3.6
Voltage Inputs
3.7
Miscellaneous
4
Reference Voltage Setup
4.1
Unidirectional Mode
4.2
Bi-directional Mode
www.ti.com
Reference Voltage Setup
The V
IN+
and V
IN–
terminals of T2 are intended to be used if the designer is configuring the EVM for
measurement without an onboard shunt resistor (see
). These inputs accept a differential voltage
that is amplified by the selected device gain and is presented at the V
OUT
terminal of T2. 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.
V
IN
and Load terminals of T1 are intended to be used if the user configures the EVM for measurement
with a shunt resistor (see
). The common-mode voltage should be connected to the V
IN
terminal
and the load should be connected to the Load terminal. The shunt can be installed in R1, R2, or the
prototype area, and wired to the R2 footprint. As in the setup for the measurement without a shunt
resistor, the input voltage range and polarity are determined by the supply voltage, reference voltage, and
the gain of the selected device.
The REF terminal of T3 allows the user to configure the INA210-214EVM for either unidirectional or
bi-directional operation
Two easily accessible oscilloscope ground pads are located on the board to facilitate easier probing.
The INA210-214 devices allow for the use of an external reference. This reference determines how the
output responds to certain input conditions. The reference also allows these devices to be used in both
unidirectional and bi-directional applications.
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 +5V. 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 V
IN–
/Load. If
the reference is set to +5V, the output is set near +5V with no input voltage, and responds to input
voltages that are negative with respect to V
IN–
/Load.
Bi-directional
refers to a load current that flows in both directions.
shows I
S
flowing in both
directions. For bi-directional applications, the reference voltage can be set anywhere within the 0V to 5V
range specified for the reference input. 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, so there is
a greater available range for positive input voltages than negative voltages because the reference voltage
is limited to the range of 0V to 5V.
The maximum range for the output of this device to accommodate a bi-directional application involves
applying 5V to the reference pin and a supply voltage of 18V. This configuration allows for a maximum
output voltage range of –4.95V/+20.8V about the 5V reference.
SBOU065 – August 2008
INA210-214EVM User's Guide
11
