19-4739; Rev 2; 7/93 MAXIM 1.2.A Max, Single/Dual/Quad, General Description The MAX406/MAX407/MAX409/MAX417-MAX419 are single, dual, and quad low-voltage, micropower, precision op amps designed for battery-operated systems. They fea- ture a supply current of less than 1.2uA per amplifier that is relatively constant over the entire supply range, which repre- sents a 15 to 20 times improvement over industry-standard micropower op amps. A unique output stage enables these op amps to operate at ultra-low supply current while main- taining linearity under loaded conditions. In addition, the out- put is capable of sourcing 1.8mA when powered by a 9V battery. The common-mode input-voltage range extends from the negative rail to within 1.1V of the positive supply (for the singles, 1.2V for the duals and quads), and the output stage swings rail-to-rail. The entire family is designed to maintain good DC characteristics over the operating temperature range, minimizing the input referred errors. The MAX406 is a single op amp with two modes of opera- tion: compensated mode and decompensated mode. Floating BW (pin 8) or connecting it to V- internally compen- sates the amplifier. In this mode, the MAX406 is unity-gain stable with a 5V/ms typical slew rate and an 8kHz gain bandwidth. Connecting BW to V+ puts the MAX406 into decompensated mode with a 20V/ms typical slew rate and a 40kHz gain bandwidth (AvcL 2 2V/V). The dual MAX407 and quad MAX418 are internally com- pensated to be unity-gain stable. The MAX409/MAX417/ MAX419 single/dual/quad op amps feature 150kHz typical bandwidth, 75V/ms slew rate, and stability for gains of 1OVNV or greater. Applications Battery-Powered Systems Medical Instruments Electrometer Amplifiers Intrinsically Safe Systems Photodiode Pre-Amps pH Meters PAAXISA Single-Supply Op Amps Features @ 1.2uA Max Quiescent Current per Amplifier # +2.5V to +10V Single-Supply Range # 500.V Max Offset Voltage (MAX406A/MAX409A) @ <0.1pA Typical Input Bias Current Output Swings Rail-to-Rail @ Input Voltage Range Includes Negative Rail Selection Table PART NO.OF | GAIN-BW GAIN OFFSET NUMBER AMPLI- | PRODUCT | STABILITY | VOLTAGE FIERS =| (kHz,TYP) (VN) (mv, MAX) MAX406A 1 8*/40"* jo" 05 MAX4068, 1 8*/40"* 1/2" 20 MAX407 2 8 1 30 MAX409A 1 150 10 05 MAX409B 1 150 10 20 MAX417 2 150 10 30 MAX418 4 8 1 40 MAX419 4 150 10 40 * With BW pin open or connected to V- ** With BW pin connected to V+ Typical Operating Circuit COAX REMOTE-SENSOR BUFFER OPERATES FROM 3V BATTERY Pin Configurations on last page. Maxim Integrated Products 1 Call toll free 1-800-998-8800 for free samples or literature 6LYXVIN-ZLDXVIW/60PXVW/LOVXVW/90PXVNMAX406/MAX407/MAX409/MAX41 7-MAX419 1.2 A Max, Single/Dual/Quad, Single-Supply Op Amps ABSOLUTE MAXIMUM RATINGS Total Supply Voltage (V+ to V-) occ ceicecetenetesieneeneneees 12V INPUt Voltage once ceneceereereneees (V+ + 0.3V) to (V- - 0.3V) Continuous Current All Input Pins 0.0.0 ccccceceneneererentereseeettirernsetentes 10mA All Other Pins .50MA Short-Circuit Duration 2... cece teeeseeeeeneee Continuous Continuous Power Dissipation (Ta = +70C) 8-Pin Plastic DIP (derate 9.09mW/C above +70C) ...727mW 8-Pin SO (derate 5.88mW/C above +70C)....... 471mWw 8-Pin CERDIP (derate 8.00mW/C above +70C)........ 