Other Parts Discussed in Thread: SN74LVC3G17, ULN2003A, TPL7407LA, CD4504B, CD40109B, UCC27517
Hello TI,
I have an applications where 3.3V to 5V and 5V to 3.3V is required
I selected SN74LV4T125 for both the cases.
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Hello TI,
I have an applications where 3.3V to 5V and 5V to 3.3V is required
I selected SN74LV4T125 for both the cases.
This looks OK.
It is common to also use smaller decoupling capacitors (typcially 100 nF).
For level shifiting from 5 V down to 3.3 V, you could replace U27 with a buffer with overvoltage-tolerant inputs, e.g., SN74LVC3G17, which has a smaller package.
If you replace the ULN2003A (U16) with a TPL7407LA, you do not need to shift the 3.3 V signals to a higher voltage and can drop U24.
Thank you for your reply and invaluable suggestion.I'll go for TPL7407LA.
I am also looking for an IC to shift voltage levels from 3.3V logic to 15V logic to generate PWM pulses of 10kHz frequency. Minimum propogation delay is desired. I tried to search in the TI's level shift logic page but couldn't get! Kindly suggest any IC if any.
waiting for your reply.
The only logic family going above 5 V is CD4000. Check out the CD40109B or CD4504B.
I'd like to have a confirmation from you regarding the OE pins which are grouped and connected to the ground.
With the OE pins connected to ground, the four buffers will be always active. (Even during power up, when the input might not yet be valid.) The behaviour is the same as with a buffer without OE, e.g., the SN74LVC3G17.
The CD40109B allows voltages down to 3 V in the recommended operating conditions on page 1. I assumed that the CD4504B also supports this, like most other devices in the CD4000 family, but that appears not to be the case.
You could also use an entirely different device, e.g., a gate driver with TTL input like the UCC27517.