General Description
The MAX4321 operational amplifier (op amp) combines
a 5MHz gain-bandwidth product and excellent DC
accuracy with Rail-to-Rail®operation at both the inputs
and the output. This device requires only 650µA and
operates from either a single +2.4V to +6.5V supply or
dual ±1.2V to ±3.25V supplies, although the MAX4321
typically operates down to +1.8V (±0.9V). The
MAX4321 remains unity-gain stable with capacitive
loads up to 500pF and is capable of driving 250Ωloads
to within 200mV of either rail.
With rail-to-rail input common-mode range and output
swing, the MAX4321 is ideal for low-voltage, single-sup-
ply applications. In addition, low ±1.2mV input offset volt-
age and high 2V/µs slew rate make this device ideal for
signal-conditioning stages for precision, low-voltage data-
acquisition systems. The MAX4321 comes in a space-
saving 5-pin SOT23 package and is guaranteed over the
extended (-40°C to +85°C) temperature range.
The MAX4321 is a low-voltage, pin-for-pin compatible
upgrade for the LMC7101 that offers five-times higher
bandwidth, two-times faster slew rate, and about half the
input voltage noise density.
________________________Applications
Battery-Powered Instruments
Portable Equipment
Data-Acquisition Systems
Sensor and Signal Conditioning
Low-Power, Low-Voltage Applications
General-Purpose Low-Voltage Applications
Features
♦Low-Voltage, Pin-for-Pin Upgrade for LMC7101
♦Guaranteed +2.4V to +6.5V Single-Supply
Operation
♦Typically Operates Down to +1.8V
♦5MHz Gain-Bandwidth Product
♦650µA Quiescent Current
♦Rail-to-Rail Common-Mode Input Voltage Range
♦Rail-to-Rail Output Voltage Range
♦Drives 250ΩLoads
♦Unity-Gain Stable for Capacitive Loads up to
500pF
♦No Phase Reversal for Overdriven Inputs
♦Low-Cost Solution in SOT23-5 Package
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
________________________________________________________________ Maxim Integrated Products 1
VCC
IN-IN+
15VEE
OUT
MAX4321
TOP VIEW
2
34
SOT23
MAX187
MAX4321
SHDN
31
2
4
5
6
8
7
VDD
+5V
AIN
VREF
GND
DOUT
SERIAL
INTERFACE SCLK
CS
Typical Operating Circuit
19-1649; Rev 0; 4/00
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.
Ordering Information
Pin Configuration/
Functional Diagram
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
PART TEMP.
RANGE
PIN-
PACKAGE
TOP
MARK
MAX4321EUK-T -40°C to +85°C
5 SOT23-5
ADOA
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(VCC = +5.0V, VEE = 0, VCM = 0, VOUT = VCC/2, RL= ∞connected to VCC/2, TA= +25°C, 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 to VEE) ....................................-0.3V to +7V
All Other Pins ..................................(VEE - 0.3V) to (VCC + 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
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage Range
VCC - VEE
2.4 6.5 V
VCC = +2.4V
650
Supply Current
VCM = VOUT = VCC/2
VCC = +6.5V
725
µA
Input Offset Voltage VOS VCM = VEE or VCC
±1.2 ±3.5
mV
Input Bias Current IBIAS VCM = VEE or VCC
±50 ±150
nA
Input Offset Current
IOFFSET
VCM = VEE or VCC ±4
±25
nA
Differential Input
Resistance RIN -1.5V < VDIFF <+1.5V
500
kΩ
Common-Mode Input Voltage
Range VCM Inferred from CMRR test
VEE VCC
V
Common-Mode Rejection
Ratio CMRR VEE ≤ VCM ≤ VCC 60 91 dB
Power-Supply Rejection Ratio
PSRR 2.4V < VCC < 6.5V 66
100
dB
Output Resistance ROUT AV = +1V/V 0.1 Ω
VOUT = 0.25V to 4.75V, R
L = 100kΩ
103
VOUT = 0.40V to 4.60V, R
L = 600Ω
100
Large-Signal Voltage Gain AV
VOUT = 0.40V to 4.60V, R
