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Among the fault response functions, we wanted to use it as a latch-off, so we designed it as follows.
(1) EN/UVLO=H
(2) RETRY_DLY=Short to GND
(3) NRETRY = Open
I tried to operate the circuit, but no voltage was output from OUT of TPS25980,
When NRETRY = Short to GND was set, the output was restored.
In Table 8-3 of the datasheet, NRETRY is set to X (Don't care), so it should work with Open, but is there something wrong with the design?
The other pins are designed as follows.
ITIMER = 0.022uF
ILIM = 375Ω(4A)
dVdt = Open
LDSTART = Short to GND
Best regards
Hi Kunal Goel
The excerpts from TPS25980 are attached.
Although if R147 is no mounet, there was no output from OUT,
However, after mounting a 0-ohm resistor on R147, the output was restored.
Best regards
Motomura
Hi Hmotomura,
So when Nretry is open device always show zero VOUT? Does VOUT rise to some value and then fall to zero?
During your startup test only cap load is there? No other external load is connected?
Can you share waveforms showing VIN,VOUT, Input current?
Regards
Kunal Goel
Hi Kunal Goel
Thank you for your response.
When NRETRY is open, VOUT rises to some value and then goes to zero.
In the startup test, only the CAP load is used, no external loads are connected.
Sorry, I don't have a waveform to show you.
Best regards
Motomura
Hi Motomura,
Waveforms will help to better debug. Definitely what you see is not expected. How much is total cap at output? Can you confirm that RETRY_DELAY is properly shorted to GND?
Behavior you see can happen if Retry_Delay is open.
Regards
Kunal Goel
Hi Kunal Goel
The total CAP at output is 0.1uF.
RETRY_DLY is shorted to GND.
Best Regards
Motomura
Hi Motomura,
Does it happen with multiple devices or on multiple boards?
Regards
Kunal Goel
Hi Kunal Goel
>Does it happen with multiple devices or on multiple boards?
=>Yes.
There are 6 TPS25980s with different output on one board, and it is happening with all of them.
I have also made 3 boards and it is happening on all of them.
Best Regards
Motomura
Hi Motomura,
Let me try checking on board and get back soon.
Regards
Kunal Goel