Low IBIAS, +1.4V/800nA, Rail-to-Rail Op Amps with +1.2V Buffered Reference

Transcription

1 ; Rev 5; 11/9 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps General Description The single MAX436/MAX437 and dual MAX438/ MAX439 operational amplifiers operate from a single +1.4V to +3.6V (without reference) or +1.8V to +3.6V (with reference) supply and consume only 8nA of supply current per amplifier, and 1.1µA for the optional reference. The MAX436/MAX438 feature a common-mode input voltage range from V to -.4V at = 1.4V. The MAX437/MAX439 feature a 1.232V voltage reference capable of sourcing 1µA and sinking 2µA. The MAX436 MAX439s rail-to-rail outputs drive 5kΩ loads to within 25mV of the rails. Ultra-low supply current, low operating voltage, and rail-to-rail outputs make the MAX436 MAX439 ideal for use in single-cell lithium-ion (Li+), or two-cell NiCd/NiMH/alkaline battery-powered applications. The MAX436 is available in an SC7 package, the MAX437 in a SOT23 package, and the MAX438/ MAX439 in UCSP, µmax, and TDFN packages. Applications Battery-Powered/Solar-Powered Systems Portable Medical Instrumentation Pagers and Cell Phones Micropower Thermostats and Potentiostats Electrometer Amplifiers Remote Sensor Amplifiers Active Badges ph Meters Pin Configurations and Selector Guide appear at end of data sheet. µmax is a registered trademark and UCSP is a trademark of Maxim Integrated Products, Inc. Functional Diagram Features Ultra-Low 8nA per Amplifier Supply Current Ultra-Low 1.4V Supply Voltage Operation (1.8V for MAX437/MAX439) Rail-to-Rail Outputs Drive 5kΩ and 5pF Load 1.232V ±.5%, 12ppm/ C (max) Reference (MAX437/MAX439) No External Reference Bypass Capacitor Required No Phase Reversal for Overdriven Inputs Low 1.pA (typ) Input Bias Current Low 2μV Input Offset Voltage Unity-Gain Stable Available in Tiny UCSP, SC7, SOT23, TDFN, and μmax Packages Available in -4 C to +125 C Temperature Range (MAX436A/MAX438A) PART Ordering Information TEMP RANGE PIN- PACKAGE +Denotes a lead(pb)-free/rohs-compliant package. -Denotes a package containing lead. *EP = Exposed pad. Ordering Information continued at end of data sheet. TOP MARK MAX436EXK-T -4 C to +85 C 5 SC7 AFR MAX436AAXK+T -4 C to +125 C 5 SC7 ASN MAX437EUT-T -4 C to +85 C 6 SOT23 ABRX MAX438ETA-T -4 C to +85 C 8 TDFN-EP* AGO MAX438EUA -4 C to +85 C 8 µmax MAX438EBL-T -4 C to +85 C 9 UCSP AEG MAX438AAUA -4 C to +125 C 8 µmax Typical Operating Circuit MAX436 MAX439 OUTA MAX439 3V INA- OUTA INA- OUTB INA+ INB- INA+ REF MAX439 INB- SENSOR REF REF INB+ INB+ OUTB ADC THREE-ELECTRODE POTENTIOSTAT APPLICATION Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at

