MAX4327EUB+ ,Single/Dual/Quad, Low-Cost, UCSP/SOT23, Low-Power, Rail-to-Rail I/O Op AmpsELECTRICAL CHARACTERISTICS—T = +25°C A(V = 5.0V, V = 0V, V = 0V, V = V /2, SHDN = V R connected to ..
MAX4329ESD ,Single/Dual/Quad / Low-Cost / SOT23 / Low-Power / Rail-to-Rail I/O Op AmpsELECTRICAL CHARACTERISTICS—T = +25°C (continued)A(V = +5V, V = 0, V = 0, V = V / 2, SHDN = V R tied ..
MAX4329ESD ,Single/Dual/Quad / Low-Cost / SOT23 / Low-Power / Rail-to-Rail I/O Op AmpsApplications6 2DOUT AINMAX4322SERIALPin Configurations appear at end of data sheet.INTERFACE8 4SCLK ..
MAX4329ESD+ ,Single/Dual/Quad, Low-Cost, UCSP/SOT23, Low-Power, Rail-to-Rail I/O Op AmpsELECTRICAL CHARACTERISTICS—T = +25°C A(V = 5.0V, V = 0V, V = 0V, V = V /2, SHDN = V R connected to ..
MAX432CPA ,【15V Chopper-Stabilized Operational Amplifierapplications.
They offer input offset and drift specifications superior to
previous "precision" b ..
MAX4330EUK ,Single/Dual/Quad, Low-Power, Single-Supply, Rail-to-Rail I/O Op Amps with ShutdownApplications MAX4334ESD -40°C to +85°C 14 SO —Selector GuidePin ConfigurationsNO. OF AMPS SHUTDOWNP ..
MAX813LMJA ,Low-Cost / uP Supervisory CircuitsELECTRICAL CHARACTERISTICS(V = 4.75V to 5.5V for MAX705/MAX707/MAX813L, V = 4.5V to 5.5V for MAX706 ..
MAX813LMJA ,Low-Cost / uP Supervisory CircuitsELECTRICAL CHARACTERISTICS(V = 4.75V to 5.5V for MAX705/MAX707/MAX813L, V = 4.5V to 5.5V for MAX706 ..
MAX814KCPA ,+-1% accuracy, low-power, microprocessor supervisory circuit. Reset trip threshold (min) 4.75V (max) 4.85V, push-pull active-low reset output, push-pull active-high reset output, manual reset, power-fail monitor, low-line detector.FeaturesThe MAX814/MAX815/MAX816 are high-accuracy' ±1% Worst-Case Reset Threshold Accuracymicropro ..
MAX814KCSA ,+-1% accuracy, low-power, microprocessor supervisory circuit. Reset trip threshold (min) 4.75V (max) 4.85V, push-pull active-low reset output, push-pull active-high reset output, manual reset, power-fail monitor, low-line detector.MAX814/MAX815/MAX81619-0412; Rev 0; 6/95±1% Accuracy, Low-Power, +3V and +5V µP Supervisory Circuit ..
MAX814KCSA ,+-1% accuracy, low-power, microprocessor supervisory circuit. Reset trip threshold (min) 4.75V (max) 4.85V, push-pull active-low reset output, push-pull active-high reset output, manual reset, power-fail monitor, low-line detector.ApplicationsL 4.65 4.75Medical EquipmentN 4.50 4.60ControllersT 3.00 3.06Intelligent InstrumentsMAX ..
MAX814KCSA ,+-1% accuracy, low-power, microprocessor supervisory circuit. Reset trip threshold (min) 4.75V (max) 4.85V, push-pull active-low reset output, push-pull active-high reset output, manual reset, power-fail monitor, low-line detector.ELECTRICAL CHARACTERISTICS, +5V Parts (MAX814/MAX815K, L, N) (continued)(V = 4.85V to 5.5V for MAX8 ..
