Datasheet
DS17285/DS17287/DS17485/DS17487/DS17885/DS17887
Real-Time Clocks
6 _____________________________________________________________________
POWER-UP/POWER-DOWN CHARACTERISTICS
(T
A
= -40°C to +85°C) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Recovery at Power-Up t
REC
(Note 9) 20 150 ms
V
CC
Fall Time, V
PF(MAX)
to
V
PF(MIN)
t
F
300 µs
V
CC
Fall Time, V
PF(MAX)
to
V
PF(MIN)
t
R
0µs
DATA RETENTION (DS17x87 ONLY)
(T
A
= +25°C)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Expected Data Retention t
DR
(Note 9) 10 Years
CAPACITANCE
(T
A
= +25°C) (Note 10)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Capacitance on All Input Pins
Except X1
C
IN
(Note 10) 12 pF
Capacitance on IRQ, SQW, and
DQ0–DQ7 Pins
C
IO
(Note 10) 12 pF
AC TEST CONDITIONS
PARAMETER CONDITIONS
Input Pulse Levels: 0 to 3.0V
Output Load Including Scope and Jig: 50pF + 1TTL Gate
Input and Output Timing Measurement Reference Levels: Input/Output: V
IL
max and V
IH
min
Input Pulse Rise and Fall Times: 5ns
Note 1: RTC modules 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. However, post-solder cleaning with water-
washing techniques is acceptable, provided that ultrasonic vibrations not used to prevent damage to the crystal.
Note 2: Limits at -40°C are guaranteed by design and not production tested.
Note 3: All voltages are referenced to ground.
Note 4: All outputs are open.
Note 5: Specified with CS = RD = WR = V
CC
, ALE, AD0–AD7 = 0.
Note 6: Applies to the AD0–AD7 pins, IRQ, and SQW when each is in a high-impedance state.
Note 7: Measured with a 32.768kHz crystal attached to X1 and X2.
Note 8: Measured with a 50pF capacitance load plus 1TTL gate.
Note 9: If the oscillator is disabled in software, or if the countdown chain is in reset, t
REC
is bypassed, and the part becomes
immediately accessible.
Note 10: Guaranteed by design. Not production tested.
WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode can cause loss of
data.