Dear Technical Support Team,
I'd like to use bidirectional level shift circuit between 3.3V and 5V with SN74CBT1G125.
I refer following 384 circuit and add 5V pull up to OEn and signal line.
If you have any concern, could you give me advice? Especially power on / power off.
■5V pullup for OEn → output disable during power up
■5V pullup for signal line → shift 5V from 3.3V
Best Regards,
ttd
TTD,
Where did you get the figure 10 drawing? I didn't see it in the SN74CBT1G384 datasheet.
The SN74CBT1G125 will be able to support 5 V signal on OE pin and signal path pins A/B.
Why use this circuit instead of a level shifter like LSF0101 or TXB0101?
Adding the diode on a 5 V supply will create a voltage drop (~0.7V) and reduce the switch supply voltage. This supply voltage will set the gate voltage of the NMOS FET and when the VGS voltage is < ~0.7 V the FET will be very high impedance. This high impedance of the FET when the Vgs voltage is low ( input voltage approaches gate voltage) will clamp the output voltage (unless you have a pull up) thus creating a level shift.
Thank you,
Adam
Hi Adam,
Thank you for your reply.
I see the following application report about figure 10 and draw 5V pullup.
CBT series is near-zero propagation delay, so I didn't use LSF0101 or TXB0101.
I'd like to use bidirectional level shift circuit between 3.3V and 5V with SN74CBT1G125(bidirectional).
In addition, SN74CB3T1G125 can use for bidirectional 3.3V and 5V such as following circuit
http://www.ti.com/lit/an/scda008/scda008.pdf?HQS=ti-null-null-ted-appn-ds-faq_sw-jp
Best Regards,
ttd
