Datasheet

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, 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
P
V
R
V
k
mW
DISS
MAX
.=
()
=
()
=
22
50
30
83 3
Ω
Precision-Matched Resistor-Divider in SOT23
4 _______________________________________________________________________________________
IN
P1
P2
P3
MAX5491
R
2
R
1
OUT
Figure 3. Buffered Attenuator
MAX5491
R
2
R
1
P1
P2
P3
IN
OUT
Figure 1. Inverting Amplifier Configuration
P1
P2
P3
MAX5491
R
2
R
1
OUT
IN
Figure 4. Attenuator with Buffer
MAX5491
R
2
R
1
P1
P2
P3
IN
OUT
Figure 2. Noninverting Amplifier Configuration
A
V
V
R
R
OUT
IN
==−
1
2
A
V
V
R
R
OUT
IN
==+1
1
2
A
V
V
R
RR
OUT
IN
==
+
2
12
A
V
V
R
RR
OUT
IN
==
+
2
12
Typical Applications