
100k ? Precision-Matched Resistor-Divider in
SOT23
Typical Operating Characteristics (continued)
(V P1-P2 = 10V, T A = +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION
SPECTRAL NOISE DENSITY
PLUS NOISE RESPONSE
1000
RATIO 1:1
SIGNAL CONNECTED TO P2
P1 GROUNDED
100
10
1:1 RATIO
20Hz TO 20kHz BANDPASS
100
10
V P1-P2 = 2V
V P1-P2 = 10V
1
0.1
0.01
0.001
0.0001
1
10
100
1k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
Pin Description
PIN
1
2
3
NAME
P1
P2
P3
R 1 Connection Terminal
R 2 Connection Terminal
Set-Point Connection Terminal
FUNCTION
( V MAX ) 2 ( 80 V ) 2
P DISS = = = 64 mW
Detailed Description
As shown in the Block Diagram , the MAX5490 consists
of two precision, low-ratio-drift resistors with an end-to-
end resistance of 100k ? (R 1 + R 2 ). P3 is the set point
of the divider. The maximum working voltage of the
MAX5490 is 80V. This device offers a wide range of
resistance ratios (R 1 /R 2 ) from 1:1 to 100:1 and is ideal
for precision operational amplifier gain/attenuation con-
trol. A maximum initial ratio accuracy of 0.035% and a
low 1ppm/ ° C ratio drift enhance system accuracy.
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:
R 100 k ?
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 = 64mW x 141°C/W = 9.02°C
If the ratio temperature coefficient is 1ppm/°C (typ), the
total error introduced by self-heating is:
9.02 ° C x 1ppm/ ° C = 9.02ppm
4
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