General Description
The MAX5491 precision resistor-divider consists of two
accurately matched resistors with access to the ends
and center of the divider. This device offers excellent
resistance matching of 0.035% (A grade), 0.05% (B
grade), and 0.1% (C grade). The MAX5491 includes an
extremely low resistance-ratio temperature drift of
2ppm/°C over -40°C to +85°C, and has an end-to-end
resistance of 30kΩ. Resistance ratios from 1:1 to 30:1 are
available. Ten standard ratios are available (see Table
1), and custom ratios are also available upon request. To
enhance device and system robustness, the MAX5491
also features ±2kV Human Body Model electrostatic dis-
charge (ESD) protection to ensure against real-world
ESD events. The MAX5491 is ideal for precision gain-set-
ting applications where tight resistance matching and
low temperature drift are necessary.
The MAX5491 is available in a space-saving 3-pin
SOT23 package, and is guaranteed over the extended
-40°C to +85°C temperature range.
Applications
Industrial Process Control
Instrumentation
Precision Gain Setting
Medical Equipment
Automatic Test Equipment
Base Stations
Features
♦Resistance Ratios from 1:1 to 30:1
♦Custom Ratios Available Upon Request
♦±2kV Human Body Model ESD Protection
♦Tight Initial Ratio Accuracy
0.035% (MAX5491A)
0.05% (MAX5491B)
0.1% (MAX5491C)
♦Low 2ppm/°C Resistor-Ratio-Drift
♦Up to 50V Operating Voltage Across Sum of R1
and R2
♦Tiny 3-Pin SOT23 Package
MAX5491
Precision-Matched Resistor-Divider in SOT23
________________________________________________________________ Maxim Integrated Products 1
P2
1
3P3
P1
MAX5491
SOT23
TOP VIEW
2
Pin Configuration
Ordering Information*
P1
P2
P3
MAX5491
R2
R1
Block Diagram
19-3009; Rev 3; 12/04
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
*See the How to Order section for more details.
PA R T T EM P
R A N G E
PIN -
PA C K A G E
RA TIO
AC CUR ACY
(%)
MAX5491_A_ _ _ _ _ -T -40°C to +85°C 3 SOT23-3 0.035
MAX5491_B_ _ _ _ _ -T -40°C to +85°C 3 SOT23-3 0.05
MAX5491_C_ _ _ _ _ -T -40°C to +85°C 3 SOT23-3 0.1
MAX5491
Precision-Matched Resistor-Divider in SOT23
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
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.
Voltage Between P1 and P2...................................................50V
Continuous Current into Any Pin....................................±1.75mA
Continuous Power Dissipation (TA = +70°C)
3-Pin SOT23 (derate 7.1mW/°C above +70°C).........571.4mW
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
MAX5491_A, TA = +25°C ±0.035
MAX5491_B, TA = +25°C ±0.05
Initial Resistor Ratio Error (Note 2)
MAX5491_C, TA = +25°C ±0.1
%
1:1 ≤ ratio ≤ 3.2:1 2
3.2:1 < ratio ≤ 10:1 4
Resistance-Ratio Temperature
Coefficient (Note 3) 10:1 < ratio ≤ 30:1 5.5
ppm/°C
Absolute Temperature Coefficient
of Resistance TCR (Note 4) 35 ppm/°C
Voltage Coefficient of Resistance VCR (Note 5) 0.1 ppm/V
End-to-End Resistance (R1 + R 2) 28.5 30 31.5 kΩ
Continuous Current IR1, IR2 ±1.75 mA
Continuous Working Voltage
Between P1 and P2 VP1-P2 050V
Power Rating 87.5 mW
Pin Capacitance 2pF
Resistance Ratio Long-Term
Stability 2000hr at +70°C ±0.03 %
Note 1: The MAX5491 is 100% production tested at TA= +25°C. Specifications over -40°C to +85°C are guaranteed by design.
Note 2: Testing conditions: TA= +25°C, VP1-P2 = 9V and 50V.
Note 3: Resistance-ratio temperature coefficient is defined as
Note 4: Absolute TCR is defined as
and is tested at 9V and 50V.