L = 250Ω70 86
dB
VCC - VOH 25
RL = 100kΩVOL - VEE 20
VCC - VOH
135
RL = 600ΩVOL - VEE 60
VCC - VOH
200 300
Output Voltage Swing VOUT
RL = 250ΩVOL - VEE
100 200
mV
Output Short-Circuit Current 50 mA
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
_______________________________________________________________________________________ 3
DC ELECTRICAL CHARACTERISTICS
(VCC = +5.0V, VEE = 0, VCM = 0, VOUT = VCC/2, RL= ∞connected to VCC/2, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)
AC ELECTRICAL CHARACTERISTICS
(VCC = +5.0V, VEE = 0, VCM = 0, VOUT = VCC/2, RL= 250Ωconnected to VCC/2, TA= +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage Range
VCC - VEE
2.4 6.5 V
Supply Current ICC VCM = VOUT = VCC/2
1200
μA
Input Offset Voltage VOS VCM = VEE or VCC ±6mV
Input Offset Voltage
Temperature Coefficient ±2
μV/°C
Input Bias Current IBIAS VCM = VEE or VCC
±180
nA
Input Offset Current
IOFFSET
VCM = VEE or VCC
±50
nA
Common-Mode Input Voltage
Range VCM Inferred from CMRR test
VEE VCC
V
Common-Mode Rejection Ratio
CMRR VEE ≤ VCM ≤ VCC 54 dB
Power-Supply Rejection Ratio PSRR 2.4V < VCC < 6.5V 62 dB
Large-Signal Voltage Gain AVVOUT = 0.40V to 4.60V, RL = 250Ω66 dB
VCC - VOH
350
Output Voltage Swing VOUT R = 250Ω
VOL - VEE
250
mV
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Gain-Bandwidth Product GBP 5 MHz
Phase Margin 64 degrees
Gain Margin 12 dB
Total Harmonic Distortion
and Noise THD+N 10kHz tone, VOUT = 2Vpp,
AV = +1V/V 0.003 %
Slew Rate SR VOUT = 1V step 2 V/μs
Settling Time to 0.01% tSETTLE VOUT = 2V step, AV = +1V/V 2 μs
Turn-On Time tON VCC = 0 to 3V step 1 μs
Input Capacitance CIN 3pF
Input Noise Voltage Density f = 1kHz 22 nV/√ Hz
Input Noise Current Density f = 1kHz 0.4 pA/√Hz
Note 1: All devices are 100% production tested at TA= +25°C. All temperature limits are guaranteed by design and characterization.
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VCC = +5V, VEE = 0, VCM = VCC/2, TA= +25°C, unless otherwise noted.)
60
-40
100 1k 10k 1M 10M100k 100M
GAIN AND PHASE vs. FREQUENCY
-20
FREQUENCY (Hz)
GAIN (dB)
0
20
40
PHASE
GAIN
AV = +1000
NO LOAD
PHASE (DEGREES)
180
144
72
0
-72
-144
-180
-108
-36
36
108
MAX4321-01
60
-40
100 1k 10k 1M 10M100k 100M
GAIN AND PHASE vs. FREQUENCY
(WITH CLOAD)
-20
MAX4321-02
FREQUENCY (Hz)
GAIN (dB)
0
20
40
PHASE
GAIN
AV = +1000
RL = ∞
CL = 500pF
PHASE (DEGREES)
180
144
72
0
-72
-144
-180
-108
-36
36
108
0
-100
10 100 1k 100k 1M 10M10k 100M
POWER-SUPPLY REJECTION
vs. FREQUENCY
-80
MAX4321-03
FREQUENCY (Hz)
PSR (dB)
-60
-40
-20
AV = +1
100
0.01
100 1k 100k 1M 10M
10k 100M
OUTPUT IMPEDANCE
vs. FREQUENCY
0.1
MAX4321-04
FREQUENCY (Hz)
OUTPUT IMPEDANCE (Ω)
1
10
AV = +1
900
500
550
600
650
700
750
800
850
-40 -25 -10 5 20 35 50 65 80 95
SUPPLY CURRENT vs. TEMPERATURE
MAX4321-05
TEMPERATURE (°C)
SUPPLY CURRENT (μA)
VCC = 6.5V
VCC = 2.7V
-3.00
-2.25
-0.75
-1.50
0
1.50
0.75
2.25
3.00
-40-25-105 20355065 8095
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX4321-06
TEMPERATURE (°C)
VOLTAGE (mV)
-50
0123456
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
MAX4321-07
COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (nA)
-40
-30
-20
-10
0
10
20
30
40
50
VCC = 2.7V
VCC = 6.5V
-60
-50
-40 -25 -10 5 20 35 50 65 80 95
INPUT BIAS CURRENT
vs. TEMPERATURE
MAX4321-08
TEMPERATURE (°C)
INPUT BIAS CURRENT (nA)
-40
-30
-20
-10
0
10
20
30
40
50
VCC = 6.5V, VCM = VCC
VCC = 2.7V, VCM = VEE
VCC = 2.7V, VCM = VCC
VCC = 6.5V, VCM = VEE
120
80
85
90
95
100
105
110
115
