Application Information

The TPMC917 is a standard single-width 32bit PMC

module providing 4MByte of SRAM with battery backup by

an on board lithium cell and four ESD protected RS232

channels (TPMC917-10R only).

The 4MByte of NV-SRAM are organized in two banks,

each providing 512K x 32bit of memory. During normal

operation (standard 5V supply applied to the SRAM) the

capacity of the lithium cell is monitored every 24 hours by

a battery monitor device and an interrupt can be

generated if the battery voltage is too low.

The monitor device switches the power supply of the

SRAM from the standard 5V to the battery if the 5V supply

drops below the battery monitor device threshold level.

Any active access to the SRAM at this point is executed

correctly within 1.5µs. After this time any further accesses

to the SRAM are not possible.

A miniature DIP switch allows the selection of the battery

backup source either from the on board lithium cell or from

an external battery via the P14 I/O connector.