Note 5: Resistance-ratio voltage coefficient is defined as
∆
∆
R
R
R
RT
1
2
1
2
⎛
⎝
⎜⎞
⎠
⎟
×
∆
∆
R
R
R
RV
1
2
1
2
⎛
⎝
⎜⎞
⎠
⎟
×
∆
∆
RR
RR T
12
12
+
()
+
()
×
MAX5491
Precision-Matched Resistor-Divider in SOT23
_______________________________________________________________________________________ 3
NORMALIZED RESISTOR-RATIO DRIFT
vs. TEMPERATURE
MAX5491 toc01
TEMPERATURE (°C)
RATIO DRIFT (ppm)
7550-25 0 25
-300
-200
-100
0
100
200
300
400
-400
-50 100
VP1-P2 = 10V
RATIO = 1:1
NORMALIZED RESISTOR-RATIO DRIFT
vs. TEMPERATURE
MAX5491 toc02
TEMPERATURE (°C)
RATIO DRIFT (ppm)
7550-25 0 25
-300
-200
-100
0
100
200
300
400
-400
-50 100
VP1-P2 = 10V
RATIO = 5:1
Typical Operating Characteristics
(VP1-P2 = 10V, TA= +25°C, unless otherwise noted.)
Pin Description
PIN NAME FUNCTION
1P1R
1 Connection Terminal
2P2R
2 Connection Terminal
3 P3 Midpoint Between R1 and R2 Connection Terminals
Detailed Description
As shown in the Block Diagram, the MAX5491 consists
of two precision, low-ratio-drift resistors with an end-to-
end resistance of 30kΩ(R1+ R2). P3 is the center tap
of the divider. The maximum working voltage of the
MAX5491 is 50V. This device offers a wide range of
resistance ratios (R1/R2) from 1:1 to 30:1 and is ideally
suited for precision operational amplifier gain/attenua-
tion control. The MAX5491 features a ±2kV ESD protec-
tion that enhances system robustness. A maximum
initial ratio accuracy of 0.035% and a low 2ppm/°C ratio
drift enhance system accuracy.
MAX5491
Applications Information
Self-Heating and Error
Applying a voltage across terminals P1 and P2 causes
the device to heat up due to power dissipation. In high-
voltage applications, consider the error in resistance-
ratio temperature coefficient caused by self-heating.
The worst-case self-heating occurs when the operating
voltage attains its maximum value. Approximate the
result of power dissipation under this condition as:
The thermal resistance from junction to ambient, θJ-A,
for a 3-pin SOT23 package is 141°C/W. Calculate the
resulting temperature rise as:
∆T = 83.3mW x 141°C/W = 11.7°C
If the ratio temperature coefficient is 2ppm/°C (typ), the
total error introduced by self-heating is:
11.7°C x 2ppm/°C = 23.4ppm
PV
R
V
kmW
DISS MAX
.=
()
=
()
=
22
50
30 83 3
Ω
Precision-Matched Resistor-Divider in SOT23
4 _______________________________________________________________________________________
IN
P1
P2
P3
MAX5491
R2
R1
OUT
Figure 3. Buffered Attenuator
MAX5491
R2R1
P1
P2
P3
IN
OUT
Figure 1. Inverting Amplifier Configuration
P1
P2
P3
MAX5491
R2
R1
OUT
IN
Figure 4. Attenuator with Buffer
MAX5491
R2R1
P1
P2
P3
IN
OUT
Figure 2. Noninverting Amplifier Configuration
AV
V
R
R
OUT
IN
==−
1
2
AV
V
R
R
OUT
IN
==+11
2
AV
V
R
RR
OUT
IN
==
+
2
12
AV
V
R
RR
OUT
IN
==
+
2
12
Typical Applications
Example Part Numbers
MAX5491
Precision-Matched Resistor-Divider in SOT23
_______________________________________________________________________________________ 5
PREFIX MAX 5491 V A 10000 -T
ROOT PART NUMBER
MAX5491 = 30kΩ End-to-End
RATIO RANGE
L through W. Resistor ratio must fall in the appropriate
ratio range. (See Table 2.)
RATIO ACCURACY
A = 0.035% (max); B = 0.05% (max); C = 0.1% (max)
RESISTANCE RATIO
Five number ratio designator. Ratios available from 1:1 to 30:1.
