19-3009; Rev 1; 2/04
Precision-Matched Resistor-Divider in SOT23
MAX5491
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.
♦
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
Features
Applications
Industrial Process Control
Instrumentation
Precision Gain Setting
Medical Equipment
Automatic Test Equipment
Base Stations
PART
Ordering Information*
TEMP
RANGE
RATIO
PIN-
ACCURACY
PACKAGE
(%)
0.035
0.05
0.1
MAX5491
_
A
_ _ _ _ _
-T -40°C to +85°C 3 SOT23-3
MAX5491
_
B
_ _ _ _ _
-T -40°C to +85°C 3 SOT23-3
MAX5491
_
C
_ _ _ _ _
-T -40°C to +85°C 3 SOT23-3
*See
the How to Order section for more details.
Block Diagram
TOP VIEW
P1
Pin Configuration
MAX5491
R
1
P3
R
2
P2
2
P1
1
MAX5491
3
P3
P2
SOT23
________________________________________________________________
Maxim Integrated Products
1
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.
Precision-Matched Resistor-Divider in SOT23
MAX5491
ABSOLUTE MAXIMUM RATINGS
Voltage Between P1 and P2...................................................50V
Continuous Current into Any Pin....................................±1.75mA
Continuous Power Dissipation (T
A
= +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
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.
DC ELECTRICAL CHARACTERISTICS
(T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Initial Resistor Ratio Error (Note 2)
SYMBOL
CONDITIONS
MAX5491_A, T
A
= +25°C
MAX5491_B, T
A
= +25°C
MAX5491_C, T
A
= +25°C
Resistance-Ratio Temperature
Coefficient (Note 3)
Absolute Temperature Coefficient
of Resistance
Voltage Coefficient of Resistance
End-to-End Resistance (R
1
+ R
2
)
Continuous Current
Continuous Working Voltage
Between P1 and P2
Power Rating
Pin Capacitance
Resistance Ratio Long-Term
Stability
2000hr at +70°C
2
±0.03
V
P1-P2
I
R1
, I
R2
0
TCR
VCR
1:1
≤
ratio
≤
3.2:1
3.2:1 < ratio
≤
10:1
10:1 < ratio
≤
30:1
(Note 4)
(Note 5)
28.5
2
4
5.5
35
0.1
30
31.5
±1.75
50
87.5
ppm/°C
ppm/V
kΩ
mA
V
mW
pF
%
ppm/°C
MIN
TYP
MAX
±0.035
±0.05
±0.1
%
UNITS
Note 1:
The MAX5491 is 100% production tested at T
A
= +25°C. Specifications over -40°C to +85°C are guaranteed by design.
Note 2:
Testing conditions: T
A
= +25°C, V
P1-P2
= 9V and 50V.
Note 3:
Resistance-ratio temperature coefficient is defined as
R
∆
1
R
2
R
1
×
∆
T
R
2
Note 4:
Absolute TCR is defined as
and is tested at 9V and 50V.
∆
(
R
1
+
R
2
)
(
R
1
+
R
2
)
×
∆
T
R
∆
1
R
2
R
1
×
∆
V
R
2
Note 5:
Resistance-ratio voltage coefficient is defined as
2
_______________________________________________________________________________________
Precision-Matched Resistor-Divider in SOT23
MAX5491
Typical Operating Characteristics
(V
P1-P2
= 10V, T
A
= +25°C, unless otherwise noted.)
NORMALIZED RESISTOR-RATIO DRIFT
vs. TEMPERATURE
MAX5491 toc01
NORMALIZED RESISTOR-RATIO DRIFT
vs. TEMPERATURE
300
200
RATIO DRIFT (ppm)
100
0
-100
-200
-300
-400
V
P1-P2
= 10V
RATIO = 5:1
MAX5491 toc02
400
300
200
RATIO DRIFT (ppm)
100
0
-100
-200
-300
-400
-50
-25
0
25
50
75
V
P1-P2
= 10V
RATIO = 1:1
400
100
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
Pin Description
PIN
1
2
3
NAME
P1
P2
P3
R
1
Connection Terminal
R
2
Connection Terminal
Midpoint Between R
1
and R
2
Connection Terminals
FUNCTION
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 (R
1
+ R
2
). 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 (R
1
/R
2
) 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.
_______________________________________________________________________________________
3
Precision-Matched Resistor-Divider in SOT23
MAX5491
Typical Applications
A
=
V
OUT
R
=
−
1
V
IN
R
2
OUT
A
=
IN
V
OUT
R
=
1
+
1
V
IN
R
2
OUT
P3
P3
P2
IN
R
2
R
1
MAX5491
P1
P2
R
2
R
1
MAX5491
P1
Figure 1. Inverting Amplifier Configuration
Figure 2. Noninverting Amplifier Configuration
IN
A
=
V
OUT
R
2
=
V
IN
R
1
+
R
2
IN
P1
A
=
V
OUT
R
2
=
V
IN
R
1
+
R
2
P1
MAX5491
R
1
MAX5491
R
1
P3
OUT
R
2
R
2
P3
OUT
P2
P2
Figure 3. Buffered Attenuator
Figure 4. Attenuator with Buffer
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:
P
DISS
=
4
The thermal resistance from junction to ambient,
θ
J-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
(
V
MAX
)
2
R
=
(
50V
)
2
30k
Ω
=
83.3mW
_______________________________________________________________________________________
Precision-Matched Resistor-Divider in SOT23
How to Order
PREFIX
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
MAX
5491
V
A
10000
-T
MAX5491
Example Part Numbers
PART
MAX5491RA02500-T
MAX5491VC10000-T
MAX5491SB03200-T
MAX5491UA07538-T
RESISTOR-RATIO RANGE
2.000 to 2.899
10.000 to 15.999
2.900 to 3.999
6.000 to 9.999
RESISTOR-RATIO
ACCURACY (% MAX)
0.035
0.100
0.050
0.035
RESISTOR RATIO
2.5:1
10:1
3.2:1
7.538:1
Table 1. Standard Ratios*
PART
MAX5491LA01000-T
MAX5491LB01000-T
MAX5491LC01000-T
MAX5491MA01100-T
MAX5491MB01100-T
MAX5491MC01100-T
MAX5491NA01500-T
MAX5491NB01500-T
MAX5491NC01500-T
MAX5491RA02000-T
MAX5491RB02000-T
MAX5491RC02000-T
MAX5491RA02500-T
RESISTOR RATIO
1:1
1:1
1:1
1.1:1
1.1:1
1.1:1
1.5:1
1.5:1
1.5:1
2:1
2:1
2:1
2.5:1
RESISTOR-RATIO
SUFFIX
01000
01000
01000
01100
01100
01100
01500
01500
01500
02000
02000
02000
02500
RESISTOR-RATIO
ACCURACY (% MAX)
0.035
0.050
0.100
0.035
0.050
0.100
0.035
0.050
0.100
0.035
0.050
0.100
0.035
TOP MARK
FZPD
FZPE
FZPF
FZPA
FZPB
FZPC
FZOX
FZOY
FZOZ
FZOO
FZOP
FZOQ
FZOL
_______________________________________________________________________________________
5
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