NVT4857

[erikcheesebroug]

I would like to interface between a memory card operating at 1.8 V or 3.0 V signal levels and a host operating at 3.3 V signaling levels.

In Table 7 (Absolute Maximum Ratings), max VCCA is given as +4.6V and max VI as +4.6V.

In Table 8 (Recomended Operating Conditions), max VCCA is given as +2.0V and max VI as VCCA+0.3V (not to exceed +3.6V)

My interpretation is that this part will work for +3.3V LVTTL host-side signaling. Am I wrong?

[TomasVaverka]

Hi Erik,

According to the Table 8, the host side interface signal voltage max is 2.3V to guarantee normal operation .

You can try higher voltage up to 3.3V, but the clock rate will drop to 25MHz possible.

Best regards,

Tomas

[YYT]

According to <NVT4857UK Product data sheet>, in chapter 6 Functional diagram we know that the host side signal are pull-uped by Vcca, whitch means the signals from card side to host side are refered by Vcca. In Vcca=1.8V system, host controller is powered up in 3.3v, and send cmd 41 to capture  the card 's information ,and then send cmd11 to enable voltage switch sequence. During above operation, host side will receive reponse from card. before the voltage switch action is finished, the response out of NVT4857 is in 1.8V level whitch is not match host side 3.3V IO??? whether the application here is right??? #NVT4857UK