Format examples:
010000 = 1:1
02500 = 2.5:1
07538 = 7.538:1
25000 = 25:1
TAPE AND REEL
How to Order
PART RESISTOR-RATIO RANGE RESISTOR-RATIO
ACCURACY (% MAX) RESISTOR RATIO
MAX5491RA02500-T 2.000 to 2.899 0.035 2.5:1
MAX5491VC10000-T 10.000 to 15.999 0.100 10:1
MAX5491SB03200-T 2.900 to 3.999 0.050 3.2:1
MAX5491UA07538-T 6.000 to 9.999 0.035 7.538:1
Table 1. Standard Ratios*
PART RESISTOR RATIO RESISTOR-RATIO
SUFFIX
RESISTOR-RATIO
ACCURACY (% MAX) TOP MARK
MAX5491LA01000-T 1:1 01000 0.035 FZPD
MAX5491LB01000-T 1:1 01000 0.050 FZPE
MAX5491LC01000-T 1:1 01000 0.100 FZPF
MAX5491MA01100-T 1.1:1 01100 0.035 FZPA
MAX5491MB01100-T 1.1:1 01100 0.050 FZPB
MAX5491MC01100-T 1.1:1 01100 0.100 FZPC
MAX5491NA01500-T 1.5:1 01500 0.035 FZOX
MAX5491NB01500-T 1.5:1 01500 0.050 FZOY
MAX5491NC01500-T 1.5:1 01500 0.100 FZOZ
MAX5491PA02000-T 2:1 02000 0.035 FZOO
MAX5491PB02000-T 2:1 02000 0.050 FZOP
MAX5491PC02000-T 2:1 02000 0.100 FZOQ
MAX5491RA02500-T 2.5:1 02500 0.035 FZPP
MAX5491
Precision-Matched Resistor-Divider in SOT23
6 _______________________________________________________________________________________
Table 1. Standard Ratios* (continued)
PART RESISTOR RATIO RESISTOR-RATIO
SUFFIX
RESISTOR-RATIO
ACCURACY (% MAX) TOP MARK
MAX5491RB02500-T 2.5:1 02500 0.050 FZPQ
MAX5491RC02500-T 2.5:1 02500 0.100 FZON
MAX5491SA03200-T 3.2:1 03200 0.035 FZOU
MAX5491SB03200-T 3.2:1 03200 0.050 FZOV
MAX5491SC03200-T 3.2:1 03200 0.100 FZOW
MAX5491TA05000-T 5:1 05000 0.035 FZOR
MAX5491TB05000-T 5:1 05000 0.050 FZOS
MAX5491TC05000-T 5:1 05000 0.100 FZOT
MAX5491UA07538-T 7.538:1 07538 0.035 FZPM
MAX5491UB07538-T 7.538:1 07538 0.050 FZPN
MAX5491UC07538-T 7.538:1 07538 0.100 FZPO
MAX5491VA10000-T 10:1 10000 0.035 FZPJ
MAX5491VB10000-T 10:1 10000 0.050 FZPK
MAX5491VC10000-T 10:1 10000 0.100 FZPL
MAX5491WA30000-T 30:1 30000 0.035 FZPG
MAX5491WB30000-T 30:1 30000 0.050 FZPH
MAX5491WC30000-T 30:1 30000 0.100 FZPI
*Standard ratios are available for ordering in any quantity. Nonstandard ratios are also available for values between 1:1 to 30:1.
A minimum order quantity of 10,000 units is required for nonstandard ratios. Please contact factory for more information.
Table 2. Ratio Ranges
LETTER SUFFIX RESISTOR-RATIO RANGE
L 1.000 to 1.099
M 1.100 to 1.349
N 1.350 to 1.699
P 1.700 to 2.000
R 2.001 to 2.899
S 2.900 to 3.999
T 4.000 to 5.999
U 6.000 to 9.999
V 10.000 to 15.999
W 16.000 to 30.000
Chip Information
TRANSISTOR COUNT: 0
PROCESS: BiCMOS
MAX5491
Precision-Matched Resistor-Divider in SOT23
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7
© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
SOT23 L.EPS
F
1
1
21-0051
PACKAGE OUTLINE, 3L SOT-23
