General Description
The MAX9943/MAX9944 is a family of high-voltage
amplifiers that offers precision, low drift, and low-power
consumption.
The MAX9943 (single) and MAX9944 (dual) op amps
offer 2.4MHz of gain-bandwidth product with only 550μA
of supply current per amplifier.
The MAX9943/MAX9944 family has a wide power supply
range operating from ±3V to ±19V dual supplies or a 6V
to 38V single supply.
The MAX9943/MAX9944 is ideal for sensor signal condi-
tioning, high-performance industrial instrumentation and
loop-powered systems (e.g., 4mA–20mA transmitters).
The MAX9943 is offered in a space-saving 6-pin TDFN
or 8-pin μMAX® package. The MAX9944 is offered in an
8-pin SO or an 8-pin TDFN package. These devices are
specified over the -40°C to +125°C automotive tempera-
ture range.
Applications
●Sensor Interfaces
●Loop-Powered Systems
●Industrial Instrumentation
●High-Voltage ATE
● High-Performance ADC/DAC Input/Output Ampliers
Features
●Wide 6V to 38V Supply Range
● Low 100μV (max) Input Offset Voltage
● Low 0.4μV/°C Offset Drift
●Unity Gain Stable with 1nF Load Capacitance
●2.4MHz Gain-Bandwidth Product
● 550μA Supply Current
●20mA Output Current
●Rail-to-Rail Output
●Package Options
• 3mm x 5mm, 8-Pin μMAX or 3mm x 3mm, 6-Pin
TDFN Packages (Single)
• 5mm x 6mm, 8-Pin SO or 3mm x 3mm, 8-Pin
TDFN Packages (Dual)
19-4433; Rev 4; 10/17
μMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations appear at end of data sheet.
RLOAD (Ω)
CLOAD (pF)
1000 10,000
1000
10,000
100,000
100
100 100,000
STABLE
UNSTABLE
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
Capacitive Load vs. Resistive Load
Supply Voltage (VCC to VEE) ................................-0.3V to +40V
All Other Pins (Note 1) ..................(VEE - 0.3V) to (VCC + 0.3V)
OUT Short-Circuit Current Duration
8-Pin μMAX (VCC - VEE ≤ 20V) .......................................... 3s
8-Pin μMAX (VCC - VEE > 20V) ............................ Momentary
6-Pin TDFN (VCC - VEE ≤ 20V) ........................................ .60s
6-Pin TDFN (VCC - VEE > 20V) .......................................... 2s
8-Pin SO (VCC - VEE ≤ 20V) ............................................. 60s
8-Pin SO (VCC - VEE > 20V) ............................................... 2s
8-Pin TDFN (VCC - VEE ≤ 20V) ......................................... 60s
8-Pin TDFN (VCC - VEE > 20V) .......................................... 2s
Continuous Input Current (Any Pins) ...............................±20mA
Thermal Limits (Note 2)
Multiple Layer PCB
Continuous Power Dissipation (TA = +70°C)
8-Pin μMAX (derate 4.8mW/°C above +70°C) .........387.8mW
6-Pin TDFN-EP (derate 23.8mW/°C above +70°C) ... 1904.8mW
8-Pin SO (derate 7.6mW/°C above +70°C) ................. 606.1W
8-Pin TDFN-EP (derate 24.4mW/°C above +70°C) ... 1951.2mW
Operating Temperature Range ......................... -40°C to +125°C
Junction Temperature ...................................................... +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) ....................................... +260°C
(Note 2)
