ESD structure of pin DVSS and pin AVSS

[armity]

ESD model:HBM , Pass Volt:2500V

Pin DVSS and Pin AVSS pass :VCC, DVSS TO AVSS (+)
VCC, AVSS TO DVSS (+)
AVSS,DVSS TO VCC(+)
Pin DVSS and Pin AVSS no pass: VCC, DVSS TO AVSS (-)
VCC, AVSS TO DVSS (-)
AVSS,DVSS TO VCC(-)

ESD structure of Pin DVSS and Pin AVSS are adopt Nwell to gnd (Psub) diode, why do the phenomenon occur in the condition of the +/- voltage?

Thanks!

 

[DenisMark]

About ESD

To share ESD protection and making path for ESD current between pin DVSS and pin AVSS u should add powercut diodes to pass+/- ESD zap. Between all suplly domains too. Instead of them one diode will have good ESD robustness in forward region and breakdown in reverse region under 2.5kV HBM condition. Another drawback one diode can pass a large amount of noise to analog circuit.

Try to study some book ragarding basic of ESD protection.
Note: Powercut cell is two branches of back-to-back connected diode's strings. Number diodes in sring can be equal 1,2,3. With number increasing noise isolation incresed too nut suffer ESD robustness.

 

[leo_o2]

About ESD

+/- means testing condition for ESD. It means adding positive/negative ESD pulse for ESD test.

 

[armity]

Re: About ESD

Thanks!
We don't add ESD between pin DVSS and pin AVSS.
ESD structure of Pin VCC to Pin AVSS is same,the difference of added voltage between Pin VCC to Pin AVSS is same. I want to ask why VCC,AVSS TO DVSS (-) is NO pass, but AVSS,DVSS TO VCC(+) is pass?

 

[DenisMark]

About ESD

For getting answer we need more clear information. Can u provide picture with pads and esd structures between them.
In ESD measurements take participation two pins. For this reason I can't take what is "VCC,AVSS TO DVSS (-)" and whta is the difference between "VCC, AVSS TO DVSS (+)" and "VCC, DVSS TO AVSS (-)"?
Can u give information in such manner:
VCC to AVSS (+) - pass
VCC to AVSS(-) - fail