Real-Time Clocks
DS17285/DS17287/DS17485/DS17487/DS17885/DS17887
POWER-UP/POWER-DOWN CHARACTERISTICS
(T
A
= -40°C to +85°C) (Note 2)
PARAMETER
Recovery at Power-Up
V
CC
Fall Time, V
PF(MAX)
to
V
PF(MIN)
V
CC
Fall Time, V
PF(MAX)
to
V
PF(MIN)
SYMBOL
t
REC
t
F
t
R
(Note 9)
CONDITIONS
MIN
20
300
0
TYP
MAX
150
UNITS
ms
µs
µs
DATA RETENTION (DS17x87 ONLY)
(T
A
= +25°C)
PARAMETER
Expected Data Retention
SYMBOL
t
DR
(Note 9)
CONDITIONS
MIN
10
TYP
MAX
UNITS
Years
CAPACITANCE
(T
A
= +25°C) (Note 10)
PARAMETER
Capacitance on All Input Pins
Except X1
Capacitance on
IRQ,
SQW, and
DQ0–DQ7 Pins
SYMBOL
C
IN
C
IO
(Note 10)
(Note 10)
CONDITIONS
MIN
TYP
MAX
12
12
UNITS
pF
pF
AC TEST CONDITIONS
PARAMETER
Input Pulse Levels:
Output Load Including Scope and Jig:
Input and Output Timing Measurement Reference Levels:
Input Pulse Rise and Fall Times:
0 to 3.0V
50pF + 1TTL Gate
Input/Output: V
IL
max and V
IH
min
5ns
CONDITIONS
WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode can cause loss of
data.
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.
6
_____________________________________________________________________
Note 1:
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