640mW 14-Pin Plastic DIP (derate 10.00mW/C above +70C)..800mW 14-Pin SO (derate 8.33mW/C above +70C) .....e 667mW 14-Pin CERDIP (derate 9.09mW/C above +70C)........ 727mMW Operating Temperature Ranges: coetesees OC to +70C 40C to +85C Storage Temperature Range Lead Temperature (soldering, 10sec) Note 1: Absolute Maximum Ratings do not apply to devices supplied in die or wafer form. 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 (V+ = 2.5V, V- = -2.5V, Ta = +25C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS MAX406A, MAX409A, 0.25 0.5 MAX406B, MAX409B 0.75 2.0 | Vi Vv nput Offset Voltage Os MAX407, MAX417 1.0 3.0 m MAX418, MAX419 1.0 4.0 Input Bias Current lB Vom = OV (Note 2) <0.1 40.0 pA MAX406A, MAX409A 200 1000 RL = 1MQ, MAX406B, MAX407 Large-Signal Vi =+2V ' Voltage Gain Avot | OUT MAX409B, MAX41_ 1001000 Vien Ri = 1MQ, Vout = +4V, V+ = 5V, V- = -5V 10 23 Compensated mode 4 8 MAX406A/B Decompensated mode hy 20 40 Gain Bandwidth GBW (Av = 2VN) kHz MAX407, MAX418 4 8 MAX409A/B, MAX417, MAX419, Avo = 10V/V 80 150 Input Common-Mode omR MAX406A/B, MAX409A/B V- V+-1.1 y Range MAX407, MAX41_ V- V+-1.2 Output Voltage Swing Vo RL = 1MQ +2.47 +2.49 Vv , MAX406A, MAX409A 70 80 Cormon-Mode Rejection Ratio CMRR | (Note 3) MAX406B, MAX407, MAX409B, 60 80 dB MAX41_ MAX406A, MAX409A 50 100 Power-Supply VIN = OV, MAX4 4 150 Rejection Ratio PSAR V+ = 2.5V to 7.5V 068, MAX4098 300 WV MAX407, MAX41_ 200 600 2 MAXIMA1.2L A Max, Single/Dual/Quad, Single-Supply Op Amps ELECTRICAL CHARACTERISTICS (continued) (V+ = 2.5V, V- = -2.5V, Ta = +25C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS Compensated mode 3 5 MAX406A/B Decompensated mode 42 20 (Ay = 2VN) Slew Rate SR Vims MAX407, MAX418 3 5 MAX409A/B, MAX417, MAX419 40 80 Avct 2 10V/V Supply Current Per Amplifier Isy 1.0 12 | pA Output Sink Current [OSINK Vout = OV 100 200 tA Output Source Current | losource | Vout = OV 300 600 pA Supply Voltage (Vs to V-) Vs 2.5 10.0 Vv fo= 150 VIN Input Noise Voltage en o= IkHz nViNH2 fo = 0.1Hz to 10Hz 6 BV p-p ELECTRICAL CHARACTERISTICS (V+ = 2.5V, V- = -2.5V, Ta = 0C to +70C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS MAX406A, MAX409A 0.95 MAX406B, MAX409B 3.00 Input Offset Voltage Vos mV MAX407 4.00 MAX41_ 5.00 Offset-Voltage of ar 6 Tempco TCvos MAX406A, MAX409A, 100% drift tested 2 10 pve Input Bias Current IB Vom = OV 20 pA Rv = 1MQ, MAX406A, MAX409A 100 Large-Signal Vout = +2V MAX406B 50 Voltage Gain AVOL Vim RL = 1MQ, (Vout = +4V, V+ = SV, V- = -5V 10 Output Voltage Swing Vo RL = 1MQ +2.45 Vv Common-Mod MAX406A, MAX409A 66 ommon-Mode Rejection Ratio CMRR | (Note 3) MAX406B, MAX407 60 aB MAX409B, MAX41_ : MAX406A, MAX409A 150 Power-Supply VIN = OV, Rejection Ratio PSRR V+ = 2.5V to 7.5V MAX4068, MAX409B 450 VN MAX407, MAX41_ 800 MAAXILMA 3 6LEXVW-ZLEUXVW/GOPVXVW/LOVXVW/90PXVNMAX406/MAX407/MAX409/MAX417-MAX419 1.2. A Max, Single/Dual/Quad, Single-Supply Op Amps ELECTRICAL CHARACTERISTICS (continued) (V+ = 2.5V, V- = -2.5V, Ta = 0C to +70C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS Supply Current Per Amplifier Isy 16 WA Output Sink Current lOSINK Vout = 0V 50 pA Output Source Current | losouRCE | VOUT = OV . 250 pA ELECTRICAL CHARACTERISTICS (V+ = 2.5V, V- = -2.5V, Ta = -40C to +85C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS MAX406A, MAX409A 1.10 MAX406B, MAX409B 3.00 Input Offset Voltage Vos mv MAX407, MAX417 4.00 MAX418, MAX419 5.00 Offset-Voltage TCvos | MAX406A, MAX409A, 100% drift tested to | uvec Tempco , , H Input Bias Current iB Vom = OV 50 pA MAX406A, MAX4! 