Rainbow Electronics DS14287 - Manual (Page 21)

DS14285/DS14287
21 of 25
POWER-DOWN/POWER-UP TIMING
POWER-DOWN/POWER-UP TIMING
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
CS at V
IH
before Power-Down
t
PD
0
µ
s
V
CC
slew from 4.5V to 0V ( CS at V
IH
)
t
F
300
µ
s
V
CC
slew from 0V to 4.5V ( CS at V
IH
)
t
R
100
µ
s
CS at V
IH
after Power-Up
t
REC
20 200 ms
Chip Enable Propagation Delay to
External SRAM t
CED
10 ns
(t
A
= 25
°
C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Expected Data Retention for DS14287 t
DR
10 years 10
NOTE:
The real-time clock will keep time to an accuracy of+1 minute per month during data retention time for
the period of t
DR
.
WARNING:
Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery
backup mode.