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19-5228; Rev 0; 6/10
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
General Description
The MAX9636/MAX9637/MAX9638 are single-supply, CMOS input op amps featuring wide bandwidth at low quiescent current, making them suitable for a broad range of battery-powered applications such as portable medical instruments, portable media players, and smoke detectors. A combination of extremely low input bias currents, low input current noise and low input voltage noise allows interface to high-impedance sources such as photodiode and piezoelectric sensors. These devices are also ideal for general-purpose signal processing functions such as filtering and amplification in a broad range of portable, battery-powered applications. The ICs feature a maximized ratio of gain bandwidth (GBW) to supply current. The devices operate from a single 2.1V to 5.5V supply at a typical quiescent supply current of 36A. For additional power conservation, the MAX9636 and MAX9638 offer a low-power shutdown mode that reduces supply current to 1A and places the amplifiers' outputs into a high-impedance state. The ICs are specified over the automotive operating temperature range (-40C to +125C). The single is offered in a space-saving, 6-pin SC70 package, while the dual is offered in tiny, 8-pin SC70 and 10-pin UTQFN packages.
Features
S Low Input Voltage-Noise Density: 38nV/Hz S Low Input Current-Noise Density: 50fA/Hz S Ultra-Low 0.1pA Bias Current S Low 36A Quiescent Current S 1A Quiescent Current in Shutdown S Wide 1.5MHz Bandwidth S Single-Supply Operation VDD = 2.1V to 5.5V S Available in Tiny 6-Pin SC70, 8-Pin SC70, and 10-Pin UTQFN Packages S -40C to +125C Operating Temperature Range
Ordering Information
PART MAX9636AXT+ MAX9637AXA+* MAX9638AVB+* TEMP RANGE -40NC to +125NC -40NC to +125NC -40NC to +125NC PIN-PACKAGE 6 SC70 8 SC70 10 UTQFN
+Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *Future product--contact factory for availability.
Applications
Portable Medical Instruments Piezoelectric Transducer Amplifiers Smoke Detectors Battery-Powered Devices General-Purpose Signal Conditioning Notebooks Portable Media Players
_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
ABSOLUTE MAXIMUM RATINGS
VDD, SHDN to VSS ..................................................-0.3V to +6V IN+, IN-, OUT ....................................GND - 0.3V to VDD + 0.3V Continuous Input Current (any pins) ............................... Q20mA Output Short Circuit to VDD or VSS Duration .......................... 5s Thermal Limits (Note 1) Multiple Layer PCB Continuous Power Dissipation (TA = +70NC) 6-Pin SC70 (derate 3.1mW/C above +70NC) ............245mW BJA .......................................................................326.5C/W BJC .........................................................................115C/W 8-Pin SC70 (derate 3.1mW/NC above +70NC) .............245mW BJA .........................................................................326C/W BJC .........................................................................115NC/W 10-Pin UTQFN (derate 7mW/NC above +70NC)........558.7mW BJA ......................................................................143.2NC/W BJC .........................................................................20.1NC/W Operating Temperature Range ........................ -40NC to +125NC Junction Temperature ....................................................+150NC Lead Temperature (soldering 10s) .................................+300NC Soldering Temperature (reflow) ......................................+260NC
