SN74LVC2G66-Q1: Are its NMOS-body and PMOS-body connected ro GND?

Yoshiki Ochi

Part Number: SN74LVC2G66-Q1

Hi team,

1. Are internal NMOS-body and PMOS-body, which make CMOS, connected to GND? (Please see attached figure, yellow marked point)

2. What happen if VCC=0V, VI=5 (or 1A pin) and VO=0V (or 1B pin)? Does internal PMOS turns on irrespective of its control input (or 1C pin)?

I know its recommended does not say its condition, however I would like to understand its operation for start up requirement.

Regards,
Ochi

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 243220 points

1. In a transmission gate, the NMOS body is typically connected to GND, and the PMOS body, to V_CC.

2. I/O voltages above V_CC + 0.5 V violate the absolute maximum ratings, and a current might flow through the ESD protection diodes into V_CC, which might turn the device partially on. With a supply below 1.65 V, the behavior is unpredictable.

0 Bryan Marshall over 3 years ago

TI__Genius 10974 points

Hi Ochi,

Thanks for your questions. The issue you are referring to is what we call power off protection. To learn more about this feature that is specified for some of our muxes, please see this video below:

https://training.ti.com/ti-precision-labs-switches-and-muxes-simplify-power-sequencing-powered-protection?context=1139747-1134454-1140317

The SN74LVC2G66-Q1 does not have this feature, so as Clemens mentioned, there might be current flow through the ESD protection diodes that could possibly back power downstream devices and allow the internal logic of the mux to be back powered as well, turning on the switch.

If you can clarify your requirements for your switch/application (VDD, RON, need for power off protection, leakage, etc.), I can help recommend some devices.

Thanks!

Bryan

+1 Sandesh Rawool over 2 years ago

TI__Intellectual 2694 points

Hi Ochi-san,

Please let us know if this is resolved or if any further help needed.

Regards,

Sandesh

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SN74LVC2G66-Q1: Are its NMOS-body and PMOS-body connected ro GND?