(VCC = 15V, VEE = -15V, VCM = 0V, RL = 10kΩ to GND, VGND = 0V, TA = -40°C to +125°C. Typical values are at TA = +25°C, unless
otherwise noted.) (Note 3)
Note 1: Operation is limited by thermal limits.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC CHARACTERISTICS
Operating Supply Voltage Range VSUPPLY Guaranteed by PSRR test ±3 ±19 V
Quiescent Supply Current per
Amplier ICC 550 950 µA
Power-Supply Rejection Ratio PSRR VS = ±3V to ±19V 105 130 dB
Input Offset Voltage VOS
TA = +25°C 20 100 µV
TA = -40°C to +125°C 240
Input Offset Voltage Drift TCVOS 0.4 µV/°C
Input Bias Current IBIAS
VEE + 0.3V ≤ VCM ≤ VCC - 1.8V 4 20 nA
VEE ≤ VCM ≤ VCC - 1.8V 90
Input Offset Current IOS VEE ≤ VCM ≤ VCC - 1.8V 1 10 nA
Input Voltage Range VIN+ , VIN-
Guaranteed by CMRR test,
TA = -40°C to +125°C VEE
VCC -
1.8 V
Common-Mode Rejection Ratio CMRR VEE + 0.3V ≤ VCM ≤ VCC - 1.8V 105 125 dB
VEE ≤ VCM ≤ VCC - 1.8V 105
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
www.maximintegrated.com Maxim Integrated
│
2
Absolute Maximum Ratings
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
8 μMAX
Junction-to-Ambient Thermal Resistance (θJA) .....206.3°C/W
Junction-to-Ambient Case Resistance (θJC) ...............42°C/W
6 TDFN-EP
Junction-to-Ambient Thermal Resistance (θJA) ..........42°C/W
Junction-to-Ambient Case Resistance (θJC) .................9°C/W
8 SO
Junction-to-Ambient Thermal Resistance (θJA) ........132°C/W
Junction-to-Ambient Case Resistance (θJC) ...............38°C/W
8 TDFN-EP
Junction-to-Ambient Thermal Resistance (θJA) ..........41°C/W
Junction-to-Ambient Case Resistance (θJC) .................8°C/W
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Package Thermal Characteristics
(VCC = 15V, VEE = -15V, VCM = 0V, RL = 10kΩ to GND, VGND = 0V, TA = -40°C to +125°C. Typical values are at TA = +25°C, unless
otherwise noted.) (Note 3)
Note 3: All devices are 100% production tested at TA = +25°C. Temperature limits are guaranteed by design.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Open-Loop Gain AVOL
-13.5V ≤ VO ≤ +13.5V, RL = 10kΩ,
TA = +25°C 115 130
dB
-13.5V ≤ VO ≤ +13.5V, RL = 10kΩ,
TA = -40°C to +125°C 100
-12V ≤ VO ≤ +12V, RL = 600Ω,
TA = +25°C 100 110
-12V ≤ VO ≤ +12V, RL = 600Ω,
TA = -40°C to +85°C 90
Output Voltage Swing
VOH
RL = 10kΩ VCC -
0.2
V
RL = 600Ω TA = +25°C VCC -
1.8
TA = -40°C to +85°C VCC - 2
VOL
RL = 10kΩ VEE +
0.1
RL = 600Ω
TA = +25°C VEE + 1
TA = -40°C to +85°C VEE +
1.1
Short-Circuit Current ISC
TA = +25°C 60 mA
TA = -40°C to +125°C 100
AC CHARACTERISTICS
Gain Bandwidth Product GBWP 2.4 MHz
Slew Rate SR -5V ≤ VOUT ≤ +5V 0.35 V/µs
Input Voltage Noise Density enf = 1kHz 17.6 nV/√Hz
Input Voltage Noise TOTAL NOISE 0.1Hz ≤ f ≤ 10Hz 500 nVP-P
Input Current Noise Density Inf = 1kHz 0.18 pA/√Hz
Capacitive Loading CLOAD No sustained oscillation 1000 pF
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
www.maximintegrated.com Maxim Integrated
│
3
Electrical Characteristics (continued)
(VCC = 15V, VEE = -15V, VCM = 0V, RL = 10kΩ to GND, VGND = 0V, TA = +25°C, unless otherwise noted.)
