Datasheet

DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
15 of 16
AC TEST CONDITIONS
Output Load: 50pF + 1TTL Gate
Input Pulse Levels: 0 to 3.0V
Timing Measurement Reference Levels:
Input: 1.5V
Output: 1.5V
Input Pulse Rise and Fall Times: 5ns
NOTES:
1) Voltages are referenced to ground.
2) Typical values are at +25°C and nominal supplies.
3) Outputs are open.
4) Battery switchover occurs at the lower of either the battery terminal voltage or V
PF
.
5) Data-retention time is at +25°C.
6) Each DS1744 has a built-in switch that disconnects the lithium source until the user first applies V
CC
.
The expected t
DR
is defined for DIP modules and assembled PowerCap modules as a cumulative time
in the absence of V
CC
starting from the time power is first applied by the user.
7) RTC modules (DIP) can be successfully processed through conventional wave-soldering techniques as
long as temperature exposure to the lithium energy source contained within does not exceed +85°C.
Post-solder cleaning with water-washing techniques is acceptable, provided that ultrasonic vibration is
not used.
In addition, for the PowerCap:
a. ) Maxim recommends that PowerCap module bases experience one pass through solder reflow
oriented with the label side up (“live-bug”).
b.) Hand soldering and touch-up: Do not touch or apply the soldering iron to leads for more than 3
seconds. To solder, apply flux to the pad, heat the lead frame pad, and apply solder. To remove
the part, apply flux, heat the lead frame pad until the solder reflows, and use a solder wick to
remove solder.
8) t
AH1
, t
DH1
are measured from WE going high.
9) t
AH2
, t
DH2
are measured from CE going high.
10) t
WC
= 200ns.
PACKAGE INFORMATION
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix
character, but the drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
28 EDIP MDF28+3
21-0245
—
34 PWRCP
PC2+2
21-0246
—