MAX4322ESA+-MAX4322EUK-MAX4322EUK+T-MAX4323EBT-T-MAX4323ESA+-MAX4326ESA+-MAX4326ESA+T-MAX4326EUA+-MAX4326EUA-T-MAX4327EUB+-MAX4329ESD+
Single/Dual/Quad, Low-Cost, UCSP/SOT23, Low-Power, Rail-to-Rail I/O Op Amps
General DescriptionThe MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
family of operational amplifiers combines wide bandwidth
and excellent DC accuracy with Rail-to-Rail®operation at
the inputs and outputs. These devices consume only
650µA per amplifier and operate from either a single sup-
ply (2.4V to 6.5V) or dual supplies (±1.2V to ±3.25V). These
unity-gain-stable amplifiers are capable of driving 250Ω
loads and have a 5MHz gain-bandwidth product. The
MAX4323 and MAX4327 feature a low-power shutdown
mode that reduces supply current to 25µA and places the
outputs in a high-impedance state.
With their rail-to-rail input common-mode range and
output swing, these amplifiers are ideal for low-voltage,
single-supply operation. In addition, low offset voltage
and high speed make them the ideal signal-condition-
ing stages for precision, low-voltage data-acquisition
systems.
The MAX4323 is offered in a small 6-bump chip-scale
package (UCSP™). The MAX4322/MAX4323 are also
available in space-saving SOT23 packages.
________________________ApplicationsBattery-PoweredData-Acquisition
InstrumentsSystems
RSSI SystemsSignal Conditioning
PA BiasingPortable Equipment
Low-Power, Low-Voltage
Applications
____________________________Features6-Bump UCSP Package (MAX4323)2.4V to 6.5V Single-Supply OperationRail-to-Rail Input Common-Mode Voltage RangeRail-to-Rail Output Voltage Swing5MHz Gain-Bandwidth Product650µA Quiescent Current per Amplifier700µV Offset VoltageNo Phase Reversal for Overdriven InputsDrive 250ΩLoads25µA Shutdown Mode (MAX4323/MAX4327)Unity-Gain Stable for Capacitive Loads
Up to 500pF
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps
Pin Configurations19-1380; Rev 3; 10/02
Ordering InformationRail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
UCSP is a trademark of Maxim Integrated Products, Inc.
Selector GuideTOP VIEW
(BUMPS ON BOTTOM)
UCSPMAX4323
VEEB
OUT
VCC
IN+
IN-
SHDN
PARTTEMP
RANGE
PIN/BUMP-
PACKAGE
TOP
MARK
MAX4322EUK-T-40oC to +85oC5 SOT23-5ACGE
MAX4322EUA-40oC to +85oC8 µMAX—
MAX4322ESA-40oC to +85oC8 SO—
Ordering Information continued at end of data sheet.Pin Configurations continued at end of data sheet.
10 µMAX, 14 SO25MAX4327Yes
8 µMAX/SO25MAX4326—
Yes
SHUTDOWN14 SO
6 SOT23/UCSP,
8 µMAX/SO
5 SOT23,
8 µMAX/SO
PIN/BUMP-
PACKAGE5MAX43295MAX4323
PART5MAX4322
NO. OF
AMPS
(MHz)
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS—TA= +25°C (VCC= 5.0V, VEE= 0V, VCM= 0V, VOUT= VCC/2, SHDN= VCC,RLconnected to VCC/2, unless otherwise noted.)
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.
