Part Number: SN74LVC1G3157
I use 74LVC1G3157, may I know
When Vcc=5V, A=3.3V , S=L,
- > B1=3.3V or 5V?
Placing a logic low on the S pin will cause the FETs on the B2 path to be Hi-Z and the FETs on the B1 path to have their gate voltages biased turning on the FET and allow conduction.
The SN74LVC1G3157 as you have shown above is a signal switch with "transmission gate architecture." This transmission gate includes a NMOS FET in parallel with a PMOS FET. This structure will allow the I/O pins (A and B1/B2) of the IC to pass "rail to rail" voltages meaning voltages from 0 to Vcc the supply rail for the IC. If you set the Vcc pin to 5 V you will be able to pass any voltage from 0 to 5V on the I/O pins (A and B1/B2).
The on-state resistance of this switch is very low across the I/O voltages with supply voltage at 5V. As you can see below and if you place 3.3 V on A pin there will be 3.3V on B1 pin since there is very little resistance across the signal path.
You can find more information about signal switch operation in this application note.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.