DS1251/DS1251P
11 of 20
PHANTOM CLOCK AC ELECTRICAL CHARACTERISTICS
(TA = Over the operating range.) (5V)
10B
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Read Cycle Time
tRC
65
ns
CE
Access Time
tCO
55
ns
OE
Access Time
tOE
55
ns
CE
to Output Low-Z
tCOE
5
ns
OE
to Output Low-Z
tOEE
5
ns
CE
to Output High-Z
tOD
25
ns
5
OE
to Output High-Z
tODO
25
ns
5
Read Recovery
tRR
10
ns
Write Cycle Time
tWC
65
ns
Write Pulse Width
tWP
55
ns
3
Write Recovery
tWR
10
ns
10
Data Setup Time
tDS
30
ns
4
Data Hold Time
tDH
0
ns
4
CE
Pulse Width
tCW
60
ns
RST
Pulse Width
tRST
65
ns
POWER-DOWN/POWER-UP TIMING
(TA = Over the operating range.) (3.3V)
11B
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
CE
at VIH before Power-Down
tPD
0
s
VCC Slew from VPF(MAX) to
VPF(MIN)(CE at VPF)
tF
300
s
VCC Slew from VPF(MIN) to VSO
tFB
10
s
VCC Slew from VPF(MAX) to
VPF(MIN) (CE at VPF)
tR
0
s
CE
at VIH after Power-Up
tREC
1.5
2.5
ms
(TA = +25°C)
4B
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Expected Data Retention Time
tDR
10
years
9
Warning: Under no circumstances are negative undershoots of any amplitude allowed when device
is in battery-backup mode.