This device is specified for current
handling of up to 50A over the entire –40°C to
+125°C temperature range using a 2oz copper pour
for the input power plane, as well as no external
airflow passing over the device.
The primary current-handling limitation
for this device is how much heat is dissipated
inside the package. Efforts to improve heat
transfer out of the package and into the
surrounding environment improve the ability of the
device to handle currents of up to 50A over a
wider temperature range.
Heat transfer improvements primarily
involve larger copper power traces and planes with
increased copper thickness (2oz.), as well as
providing airflow to pass over the device. Thermal
vias help spread the current and power dissipated
over multiple board layers. The INA790x evaluation module
(EVM) features a 2oz copper pour for the planes,
and is capable of supporting 50A at temperatures
up to 125°C.
The bypass capacitor must be placed
close to device ground and supply pins, but can be
moved farther out if needed to avoid cutting
thermal planes. The recommended value of this
bypass capacitor is 0.1µF. Additional decoupling
capacitance can be added to compensate for noisy
or high-impedance power supplies.