50 Rt = 1MQ, O6A, O9A Large-Signal Vout = +2V MAX406B, MAX407, Voltage Gain AVOL MAX409B, MAX41_ 25 Vim Ri = 1MQ, Vout = +4V, V+ = 5V, V- = -5V 10 Output Voltage Swing Vo RL = IMQ +2.45 Vv MAX406A, MAX409A 66 Common-Mode Rejection Ratio CMRR (Note 3) MAX406B, MAX407, 60 dB MAX409B, MAX41_ MAX406A, MAX409A 150 Power-Supply VIN = OV, Rejection Ratio PSRR | V4 = 2.5V to 7.5V MAXA06B, MAX409B 450 | VN MAX407, MAX41_ 800 Supply Current Per Amplifier Isy 7 HA Output Sink Current IOSINK VouT = OV 40 pA Output Source Current losource | Vout = 0V 250 HA 40 MAAXIIA1.2u A Max, Single/Dual/Quad, Single-Supply Op Amps ELECTRICAL CHARACTERISTICS (V+ = 2.5V, V- = -2.5V, Ta = -55C to +125C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS MAX406A, MAX409A 1.5 MAX406B, MAX409B 40 Input Offset Voltage Vos MAX40T, MAX417 50 mV MAX418, MAX419 6.0 Offset-Voltage TCvos | MAX406A,MAX409A, 100% drift tested 10 | pvec Tempco Input Bias Current Ip Vom = OV 1.0 nA MAX406A, MAX409A 10 RL = 1MQ, Large-Signal VouT = 2V MAX406B, MAX407, Voltage Gain AVOL MAX409B, MAX41_ 5 Vim RL = 1MQ, Vout = 4V, V+ = 5V, V- = -5V 10 Output Voltage Swing Vo Ri = 1MQ +2.45 Vv C Mod MAX406A, MAX409A 66 ommon-Mode Rejection Ratio CMRR (Note 3) MAX406B, MAX407, 60 dB MAX409B, MAX41_ MAX406A, MAX409A 150 Power-Supply VIN = OV, Rejection Ratio PSRR V+ = 2.5V to 7.5V MAX406B, MAX409B 450 WV MAX407, MAX41_ 800 Supply Current Per Amplifier Isy 20 HA Output Sink Current lOSINK VouT = OV 20 pA Output Source Current | lOSOURCE Vout = OV 200 pA Note 2: Production-automated test equipment cannot resolve input bias currents below 1pA. Lab equipment has shown the MAX40__, MAX41__ typical input bias currents below 0.1pA. Note 3: MAX406A/MAX409A: Vom = V- to (V+ - 1.1V). MAX407, MAX41_ Vem = V- to (V+ - 1.2V). MAAXLMA 5 6LPUXVIN-ZELPXVIN/GOPXVW/LOVXVW/90PXUINMAX406/MAX407/MAX409/MAX417-MAX419 1.2..A Max, Single/Dual/Quad, Single-Supply Op Amps (V+ 2.5V, V- = -2.5V, Ta = +25C, unless otherwise noted.) SUPPLY CURRENT PER AMPLIFIER vs. SUPPLY CURRENT PER AMPLIFIER Typical Operating Characteristics SUPPLY CURRENT PER AMPLIFIER SUPPLY VOLTAGE vs. SUPPLY VOLTAGE IN OVERDRIVE vs. TEMPERATURE 2.00 100 15 1.75 | NO LOAD Ywat > _ _ < No = 1.50 = 10 Vin = -100mV .= B 125 z eo? gq z eo & & as => 1.00 3 1 on Oo So > > > Vin = +106mV a2 a 075 a Se s g Bw 05 2 0.50 a O14 0.25 0 0.01 Q 012345678 9 101112 0 2 4 6 8 0 1 55-25 (0555S SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) TEMPERATURE (C) MAX406/MAX407/MAX418 MAX409/MAX417/MAX419 INPUT BIAS CURRENT POWER-SUPPLY REJECTION RATIO POWER-SUPPLY vs. TEMPERATURE vs. FREQUENCY REJECTION RATIO vs. FREQUENCY 100 80 V-=-2.5V V- = -2.5V Va = 1.8V TO 2.5V V+ = 1.8V TO 2.5V = 50 SINUSOID SINUSOID & 10 Ave. = 1VV a _ 40 = E g 3 ao 4 = 30 5 20 = oO 10 0.0t 0 65-25 35 65 95 125 0.01 0.1 1 10 100 0.01 of 1 10 100 TEMPERATURE (C) FREQUENCY (kHz) FREQUENCY (kHz) LARGE-SIGNAL D.C. GAIN LARGE-SIGNAL D.C. GAIN vs. SUPPLY VOLTAGE vs. TEMPERATURE 10000 10000 LOAD = 1Ma TO 2 1000 = = = 1000 z 2 < = = 100 a Qo Qo g 5 Fr = 100 S 10 3g LOAD = 1MQ TO GROUND 10 12345 6 7 8 9 1011 12 55 4-25 0SS 85S CHSNDS SUPPLY VOLTAGE (V) TEMPERATURE (C) 6 MAAXLAMA1.2uA Max, Single/Dual/Quad, Single-Supply Op Amps Typical Operating Characteristics (continued) (V+ = 2.5V, V- = -2.5V, Ta = +25C, unless otherwise noted). MAX406 OPEN-LOOP GAIN AND PHASE MAX406/MAX407/MAX418 CLOSED-LOOP GAIN (80dB) vs. FREQUENCY OPEN-LOOP GAIN AND PHASE vs. FREQUENCY vs. FREQUENCY (DECOMPENSATED MODE) (COMPENSATED MODE FOR MAX406) 100 7 40 0 40 0 N 80 i i S RGNCNP occomrensereo] fl] g 0 . 