Operation
9
SBOU209A – August 2019 – Revised March 2020
Copyright © 2019–2020, Texas Instruments Incorporated
TMCS1100EVM
WARNING
Do not leave EVM powered when unattended.
Hot surface. Contact may cause burns. Do not touch!
4.1
Measurements
The following procedures are used to configure a measurement evaluation with an electronic load. For the
following instructions, x = A to D for the A1 to A4 gain variants, respectively.
Step 1.
According to
, for a low-side measurement, connect the electronic load positive input
terminal to the positive terminal of a
≥
20-A capable hot-supply. For a high-side
measurement, connect the electronic load positive input terminal to the load sourcing terminal
(IS+ or IS–) of the EVM. For high-side measurement of forward current, IS– sources to the
electronic load; for reverse current, IS+ sources to the load. Reverse current can only be
measured if VREF is set to a potential higher than GND.
Step 2.
Connect the electronic load negative output terminal to the external hot supply GND terminal
for high-side measurements, or to the load sinking terminal of the EVM for low-side
measurements.
Step 3.
For high-side measurements, connect the external supply to the load sinking terminal of the
EVM. Otherwise, for low-side measurements, connect the load sourcing terminal of the EVM
(IS+ or IS–) to the external supply GND.
Step 4.
Turn on all the connected supplies.
Step 5.
Apply load with electronic load.
Step 6.
Measure the output voltage at the VOUT test point.
NOTE:
The output voltage is equal to the gain of the device multiplied by the load current passing
through the leadframe of the DUT.
4.2
Advanced Measurement Tips
To assess whether the expected load matches the measured load, use a precision shunt resistor rated for
the maximum intended current in series with the DUT. The precision shunt should have a kelvin
connection where the generated sense voltage can be measured by a precision multimeter, such as the
3458a multimeter. Sensing the shunt voltage is preferred as a typical multimeter may have a current limit
far below 20 A. Additionally, some meters have better voltage measurement precision than current
measurement precision.
For evaluating performance when the DUT is subjected to quick current pulses, use short, large-gauge
wire or short bus bars to reduce the inductance and resistance between the hot-supply, load, and EVM.
By minimizing the inductance, the rate of load slew can be increased. If assessing the performance over
large transient current spikes (>20 A) is desired, be sure to use a supply with sufficient voltage headroom
to accommodate the series resistance of the wires/bus bars, board planes, and DUT lead frame
resistance. A large capacitor bank between the supply terminals should be used to ensure there is an
adequate charge reservoir available to prevent the supply from drooping and help supply the large current
inrush through the device.
If assessing temperature performance is desired, use wide, thin bus bars to reduce the thermal sinking
ability of the system and minimize the inductance of the system. While the board provides an onboard
temperature sensor, board temperature may not be an exact indicator of DUT temperature. More precise
measurements can be obtained by placing a layer of thermally conductive grease on top of the DUT
package and placing a thermal sensor directly on the thermal grease.