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
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
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VCM = VDD/2, RL = 10kI to VDD/2, SHDN = VDD, TA = -40NC to +125NC. Typical values are at TA = +25NC, unless otherwise noted.) (Note 2) PARAMETER DC CHARACTERISTICS Input Voltage Range Input Offset Voltage Input Offset Voltage Drift Input Bias Current (Note 3) VIN+, VINVOS TCVOS IB Guaranteed by CMRR TA = +25NC TA = -40NC to +125NC (Note 3) TA = +25NC TA = -40NC to +85NC TA = -40NC to +125NC Common-Mode Rejection Ratio CMRR VSS < VCM < (VDD - 1.4V) TA = +25NC TA = -40NC to +125NC 72 68 58 104 100 77 124 120 10 40 RL = 10kI RL = 600I RL = 10kI RL = 600I 0.014 0.044 0.019 0.057 0.01 0.03 0.08 0.04 0.1 1 dB mA V V FA 86 dB 0.1 VSS 0.1 0.01 VDD + 0.1 2.2 3.5 7 0.8 50 800 pA V mV FV/NC SYMBOL CONDITIONS MIN TYP MAX UNITS
(VSS - 0.1V) < VCM < (VDD + 0.1V) Open-Loop Gain Output Short-Circuit Current Output Voltage Low Output Voltage High Output Leakage in Shutdown (MAX9636, MAX9638 Only) AOL ISC
VOL
VOUT = 0.25V from rails VOUT = 0.4V from rails, RL = 600I Short to VDD Short to VSS VOUT VDD - VOUT
VOH
SHDN = VSS, VOUT = 0V to VDD
2
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VCM = VDD/2, RL = 10kI to VDD/2, SHDN = VDD, TA = -40NC to +125NC. Typical values are at TA = +25NC, unless otherwise noted.) (Note 2) PARAMETER AC CHARACTERISTICS Input Voltage Noise Density Input Voltage Noise Input Current Noise Density Input Capacitance Gain Bandwidth Slew Rate Capacitive Loading Distortion Settling Time POWER-SUPPLY CHARACTERISTICS Power-Supply Range Power-Supply Rejection Ratio Quiescent Current Shutdown Supply Current (MAX9636, MAX9638 Only) Shutdown Input Low (MAX9636, MAX9638 Only) Shutdown Input High (MAX9636, MAX9638 Only) Shutdown Input Bias Current (MAX9636, MAX9638 Only) Turn-On Time (MAX9636, MAX9638 Only) Power-Up Time VDD PSRR IDD IDD_SHDN VIL VIH ISHDN tON tUP Guaranteed by PSRR VIN+ = VIN- = VSS, VDD - VSS = 2.1V to 5.5V Per amplifier VSHDN P VIL Over the power-supply range Over the power-supply range (Note 3) VSHDN = 0V to 3V VDD = 0V to 3.3V 1.4 1 60 18 100 TA = +25NC TA = -40NC to +125NC TA = +25NC TA = -40NC to +125NC 2.1 72 69 36 55 60 1 0.5 100 5.5 V dB IN CIN GBW SR CLOAD THD No sustained oscillations f = 10kHz, VO = 2VP-P, AV = 1V/V f = 10kHz, VO = 2VP-P, AV = 1V/V, VDD = 5.5V To 0.1%, VOUT = 2V step, AV = 1V/V eN f = 1kHz 0.1Hz f 10Hz f = 1kHz 38 5 50 2 1.5 0.9 300 -68 -74 11.5 dB Fs nV/Hz FVP-P fA/Hz pF MHz V/Fs pF SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX9636/MAX9637/MAX9638
FA FA V V nA Fs Fs
Note 2: All devices are 100% production tested at TA = +25NC. Temperature limits are guaranteed by design. Note 3: Parameter is guaranteed by design.
3
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
Typical Operating Characteristics
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VCM = VDD/2, RL = 10kI to VDD/2, SHDN = VDD, TA = -40NC to +125NC. Typical values are at TA = +25NC, unless otherwise noted.)
OFFSET VOLTAGE HISTOGRAM
MAX9636 toc01
OFFSET VOLTAGE THERMAL COEFFICIENT HYSTOGRAM
MAX9636 toc02
INPUT OFFSET VOLTAGE vs. COMMON-MODE VOLTAGE
450 400 OFFSET VOLTAGE (V) 350 300 250 200 150 100 50 0 TA = 0C TA = +25C TA = +85C TA = +125C -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 COMMON-MODE VOLTAGE (V) TA = -40C
MAX9636 toc03
20 18 PERCENT OCCURANCE (%) 16 14 12 10 8 6 4 2 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 OFFSET VOLTAGE (mV)
40 35 PERCENT OCCURANCE (%) 30 25 20 15 10 5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
500
OFFSET VOLTAGE THERMAL COEFFICIENT (V/C)