Supply Voltage (VCC - VEE)...................................................7.5V
All Other Pins...................................(VCC+ 0.3V) to (VEE- 0.3V)
Output Short-Circuit Duration.....................................Continuous
(Short to Either Supply)
Continuous Power Dissipation (TA= +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
6-Bump UCSP (derate 3.9mW/°C above +70°C).........308mW
6-Pin SOT23 (derate 7.1mW/°C Above + 70°C)..........571mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
8-Pin µMAX (derate 4.10mW/°C above +70°C)...........330mW
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
14-Pin SO (derate 8.00mW/°C above +70°C)..............640mW
Operating Temperature Range
MAX432_E__...................................................-40°C to +85°C
Maximum Junction Temperature.....................................+150°C
Storage Temperature Range.............................-65°C to +160°C
Bump Reflow Temperature..............................................+235°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSMAX432_ESA/
MAX4327ESD±0.7±2.0Input Offset VoltageVOSVCM = VEE or VCC
All other packages±1.2±2.50
Input Bias CurrentIBVCM = VEE or VCC±50±150nA
Input Offset CurrentIOSVCM = VEE or VCC±1±12nA
Differential Input ResistanceRIN-1.5V < VDIFF < +1.5V500kΩ
Common-Mode Input Voltage
RangeCMVRInferred from CMRR testVEEVCCV
MAX432_ESA/
MAX4327ESD6294
Common-Mode Rejection RatioCMRRVEE ≤ VCM ≤ VCC
All other packages6091
Power-Supply Rejection RatioPSRRVCC = 2.4V to 6.5V66100dB
Output ResistanceROUTAV = +1V/V0.1Ω
VOUT = 0.25V to 4.75V, RL = 100kΩ106Large-Signal Voltage GainAVVOUT = 0.4V to 4.6V, RL = 250Ω7086dB
VCC - VOH12RL = 100kΩVOL - VEE20
VCC - VOH200300
MAX4322/
MAX4323
RL = 250ΩVOL - VEE100200
VCC - VOH15RL = 100kΩVOL - VEE25
VCC - VOH220350
Output Voltage SwingVO
MAX4326/
MAX4327/
MAX4329RL = 250ΩVOL - VEE120250
Output Short-Circuit CurrentISC50mA
VILLow0.8SHDN Logic ThresholdVIHMAX4323/MAX4327High2.0V
SHDN Input CurrentMAX4323/MAX4327±1±4µA
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps
DC ELECTRICAL CHARACTERISTICS—TA= -40°C to +85°C(VCC= 5V, VEE= 0V, VCM= 0V, VOUT= VCC/2, SHDN= VCC, RLconnected to VCC/2, unless otherwise noted.) (Note 1)
DC ELECTRICAL CHARACTERISTICS—TA= +25°C (continued)(VCC= 5V, VEE= 0V, VCM= 0V, VOUT= VCC/2, SHDN= VCC, RLconnected to VCC/2, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSMAX432_ESA/
MAX4327ESD±3.0Input Offset VoltageVOSVCM = VEE or VCC
All other packages±6.0
Input Offset Voltage TempcoTCVOS±2µV/°C
Input Bias CurrentIBVCM = VEE or VCC±180nA
Input Offset CurrentIOSVCM = VEE or VCC±20nA
Common-Mode Input
Voltage RangeCMVRInferred from CMRR testVEEVCCV
MAX432_ESA/
MAX4327ESD59Common-Mode Rejection RatioCMRRVEE ≤ VCM ≤ VCC
All other packages54
Power-Supply Rejection RatioPSRRVCC = 2.4V to 6.5V62dB
Large-Signal Voltage GainAVVOUT = 0.4V to 4.6V, RL = 250Ω66dB
VCC - VOH350MAX4322/
MAX4323RL = 250ΩVOL - VEE250
VCC - VOH400Output Voltage SwingVOMAX4326/
MAX4327/
MAX4329
RL = 250Ω
VOL - VEE300
VILLow0.8SHDN Logic ThresholdVIHMAX4323/MAX4327High2.0V
SHDN Input CurrentMAX4323/MAX4327±5µA
Operating Supply Voltage RangeVCC2.46.5V
Supply Current per AmplifierICCVCM = VOUT = VCC/21200µA
Shutdown Supply Current
per AmplifierI SHDNV SHDN ≤ 0.8V, MAX4323/MAX432770µA
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSOperating Supply Voltage RangeVCCInferred from PSRR test2.46.5V
VCC = 2.4V650Supply Current per AmplifierICCVCM = VOUT = VCC/2VCC = 5V7251100µA
VCC = 2.4V25Shutdown Supply Current
per AmplifierI SHDNV SHDN ≤ 0.8V,
MAX4323/MAX4327VCC = 5V4060µA
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps
AC ELECTRICAL CHARACTERISTICS(VCC= 5V, VEE= 0V, VCM= VOUT= VCC/2, SHDN= VCC,TA= +25°C, unless otherwise noted.)
