENT (µA) LOAD RESISTOR (kΩ) SMALL-SIGNAL TRANSIENT RESPONSE (INVERTING CONFIGURATION) MAX4291 toc20 VCC = 5.5V 105 VCC = 2.4V 90 75 60 45 VCC = 1.8V 30 500 VCC = 1.8V 15 0 0 0 5 10 15 20 SINK CURRENT (mA) 25 30 0 5 10 15 20 25 SOURCE CURRENT (mA) _______________________________________________________________________________________ 7 MAX4291/MAX4292/MAX4294 Typical Operating Characteristics (continued) (VCC = 2.4V, VEE = VCM = 0, VOUT = VCC/2, no load, TA = +25°C, unless otherwise noted.) MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps Pin Description PIN MAX4291 MAX4292 MAX4294 NAME FUNCTION µMAX/SO UCSP 1 — — — IN+ Noninverting Input 2 4 C2 11 VEE Negative Supply. Connect to ground for single-supply operation. 3 — — — IN- Inverting Input 4 — — — OUT Amplifier Output 5 8 A2 4 VCC Positive Supply — 1, 7 A1, A3 1, 7 OUTA, OUTB — 2, 6 B1, B3 2, 6 INA-, INB- — 3, 5 C1, C3 3, 5 INA+, INB+ — — — 8, 14 OUTC, OUTD — — — 9, 13 INC-, IND- — — — 10, 12 INC+, IND+ Outputs for Amplifiers A and B Inverting Inputs to Amplifiers A and B Noninverting Inputs to Amplifiers A and B Outputs for Amplifiers C and D Inverting Inputs to Amplifiers C and D Noninverting Inputs to Amplifiers C and D Detailed Description Rail-to-Rail Input Stage The MAX4291/MAX4292/MAX4294 have rail-to-rail inputs and output stages that are specifically designed for low-voltage, single-supply operation in the smallest package possible. The input stage consists of separate NPN and PNP differential stages, which operate together to provide a common-mode range extending to both supply rails. The crossover region of these two pairs occurs halfway between VCC and VEE. The input offset voltage is typically ±200µV (MAX4292/MAX4294). Low operating supply voltage, low supply current, rail-to-rail common-mode input range, and rail-to-rail outputs make this family of operational amplifiers (op amps) an excellent choice for precision or general-purpose, lowvoltage, battery-powered systems. Since the input stage consists of NPN and PNP pairs, the input bias current changes polarity as the commonmode voltage passes through the crossover region. Match the effective impedance seen by each input to reduce the offset error caused by input bias currents flowing through external source impedances (Figures 1a and 1b). The combination of high-source impedance plus input capacitance (amplifier input capacitance plus stray 8 MAX4291 MAX4292 MAX4294 IN R3 R3 = R1 R2 R1 R2 Figure 1a. Minimizing Offset Error Due to Input Bias Current (Noninverting) MAX4291 MAX4292 MAX4294 R3 R3 = R1 R2 IN R1 R2 Figure 1b. Minimizing Offset Error Due to Input Bias Current (Inverting) _______________________________________________________________________________________ Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps MAX4291/MAX4292/MAX4294 Table 1. MAX4291 Characteristics with Typical Battery Systems VEND-OF-LIFE (V) CAPACITY, AA SIZE (mA-h) MAX4291 OPERATING TIME IN NORMAL MODE (h) 3.0 1.8 2000 20,000 Yes 2.4 1.8 750 7500 Lithium-Ion (1 cell) Yes 3.5 2.7 1000 10,000 Nickel-MetalHydride (2 cells) Yes 2.4 1.8 1000 10,000 BATTERY TYPE RECHARGEABLE VFRESH (V) Alkaline (2 cells) No Nickel-Cadmium (2 cells) IN+ VCC = 2.5V, VEE = -2.5V 10.6kΩ IN 2.5V/div 0 OUT 2.5V/div 0 IN10.6kΩ Figure 2. Input Protection Circuit capacitance) creates a parasitic pole that produces an underdamped signal response. Reducing input capacitance or placing a small capacitor across the feedback resistor improves response in this case. The MAX4291/MAX4292/MAX4294 family’s inputs are protected from large differential input voltages by internal 10.6kΩ series resistors and back-to-back triplediode stacks across the inputs (Figure 2). For differential input voltages (much less than 1.8V), input resistance is typically 0.75MΩ. For differential input voltages greater than 1.8V, input resistance is around 21.2kΩ, and the input bias current can be approximated by the following equation: (V - 1.8V) IBIAS = DIFF 21.2kΩ In the region where the differential input voltage approaches 1.8V, the input resistance decreases exponentially from 0.75MΩ to 21.2kΩ as the diode block begins to conduct. Conversely, the bias current increases with the same curve. In unity-gain configuration, high slew-rate input signals may capacitively couple to the output through the triplediode stacks. 