2 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 ABSOLUTE MAXIMUM RATINGS to...-.3v to +4.V INA+, INB+, INA-, INB-, IN+, IN-, OUTA, OUTB, OUT, REF...( -.3V) to ( +.3V) OUTA, OUTB, OUT, REF Shorted to or...continuous Maximum Continuous Power Dissipation (T A = +7 C) 5-Pin SC7 (derate 3.1mW/ C above +7 C)...247mW 6-Pin SOT23 (derate 8.7mW/ C above +7 C)...696mW 8-Pin µmax (derate 4.5mW/ C above +7 C)...362mW 8-Pin TDFN (derate 24.4mW/ C above +7 C) mW 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 9-Bump UCSP (derate 5.2mW/ C above +7 C)...412mW 1-Pin µmax (derate 5.6mW/ C above +7 C)...444mW 1-Pin TDFN (derate 24.4mW/ C above +7 C) mW Operating Temperature Range MAX43_E...-4 C to +85 C MAX43_A...-4 C to +125 C Junction Temperature C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1s)...+3 C ( = +3V, = V CM = V, V OUT_ = /2, R L to /2, C L = 15pF, T A = +25 C, unless otherwise specified.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS MAX436/MAX438, guaranteed by PSRR tests V Supply Voltage Range MAX437/MAX439, guaranteed by PSRR and line regulation tests MAX436 = 1.4V = 3.6V Supply Current I DD MAX437 = 1.8V = 3.6V MAX438 = 1.4V = 3.6V µa MAX439 = 1.8V = 3.6V OPERATIONAL AMPLIFIERS Input Offset Voltage V OS ±.2 ±2. mv Input Bias Current I B (Note 1) ±1. ±1 pa Input Offset Current I OS (Note 1) ±.3 ±2 pa Input Common-Mode Voltage Range Common-Mode Rejection Ratio Power-Supply Rejection Ratio V CM CMRR PSRR Guaranteed by CMRR test V D D = 1.4V ( M AX 436/M AX 438 onl y) -.4 = 1.8V -.3 = 3.3V -.2 = 1.4V, V CM ( -.4V) (MAX436/MAX438 only) 5 7 = 1.8V, V CM ( -.3V) 5 7 = 3.3V, V CM ( -.2V) V 3.6V (MAX436/MAX438 only) V 3.6V V db db 2

3 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps ELECTRICAL CHARACTERISTICS (continued) ( = +3V, = V CM = V, V OUT_ = /2, R L to /2, C L = 15pF, T A = +25 C, unless otherwise specified.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS R L = 1kΩ, 5mV V OUT ( - 5mV) 8 18 Large-Signal Voltage Gain A VOL R L = 5kΩ, 15mV V OUT ( - 15mV) R L = 1kΩ 2 5 Output Voltage Swing High - V OH RL = 5kΩ 25 5 R L = 1kΩ 2 5 Output Voltage Swing Low V OL - R L = 5kΩ 25 5 Output Short-Circuit Current I SCO To or ±13 ma Gain-Bandwidth Product GBW 4 khz Phase Margin θ M 9 Degrees Slew Rate SR 4 V/ms Power-On Time t ON (Note 3).25 ms Input Noise-Voltage Density e n f = 1kHz 5 nv/ Hz Capacitive-Load Stability C LOAD A VCL = 1V/V, no sustained oscillations 5 pf REFERENCE (MAX437/MAX439) Reference Voltage V REF V Line Regulation Load Regulation ΔV REF / Δ = +1.8V to +3.6V.3 %/V ΔV REF / I LOAD 1µA, sourcing.15 ΔI LOAD -2µA ILOAD, sinking.75 db mv mv %/µa MAX436 MAX439 Reference Output Voltage Noise e n.1hz to 1Hz 6 µv P-P Short to.25 Output Short-Circuit Current I SCR Short to 1.9 Capacitive-Load Stability Range C LOAD (Note 1) 25 pf ma ELECTRICAL CHARACTERISTICS ( = +3V, = V CM = V, V OUT_ = /2, R L to /2, C L = 15pF, T A = T MIN to T MAX, unless otherwise specified.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS MAX436/MAX438, guaranteed by PSRR test V Supply Voltage Range MAX437/MAX439, guaranteed by PSRR and line regulation tests MAX436 = 1.4V 1.7 = 3.6V 1.8 Supply Current I DD MAX436A = 1.4V 2. = 3.6V 2.1 µa MAX437 = 1.8V 3.1 = 3.6V 3.2 3