0
20
10
40
30
60
50
70
-0.3 -0.2
-0.15
-0.1
-0.25 -0.05
00.050.1
0.15
0.20.25 0.3
INPUT VOLTAGE OFFSET
DRIFT HISTOGRAM
MAX9943 toc02
V
OS
DRIFT (µV/°C)
FREQUENCY (%)
300
400
350
500
450
550
600
650
700
6 14 1810 22 26 30 34 38
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX9943 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
300
400
600
500
700
800
-50 0-25 25 50 75 100 125
SUPPLY CURRENT vs. TEMPERATURE
MAX9943 toc04
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
0
5
10
15
20
25
30
6 1410 18 22 26 30 34 38
OFFSET VOLTAGE vs. SUPPLY VOLTAGE
MAX9943 toc05
SUPPLY VOLTAGE (V)
OFFSET VOLTAGE (µV)
0
10
5
20
15
25
30
-14 -2 2-10 -6 6 10 14
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
MAX9943 toc06
COMMON-MODE VOLTAGE (V)
OFFSET VOLTAGE (µV)
0
5
10
15
20
25
-60 -40 -30-50 -20 -10 02010 30 40 50 60
OFFSET VOLTAGE HISTOGRAM
MAX9943 toc01
OFFSET VOLTAGE (µV)
FREQUENCY (%)
-40
0
-20
40
20
80
60
100
-50 0 25-25 50 75 100 125
OFFSET VOLTAGE vs. TEMPERATURE
MAX9943 toc07
TEMPERATURE (°C)
OFFSET VOLTAGE (µV)
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
Maxim Integrated
│
4
www.maximintegrated.com
Typical Operating Characteristics
(VCC = 15V, VEE = -15V, VCM = 0V, RL = 10kΩ to GND, VGND = 0V, TA = +25°C, unless otherwise noted.)
0
1.0
0.5
2.0
1.5
2.5
3.0
-14 -2 2-10 -6 6 10 14
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
MAX9943 toc08
COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (nA)
0
0.5
1.0
1.5
2.0
2.5
3.0
6 1410 18 22 26 30 34 38
INPUT BIAS CURRENT
vs. SUPPLY VOLTAGE
MAX9943 toc09
SUPPLY VOLTAGE (V)
INPUT BIAS CURRENT (nA)
COMMON-MODE REJECTION
RATIO vs. FREQUENCY
MAX9943 toc10
FREQUENCY (kHz)
CMRR (dB)
10001000.01 0.1 1 10
70
80
90
100
110
120
130
140
60
0.001 10,000
POWER-SUPPLY REJECTION
RATIO vs. FREQUENCY
MAX9943 toc11
FREQUENCY (kHz)
PSRR (dB)
10001000.01 0.1 1 10
20
40
60
80
100
120
140
160
0
0.001 10,000
VOH vs. OUTPUT CURRENT
MAX9943 toc12
0 105 15 20 25 30
OUTPUT VOLTAGE (V)
16
15
14
13
12
TA = +85°C
TA = +25°C
TA = -40°C
OUTPUT CURRENT (mA)
TA = +125°C
VOL vs. OUTPUT CURRENT
MAX9943 toc13
OUTPUT VOLTAGE (V)
0 105 15 20 25 30
-12
-13
-14
-15
-16
TA = +85C
TA = +125C
TA = -40C
TA = +25C
OUTPUT CURRENT (mA)
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
Maxim Integrated
│
5
www.maximintegrated.com
Typical Operating Characteristics (continued)
(VCC = 15V, VEE = -15V, VCM = 0V, RL = 10kΩ to GND, VGND = 0V, TA = +25°C, unless otherwise noted.)
OUTPUT IMPEDANCE vs. FREQUENCY
MAX9943 toc14
FREQUENCY (kHz)
OUTPUT IMPEDANCE (
Ω)
1000100101
0.1
1
10
100
1000
0.01
0.1 10,000
INPUT VOLTAGE NOISE
vs. FREQUENCY
MAX9943 toc15
FREQUENCY (Hz)
10,000100010010
10
20
30
40
50
60
70
80
90
100
0
1 100,000
INPUT VOLTAGE NOISE (nV/
Hz)
OPEN-LOOP GAIN vs. FREQUENCY
MAX9943 toc16
FREQUENCY (kHz)
OPEN-LOOP GAIN (dB)
100
10
0.0001
0.001 0.01 0.1 1
0
20
40
60
80
100
120
140
-20
0.00001 1000
10,000
CAPACITIVE LOAD vs. RESISTIVE LOAD
MAX9943 toc17
RLOAD (Ω)
CLOAD (pF)
1000 10,000
1000
10,000
100,000
100
100 100,000
STABLE
UNSTABLE
10µs/div
LARGE SIGNAL-STEP RESPONSE
1V/div
MAX9943 toc19
OUT
1µs/div
SMALL SIGNAL-STEP RESPONSE
20mV/div
MAX9943 toc18
OUT
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
Maxim Integrated
│
6
www.maximintegrated.com
Typical Operating Characteristics (continued)
MAX9943
6 TDFN-EP
MAX9943
8 µMAX
MAX9944
8 SO/TDFN-EP NAME FUNCTION
1 6 — OUT Output
— — 1 OUTA Output A
— — 7 OUTB Output B
2 4 4 VEE Negative Power Supply. Bypass with a 0.1µF capacitor to ground.
