Texas Instruments UCC14240EVM-052, User Manual

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4.3 Powering the EVM
CAUTION: Do not attempt to start the EVM by applying the EN shorting jumper while VIN and +5V DC Bias
power supplies are enabled. Doing so can result in unpredictable, erratic start up due to excessive signal bounce
induced at J3, EN, as seen in
Figure 4-2 . It is recommended to leave the EN shorting jumper in the J3:2-3
position and control ON/OFF by enabling or turning ON/OFF the +5V DC Bias power supply. If it is desired to
use the EN shorting jumper for ON/OFF control, a simple RC filter can be applied to the J3 header, on the
bottom of the PCB, as shown in
Figure 4-3 which gives the proper start-up signals shown in Figure 4-4 . Adding
the RC filter inverts the ENA logic as described in Table 4-1 such that removing the jumper turns ON the EVM
with controlled ENA and inserting the EN jumper into J3:1-2 (OFF) turns OFF the EVM. Applying the shorting
jumper to J3:2-3 (ON) has no effect, even though the RC filter is applied as shown in
Figure 4-3
Figure 4-2. ENA Erratic Signal Bounce Causing VDD Collapse (top: ENA, 5V/div, mid: /PG, 5V/div, bot:
VDD, 10V/div), time = 10ms/div unless otherwise noted.
Figure 4-3. RC Debounce Filter, J3 PCB Bottom, R=5.11 kΩ, C=100 nF
EVM Setup and Operation www.ti.com
8 Using the UCC14240EVM-052 for Biasing Traction Inverter Gate Driver ICs
Requiring Single, Positive or Dual, Positive/Negative Bias Power SLUUCJ2 – JULY 2021
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