20µs/div Figure 3. Rail-to-Rail Input/Output Voltage Range Rail-to-Rail Output Stage The MAX4291/MAX4292/MAX4294 output stage can drive up to a 2kΩ load and still swing to within 46mV of the rails. Figure 3 shows the output-voltage swing of a MAX4291 configured as a unity-gain buffer, powered from a ±2.5V supply. The output for this setup typically swings from (VEE + 25mV) to (VCC - 2mV) with a 100kΩ load. Applications Information Power-Supply Considerations The MAX4291/MAX4292/MAX4294 operate from a single 1.8V to 5.5V supply (or dual ±0.9V to ±2.75V supplies) and consume only 100µA of supply current per amplifier. A high power-supply rejection ratio of 100dB allows the amplifiers to be powered directly off a decaying battery voltage, simplifying design and extending battery life. The MAX4291/MAX4292/MAX4294 are ideally suited for use with most battery-powered systems. Table 1 lists a _______________________________________________________________________________________ 9 MAX4291 OFFSET VOLTAGE vs. SUPPLY VOLTAGE -450 30 -550 TA = +25°C -600 TA = -40°C -650 OUTPUT SOURCE CURRENT (mA) -500 OFFSET VOLTAGE (µV) OUTPUT SOURCE CURRENT vs. TEMPERATURE VCM = VCC/2 TA = +85°C -700 25 20 15 10 VCC = 1.8V VOH = 200mV VCC = 5.5V VOH = 100mV VCC = 5.5V VOH = 50mV VCC = 1.8V VOH = 100mV VCC = 1.8V VOH = 50mV 0 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 SUPPLY VOLTAGE (V) TEMPERATURE (°C) Figure 6a. Output Source Current vs. Temperature OUTPUT SINK CURRENT vs. TEMPERATURE 18 140 16 100 80 TA = +25°C TA = -40°C TA = +85°C 20 OUTPUT SINK CURRENT (mA) 120 40 VOH = VCC - VOUT 5 SUPPLY CURRENT PER AMPLIFIER vs. SUPPLY VOLTAGE 60 VCC = 5.5V VOH = 200mV 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Figure 4. Offset Voltage vs. Supply Voltage SUPPLY CURRENT (µA) MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps VCC = 5.5V VOL = 200mV 14 12 10 8 VCC = 5.5V VOL = 100mV VOL = VOUT - VEE VCC = 5.5V VOL = 50mV VCC = 1.8V VOL = 200mV VCC = 1.8V VOL = 100mV VCC = 1.8V VOL = 50mV 6 4 2 0 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -55 -40 -25 -10 5 20 35 50 65 80 95 110 125 SUPPLY VOLTAGE (V) TEMPERATURE (°C) Figure 5. Supply Current per Amplifier vs. Supply Voltage Figure 6b. Output Sink Current vs. Temperature variety of typical battery types showing voltage when fresh, voltage at end-of-life, capacity, and approximate operating time from a MAX4291 (assuming nominal conditions). Although the amplifiers are fully guaranteed over temperature for operation down to a 1.8V single supply, even lower voltage operation is possible in practice. Figures 4 and 5 show the offset voltage and supply current as a function of supply voltage and temperature. as a current source when driving the load toward VCC, and as a current sink when driving the load toward VEE. The limit of this current source/sink varies with supply voltage, ambient temperature, and lot-to-lot variations of the units. Figures 6a and 6b show the typical current source and sink capabilities of the MAX4291/MAX4292/MAX4294 family as a function of supply voltage and ambient temperature. The contours on the graph depict the output current value, based on driving the output voltage to within 50mV, 100mV, and 200mV of either power-supply rail. For example, a MAX4291 running from a single 1.8V supply, operating at TA = +25°C can source 3.5mA to Load-Driving Capability The MAX4291/MAX4292/MAX4294 are fully guaranteed over temperature and supply voltage range to drive a maximum resistive load of 2kΩ to V CC /2, although heavier loads can be driven in many applications. The rail-to-rail output stage of the amplifier can be modeled 10 ______________________________________________________________________________________ Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps IN RISO 0 OUT IN MAX4291 MAX4292 MAX4294 RL CL 100mV OUT 0 AV = RL ≈1 RL + RISO Figure 7a. Using a Resistor to Isolate a Capacitive Load from the Op Amp 100mV IN 0 100mV OUT 0 10µs/div VCC = 2.4V, RL = 2kΩ TO VEE, CL = 1000pF Figure 7b. Pulse Response Without Isolating Resistor within 100mV of VCC and is capable of driving a 485Ω load resistor to VEE: RL = (1.8V − 0.1V) = 485Ω to VEE 3.5mA The same application can drive a 220kΩ load resistor when terminated in VCC/2 (0.9V in this case). Driving Capacitive Loads The MAX4291/MAX4292/MAX4294 are