Note 1:All devices are 100% tested at TA= +25°C. All temperature limits are guaranteed by design.
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSGain-Bandwidth ProductGBWP5MHz
Phase MarginφM64Degrees
Gain MarginGM12dB
Total Harmonic DistortionTHDf = 10kHz, VOUT = 2VP-P, AV = +1V/V0.003%
Slew RateSR2V/µs
Settling Time to 0.01%tSAV = +1V/V, VOUT = 2V step2.0µs
Turn-On TimetONVCC = 0 to 3V step1µs
Enable1SHDN DelayMAX4323/MAX4327Disable0.2µs
Input CapacitanceCIN3pF
Input Noise-Voltage Densityenf = 1kHz22nV/√Hz
Input Noise-Current Densityinf = 1kHz0.4pA/√Hz
Amp-Amp Isolation135dB
Capacitive-Load StabilityCLAV = +1V/V250pF
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps1001k10k1M10M100k100M
GAIN AND PHASE vs. FREQUENCYFREQUENCY (Hz)
GAIN (dB)0
PHASE
GAIN
AV = +1000
NO LOAD
PHASE (DEGREES)
MAX4322/26/29-0160
1001k10k1M10M100k100M
GAIN AND PHASE vs. FREQUENCY
(WITH CLOAD)MAX4322/26/29-02
FREQUENCY (Hz)
GAIN (dB)0
PHASE
GAIN
AV = +1000
RL = ∞
CL = 500pF
PHASE (DEGREES)
-1001001k100k1M10M10k100M
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCYMAX4322/26/29-03
FREQUENCY (Hz)
PSRR (dB)-60
-20
AV = +1
__________________________________________Typical Operating Characteristics(VCC= 5V, VEE= 0V, VCM= VCC/2, SHDN= VCC,TA = +25°C, unless otherwise noted.)10k10M
FREQUENCY (Hz)
100k1M100
MAX4326/MAX4327/MAX4329
CHANNEL SEPARATION vs. FREQUENCY
MAX4322/26/29-04
CHANNEL SEPARATION (dB)
1001k100k1M10M10k100M
OUTPUT IMPEDANCE
vs. FREQUENCYMAX4322/26/29-05
FREQUENCY (Hz)
OUTPUT IMPEDANCE (
AV = +1
SUPPLY CURRENT PER AMPLIFIER
vs. TEMPERATURE
MAX4322/26/29-07
TEMPERATURE (°C)
SUPPLY CURRENT (VCC = 6.5V
VCC = 2.7V
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX4322/26/29-08
TEMPERATURE (°C)
VOLTAGE (mV)
SOT23-5/6
PACKAGE
SO PACKAGE
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
MAX4322/26/29-09
COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (nA)
VCC = 2.7V
VCC = 6.5V
MAX4323/MAX4327
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX4323-06
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (VCC = 6.5V
VCC = 2.7V
VSHDN = 0V
_____________________________Typical Operating Characteristics (continued)(VCC= 5V, VEE= 0V, VCM= VCC/2, SHDN= VCC, TA = +25°C, unless otherwise noted.)
