Texas Instruments TPS7A74EVM-068, Руководство пользователя, Страница: 7 / 19

After the EVM is modified (if needed), connect a power supply to banana connectors J24 (VDD) and J30 (GND)
with a 5-V DC supply and a 1-A DC current limit. As illustrated in
Figure 2-3 and Figure 2-4 , the TPS7A74
transient response is very fast and the output voltage recovers in well under 1 ms after the initial load transient.
Use a pulse-duration limit of 1 ms to prevent excessive heating of the pulsed resistors (R12, R13, R14, R15,
and R16). Configure a function generator for the 50-Ω output, in a 0-V DC to 5-V DC square pulse. If necessary,
burst mode can be configured in the function generator for repetitive, low duty cycle, load transient testing.
Use J16 to short R2 to GND and configure VOUT to be 1-V DC. The series combination of R1 and R2 provide
50-μA of DC load current. A 20-kΩ resistor is installed on the EVM at R18, and a 20-kΩ resistor is installed on
the EVM at R20. These resistors provide approximately 0.75-A/μs slew rate from 0 mA to 1.5 A, and 0.5-A/μs
slew rate from 1.5 A to 0 mA.
Figure 2-3 and Figure 2-4 provide example test data with R18 = 20 kΩ and R20 =
20 kΩ. The orange trace is the input voltage, the green trace is the output voltage, and the red trace is the output
current. R12, R13, R14, R15, and R16 provide 1.42 A of pulsed load. The resulting test data shows a 50-μA to
1.42-A load step on VOUT of the LDO, with only a 47-μF capacitor on the output of the LDO.
Figure 2-3. TPS7A74EVM-068 Load Transient
Results: 50-μA to 1.42-A Load Step
Figure 2-4. TPS7A74EVM-068 Load Transient
Results: 1.42-A to 50-μA Load Step
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SBVU076 – APRIL 2022
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TPS7A74EVM-068 Evaluation Module 7
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