INA190EVM Circuit and Components
6
SBOU201A – April 2018 – Revised September 2018
Copyright © 2018, Texas Instruments Incorporated
INA190EVM User's Guide
4.8
J0x, J1x
J0x and J1x are 0.240 inch non-insulated, quick-fit terminals that are designed to insert into similarly-sized
female receptacles. The kit provides two receptacles. Using insulated receptacles with J0x and J1x
terminals allows the user to ensure a strong and safe connection between the current source and EVM
when dealing with high currents.
WARNING
If using the EVM to measure currents, ensure a proper power
resistor is soldered at the R8x pad and the receptacles (connecting
to J0x and J1x) and their crimped wires can support the amperage
of
the
current
being
measured
and
the
necessary
power
dissipation. Do not exceed 15 A of current flowing between J0x
and J1x. If using the "Guarded Inputs" panel, ensure current
flowing from J0 to J1 does not exceed 10 A. Failure to do any of
this could result in hot surfaces (> 55°C), damage to the EVM, or
personal injury.
Standard metal clips can electrically interface with these tabs for lower currents.
The IN+ (J0x) and IN– (J1x) inputs accept a differential voltage that is amplified by the selected device
gain and is presented at the OUT test point (TP5x). These inputs could also be used to connect the
differential voltage developed across an external shunt in an existing circuit. The acceptable differential
input voltage range and polarity are determined by the supply voltage, reference voltage, and gain of the
selected device.
5
Reference Voltage Setup
The INA190 devices allow for the use of an external reference through the REF pin. The INA190EVM
provides a test point to drive the REF pin externally or pads to solder a buffer amplifier to drive a custom
voltage generated from the resistor divider off the VS power plane. The reference determines what offset
the output will have and allows these devices to be used in both unidirectional and bi-directional current
sensing applications.
5.1
Unidirectional Mode
Unidirectional
refers to a load current that flows in only one direction. For unidirectional applications, the
reference voltage can be set to ground or to 5 V. If the reference is set to ground, the output is set at near
ground with no input voltage, and responds to input voltages that are positive with respect to IN– / Load. If
the reference is set to 5 V, the output is set near 5 V with no input voltage, and responds to input voltages
that are negative with respect to IN– / Load.
5.2
Bi-Directional Mode
Bi-directional
refers to a load current that flows in both directions. For bi-directional applications, the
reference voltage should be set anywhere within the GND to VS range. The voltage applied to the
reference pin establishes the output voltage of the device with no input voltage. The output voltage is
limited by the supply voltage minus the specified output swing to VS in the data sheet.
5.3
REF Pin Configuration
The REF test point (TP6x) allows configuration of the INA190EVM for either unidirectional or bi-directional
operation. The INA190EVM has an onboard circuit that allows the supply of a custom reference voltage
that is powered through the supply voltage.