INPUT OFFSET VOLTAGE vs. SUPPLY VOLTAGE VCM = VDD/2
MAX9636 toc04
INPUT BIAS CURRENT vs. COMMON-MODE VOLTAGE
MAX9636 toc05
OUTPUT VOLTAGE LOW vs. SINK CURRENT VDD = 2.1V
450 OUTPUT VOLTAGE LOW (mV) 400 350 300 250 200 150 100 50 0 0 2 TA = +25C TA = 0C TA = -40C 4 6 8 10 12 SINK CURRENT (mA) TA = +85C TA = +125C
MAX9636 toc06
400 380 360 OFFSET VOLTAGE (V) 340 320 300 280 260 240 220 200 0 1 2 3 4 5 TA = +85C TA = +125C TA = 0C TA = +25C TA = -40C
600 400 INPUT BIAS CURRENT (pA) 200 0 -200 -400 TA = +125C -600 TA = +85C TA = +25C
500
6
-0.5
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 COMMON-MODE VOLTAGE (V)
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE LOW vs. SINK CURRENT VDD = 3.3V
MAX9636 toc07
MAX9636 toc08
TA = +125C OUTPUT VOLTAGE LOW (mV) 200 150 100 50 0 0 2 4 6 8 10 TA = 0C TA = -40C TA = +85C TA = +25C
TA = +125C TA = +85C
300 OUTPUT VOLTAGE LOW (mV) 250 200 150 100 50 0 TA = 0C TA = -40C 0 5 10 15 20
OUTPUT VOLTAGE HIGH (mV)
1000 800 600 400 200 0 TA = -40C 0 1 2 3 4 5 6 7 8 9 TA = +125C
TA = +25C
TA = +85C
TA = +25C TA = 0C
12
25
10
SINK CURRENT (mA)
SINK CURRENT (mA)
SOURCE CURRENT (mA)
4
MAX9636 toc09
250
350
OUTPUT VOLTAGE LOW vs. SINK CURRENT VDD = 5V
OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT VDD = 2.1V, VOH = VDD - VOUT
1200
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
Typical Operating Characteristics (continued)
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VCM = VDD/2, RL = 10kI to VDD/2, SHDN = VDD, TA = -40NC to +125NC. Typical values are at TA = +25NC, unless otherwise noted.)
OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT VDD = 3.3V, VOH = VDD - VOUT
MAX9636 toc10
MAX9636/MAX9637/MAX9638
OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT VDD = 5V, VOH = VDD - VOUT
MAX9636 toc11
SUPPLY CURRENT vs. SUPPLY VOLTAGE
43 41 SUPPLY CURRENT (A) 39 37 35 33 31 29 27 25 2.0 TA = -40C 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 TA = 0C TA = +25C TA = +125C TA = +85C
MAX9636 toc12
2000 1800 OUTPUT VOLTAGE HIGH (mV) 1600 1400 1200 1000 800 600 400 200 0 0 5 10 15 TA = -40C 20 25 30 TA = +125C TA = +85C TA = +25C TA = 0C
1200 1000 800 600 400 200 TA = 0C 0 TA = -40C TA = +125C TA = +85C TA = +25C
45
OUTPUT VOLTAGE HIGH (mV)
35
0
5
10 15 20 25 30 35 40 45 50 SOURCE CURRENT (mA)
SOURCE CURRENT (mA)
SUPPLY VOLTAGE (V)
OPEN-LOOP GAIN AND PHASE vs. FREQUENCY
140 120 100 OPEN-LOOP GAIN (dB) 80 60 40 20 0 -20 -40 -60 0.001 0.01 0.1 1 10 100 PHASE GAIN
MAX9636 toc13
COMMON-MODE REJECTION RATIO vs. FREQUENCY
MAX9636 toc14
DC COMMON-MODE REJECTION RATIO vs. TEMPERATURE
DC COMMON-MODE REJECTION RATIO (dB) 98 96 94 92 90 88 86 84 82 80 -50 -25 0 25 50 75 100 125
MAX9636 toc15
180 135 90 PHASE (DEG) 45 0 -45 -90 -135 COMMON-MODE REJECTION RATIO (dB)
100 90 80 70 60 50 40 30 20 10 0 0.01 0.1 1 10 100
100
-180 1000 10,000
1000 10,000
FREQUENCY (kHz)
FREQUENCY (kHz)
TEMPERATURE (C)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX9636 toc16
DC POWER-SUPPLY REJECTION RATIO vs. TEMPERATURE
DC POWER-SUPPLY REJECTION RATIO (dB) 98 96 94 92 90 88 86 84 82 80
0
MAX9636 toc17
INPUT VOLTAGE NOISE vs. FREQUENCY
MAX9636 toc18
100 POWER-SUPPLY REJECTION RATIO (dB) 90 80 70 60 50 40 30 20 10 0 0.01 0.1 1 10 100
100
300 INPUT VOLTAGE NOISE (nV/Hz) 250 200 150 100 50
1000 10,000
-50
-25
0
25
50
75
100
125
0.01
0.1
1 FREQUENCY (kHz)
10
100
FREQUENCY (kHz)
TEMPERATURE (C)
5
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
Typical Operating Characteristics (continued)
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VCM = VDD/2, RL = 10kI to VDD/2, SHDN = VDD, TA = -40NC to +125NC. Typical values are at TA = +25NC, unless otherwise noted.)