6 ge 6y 2 LN TT 2 \ = E 3 =< 3 oa 3 THN REMIT Hatin) 3 n N em wo 2 CIN mm \ 3 & J 2 LUI VAIN CaS NY = < o. 59 | COMPENSATED N nN TU 10 135 10 138 wax4oe/407/418) | | (TK NING N , i 0 ot e 1 10 100 1000 10000 100000 100 1000 10000 100000 100 1000 10000 FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (Hz) MAX409, MAX417, MAX419 OPEN-LOOP GAIN AND PHASE MAXIMUM OUTPUT SINK CURRENT MAXIMUM OUTPUT SOURCE CURRENT vs. FREQUENCY vs. SUPPLY VOLTAGE vs. SUPPLY VOLTAGE 80 0 1000 10000 ,_ 2 3 & 60 eg F & 1000 = eB 100 g 3 os 3 & 40 woe & 8 100 2 a & 3 = = z 2 10 2 20 ik = 10 oa 0 180 1 1 0.1 i 10 100 0123 45 678 9 10 0123 45 6 78 9 10 FREQUENCY (kHz) SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) MAXIMUM OUTPUT VOLTAGE MAX406, MAX407, MAX418 MAX406 vs. LOAD RESISTANCE PERCENT OVERSHOOT vs. CAPACITIVE LOAD PERCENT OVERSHOOT vs. CAPACITIVE (SINGLE SUPPLY) (COMPENSATED MODE) LOAD (DECOMPENSATED MODE) 100 80 Avo =1 Avet = 10 80 Vsurety= +10V Vguppcy = +10V Vsuppty = +5 60 - E Ss 2 60 3 3 & ui 40 Vsuppiy = +5V > 6 6 ae) z 20 Vsuppy = +3V 20 Vsuppy = +3V 0 0 0 1 10 100 1000 0.001 0.01 0.1 1 10 100 1000 10000 0.001 0.01 0.1 1 10 100 100010000 100000 LOAD RESISTANCE (ka) CAPACITIVE LOAD (nF) CAPACITIVE LOAD (nF) MAXIM 7 6LUXUW-ZLEPXVI/6GOVXVW/LOPXVW/90PXUNMAX406/MAX407/MAX409/MAX41 7-MAX419 1.2..A Max, Single/Dual/Quad, Single-Supply Op Amps (Ta = +25C, unless otherwise noted). Typical Operating Characteristics MAX406/MAX407/MAX418 MAX406/MAX407/MAX418 MAX406 (DECOMPENSATED MODE) Cae LARGE-SIGNAL TRANSIENT RESPONSE LARGE-SIGNAL TRANSIENT RESPONSE NONINVERTING, Avet = 1V/V, NONINVERTING, Ayc. =1V/V, Vsuppcy = #2.5V, Ayct = 2V/V, VsuppLy = #2.5V, LOAD = 1MQ |] 250pF Vsuppy = #2.5V, LOAD = 1MQ II 1000pF LOAD = 1MQ II 15pF MAX406/MAX407/MAX418 MAX406/MAX407/MAX418 MAX406 (DECOMPENSATED MODE) SMALL-SIGNAL TRANSIENT RESPONSE SMALL-SIGNAL TRANSIENT RESPONSE SMALL-SIGNAL TRANSIENT RESPONSE i teste pee tede eter ret abaa de NONINVERTING, Avct = 1V/V, NONINVERTING, Aycl = 1V/V, Avci = 10VN, VsuppLy = #2.5V, LOAD = 1MQ II 250pF Vsuppcy = 2.5V, LOAD = 1MQ II 1000pF Vsupey = +2.5V, LOAD = 1MQ |! 1000pF MAX409/MAX417/MAX419 MAX409/MAX417/MAX419 LARGE-SIGNAL TRANSIENT RESPONSE SMALL-SIGNAL TRANSIENT RESPONSE Ay = 10VNV, Vsuppty = +2.5V, LOAD = 1M&Q Il 10pF reer Eh Ay = 10V/NV, Veupply = +2.5V, LOAD = 1Ma2 Il 110pF MAMXLAN1.2. A Max, Single/Dual/Quad, Single-Supply Op Amps Typical Operating Characteristics (continued) MAX409/MAX417/MAX419 MAX409/MAX417/MAX419 LARGE-SIGNAL TRANSIENT RESPONSE LARGE-SIGNAL TRANSIENT RESPONSE Ay = 10VNV, Veuppy = 22.5V, LOAD = {MQ tl 10pF Ay = 10VA, Vsuppy = +2.5V, LOAD = 1MQ II 110pF Pin Description MAX407 MAX418 MAX406 | MAX417 | MAX409 | MAX419 NAME FUNCTION PIN PIN PIN PIN { 1 NULL Nulling. Connect to one end of 100k potentiometer for offset voltage trimming. See Figure 1. 