3 3 — IN+ Positive Input
— — 3 INA+ Positive Input A
— — 5 INB+ Positive Input B
4 2 — IN- Negative Input
— — 2 INA- Negative Input A
— — 6 INB- Negative Input B
5 1, 5, 8 — N.C. No Connection
6 7 8 VCC Positive Power Supply. Bypass with a 0.1µF capacitor to ground.
— — — EP Exposed Pad (TDFN Only). Connect to a large VEE plane to maximize
thermal performance. Not intended as an electrical connection point.
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
www.maximintegrated.com Maxim Integrated
│
7
Pin Descriptions
MAX9943
TOP VIEW
8 µMAX
4
5
6
3
2
1
IN+
OUT
VEE
IN-
VCC
N.C.
MAX9943
TOP VIEW
*EP
TOP VIEW
6 TDFN
OUT
N.C.
8
7
N.C.
VCC
6
5
VEE
1
2IN-
IN+
N.C.
3
4
MAX9944
8 SO
OUTB
INB+
8
7
INB-
VCC
6
5
VEE
1
2INA-
INA+
OUTA
3
4
MAX9944
OUTB
INB+
8
7
INB-
VCC
6
5
VEE
1
2INA-
INA+
OUTA
3
4
TOP VIEW
8 TDFN
*EP
NOT TO SCALE.
*EP = EXPOSED PAD.
+
+
+
4
5
6
3
2
1
IN+
OUT
VEE
IN-
VCC
N.C.
MAX9943
*EP
TOP VIEW
6 TDFN-EP
Pin Congurations
Detailed Description
The MAX9943/MAX9944 are single/dual operational
amplifiers designed for industrial applications. They
operate from 6V to 38V supply range while maintaining
excellent performance. These devices utilize a three-
stage architecture optimized for low offset voltage and low
input noise with only 550μA supply current. The devices
are unity gain stable with a 1nF capacitive load. These
well-matched devices guarantee the high open-loop gain,
CMRR, PSRR, and low voltage offset.
The MAX9943/MAX9944 provide a wide input/output
voltage range. The input terminals of the MAX9943/
MAX9944 are protected from excessive differential
voltage with back-to-back diodes. The input signal current
is also limited by an internal series resistor. With a 40V
differential voltage, the input current is limited to 20mA.
The output can swing to the negative rail while delivering
20mA of current, which is ideal for loop-powered system
applications. The specifications and operation of the
MAX9943/MAX9944 family is guaranteed over the -40°C
to +125°C temperature range.
Application Information
Bias Current vs. Input Common Mode
The MAX9943/MAX9944 use an internal bias current
cancellation circuit to achieve very low bias current over
a wide input common-mode range. For such a circuit to
function properly, the input common mode must be at
least 300mV away from the negative supply VEE. The
input common mode can reach the negative supply VEE.
However, in the region between VEE and VEE + 0.3V,
there is an increase in bias current for both inputs.
Capacitive Load Stability
Driving large capacitive loads can cause instability in many
op amps. The MAX9943/MAX9944 are stable with capacitive
loads up to 1nF. The Capacitive Load vs. Resistive Load
graph in the Typical Operating Characteristics gives the
stable operation region for capacitive versus resistive loads.
Stability with higher capacitive loads can be improved
by adding an isolation resistor in series with the op-amp
output, as shown in Figure 1. This resistor improves the
circuit’s phase margin by isolating the load capacitor from
the amplifier’s output.