-40-25-105 20355065 8095
COMMON-MODE REJECTION
vs. TEMPERATURE
MAX4321-09
TEMPERATURE (°C)
COMMON-MODE REJECTION (dB)
VCM = 0 TO 5.0V
VCM = -0.2V TO 5.2V
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
_______________________________________________________________________________________ 5
250
0
-40 -25 -10 5 20 35 50 65 80 95
MINIMUM OUTPUT VOLTAGE
vs. TEMPERATURE
50
200
MAX4321-10
TEMPERATURE (°C)
VOUT - VEE (mV)
150
100
RL TO VCC
VCC = 6.5V, RL = 500Ω
VCC = 2.7V, RL = 100kΩ
VCC = 2.7V, RL = 500Ω
VCC = 6.5V, RL = 100kΩ
0
50
100
150
200
250
300
-40 -25 -10 5 20 35 50 65 80 95
MAXIMUM OUTPUT VOLTAGE
vs. TEMPERATURE
MAX4321-11
TEMPERATURE (°C)
VCC - VOUT (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)
120
60
0600
110
OUTPUT VOLTAGE: FROM VCC (mV)
GAIN (dB)
300
90
80
70
100 200 500
100
400
MAX4321-12
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGE
VCC = 2.7V
RL TO VEE
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
120
60
0600
110
OUTPUT VOLTAGE: FROM VCC (mV)
GAIN (dB)
300
90
80
70
100 200 500
100
400
MAX4321-13
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGE
VCC = 6.5V
RL TO VEE
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
120
60
0600
110
GAIN (dB)
300
90
80
70
100 200 500
100
400
MAX4321-14
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGE
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
VCC = 2.7V
RL TO VCC
OUTPUT VOLTAGE: FROM VEE (mV)
120
60
0600
110
GAIN (dB)
300
90
80
70
100 200 500
100
400
MAX4321-15
LARGE-SIGNAL GAIN
vs. OUTPUT VOLTAGE
VCC = 6.5V
RL TO VCC
RL = 500Ω
RL = 100kΩ
RL = 10kΩ
RL = 2kΩ
OUTPUT VOLTAGE: FROM VEE (mV)
125
75
-40 -25 -10 5 20 35 50 65 80 95
LARGE-SIGNAL GAIN
vs. TEMPERATURE
85
115
MAX4321-16
TEMPERATURE (°C)
GAIN (dB)
105
95
80
90
120
110
100
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
125
75
-40 -25 -10 5 20 35 50 65 80 95
LARGE-SIGNAL GAIN
vs. TEMPERATURE
85
115
MAX4321-17
TEMPERATURE (°C)
GAIN (dB)
105
95
80
90
120
110
100
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
1.2
1.3
1.5
1.4
1.6
1.7
1.8
1.9
-40 -25 -10 5 20 35 50 65 80 95
MINIMUM OPERATING VOLTAGE
vs. TEMPERATURE
MAX4321-18
TEMPERATURE (°C)
MINIMUM OPERATING VOLTAGE (V)
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, VCM = VCC/2, TA= +25°C, unless otherwise noted.)
Pin Description
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
6 _______________________________________________________________________________________
10 100k10k
FREQUENCY (Hz)
100 1k
0.040
0
0.005
0.010
0.015
0.020
0.025
0.030
0.035
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX4321-19
THD + NOISE (%)
AV = +1
2Vp-p SIGNAL
500kHz LOWPASS FILTER
RL = 10kΩ
TO VCC / 2
0.1
0.001
4.0 4.44.2 5.04.84.6
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. PEAK-TO-PEAK SIGNAL AMPLITUDE
MAX4321-20
PEAK-TO-PEAK SIGNAL AMPLITUDE (V)
THD + NOISE (%)
0.01
AV = +1
10kHz SINE WAVE
RL TO VCC / 2
500kHz LOWPASS
FILTER
RL = 10kΩRL = 100kΩ
RL = 2kΩ
RL = 250Ω
IN
200ns/div
VOLTAGE
50mV/div
OUT
AV = +1
SMALL-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)
MAX4321-21
IN
200ns/div
VOLTAGE
50mV/div
OUT
AV = -1
SMALL-SIGNAL TRANSIENT
RESPONSE (INVERTING)
MAX4321-22
IN
2μs/div
VOLTAGE
2V/div
OUT
AV = +1
LARGE-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)
MAX4321-23
IN
2μs/div
VOLTAGE
2V/div
OUT
AV = -1
LARGE-SIGNAL TRANSIENT
RESPONSE (INVERTING)
MAX4321-24
Typical Operating Characteristics (continued)
(VCC = +5V, VEE = 0, VCM = VCC/2, TA= +25°C, unless otherwise noted.)