1 1 OUTA Amplifier Output A 2 2 IN- Inverting Input 2 2 INA- Inverting Input A 3 3 IN+ Noninverting Input 3 3 INA+ Noninverting Input A 4 4 4 11 V- Negative Power-Supply Pin. Connect to (-) terminal of power supply or ground. 5 5 NULL Nulling. Connect to one end of 100k potentiometer for offset voltage trimming. Connect wiper to V+. See Figure 1. 5 5 INB+ Noninverting Inout B 6 6 OUT Amplifier Output 6 INB- Inverting Input B 7 8 7 4 V+ Positive Supply Pin. Connect to (+) terminal of power supply. 7 7 OUTB Amplifier Output B Bandwidth Selection Pin. Leave floating or connect to V- for 8 BW unity-gain stability (compensated mode) or connect to V+ . (decompensated mode). 8 LC. Internal Connection. Make no connection to this pin. 8 OUTC Amplifier Output C 9 INC- Inverting Input C 10 INC+ Noninverting Input C 12 IND+ Noninverting Input D 13 IND- Inverting Input D 14 OUTD Amplifier Output D MAXUM 9 6LYXUVUIN-ZLLDXVIN/6GOPXVW/LOPXVW/90PXVNMAX406/MAX407/MAX409/MAX41 7-MAX419 1.2uUA Max, Single/Dual/Quad, Single-Supply Op Amps V+ MAAXISAA MAX406 MAK407 MAX409 MAX417 MAX418 MAX419 1 2pF to 10pF Figure 1. Offset-Voltage Adjustment Applications Information Trimming Voltage Offset The MAX406/MAX409's typical! input offset voltage is between 0.25mV and 0.75mV, depending on the grade. If the application requires additional offset adjustment, connect a 100kQ trim pot between pins 1, 5, and 7 for the MAX406/MAX409 (Figure 1). The dual and quad amplifiers offset voltages are not adjustable. input Overdrive vs. Supply Current The supply current of the MAX406/MAX407/MAX409/ MAX417-MAX419 remains relatively constant over the supply range if the amplifier output is not overdriven to the negative supply rail. For example, when connect- ing the amplifier as a comparator and applying a -100mV input overdrive, supply current rises above the 1pA per amplifier typical value and varies with supply voltage. (see Supply Current vs. Supply Voltage in Overdrive, Typical! Operating Characteristics). Total Supply-Voitage Considerations Although the MAX406/MAX407/MAX409/MAX41/7- MAX419 can operate with supply voltages between 2.5V and 10V, best performance is achieved with supply voltages below 7V. The Open-Loop Gain vs. Supply Voltage graph in the Typical Operating Characteristics shows how open-loop gain is reduced at voltages that exceed 7V. Bandwidth The MAX407/MAX418 are internally compensated for stable unity-gain operation, with an 8kHz typical gain bandwidth. The MAX409/MAX417/MAX419 have a 150kHz typical gain-bandwidth product and are stable with a gain of 10V/V or greater. 10 Figure 2. Compensation for Feedback Node Capacitance The MAX406 operates in one of two modes. Floating BW or connecting BW to V- internally compensates the amplifier for stable unity-gain operation. Connecting BW to V+ reduces the compensation and allows the amplifier to be used at higher speeds. When operating in decompensated mode, the MAX406 is stable for closed loop gains 2 2V/V, with a 40kHz typical gain bandwidth and a 20V/ms typical slew rate. Stability Unlike other industry-standard micropower CMOS op amps, the MAX406/MAX407/MAX409/MAX4 1 7-MAX419 maintain stability in their minimum gain configuration while driving heavy capacitive loads, as demonstrated in the Percent Overshoot vs. Capacitive Load graph in the Typical Operating Characteristics. Although this product family is primarily designed for low-frequency applications, good