INPUT CURRENT NOISE vs. FREQUENCY
120 100 80 60 40 20 0 0.01 0.1 1 FREQUENCY (kHz) 10 100
MAX9636 toc19
0.1Hz TO 10Hz VOLTAGE vs. TIME
MAX9636 toc20
140 INPUT CURRENT NOISE (fA/Hz)
5VP-P NOISE
2V/div
10s/div
TOTAL HARMONIC DISTORTION vs. INPUT VOLTAGE AMPLITUDE VDD = 5.5V, AO = 1V/V
TOTAL HARMONIC DISTORTION (dB) TOTAL HARMONIC DISTORTION (dB) -10 -20 -30 -40 -50 -60 -70 -80 -90 0 1 2 3 4 5 6 INPUT VOLTAGE AMPLITUDE (VP-P)
MAX9636 toc21
TOTAL HARMONIC DISTORTION vs. FREQUENCY VDD = 5.5V, AO = 1V/V, VOUT = 2VP-P, RL = 10kI to VDD/2
MAX9636 toc22
0
0 -20 -40 -60 -80 -100 -120 0.01 0.1 1 FREQUENCY (kHz) 10
100
SMALL-SIGNAL TRANSIENT RESPONSE
MAX9636 toc23
LARGE-SIGNAL TRANSIENT RESPONSE
MAX9636 toc24
VIN 100mV/div
VIN 2V/div
VOUT 20mV/div VOUT 500mV/div 1s/div 2s/div
6
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
Typical Operating Characteristics (continued)
(VDD = 3.3V, VSS = 0V, VIN+ = VIN- = VCM = VDD/2, RL = 10kI to VDD/2, SHDN = VDD, TA = -40NC to +125NC. Typical values are at TA = +25NC, unless otherwise noted.)
PERCENT OVERSHOOT vs. RESISTIVE LOAD
MAX9636 toc25
MAX9636/MAX9637/MAX9638
STABILITY vs. CAPACITIVE AND RESISTIVE LOAD RISO IN SERIES WITH CLOAD
90 80 RESISTIVE LOAD (I) 70 60 50 40 30 20 10 0 UNSTABLE STABLE
MAX9636 toc26
30 25 PERCENT OVERSHOOT (%) CLOAD = 300pF 20 15 10 5 0 -5 10 100 1000 CLOAD = 50pF
100
CLOAD = 100pF
10,000 100,000 1,000,000
100
1000
10,000
100,000
RESISTIVE LOAD (I)
CAPACITIVE LOAD (pF)
STABILITY vs. CAPACITIVE AND RESISTIVE LOAD RP IN PARALLEL WITH CL
90 80 RESISTIVE LOAD (kI) 70 60 50 40 30 20 10 0 100 1000 CAPACITIVE LOAD (pF) 10,000 VOUT 500mV/div STABLE UNSTABLE
MAX9636 toc27
POWER-UP TIME
MAX9636 toc28
100
VDD 2V/div
40s/div
TURN-ON TIME
MAX9636 toc29
SHDN 2V/div
VOUT 500mV/div
100s/div
7
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
Pin Configurations
TOP VIEW
IN+ 1
+
MAX9636
6
VDD
OUTA INAINA+
1 2 3
+
MAX9637
8 7 6 5
VDD OUTB INBINB+
VSS 2
5
SHDN
IN- 3
4
OUT
VSS 4
SC70
SHDNB SHDNA 7 OUTA INAOUTB 8 9 10 6 5 VSS INA+ INB-
SC70
MAX9638
4 3
+
1 VDD
2 INB+
UTQFN
Pin Description
MAX9636 (6 SC70) 1 -- -- 2 3 -- -- 4 -- -- -- -- 5 6 MAX9637 (8 SC70) -- 3 5 4 -- 2 6 -- 1 7 -- -- -- 8 MAX9638 (10 UTQFN) -- 4 2 5 -- 9 3 -- 8 10 6 7 -- 1 NAME IN+ INA+ INB+ VSS ININAINBOUT OUTA OUTB SHDNA SHDNB SHDN VDD Positive Input Positive Input A Positive Input B Negative Power Supply. Bypass with a 0.1FF capacitor to ground. Negative Input Negative Input A Negative Input B Output Output A Output B Active-Low Shutdown A Active-Low Shutdown B Active-Low Shutdown Positive Power Supply. Bypass with a 0.1FF capacitor to ground. FUNCTION
8
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
Detailed Description
The MAX9636/MAX9637/MAX9638 are single-supply, CMOS input op amps. They feature wide bandwidth at low quiescent current, making them suitable for a broad range of battery-powered applications such as portable medical instruments, portable media players, and smoke detectors. A combination of extremely low input bias currents, low input current noise, and low input voltage noise allows interface to high-impedance sources such as photodiode and piezoelectric sensors. These devices are also ideal for general-purpose signal processing functions such as filtering and amplification in a broad range of portable, battery-powered applications. The devices' operational common-mode range extends 0.1V beyond the supply rails, allowing for a wide variety of single-supply applications. The ICs also feature low quiescent current and a shutdown mode that greatly reduces quiescent current while the device is not operational. This makes the device suitable for portable applications where power consumption must be minimized. The operational amplifiers have parallel-connected nand p-channel differential input stages that combine to accept a common-mode range extending 100mV beyond the supply rails. The n-channel stage is active for common-mode input voltages typically greater than (VDD - 1.2V), and the p-channel stage is active for