DS9502

This DS9502 was designed as an additional ESD protection for SRAMbased batterybuffered portable memory modules. The memory chips used for these modules have already a strong ESDprotection structure on their I/O line. Together with the DS9502 the ESD protection level is raised to more than 27 kV (IEC 8012 Reference model). In case of abnormal ESD hits beyond its maximum ratings the DS9502 will eventually fail "short" thus preventing further damage.

During normal operation the DS9502 behaves like a regular 7.5V Zener Diode. When the voltage exceeds the trigger voltage, the I/V characteristic of the device will "snapback" allowing the same or higher amount of current to flow, but at a significantly lower voltage. As long as a minimum current or voltage is maintained, the device will stay in the "snapback mode". If the voltage or the current falls below the holding voltage or holding current, the device will abruptly change to its normal mode and conduct only a small leakage current.