4 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 ELECTRICAL CHARACTERISTICS (continued) ( = +3V, = V CM = V, V OUT_ = /2, R L to /2, C L = 15pF, T A = T MIN to T MAX, unless otherwise specified.) (Note 2) Supply Current PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS OPERATIONAL AMPLIFIERS I DD MAX438 MAX438A MAX439 = 1.4V 2.9 = 3.6V 3.2 = 1.4V 3.4 = 3.6V 3.7 = 1.8V 5.2 = 3.6V 5.3 Input Offset Voltage V OS ±8 mv Input Offset Voltage Temperature Coefficient TCV OS ±1 µv/ C Input Bias Current I B ±1 pa Input Offset Current I OS ±2 pa Input Common-Mode Voltage Range V CM Guaranteed by CMRR test = 1.4V (MAX436/MAX438 only) = 1.8V.4 - = 3.3V.2 µa V Common-Mode Rejection Ratio CMRR = 1.4V, V CM ( -.5V) (MAX436/MAX438 only) 44 = 1.8V, V CM ( -.4V) 5 db = 3.3V, V CM ( -.3V) 52 Power-Supply Rejection Ratio PSRR 1.4V 3.6V (MAX436/MAX438 only) 6 db 1.8V 3.6V 6 Large-Signal Voltage Gain A VOL R L = 1kΩ, 5mV V OUT ( - 5mV) 75 R L = 5kΩ, 15mV V OUT ( - 15mV) 73 db Output Voltage Swing High - V OH R L = 1kΩ 1 RL = 5kΩ 1 Output Voltage Swing Low V OL - R L = 1kΩ 1 R L = 5kΩ 1 mv mv REFERENCE (MAX437/MAX439) MAX437EUT-T, MAX439ETB, Reference Voltage Temperature TCV REF (Note 1) MAX439EUB ppm/ C Coefficient MAX439EBL-T 35 2 ΔV Line Regulation REF / = 1.8V to 3.6V.6 %/V Δ ΔV I LOAD 1µA, sourcing.3 Load Regulation REF / %/µa ΔI LOAD -2µA ILOAD, sinking.15 Capacitive-Load Stability Range C LOAD (Note 1) 25 pf Note 1: Guaranteed by design. Note 2: All devices are production tested at T A = +25 C. All temperature limits are guaranteed by design. Note 3: Output settles within 1% of final value. 4

5 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Typical Operating Characteristics ( = 3V, = V CM = V, R L to /2, T A = +25 C, unless otherwise noted.) SUPPLY CURRENT (μa) SUPPLY CURRENT (μa) MAX436 SUPPLY CURRENT vs. SUPPLY VOLTAGE AND TEMPERATURE T A = +85 C T A = -4 C T A = +25 C SUPPLY VOLTAGE (V) MAX439 SUPPLY CURRENT vs. SUPPLY VOLTAGE AND TEMPERATURE T A = +85 C T A = -4 C T A = +25 C MAX436 toc1 MAX436 toc4 SUPPLY CURRENT (μa) OFFSET VOLTAGE (mv) MAX437 SUPPLY CURRENT vs. SUPPLY VOLTAGE AND TEMPERATURE T A = +85 C T A = -4 C T A = +25 C SUPPLY VOLTAGE (V) OFFSET VOLTAGE vs. COMMON-MODE VOLTAGE = 1.8V = 3.V = 1.4V MAX436 toc2 MAX436 toc5 OFFSET VOLTAGE (mv) SUPPLY CURRENT (μa) MAX438 SUPPLY CURRENT vs. SUPPLY VOLTAGE AND TEMPERATURE T A = +85 C T A = -4 C T A = +25 C SUPPLY VOLTAGE (V) OFFSET VOLTAGE vs. TEMPERATURE MAX436 toc3 MAX436 toc6 MAX436 MAX SUPPLY VOLTAGE (V) COMMON-MODE VOLTAGE (V) TEMPERATURE ( C) INPUT BIAS CURRENT (pa) INPUT BIAS CURRENT vs. TEMPERATURE V CM = 3V V CM = V TEMPERATURE ( C) MAX436 toc7 INPUT BIAS CURRENT (pa) INPUT BIAS CURRENT vs. COMMON-MODE VOLTAGE T A = +85 C T A = +25 C COMMON-MODE VOLTAGE (V) MAX436 toc8 PSRR (db) OP AMP POWER-SUPPLY REJECTION RATIO vs. FREQUENCY A V = 1V/V k 1k FREQUENCY (Hz) MAX436 toc9 5

