MAX44246
36V, Low-Noise, Precision, Dual Op Amp
The MAX11211 ADC operates from a single 2.7V to 3.6V
analog supply, offers 1ꢁ-bit noise-free resolution and
ꢂ.ꢁ6mW power dissipation. The MAX11211 also offers
> 1ꢂꢂdB rejection at ꢀꢂHz and 6ꢂHz. This ADC is part of
a family of 16-, 1ꢁ-, 2ꢂ-, and 24-bit delta sigma ADCs with
high precision and < 1mW power dissipation.
V
SUPPLY
I
LOAD
MAX44246
OUT
The low input offset voltage and low noise of MAX44246
allows a gain circuit to precede the MAX11211 without
losing any dynamic range at the ADC. See the Typical
Operating Circuit.
R
SENSE
R2
R1
Precision Low-Side Current Sensing
The ICs’ ultra-low offset voltage and drift make them
ideal for precision current-sensing applications. Figure 1
shows the ICs in a low-side current-sense configuration.
This circuit produces an accurate output voltage, V
OUT
Figure 1. Low-Side Current Sensing
equal to I
x R x (1 + R /R ).
SENSE 2 1
LOAD
the amplifier away from potential heat sources on the
board, if possible. Orient the resistors such that both
the ends are heated equally. It is a good practice to
match the input signal path to ensure that the type and
number of thermoelectric junctions remain the same. For
example, consider using dummy ꢂΩ resistors oriented
in such a way that the thermoelectric sources, due to
the real resistors in the signal path, are cancelled. It is
recommended to flood the PCB with ground plane. The
ground plane ensures that heat is distributed uniformly
reducing the potential offset voltage degradation due to
Seebeck effect.
Layout Guidelines
The MAX44246 features ultra-low offset voltage and
noise. Therefore, to get optimum performance follow the
following layout guidelines.
Avoid temperature gradients at the junction of two dis-
similar metals. The most common dissimilar metals used
on a PCB are solder-to-component lead and solder-to-
board trace. Dissimilar metals create a local thermo-
couple. A variation in temperature across the board can
cause an additional offset due to Seebeck effect at the
solder junctions. To minimize the Seebeck effect, place
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