PIN NAME FUNCTION
1 OUT Output
2V
CC Positive Supply
3 IN+ Noninverting Input
4 IN- Inverting Input
5V
EE Negative Supply. Connect to ground for single-supply operation.
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
_______________________________________________________________________________________ 7
__________
Applications Information
Rail-to-Rail Input Stage
The MAX4321 high-speed amplifier has 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 combine to
provide an input common-mode range extending 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 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. Its low offset
voltage, high bandwidth, and rail-to-rail common-mode
range makes this op amp an excellent choice for preci-
sion, 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 MAX4321’s inputs are protected from large differen-
tial input voltages by 1kΩseries resistors and back-to-
back triple diodes across the inputs (Figure 2). For
differential input voltages less than 1.8V, the input resis-
tance 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 fol-
lowing equation:
I = V - 1.8V
2k
BIAS DIFF
Ω
R3
R3 = R1 R2
R1 R2
MAX4321
Figure 1a. Reducing Offset Error Due to Bias Current
(Noninverting)
R3
R3 = R1 R2
R1 R2
MAX4321
Figure 1b. Reducing Offset Error Due to Bias Current
(Inverting)
1k
1k
Figure 2. Input Protection Circuit
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
8 _______________________________________________________________________________________
Rail-to-Rail Output Stage
The minimum output voltage will be within millivolts of
ground for single-supply operation where the load is
referenced to ground (VEE). Figure 3 shows the input
voltage range and output voltage swing of a MAX4321
connected as a voltage follower. With a +3V supply
and the 100kΩload tied to ground, the output swings
from 0.02V to 2.97V. The maximum output voltage
swing depends on the load but will be within 300mV of
a +5V supply, even with the maximum load (250Ωto
ground).
Driving a capacitive load can cause instability in most
high-speed op amps, especially those with low quies-
cent current. The MAX4321 has a high tolerance for
capacitive loads. It is stable with capacitive loads up to
500pF. Figure 4 gives the stable operating region for
capacitive loads. Figures 5 and 6 show the response
with capacitive loads and the results of adding an isola-
tion resistor in series with the output (Figure 7). The
resistor improves the circuit’s phase margin by isolating
the load capacitor from the op amp’s output.
Figure 3. Rail-to-Rail Input /Output Voltage Range Figure 4. Capacitive-Load Stability
Figure 5. Small-Signal Transient Response with Capacitive
Load
Figure 6. Transient Response to Capacitive Load with Isolation
Resistor
IN
400ns/div
VOLTAGE
50mV/div
OUT
AV = +1
CL = 500pF
IN
400ns/div
VOLTAGE
50mV/div
OUT
AV = +1
CL = 1000pF
RS = 39Ω
IN
2μs/div
VOLTAGE
1V/div
OUT
VCC = 3V
AV = +1
RL = 100kΩ
10,000
100
100 1k 100k10k
RESISTIVE LOAD (Ω)
LOAD CAPACITIVE (pF)
1000
UNSTABLE
REGION
RL TO VEE
VOUT = VCC / 2
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
_______________________________________________________________________________________ 9
RS
CL
MAX4321
Figure 7. Capacitive-Load-Driving Circuit
VOUT
0V TO 2.7V
STEP FOR
POWER-UP
TEST
SUPPLY-CURRENT
MONITORING POINT
VCC
10Ω2k 10k
2k
MAX4321
Figure 8. Power-Up Test Circuit
Figure 10. Power-Up Supply Current
VCC
5μs/div
VOLTAGE
1V/div
OUT
Figure 9. Power-Up Output Voltage
VCC
1V/div
5μs/div
ICC
500μA/div
Power-Up
The MAX4321 typically settles within 1µs after power-up.
Using the test circuit of Figure 8, Figures 9 and 10 show
the output voltage and supply current on power-up.
Power Supplies and Layout
The MAX4321 operates from single +2.4V to +6.5V or
dual ±1.2V to ±3.25V supplies, though it typically oper-
ates down to +1.8V (±0.9V). For single-supply opera-
tion, bypass the power supply with a 0.1µF ceramic
capacitor in parallel with at least 1µF. For dual supplies,
bypass each supply to ground.
Good layout improves performance by decreasing the
amount of stray capacitance at the op amp’s inputs
and outputs. To decrease stray capacitance, minimize
trace lengths and resistor leads by placing external
components close to the op amp’s pins.
Package Information
TRANSISTOR COUNT: 84
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
10 ______________________________________________________________________________________
Package Information
SOT-23 5L .EPS
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
______________________________________________________________________________________ 11
NOTES
MAX4321
Low-Cost, Low-Voltage, Rail-to-Rail,
Input/Output, SOT23 5MHz Op Amp
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
NOTES