6 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 Typical Operating Characteristics (continued) ( = 3V, = V CM = V, R L to /2, T A = +25 C, unless otherwise noted.) VDD - VOH (mv) OUTPUT VOLTAGE SWING HIGH vs. TEMPERATURE R L = 5kΩ R L = 1kΩ TEMPERATURE ( C) MAX436 toc1 VOL - VSS (mv) OUTPUT VOLTAGE SWING LOW vs. TEMPERATURE R L = 5kΩ R L = 1kΩ TEMPERATURE ( C) MAX436 toc11 AV (db) A V vs. OUTPUT SWING LOW V OL (mv) R L = 5kΩ R L = 1kΩ MAX436 toc12 AV (db) A V vs. OUTPUT SWING HIGH R L = 5kΩ R L = 1kΩ MAX436 toc13 AVOL (db) A V vs. TEMPERATURE R L = 5kΩ R L = 1kΩ MAX436 toc14 CROSSTALK (db) MAX438/MAX439 A V = 1V/V CROSSTALK vs. FREQUENCY R L = 1kΩ R L = 5kΩ MAX436 toc V OH (mv) TEMPERATURE ( C) k 1k 1k FREQUENCY (Hz) THD+N (%) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 1 A V = 1V/V V IN_ = / V OUT = 2.5V P-P R L = 1kΩ TO FREQUENCY (khz) V OUT = 2.5V P-P R L = 5kΩ TO MAX436 toc16 CAPACITIVE LOAD (pf) 1, 1, 1 OP AMP STABILITY vs. CAPACITIVE AND RESISTIVE LOADS STABLE REGION UNSTABLE REGION 1 1k 1k 1M RESISTIVE LOAD (Ω) R L TO 6 MAX436 toc17 SINK CURRENT (ma) V ID = -1mV OP AMP SINK CURRENT vs. OUTPUT VOLTAGE = 1.8V = 3.V V OUT_ (V) MAX436 toc18

7 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Typical Operating Characteristics (continued) ( = 3V, = V CM = V, R L to /2, T A = +25 C, unless otherwise noted.) SOURCE CURRENT (ma) OP AMP SOURCE CURRENT vs. OUTPUT VOLTAGE = 3.V = 1.8V V OUT_ (V) V ID = +1mV MAX436 toc19 INPUT VOLTAGE NOISE (nv/ Hz) INPUT VOLTAGE NOISE DENSITY vs. FREQUENCY k 1k FREQUENCY (Hz) MAX436 toc2 MAX436 MAX439 OP AMP SMALL-SIGNAL TRANSIENT RESPONSE OP AMP SMALL-SIGNAL TRANSIENT RESPONSE 2.55V A V = 1V/V C L = 12pF TO R L = 1MΩ TO MAX436 toc21 V IN V MAX436 toc22 A V = 1V/V C L = 25pF TO R L = 1MΩ TO V IN V 2.45V 2.55V 2.55V V OUT_ V OUT_ 2.45V 2.45V 4μs/div OP AMP LARGE-SIGNAL TRANSIENT RESPONSE OP AMP TURN-ON TRANSIENT RESPONSE 2.5V 1.5V MAX436 toc23 A V = 1V/V C L = 12pF TO R L = 1MΩ TO V IN + A V = 1V/V C L = 12pF TO GND R L = 1MΩ TO GND V IN + = / 2 MAX436 toc24 3.V V V OUT_ 5mV/div V OUT_ 5mV/div 1μs/div 1μs/div 7

