daraemon_liu
Junior Member level 1
Recently in my project I need to design a JTAG chain which contains two diffenent voltage powered JTAG I/Os,one is 3.3V LVTTL,the other is 2.5V LVTTL.
The chain can be seen in the attachment,the JATG scanner itself is powered by 3.3V.So it surely can connect to the first chip in this chain.But the second chip needs to be considered carefully.Does the 3.3V LVTTL output make overshoot in the signal for the 2.5V LVTTL input ?Can it damage the second chip? If so, what circuit should I use to avoid it? Dose the 2.5V LVTTL output meet the VIH for the JATG scanner?
TKS for your advices
The chain can be seen in the attachment,the JATG scanner itself is powered by 3.3V.So it surely can connect to the first chip in this chain.But the second chip needs to be considered carefully.Does the 3.3V LVTTL output make overshoot in the signal for the 2.5V LVTTL input ?Can it damage the second chip? If so, what circuit should I use to avoid it? Dose the 2.5V LVTTL output meet the VIH for the JATG scanner?
TKS for your advices