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op AmpsCOMMON-MODE REJECTION RATIO
vs. TEMPERATURE
MAX4322/26/29-11
TEMPERATURE (°C)
CMRR (dB)
VCM = 0 TO 5.0V
VCM = -0.2V TO 5.2V
MINIMUM OUTPUT VOLTAGE
vs. TEMPERATURE
200MAX4322/26/29-12
TEMPERATURE (°C)
OUT
- V
(mV)150
RL TO VCC
VCC = 6.5V, RL = 500Ω
VCC = 2.7V, RL = 100kΩ
VCC = 2.7V, RL = 500Ω
VCC = 6.5V, RL = 100kΩ
MAXIMUM OUTPUT VOLTAGE
vs. TEMPERATURE
MAX4322/26/29-13
TEMPERATURE (°C)
- V
OUT
(mV)
RL TO VEE
VCC = 6.5V, RL = 500Ω
VCC = 2.7V, RL = 100kΩ (BOTTOM)
VCC = 2.7V, RL = 500Ω
VCC = 6.5V, RL = 100kΩ (TOP)
OUTPUT VOLTAGE: FROM VCC (mV)
GAIN (dB)
MAX4322/26/29-14
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGEVCC = 2.7V
RL TO VEE
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
OUTPUT VOLTAGE: FROM VCC (mV)
GAIN (dB)
MAX4322/26/29-15
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGEVCC = 6.5V
RL TO VEE
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
LARGE-SIGNAL GAIN
vs. TEMPERATURE
MAX4322/26/29-16
TEMPERATURE (°C)
GAIN (dB)
VCC = 2.7V,
RL TO VEE
VCC = 6.5V, RL TO VCC
VCC = 2.7V, RL TO VCC
RL = 500Ω
VOUT(P-P) = VCC - 1V
VCC = 6.5V,
RL TO VEE
GAIN (dB)
MAX4322/26/29-17
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGERL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
VCC = 2.7V
RL TO VCC
OUTPUT VOLTAGE: FROM VEE (mV)
GAIN (dB)
MAX4322/26/29-18
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGEVCC = 6.5V
RL TO VCC
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
OUTPUT VOLTAGE: FROM VEE (mV)
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX4322/26/29-10
TEMPERATURE (°C)
INPUT BIAS CURRENT (nA)
VCC = 6.5V, VCM = VCC
VCC = 2.7V, VCM = VEE
VCC = 2.7V, VCM = VCC
VCC = 6.5V, VCM = VEE
_____________________________Typical Operating Characteristics (continued)(VCC= 5V, VEE= 0V, VCM= VCC/2, SHDN= VCC,TA = +25°C, unless otherwise noted.)
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op AmpsMINIMUM OPERATING VOLTAGE
vs. TEMPERATURE
MAX4322/26/29-20
TEMPERATURE (°C)
MINIMUM OPERATING VOLTAGE (V)100k10k
FREQUENCY (Hz)
1001k
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4322/26/29-21
THD + N (%)
AV = +1
2VP-P SIGNAL
500kHz LOWPASS FILTER
RL = 10kΩ TO VCC/2
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. PEAK-TO-PEAK SIGNAL AMPLITUDE
MAX4322/26/29-22
PEAK-TO-PEAK SIGNAL AMPLITUDE (V)
THD + N (%)
AV = +1
10kHz SINE WAVE
RL TO VCC/2
500kHz LOWPASS FILTER
RL = 10kΩRL = 100kΩ
RL = 2kΩRL = 250Ω
200ns/div
VOLTAGE (50mV/div)
OUT
AV = +1
SMALL-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)MAX4322/26/29-23
200ns/div
VOLTAGE (50mV/div)
OUT
AV = -1
SMALL-SIGNAL TRANSIENT
RESPONSE (INVERTING)MAX4322/26/29-24
LARGE-SIGNAL GAIN
vs. TEMPERATURE
115MAX4322/26/29-19
TEMPERATURE (°C)
GAIN (dB)
VOUT(P-P) = VCC - 600mV
RL = 100kΩ
VCC = 6.5V, RL TO VEE
VCC = 2.7V, RL TO VCC
VCC = 2.7V, RL TO VEE
VCC = 6.5V, RL TO VCC
2μs/div
VOLTAGE (2V/div)
OUT
AV = +1
LARGE-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)MAX4322/26/29-25
2μs/div
VOLTAGE (2V/div)
OUT
AV = -1
LARGE-SIGNAL TRANSIENT
RESPONSE (INVERTING)MAX4322/26/29-26
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps
Pin Description
PIN
MAX4322MAX4323MAX4327
SOT23SO/µMAXSOT23SO/µMAXUCSP
MAX4326
µMAXSO
MAX4329
NAMEFUNCTION16A2————OUTOutput24A144411VEE
Negative Supply.