8 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 Typical Operating Characteristics (continued) ( = 3V, = V CM = V, R L to /2, T A = +25 C, unless otherwise noted.) GAIN (db) GAIN AND PHASE vs. FREQUENCY MAX436 toc GAIN PHASE A -3 V = 1V/V V IN_ = 1mV P-P k 1k 1k FREQUENCY (Hz) PHASE (DEGREES) GAIN (db) A V = 1 V OUT_ = 1V P-P C L = 12pF LARGE-SIGNAL GAIN vs. FREQUENCY R L = 5kΩ 1 1k 1k 1k FREQUENCY (Hz) R L = 1MΩ R L = 1kΩ MAX436 toc26 VREF (V) REFERENCE VOLTAGE vs. TEMPERATURE MAX437/MAX439 MAX436 toc27 VREF (V) REFERENCE VOLTAGE CHANGE vs. TIME MAX437 MAX439 MAX436 toc28 NORMALIZED VREF REFERENCE VOLTAGE CHANGE vs. LOAD CURRENT T A = +85 C T A = +25 C T A = -4 C MAX436 toc TEMPERATURE ( C) TIME (HR) LOAD CURRENT (μa) NORMALIZED VREF REFERENCE VOLTAGE CHANGE vs. SUPPLY VOLTAGE T A = -4 C MAX436 toc3 3.6V 1.8V V REFERENCE LINE-TRANSIENT RESPONSE MAX436 toc T A = +25 C T A = +85 C V REF AC-COUPLED 5mV/div (V) 1ms/div 8

9 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Typical Operating Characteristics (continued) ( = 3V, = V CM = V, R L to /2, T A = +25 C, unless otherwise noted.) I REF 2μA V REF 5mV/div REFERENCE LOAD-TRANSIENT RESPONSE (SINKING CURRENT) 2.5ms/div MAX436 toc32 I REF 2μA V REF 5mV/div REFERENCE LOAD-TRANSIENT RESPONSE (SINKING CURRENT) 2.5ms/div MAX436 toc33 MAX436 MAX439 REFERENCE LOAD-TRANSIENT RESPONSE (SOURCING CURRENT) MAX436 toc34 REFERENCE LOAD-TRANSIENT RESPONSE (SOURCING CURRENT) MAX436 toc35 1μA 1μA I REF I REF V REF 5mV/div 1ms/div V REF 5mV/div 1ms/div REFERENCE TURN-ON TRANSIENT RESPONSE MAX436 toc36.1hz TO 1Hz REFERENCE NOISE MAX436 toc37 3V V V REF V 1ms/div 1s/div 2μV/div 9

10 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 PIN MAX438/ MAX436/ MAX439 MAX438A MAX436A MAX437 µmax*/tdfn UCSP µmax/tdf UCSP NAME FUNCTION 1 3 IN+ Noninverting Amplifier Input A2 5 A2 Negative Power-Supply Voltage 3 4 IN- Inverting Amplifier Input 4 1 OUT Amplifier Output C2 1 C2 Positive Power-Supply Voltage 5 6 B2 REF Reference Voltage Output 1 C1 1 C1 OUTA Amplifier Output (Channel A) 2 B1 2 B1 INA- Inverting Amplifier Input (Channel A) 3 A1 3 A1 INA+ Noninverting Amplifier Input (Channel A) 5 A3 7 A3 INB+ Noninverting Amplifier Input (Channel B) 6 B3 8 B3 INB- Inverting Amplifier Input (Channel B) 7 C3 9 C3 OUTB Amplifier Output (Channel B) B2 4 N.C. No Connection. Not internally connected. *Both MAX438/MAX438A available in µmax package only. EP (TDFN only) Exposed Paddle. Solder EP to or leave unconnected (TDFN packages only). Detailed Description The MAX436 MAX439 consume an ultra-low supply current and have rail-to-rail output stages specifically designed for low-voltage operation. The input commonmode voltage range extends from -.4V to, although full rail-to-rail input range is possible with degraded performance when operating from a supply voltage above 3.V. The input offset voltage is typically 2µV. Low-operating supply voltage, low supply current, and rail-to-rail outputs make the MAX436 MAX439 an excellent choice for precision or general-purpose lowvoltage, battery-powered systems. Rail-to-Rail Outputs The MAX436 MAX439 output stages can drive a 5kΩ load and still swing to within 4mV of the rails. Figure 1 shows the output voltage swing of the MAX436 MAX439 configured as a unity-gain buffer, powered from a single 2.4V supply. The output for this setup typically swings from 5mV to - 5mV with a 1kΩ load. V IN_+ 1.5V V OUT+ 2ms/div 1V/div A V = 1V/V Figure 1. Rail-to-Rail Input/Output Voltage Range 1.5V 1