common-mode input voltages typically less than (VDD - 1.4V). A small transition region exists, typically VDD - 1.4 to VDD - 1.2V, during which both pairs are on. The maximum output voltage swing is load dependent. However, it is guaranteed to be within 100mV of the positive rail even with 3mA of load current. To maximize the output current sourcing capability, these parts do not come with built-in short-circuit protection. If loads heavier than 600 must be driven, then ensure that the maximum allowable power dissipation is not exceeded (see the Absolute Maximum Ratings section). This op-amp family features ultra-low 0.1pA (typ) input bias current and guaranteed maximum current of Q50pA over -40NC to +85NC when the input common-mode voltage is at midrail. For the -40NC to +85NC temperature range, the variation in the input bias current is small with changes in the input voltage due to very high input impedance (in the order of 100GI). The ICs typically require a power-up time of 18s. Supply settling time depends on the supply voltage, the value of the bypass capacitor, the output impedance of the incoming supply, and any lead resistance or inductance between components. Op amp settling time depends primarily on the output voltage and is slew-rate limited. The output settles in approximately 11.5s for VDD = 3V and VOUT = VDD/2V (see the Power-Up Time graph in the Typical Operating Characteristics section).
Rail-to-Rail Output Stage
MAX9636/MAX9637/MAX9638
Low Input Bias Current
Power-Up Time
Rail-to-Rail Input Stage
9
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
The ICs have a high tolerance for capacitive loads. In unity-gain configuration, the op amps can typically drive up to 300pF pure capacitive load. Increasing the gain enhances the amplifier's ability to drive greater capacitive loads. In unity-gain configurations, capacitive load drive can be improved by inserting a small (5I to 30I) isolation resistor, RISO, in series with the output, as shown in Figure 1. This significantly reduces ringing while maintaining DC performance for purely capacitive loads. However, if the load also has a resistive component then a voltage-divider is created, introducing a direct current (DC) error at the output. The error introduced is proportional to the ratio RISO/RL, which is usually negligible in most cases. Applications that cannot tolerate this slight DC error can use an alternative approach of providing stability by placing a suitable resistance in parallel with the capacitive load as shown in Figure 2 (see the Typical Operating Characteristics section for graphs of the stable operating region for various capacitive loads vs. resistive loads). While this approach of adding a resistor parallel to the load does not introduce DC error, it nevertheless reduces the output swing proportionally.
Driving Capacitive Loads
High-Impedance Sensor Front-Ends
The ICs interface to both current-output sensors, such as photodiodes (Figure 3), and high-impedance voltage sources, such as piezoelectric sensors. For currentoutput sensors, a transimpedance amplifier is the most noise-efficient method for converting the input signal to a voltage. High-value feedback resistors are commonly chosen to create large gains, while feedback capacitors help stabilize the amplifier by cancelling any poles introduced in the feedback function by the highly capacitive sensor or cabling. A combination of low-current noise and low-voltage noise is important for these applications. Take care to calibrate out photodiode dark current if DC accuracy is important. The high bandwidth and slew rate also allows AC signal processing in certain medical photodiode sensor applications such as pulse oximetry. For voltage-output sensors, a noninverting amplifier is typically used to buffer and/or apply a small gain to the input voltage signal. Due to the extremely high impedance of the sensor output, a low input bias current with minimal temperature variation is very important for these applications.