layout is extremely important. This is because low power requirements demand high-impedance circuits. A 10MQ impedance and a ipF capacitance will provide a breakpoint at approximately 16kHz, which is near the amplifier's bandwidth. The layout should minimize stray capaci- tance at the amplifier's inputs. However, some stray capacitance may be unavoidable, and it may be necessary to add a 2pF to 10pF capacitor across the feedback resistor as shown in Figure 2. Select the smallest capacitor value that insures stability. Typical Application Circuits Buffered pH Probe Allows Low-Cost Cable The MAX406 has less than 20pA input leakage current over the commercial temperature range, and is typically less than 100fA at +25C. These characteristics are ideal for buffering pH probes and a variety of other high output impedance chemical sensors. The circuit in FAAXUIM1.2UA Max, Single/Dual/Quad, Single-Supply Op Amps GENERAL- PURPOSE 7 COMBINATION _ COAX pH PROBE \ (CORNING 476540) |AAAXLAA 3V (DURACELL ba, 0L1620) |, = D+ 10M R2 10M 1 1 1 t 1 ( 1 | | | BATTERY | | ' ' 1 1 1 1 , ALL COMPONENTS CONTAINED WITHIN THE pH PROBE O.1uF ok 3 34 33 1M ail CREF CREF- SW tT IN HI 2.19 O.1NF MAXIM 22-25 n3 30 MAX131 TOLGD 11K iN DISPLAY 4 wl 2 COMMON 28 200k BUFF 470k & 0.047yF = Fy aa NZ rer 100k nerf 0.22pF Ta INT v-[2 OSC2_0SC3 Osc 39 38 50pF 40 I+ 180k Figure 3. Buffered pH Probe Allows Low-Cost Cable Figure 3 eliminates expensive low-leakage cables that often connect pH probes to meters. A MAX406 and a lithium battery are included in the probe housing. A conventional low-cost coaxial cable carries the buffered pH signal to the MAX131 A/D converter. In most cases, the probe assembly's battery life exceeds the functional life of the probe itself. Micropower, 4-Channel Simultaneous Sample-and-Hold Switch leakage and buffer input bias current in sample and hold circuits limit performance by discharging the signal voltage on the hold capacitor (an effect called droop). The 2pA typical room temperature leakage current for the MAX327 and 100fA typical input bias current for the MAX407 translates to a typical droop rate of 200uV/sec for Figure 4's circuit. Another advan- tage is low power consumption. The MAX327 guaran- tees no more than 250pA supply current with +15V supplies, but most of this is drawn by internal logic- level translators. By using rail-to-rail logic (CD4000, 74C00, or 74HCOO families) to drive IN1-IN3, the level MAXUM translators are turned off and the supply current falls well below 1A when the switches are off. This tech- nique turns any Maxim switch or multiplexer into an ultra low-power device. Figure 4's circuit typically draws 6pA with OV to 9V logic input levels. Remotely Powered Sensor Amp Figure 5 shows a simple 2-wire current transmitter that uses no power at the transmitting end except from the transmitted signal itself. At the transmitter, a OV to 1V input drives both a MAX406 and an NPN transistor con- nected as a voltage-controlled current sink. The OmA to 2mA output is sent through a twisted pair to the receiver and develops a voltage across the receiver sense resistor R2. The resulting sense voltage is buffered by another MAX406, producing a OV to 1V ground-referenced output signal. R1 and R2 should be well matched. The MAX406's supply current is added to the OmA to 2mA signal, resulting in a 500uV offset at the output. This offset, in addition to the MAX406's input offset, varies with temperature. 