11 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Applications Information Power-Supply Considerations The MAX436 MAX439 operate from a single 1.4V (MAX436/MAX438) or 1.8V (MAX437/MAX439) to 3.6V supply. A high amplifier power-supply rejection ratio of 82dB and the excellent reference line regulation allow the devices to be powered directly from a decaying battery voltage, simplifying design and extending battery life. The MAX436 MAX439 are ideally suited for low-voltage battery-powered systems. The Typical Operating Characteristics show the changes in supply current and reference output as a function of supply voltage. Power-Up Settling Time The MAX436 MAX439 typically require.25ms to power-up. During this startup time, the output is indeterminate. The application circuit should allow for this initial delay. See the Typical Operating Characteristics for amplifier and reference settling time curves. Driving Capacitive Loads: Op Amps The MAX436 MAX439 amplifier(s) require no output capacitor for stability, and are unity-gain stable for loads up to 5pF. Applications that require greater capacitive-drive capability should use an isolation resistor between the output and the capacitive load (Figure 2). Note that this solution reduces the gain and output voltage swing because R ISO forms a voltagedivider with the load resistor. Crossover Distortion The MAX436 MAX439 output stages are capable of sourcing and sinking currents with orders of magnitude greater than the stages quiescent current, which is less than 1µA. This ability to drive heavy loads with such a small quiescent current introduces crossover MAX438 R ISO R L R L A V = = 1 R L + R ISO CL INPUT OUTPUT V THR V THF Figure 3. Hysteresis distortion as the output stage passes between sinking and sourcing. In the crossover regions, the output impedance of the MAX436 MAX439 increases substantially, thereby changing the load-driving characteristics. The distortion can be greatly reduced by increasing the load resistance. For applications where low load resistance is required, bias the load such that the output current is always in one direction, to avoid crossover distortion. Reference Bypassing The MAX437/MAX439 reference requires no external capacitors. Using the MAX436 MAX439 as a Comparator Although optimized for use as an operational amplifier, the MAX436 MAX439 can be used as a rail-to-rail I/O comparator (Figures 3, 4). External hysteresis can be used to minimize the risk of output oscillation. The positive feedback circuit, shown in Figure 4, causes the input threshold to change when the output voltage changes state. Battery Monitoring Using the MAX437/MAX439 and Hysteresis The internal reference and low operating voltage of the MAX437/MAX439 make the devices ideal for batterymonitoring applications. Hysteresis can be set using resistors as shown in Figure 4, and the following design procedure: 1) Choose R3. The input bias current of IN_+ is under 1pA over temperature, so a current through R3 around 1nA maintains accuracy. The current through R3 at the trip point is V REF / R3, or 1nA for R3 = 12MΩ. 1MΩ is a good practical value. 2) Choose the hysteresis voltage (V HB ), the voltage between the upper and lower thresholds. In this example, choose V HB = 5mV (see Figure 3). V HB V OH V OL MAX436 MAX439 Figure 2. Using a Resistor to Isolate a Capacitive Load from the Op Amp 11

12 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 3) Calculate R1: 4) Choose the threshold voltage for V IN rising (V THR ). In this example, choose V THR = 2.V. 5) Calculate R2: R2 = = = 6) Verify the threshold voltages with these formulas: V IN rising: VTHR = VREF R1 + + R1 R2 R3 V IN falling: VTHR 1 1 VREF R1 R1 R V V 21kΩ 21kΩ 1MΩ 325kΩ VTHF R1 = R3 VHB VDD = 1MΩ 5. V 24. V = 21kΩ 1 = VTHR R1 VDD R3 In this application, the MAX436 MAX439 supply current will vary, depending on the output state of the comparator. Power Supplies and Layout The MAX436 MAX439 operate from a single 1.4V (MAX436/MAX438) or 1.8V (MAX437/MAX439) to 3.6V power supply. Bypass with a.1µf capacitor to ground to minimize noise. Good layout techniques optimize performance by decreasing the amount of stray capacitance to the op amp s inputs and outputs. To decrease stray capacitance, minimize trace lengths by placing external components close to the device. The exposed paddle (EP) on the TDFN packages of the MAX438 and MAX439 is internally connected to the device substrate,. Connect the exposed paddle to or leave EP unconnected. Running traces below the exposed paddle is not recommended. V BATT R1 R2 IN+ V REF Chip Information MAX436 TRANSISTOR COUNT: 49 MAX437 TRANSISTOR COUNT: 119 MAX438 TRANSISTOR COUNT: 146 MAX439 TRANSISTOR COUNT: 146 PROCESS: BiCMOS REF Figure 4. Battery Monitoring R3 MAX437 OUT V BGOOD Selector Guide PART NO. OF AMPLIFIERS REFERENCE MAX436 1 MAX437 1 MAX438 2 MAX439 2 Ordering Information (continued) PART TEMP RANGE IN- PIN- PACKAGE TOP MARK MAX439EBL-T -4 C to +85 C 9 UCSP AEH MAX439ETB-T -4 C to +85 C 1 TDFN-EP* AAN MAX439EUB -4 C to +85 C 1 µmax -Denotes a package containing lead. *EP = Exposed pad. 12