MAX9636/ MAX9637/ MAX9638 RISO
MAX9636/ MAX9637/ MAX9638
+
RL RL AV = 1V/V RL + RISO
CL
+
RP
RL
CL
Figure 1. Using a Series Resistor to Isolate the Capacitive Load from the Op Amp
Figure 2. Using a Parallel Resistor to Degenerate the Effect of the Capacitive Load and Increase Stability
PHOTODIODE IN-
VDD SIGNAL CONDITIONING/ FILTERS
MAX1286
ADC
MAX9636 IN+
OUT
REF
Figure 3. MAX9636 in a Sensor Preamp Configuration 10
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
For best performance, follow standard high-impedance layout techniques, which include the following: U Using shielding techniques to guard against parasitic leakage paths. For example, put a trace connected to the noninverting input around the inverting input. U Minimizing the amount of stray capacitance connected to op amp's inputs to improve stability. To achieve this, minimize trace lengths and resistor leads by placing external components as close as possible to the package. U Use separate analog and digital power supplies.
ADC Driver
The MAX9636/MAX9637/MAX9638 are low-power amplifiers ideal for driving high to medium-resolution ADCs. Figure 3 shows how the MAX9636 is connected to a photodiode, with the amplifier output connected to additional signal conditioning/filtering, or directly to the ADC. The MAX1286-MAX1289 family of low-power, 12-bit ADCs are ideal for connecting to the MAX9636/MAX9637/MAX9638. The MAX1286-MAX1289 ADCs offer sample rates up to 150ksps, with 3V and 5V supplies, as well as 1- and 2-channel options. These ADCs dissipate just 15A when sampling at 10ksps and 0.2A in shutdown. Offered in tiny 8-pin SOT23 and 3mm x 3mm TDFN packages, the MAX1286-MAX1289 ADCs are an ideal fit to pair with the MAX9636/MAX9637/MAX9638 amplifiers in portable applications. Similarly, the MAX1086-MAX1089 is a family of 10-bit pin-compatible low-power ADCs with the same 3V/5V, 1- and 2-channel options. Table 1 details the amplifier and ADC pairings for single- and dual-channel applications.
MAX9636/MAX9637/MAX9638
Applications Information
The MAX9636/MAX9638 feature an active-low shutdown mode that sends the inputs and output into high impedance and substantially lowers the quiescent current.
Shutdown Operation
Active-Low Input The shutdown active-low (VIL) and high (VIH) threshold voltages are designed for ease of integration with digital controls, such as microcontroller outputs. These thresholds are independent of supply, eliminating the need for external pulldown circuitry. Output During Shutdown The MAX9638 output is in a high-impedance state while SHDN is low. The device structure limits the output leakage current in this state to 0.01A when the output is between 0V to VDD.
Chip Information
PROCESS: BiCMOS
Table 1. Recommended Amplifiers/ADCs
CHANNELS 1 2 2 AMPLIFIER MAX9636 MAX9637 MAX9638 ADC 3V, 10 BIT MAX1089 MAX1087 MAX1087 3V, 12 BIT MAX1289 MAX1287 MAX1287 5V, 10 BIT MAX1088 MAX1086 MAX1086 5V, 12 BIT MAX1288 MAX1286 MAX1286
11
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 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 TYPE 6 SC70 8 SC70 10 UTQFN PACKAGE CODE X6SN+1 X8CN+1 V101A1CN+1 DOCUMENT NO. 21-0077 21-0460 21-0028
12
SC70, 6L.EPS
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 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.
MAX9636/MAX9637/MAX9638
13
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9638
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 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.
14
TABLE 1
TABLE 2
ULTRA TQFN.EPS
3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. 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.
MAX9636/MAX9637/MAX9638
TABLE 1
TABLE 2
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3V/5V Low-Power, Low-Noise, CMOS, Rail-to-Rail I/O Op Amps MAX9636/MAX9637/MAX9738
Revision History
REVISION NUMBER 0 REVISION DATE 6/10 Initial release DESCRIPTION PAGES CHANGED --
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.
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(c)
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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