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Tool/software:
Hi,
We use the TPS38 to delay the power on of an external supply.
To switch the supply, we use an ideal diode controller (LM74800), see figure below.
The exact PN is TPS38A0101DDDSKR, the label on the housing is 32GL.
When testing the circuit, we observed some unexpected behavior.
The output behaves like the active high type.
The figure below shows the power on sequence.
Yellow is the voltage at the RESET1
Magenta is the SENS1 input
The figure below shows the power off sequence
Yellow is the voltage at the RESET1
Magenta is the VDD
From the datasheet, this looks like the active high type:
Is there anything wrong in how we use the TPS38A in our design?
Hi Alexander,
Can you remove the C161 capacitor placed on the CTS1 pin and provide a power on scope capture?
Thanks,
Joshua
Looks better now. The reset later on comes from a pull on the MR. Please ignore it.
Thanks to your hint I discovered that I mixed up CRT and CSR caps in the schematic.
Works as expected when using 220nF for CTR.
Tank you very much!