13 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps TOP VIEW IN+ 1 2 IN- 3 OUTA INA- 1 2 INA+ 3 MAX436 MAX436A SC7 MAX438 MAX438A 5 4 OUT OUTB INB- Pin Configurations OUT IN OUTA 1 INA- 2 INA+ 3 MAX REF 4 IN- SOT OUTB MAX438 6 INB- MAX436 MAX INB+ 4 5 INB+ μmax 3mm x 3mm x.8mm TDFN TDFN EXPOSED PAD CONNECTED TO. OUTA 1 1 OUTA 1 1 INA- 2 9 OUTB INA- 2 9 OUTB INA+ 3 MAX439 8 INB- INA+ 3 MAX439 8 INB- N.C. 4 7 INB+ N.C. 4 7 INB+ 5 6 REF 5 6 REF μmax 3mm x 3mm x.8mm TDFN TDFN EXPOSED PAD CONNECTED TO. (BUMP SIDE DOWN) A INA+ MAX438 INB+ (BUMP SIDE DOWN) A INA+ MAX439 INB+ B INA- N.C. B INA- REF INB- INB- C OUTA OUTB C OUTA OUTB UCSP UCSP 13

14 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 Package Information For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. SC7, 5L.EPS PACKAGE OUTLINE, 5L SC E 1 14

15 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 6LSOT.EPS MAX436 MAX439 PACKAGE OUTLINE, SOT 6L BODY I 2 15

16 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE OUTLINE, SOT 6L BODY I 2 16

17 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. α MAX436 MAX439 α 17

18 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 18

19 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. COMMON DIMENSIONS SYMBOL MIN. MAX. A.7.8 D E A1..5 L.2.4 k.25 MIN. A2.2 REF. PACKAGE VARIATIONS PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e T ±.1 2.3±.1.95 BSC MO229 / WEEA.4± REF T ±.1 2.3±.1.65 BSC MO229 / WEEC.3± REF T ±.1 2.3±.1.65 BSC MO229 / WEEC.3± REF T ±.1 2.3±.1.5 BSC MO229 / WEED-3.25±.5 2. REF T133MK ±.1 2.3±.1.5 BSC MO229 / WEED-3.25±.5 2. REF T ±.1 2.3±.1.5 BSC MO229 / WEED-3.25±.5 2. REF T ±.1 2.3±.1.4 BSC ± REF T ±.1 2.3±.1.4 BSC ± REF T1433-3F ±.1 2.3±.1.4 BSC ± REF MAX436 MAX439 19

20 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 1LUMAX.EPS α α 2

21 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps Package Information (continued) For the latest package outline information and land patterns, go to Note that a +, #, or - in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 9LUCSP, 3x3.EPS MAX436 MAX439 PACKAGE OUTLINE, 3x3 UCSP L 1 21

22 Low IBIAS, +1.4V/8nA, Rail-to-Rail Op Amps MAX436 MAX439 REVISION NUMBER REVISION DATE DESCRIPTION Revision History PAGES CHANGED 5 11/9 Updated TOC 2 7 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. 22 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.