11 6LUXVW-LLUXVW/60PXVW/LOPXVW/90PXUNMAX406/MAX407/MAX409/MAX4 1 7-MAX419 1.2UA Max, Single/Dual/Quad, Single-Supply Op Amps +9V lis V+ MAXIM aad 2| D1 $1 | 3 MAXAO7 MRO CHT = oo F ' L O.01pF ?-_ T POLYPROPYLENE | \ I ' CHo we 15 | D2 ws so | 14 . aN L 0.01KF Voy POLYPROPYLENE 1 ; ' I MAXIMA EL 1 MAX327 tL MAXIM hed jo | D3 s3 | 11 MAXAO? MRO CHS me oo \ I 0.01pF a T POLYPROPYLENE |! \ 7 t = 1 I CH4 mm 7 | b4 oo SA Th O.01pF ; ' > IN3 IN4 IN2 IN1 V- GND I POLYPROPYLENE 1 | TYPICAL DROOP AT +25C = S0uV/sec TYPICAL SUPPLY CURRENT WITH OV TO +9V LOGIC INPUTS = 6pA. Figure 4. Micropower, 4-Channel, Simultaneous Sample-and-Hold +5V +5V TWISTED PAIR ay [N@, 2N2222 Rl 500Q MA axiar>4 MAX406, y -1V FS C iff Figure 5. Remotely Powered Sensor Amp 12 MAXIM1.2.A Max, Single/Dual/Quad, Single-Supply Op Amps Negative Reference Circuit Draws Less Than 11, A By biasing a low-power, low-dropout reference (MAX872) so it sits in the feedback path of a MAX406, a precise -2.50V reference is produced that requires no external components, as shown in Figure 6. This is superior to a standard inverting configuration, which requires two resistors that can add errors. Other advantages of this circuit are: 1. Maximum current drain is 11pA. 2. The output load is driven by the op amp so there is no degradation of voltage due to load regulation. 3. No compensation is needed for load capacitance. The supplies do not have to be carefully regulated. The positive supply can be as low as 1.1V and the neg- ative supply can be as little as 2.7V. +1.5V DC 11pA MAX TOTAL SUPPLY CURRENT MAXIMA MAX872 Vout Vout = -2.50V -3.0V DC Figure 6. Micropower, Low-Dropout Negative Reference MAXIM Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX406ACPA 0C to +70C 8 Plastic DIP MAX406BCPA 0C to +70C 8 Plastic DIP MAX406ACSA 0C to +70C 8SO0 MAX406BCSA 0C to +70C 8SO MAX406C/D OC to +70C Dice* MAX406AEPA -40C to +85C 8 Plastic DIP MAX406BEPA -40C to +85C 8 Plastic DIP MAX406AESA -40C to +85C 8S0 MAX406BESA -40C to +85C 8SO0 MAX406AMJA -55C to +125C 8 CERDIP MAX406BMJA -58C to +125C 8 CERDIP MAX407CPA OC to +70C 8 Plastic DIP MAX407CSA 0C to +70C 8SO MAX407C/D OC to +70C Dice* MAX407EPA -40C to +85C 8 Plastic DIP MAX407ESA -40C to +85C 8SO MAX407MJA -55C to +125C 8 CERDIP MAX409ACPA 0C to +70C 8 Plastic DIP MAX409BCPA OC to +70C 8 Plastic DIP MAX409ACSA 0C to +70C 8S0 MAX409BCSA 0C to +70C 8S0 MAX409BC/D 0C to +70C Dice* MAX409AEPA -40C to +85C 8 Plastic DIP MAX409BEPA -40C to +85C 8 Plastic DIP MAX409AESA -40C to +85C 8S0 MAX409BESA -40C to +85C 8SO MAX409AMJA -55C to +125C 8 CERDIP MAX409BMJA -55C to +125C 8 CERDIP MAX417CPA OC to +70C 8 Plastic DIP MAX417CSA 0C to +70C 8SO MAX417C/D 0C to +70C Dice* MAX417EPA -40C to +85C 8 Plastic DIP MAX417ESA -40C to +85C 8SO MAX417MJA -55C to +125C 8 CERDIP MAX418CPD OC to +70C 14 Plastic DIP MAX418CSD 0C to +70C 14S0 MAX418EPD -40C to +85C 14 Plastic DIP MAX418ESD -40C to +85C 14S0 MAX418MJD -55C to +125C 14 CERDIP MAX419CPD OC to +70C 14 Plastic DIP MAX419CSD 0C to +70C 14S0 MAX419EPD -40C to +85C 14 Plastic DIP MAX419ESD -40C to +85C 14S0 MAX419MJD -55C to +125C 14 CERDIP Dice are specified at +25C, DC parameters only. 13 