DS1345W Datasheet, PDF (8/12 Pages) Dallas Semiconductor – 3.3V 1024k Nonvolatile SRAM with Battery Monitor

POWER-DOWN/POWER-UP TIMING
PARAMETER
SYMBOL MIN
V_CC Fail Detect to CE and
WE Inactive
t_PD
V_CC slew from V_TP to 0V
t_F
150
V_CC Fail Detect to RST
Active
t_RPD
V_CC slew from 0V to V_TP
t_R
150
V_CC Valid to CE and WE
Inactive
t_PU
V_CC Valid to End of Write
Protection
t_REC
V_CC Valid to RST Inactive
t_RPU
150
V_CC Valid to BW Valid
t_BPU
TYP
200
MAX
1.5
15
2
DS1345W
(T_A: See Note 10)
UNITS NOTES
µs
11
µs
µs
14
µs
ms
125
ms
350
ms
14
1
s
14
BATTERY WARNING TIMING
PARAMETER
SYMBOL
Battery Test Cycle
Battery Test Pulse Width
Battery Test to BW Active
t_BTC
t_BTPW
t_BW
MIN
TYP
24
PARAMETER
Expected Data
Retention Time
SYMBOL
t_DR
MIN
10
TYP
MAX
1
1
MAX
(T_A: See Note 10)
UNITS NOTES
hr
s
s
(T_A= 25°C)
UNITS NOTES
years
9
WARNING:
Under no circumstance are negative undershoots, of any amplitude, allowed when device is in battery
backup mode.
NOTES:
1. WE is high for a read cycle.
2. OE = V_IH or V_IL . If OE = V_IH during write cycle, the output buffers remain in a high impedance state.
3. t_WP is specified as the logical AND of CE and WE . t_WP is measured from the latter of CE or WE
going low to the earlier of CE or WE going high.
4. t_DS is measured from the earlier of CE or WE going high.
5. These parameters are sampled with a 5 pF load and are not 100% tested.
6. If the CE low transition occurs simultaneously with or latter than the WE low transition, the output
buffers remain in a high impedance state during this period.
7. If the CE high transition occurs prior to or simultaneously with the WE high transition, the output
buffers remain in high impedance state during this period.
8. If WE is low or the WE low transition occurs prior to or simultaneously with the CE low transition,
the output buffers remain in a high impedance state during this period.
9. Each DS1345W has a built-in switch that disconnects the lithium source until V_CC is first applied by
the user. The expected t_DR is defined as accumulative time in the absence of V_CC starting from the
time power is first applied by the user.
8 of 12