unity-gain stable for loads up to 100pF (see the Load Resistor vs. Capacitive Load graph in the Typical Operating Characteristics). Applications that require greater capacitive-drive capability should use an isolation 10µs/div VCC = 2.4V, RL = 2kΩ TO VEE, CL = 1000pF, RISO = 100Ω Figure 7c. Pulse Response with Isolating Resistor (100Ω) resistor between the output and the capacitive load (Figure 7). Note that this alternative results in a loss of gain accuracy because RISO forms a voltage divider with the load resistor. Power-Supply Bypassing and Layout The MAX4291/MAX4292/MAX4294 family operates from either a single 1.8V to 5.5V supply or dual ±0.9V to ±2.75V supplies. For single-supply operation, bypass the power supply with a 100nF capacitor to VEE (in this case GND). For dual-supply operation, both the VCC and the VEE supplies should be bypassed to ground with separate 100nF capacitors. Good PC board layout techniques optimize performance by decreasing the amount of stray capacitance at the op amp’s inputs and output. To decrease stray capacitance, minimize trace lengths and widths by placing external components as close as possible to the op amp. Surface-mount components are an excellent choice. Using the MAX4291/MAX4292/MAX4294 as Comparators Although optimized for use as operational amplifiers, the MAX4291/MAX4292/MAX4294 can also be used as rail-to-rail I/O comparators. Typical propagation delay depends on the input overdrive voltage, as shown in Figure 8. External hysteresis can be used to minimize the risk of output oscillation. The positive feedback circuit, shown in Figure 9, causes the input threshold to change when the output voltage changes state. The two thresholds create a hysteresis band that can be calculated by the following equations: ______________________________________________________________________________________ 11 MAX4291/MAX4292/MAX4294 100mV PROPAGATION DELAY vs. INPUT OVERDRIVE 1000 HYSTERESIS VHI INPUT VLO VOH tPD+, VCC = 5.5V OUTPUT VOL tPD (µs) VSIG tPD-, VCC = 5.5V 100 RHYST R1 tPD-, VCC = 1.8V tPD+, VCC = 1.8V VCC VOUT MAX4291 R2 VREF 10 0 10 20 30 40 50 60 MAX4294 VEE = GND VOD (mV) Figure 8. Propagation Delay vs. Input Overdrive VHYST = VHI − VLO R1 R1 VHI = 1 + + VREF R2 RHYST R1 VLO = VHI − VCC RHYST When the output of the comparator is low, the supply current increases. The output stage has biasing circuitry to monitor the output current. When the amplifier is used as a comparator, the output stage is overdriven and the current through the biasing circuitry increases to maximum. For the MAX4291, typical supply currents increase to 1.5mA with VCC = 1.8V and to 9mA when VCC = 5.0V (Figure 10). Using the MAX4291/MAX4292/MAX4294 as Low-Power Current Monitors The MAX4291/MAX4292/MAX4294 are ideal for applications powered from a two-cell battery stack. Figure 11 shows an application circuit in which the MAX4291 is used for monitoring the current of a two-cell battery stack. In this circuit, a current load is applied, and the voltage drop at the battery terminal is sensed. The voltage on the load side of the battery stack is equal to the voltage at the emitter of Q1 due to the feedback loop containing the op amp. As the load current increases, the voltage drop across R1 and R2 increases. Thus, R2 provides a fraction of the load current (set by the ratio of R1 and R2) that flows into the 12 VEE = GND MAX4292 70 80 90 100 Figure 9. Hysteresis Comparator Circuit MAXIMUM SUPPLY CURRENT PER AMPLIFIER vs. SUPPLY VOLTAGE 12 MAXIMUM SUPPLY CURRENT (mA) MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps 10 COMPARATOR CONFIGURATION VIN+ = (VIN-) - 100mV 8 6 4 2 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) Figure 10. Maximum Supply Current per Amplifier vs. Supply Voltage emitter of the PNP transistor. Neglecting PNP base current, this current flows into R3, producing a ground-referenced voltage proportional to the load current. To minimize errors, scale R1 to give a voltage drop that is large enough in comparison to the op amp’s VOS. Calculate the output voltage of the application using the following equation: R1 VOUT = ILOAD × × R3 R2 ______________________________________________________________________________________ Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps ILOAD R1 VCC UCSP Information Layout Issues Design the