6LPXUVIW-ZEPXVIN/6GOPXVW/LOVXVW/90PXVNMAX406/MAX407/MAX409/MAX417-MAX419 1.2uA Max, Single/Dual/Quad, Single-Supply Op Amps Pin Configurations I TOP VIEW nu [7] 8 | BW mL] Ht W IN+ [3] ate 6 ] OUT OUTA [1] 14 ouTD V-L4 Fen NULL 1 e VV re] IC. INA- & 3] IND- INAt [3 12] IND DIP/SO IN- [2] MAXIM 7 | V+ \ aaanian 2) + wef] AX409 Fe) our TE axang = Li ~W ourala |? a | Vs vf FS) uu Ina [5 | 70] INC+ wwa- (2 | main [7] ours DIRISO Ins- [6 | rg] inc- INAt[3] maxdi7 [6] in ours [7 | rs] ourc v- [4] [5 | INBt DIP/SO DIP/SO Chip Topographies MAX407/MAX417 OUTA V+ OUTB MAX406/MAX409 nue 1 ain oe a rs INA- INB- ate 2 fe 0.069" INA+ WA 0.095" " (1.752mm) : t OUT (2.413mm) IN+ y- 4 INB+ < 0.071" \ (1.803mm) : v- 0.072" (1.829mm) >| Vy V+ TRANSISTOR COUNT: 98; SUBSTRATE CONNECTED TO V+. 14 TRANSISTOR COUNT: 148; SUBSTRATE CONNECTED TO V+. MAXIMA1.2uUA Max, Single/Dual/Quad, Single-Supply Op Amps Package Information INCHES MILLIMETERS ~| | D1 DIM Twin | Max |_MIN | MAX 1 oo oon A _ 0.200 _ 5.08 Al | 0.015 | 0.38 = a2 | 0.125 | 0.175 | 3.18 | 4.45 C A3 | 0.055 | 0.080 | 1.40 | 2.03 B [0.016 | 0.022 | 041 | 0.56 B1 | 0.050 | 0.065 | 1.27 | 1.65 Lee Cc | 0.008 | 0.012 | 0.20 | 0.30 E Db | 0348 | 0.390 | 884 | 9.91 Di | 0.005 | 0.035 | 013 | 0.89 | 54 _>! E [0300 | 0.325 | 762 | 8.26 - D , E1 | 0.240 [ 0.280 | 6.10 | 7.11 A A A3 e 9.100 BSC 2.54 BSC a2 ea | 0.300 BSC 7.62 BSC A Y 4 eg |_- 10400 | | 10.16 | u | o115 [0.150 | 292 | 3.81 | i ' a 0" 15 0" 15 a M 21-324A i iL Yl ; \ 8-PIN PLASTIC a Bt Cc DUAL-IN-LINE }<- | B eA PACKAGE eg _| pit |___INCHES MILLIMETERS MIN MAX MIN MAX 0.053 | 0.069 1.35 1.75 0.004 | 0.010 0.10 0.25 0.014 | 0.019 0.35 0.49 0.007 | 0.010 0.19 0.25 0.189 | 0.197 4.80 5.00 0.150 | 0.157 3.80 4.00 0.050 BSC 1.27 BSC 0.228 | 0.244 5.80 6.20 0.010 | 0.020 0.25 0.50 0.016 | 0.050 0.40 1.27 0 8 0 8 21-325A el-|[sizlo |mlololal2l> SMALL-OUTLINE IAB + : 4 8-PIN PLASTIC Cc L PACKAGE ! f MAXIMA 15 6LPXVIN-ZLPXVIN/GOPXVW/LOVXVW/90PXVNMAX406/MAX407/MAX409/MAX417-MAX419 1.2L A Max, Single/Dual/Quad, Single-Supply Op Amps Package Information (continued) INCHES MILLIMETERS | [D1 DIM Twin | MAX [MIN | MAX At | 0.015 - 0.38 ~ A2 | 0.125 | 0.150 | 3.18 | 3.81 A3 | 0.055 | 0.080 | 1.40 | 2.03 B | 0.016 | 0.022 | 041 | 0.56 B1 | 0.050 | 0.065 | 1.27 | 1.65 ee ee C_| 0.008 | 0.012 | 0.20 | 0.30 E D | 0.735 | 0.765 | 18.67 | 19.43 * , D1 | 0.050 | 0.080 | 1.27 | 2.03 D Lt 54 pe E | 0300 | 0325 | 7.62 | 8.26 + | 1 E1 | 0.240 | 0280 [ 6.10 | 7.11 j i | A3 e 0.100 BSC 2.54 BSC A2 ea | 0.300 BSC 7.62 BSC A 1 4 ea | 0.400 ~ 10.16 ' : L_[ 0.115 [ 0150 | 292 | 3.81 ' o 0 15 0 15 iq ny 21-3304 Lat ay " Y ee 14-PIN PLASTIC a > DUAL-IN-LINE Bt e_ PACKAGE B ea DIM INCHES MILLIMETERS MIN | MAX | MIN | MAX A_| 0.053 | 0.069 | 1.35 | 1.75 Ai | 0.004 [ 0.010 | 010 | 0.25 B [0.014 | oo19 | 035 | 049 _| 0.007 [ 0.010 [ o19 | 025 H D | 0.337 | 0344 | 55 | 675 E [0.150 | 0.157 | 3.80 | 4.00 e 0.050 BSC 1.27 BSC H_| 0.228 | 0.244 | 5.80 | 6.20 h_| 0.010 | 0.020 | 025 | 0.50 L_| 0.016 | 0.050 | 040 | 1.27 a | o 8 O 8 21-331A {~- -) >| 1 hx 45 | ~ I Loh ; | Cae zinn + 4 14-PIN PLASTIC | 6 le rR c SMALL-OUTLINE L PACKAGE 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. 16 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 1993 Maxim Integrated Products Printed USA MAXIMA is a registered trademark of Maxim Integrated Products.