Power Supplies and Layout
The MAX9943/MAX9944 can operate with dual supplies
from ±3V to ±19V or with a single supply from +6V to +38V
with respect to ground. When used with dual supplies,
bypass both VCC and VEE with their own 0.1μF capacitor
to ground. When used with a single supply, bypass VCC
with a 0.1μF capacitor to ground. Careful layout technique
helps optimize performance by decreasing the amount of
stray capacitance at the op amp’s inputs and outputs. To
decrease stray capacitance, minimize trace lengths by
placing external components close to the op amp’s pins.
Output Current Capability
The MAX9943/MAX9944 are capable of driving heavy
loads such as the ones that can be found in loop-powered
systems for remote sensors. The information is transmitted
through ±20mA or 4mA–20mA current output across
long lines that are terminated with low resistance loads
(e.g., 600Ω). The Typical Application Circuit shows the
MAX9944 used as a voltage-to-current converter with a
current-sense amplifier in the feedback loop. Because
of the high output current capability of the MAX9944, the
device can be used to directly drive the current-loop.
The specifications and operation of the MAX9943/MAX9944
family is guaranteed over the -40°C to +125°C temperature
range, However, when used in applications with ±15V
supply voltage (see Figure 3), the capability of driving more
than ±20mA of current is limited to the -40°C to +85°C
temperature range. Use a lower supply voltage if this
current must be delivered at a higher temperature range.
Figure 1. Capacitive Load Driving Circuit
Figure 2. Input Protection Circuit
RISO
INPUT
OUTPUT
CL
MAX9943
1.5kΩ
1.5kΩ
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
www.maximintegrated.com Maxim Integrated
│
8
Input Common Mode and Output Swing
The MAX9943/MAX9944 input common-mode range can
swing to the negative rail VEE. The output voltage can
swing to both the positive VCC and the negative VEE
rails if the output stage is not heavily loaded. These two
features are very important for applications where the
MAX9943/MAX9944 are used with a single-supply (VEE
connected to ground). One of the applications that can
benefit from these features is when the single-supply op
amp is driving an ADC.
Input Differential Voltage Protection
During normal op-amp operation, the inverting and
noninverting inputs of the MAX9943/MAX9944 are at
essentially the same voltage. However, either due to fast
input voltage transients or due to other fault conditions,
these pins can be forced to be at two different voltages.
Internal back-to-back diodes and series resistors protect
the inputs from an excessive differential voltage (see
Figure 2). Therefore, IN+ and IN- can be any voltage
within the range shown in the absolute maximum rating.
Note the protection time is still dependent on the package
thermal limits.
Figure 3. Typical ±20mA Current-Source in Loop-Powered Systems
-15V
RSENSE
RLOAD
VREF
-15V
+15V
DAC
MAX9944
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
www.maximintegrated.com Maxim Integrated
│
9
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
8 μMAX U8+1 21-0036 90-0092
6 TDFN-EP T633+2 21-0137 90-0058
8 SO S8+4 21-0041 90-0096
8 TDFN-EP T833+2 21-0137 90-0059
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
www.maximintegrated.com Maxim Integrated
│
10
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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.
Chip Information
PROCESS: BiCMOS
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
PART TEMP RANGE PIN-
PACKAGE
TOP
MARK
MAX9943AUA+ -40°C to +125°C 8 µMAX AACA
MAX9943ATT+ -40°C to +125°C 6 TDFN-EP* AUF
MAX9944ASA+ -40°C to +125°C 8 SO —
MAX9944ATA+ -40°C to +125°C 8 TDFN-EP* BLN
Ordering Information
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 3/09 Initial release —
1 4/09 Removed future product reference for the MAX9944, updated EC table 1, 2
2 6/09 Corrected TOC 13 and added rail-to-rail output feature 1, 3, 5, 8
3 4/11 Updated Pin Description section 7
4 10/17 Added TOC20 to Typical Operating Characteristics section 6
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX9943/MAX9944 High-Voltage, Precision, Low-Power Op Amps
© 2017 Maxim Integrated Products, Inc.
│
11
Revision History
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
