In order for the remote sense feature
of the TPS40100EVM-001 to function properly, it is essential that the test setup be
configured correctly. Use the following steps to set up the remote sense:
- Ensure that the remote sense
jumpers J7 and J8 are shunted across pins 1 and 2.
- Connect load wires with a maximum
length of six inches from pin 2 of J5 (+Vout) to the positive terminal of the
load. Connect the same length of wire from pin 3 of J5 (RTN) to the negative
terminal of the load. Be sure to properly gauge the load wires for 10 A. AWG#16
is recommended.
- Connect a sense wire from J5 pin
1 to the positive terminal of the load. This is the +senseline. Be sure to not
exceed six inches in length. AWG#22 wire is recommended.
- Connect a sense wire from J5 pin
4 to the negative terminal of the load. This is the –sense line. Be sure to not
exceed six inches in length. AWG#22 wire is recommended.
- Monitor voltage at TP13 and TP14
using a voltmeter. This will be the regulated voltage at the load.
- Monitor voltage at J5 pins 2 and
3. This is the voltage at the output connector. This voltage will increase based
on the load.
- Set load to 0 A, constant
current. Both monitoring points should read very close to the same value.
- Increase the load gradually and
observe the difference in voltages present at the monitoring points. The set
voltage (3.3 V) will be regulated at the load; this will be noted at TP13 and
TP14. The direct output of the converter (J5 pins 2 and 3) will read a higher
voltage. As IR losses increase over load wires and terminals, the direct output
of the converter will compensate by raising the voltage to keep within
regulation at the load.
CAUTION: Long distance runs
from the output of the converter and the load will cause erratic behavior. This can
show up as pulse width jitter or an oscillatory effect on the ripple voltage. If
this condition occurs, check the setup and make adjustments. Please see
Figure 5-3 for test setup.