Rainbow Electronics DS1670 - Manual (Page 7)

DS1670
7 of 17
The DS1670 nonvolatilizes the external SRAM(s) by write protecting the SRAM(s) and by providing a
back-up power supply in the absence of V
CC
. When V
CC
falls below 2.88 volts (typical), access to the
external SRAM(s) are prohibited by forcing CEOL and CEOH high regardless of the level of CEI , BLE ,
and BHE . Also at this point, the SRAM power supply (V
CCO
) is switched from V
CC
to V
BAT
. Upon
power up, access is prohibited until the end of t
RPU
.