layout for the IC to be as compact as possible to minimize parasitics. The UCSP uses a bump pitch of 0.5mm (19.7mil) and bump diameter of 0.3 (~12mil). Therefore, lay out the solder-pad spacing on 0.5mm (19.7mil) centers, using a pad size of 0.25mm (~10mil) and a solder mask opening of 0.33mm (13mil). Round or square pads are permissible. Connect multiple vias from the ground plane as close to the ground pins as possible. Install capacitors as close as possible to the IC supply voltage pin. Place the ground end of these capacitors near the IC GND pins to provide a low-impedance return path for the signal current. R2 Q1 VOUT R3 MAX4291 VEE Figure 11. Current Monitor for a 2-Cell Battery Stack Marking Information Prototype Chip Installation Alignment keys on the PC board, around the area where the chip is located, will be helpful in the prototype assembly process. It is better to align the chip on the board before any other components are placed, and then place the board on a hot plate or hot surface until the solder starts melting. Remove the board from the hot plate without disturbing the position of the chip and let it cool down to room temperature before processing the board further. ORIENTATION PRODUCT ID CODE LOT CODE AAA AAA UCSP Reliability The UCSP represents a unique packaging form factor that may not perform as well as a packaged product through traditional mechanical reliability tests. UCSP reliability is integrally linked to the user’s assembly methods, circuit board material, and usage environment. The user should closely review these areas when considering use of a UCSP. Performance through operating-life test and moisture resistance remains uncompromised. The wafer-fabrication process primarily determines the performance. Mechanical stress performance is a greater consideration for UCSPs. UCSPs are attached through direct solder contact to the user’s PC board, foregoing the inherent stress relief of a packaged product lead frame. Solder-joint contact integrity must be considered. Comprehensive reliability tests have been performed and are available upon request. In conclusion, the UCSP performs reliably through environmental stresses. ______________________________________________________________________________________ 13 MAX4291/MAX4292/MAX4294 For a 1V output and a current load of 50mA, the choice of resistors can be R1 = 2Ω, R2 = 100kΩ, and R3 = 1MΩ. MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps Pin Configurations (continued) TOP VIEW OUTA 1 INA- 2 1 8 VCC INA- 2 7 OUTB OUTA IN+ 1 VEE 2 5 VCC MAX4291 4 OUT IN- 3 SC70/SOT23 MAX4292 14 OUTD MAX4294 13 IND- INA+ 3 12 IND+ VCC 4 11 VEE INB+ 5 10 INC+ INA+ 3 6 INB- INB- 6 9 INC- VEE 4 5 INB+ OUTB 7 8 OUTC µMAX/SO TSSOP/SO Chip Information MAX4291 TRANSISTOR COUNT: 149 MAX4292 TRANSISTOR COUNT: 356 MAX4294 TRANSISTOR COUNT: 747 PROCESS: BiCMOS 14 ______________________________________________________________________________________ Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps SOT5L.EPS SC70, 5L.EPS ______________________________________________________________________________________ 15 MAX4291/MAX4292/MAX4294 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Package Information (continued) 4X S 8 E ÿ 0.50±0.1 8 INCHES DIM A A1 A2 b H c D e E H 0.6±0.1 1 L 1 α 0.6±0.1 S BOTTOM VIEW D MIN 0.002 0.030 MAX 0.043 0.006 0.037 0.014 0.010 0.007 0.005 0.120 0.116 0.0256 BSC 0.120 0.116 0.198 0.188 0.026 0.016 6∞ 0∞ 0.0207 BSC 8LUMAXD.EPS (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0∞ 6∞ 0.5250 BSC TOP VIEW A1 A2 e FRONT VIEW A α c b L SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0036 REV. J 1 1 Note: The MAX4292 does not have an exposed pad. TSSOP.EPS MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps Note: The MAX4294 does not have an exposed pad. 16 ______________________________________________________________________________________ Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps SOICN.EPS ______________________________________________________________________________________ 17 MAX4291/MAX4292/MAX4294 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 9LUCSP, 3x3.EPS MAX4291/MAX4292/MAX4294 Ultra-Small, 1.8V, µPower, Rail-to-Rail I/O Op Amps 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. 18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.