Ground for single-
supply operation.—33B1————IN+Noninverting Input—42B2————IN-Inverting Input767A3810144VCCPositive Supply1, 5, 8—1, 5———5, 7,
8 , 10—N.C.No Connection. Not
internally connected.58B3———SHDN
Shutdown Control.
Connected high or
leave floating to
enable amplifier.———1, 71, 91, 131, 7OUT1,
OUT2
Outputs for Amps 1
and 22———2, 62, 82, 122, 6IN1-, IN2-Inverting Inputs for
Amps 1 and 23———3, 53, 73, 113, 5IN1+,
IN2+
Noninverting Inputs
for Amps 1 and 2————5, 65, 9—SHDN1,
SHDN2
Shutdown Control for
Amps 1 and 2.
Connected high or
leave floating to
enable amplifier.——————8, 14OUT3,
OUT4
Outputs for Amps 3
and 4——————9, 13IN3-, IN4-Inverting Inputs for
Amps 3 and 4——————10, 12IN3+,
IN4+
Noninverting Inputs
for Amps 3 and 4
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op AmpsR3 = R1 R2R2
MAX4322/MAX4323
MAX4326/MAX4327
MAX4329
Figure 1a. Reducing Offset Error Due to Bias Current
(Noninverting)
R3 = R1 R2R2
MAX4322/MAX4323
MAX4326/MAX4327
MAX4329
Figure 1b. Reducing Offset Error Due to Bias Current
(Inverting)
1kΩ
1kΩ
Figure 2. Input Protection Circuit
__________Applications Information
Rail-to-Rail Input StageDevices in the MAX4322/MAX4323/MAX4326/MAX4327/
MAX4329 family of high-speed amplifiers have rail-to-
rail input and output stages designed for low-voltage,
single-supply operation. The input stage consists of
separate NPN and PNP differential stages, which com-
bine to provide an input common-mode range extend-
ing to the supply rails. The PNP stage is active for input
voltages close to the negative rail, and the NPN stage
is active for input voltages near the positive rail. The
input offset voltage is typically below 250µV. The
switchover transition region, which occurs near VCC/2,
has been extended to minimize the slight degradation in
CMRR caused by the mismatch of the input pairs. Their
low offset voltage, high bandwidth, and rail-to-rail
common-mode range make these op amps excellent
choices for precision, low-voltage, data-acquisition
systems.
Since the input stage switches between the NPN and
PNP pairs, the input bias current changes polarity as
the input voltage passes through the transition region.
To reduce the offset error caused by input bias cur-
rents flowing through external source impedances,
match the effective impedance seen by each input
(Figures 1a, 1b). High-source impedances, together
with the input capacitance, can create a parasitic pole
that produces an underdamped signal response.
Reducing the input impedance or placing a small (2pF
to 10pF) capacitor across the feedback resistor
improves the response.
The MAX4322/MAX4323/MAX4326/MAX4327/MAX4329s’
inputs are protected from large differential input voltages
by 1kΩseries resistors and back-to-back triple diodes
across the inputs (Figure 2). For differential input volt-
ages less than 1.8V, the input resistance is typically
500kΩ. For differential input voltages greater than 1.8V,
the input resistance is approximately 2kΩ, and the input
bias current is determined by the following equation:
