DS17285_1 Datasheet, PDF (6/31 Pages) Maxim Integrated Products – Real-Time Clocks

Real-Time Clocks
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)
SYMBOL
t_REC (Note 9)
t_F
CONDITIONS
V_CC Fall Time, V_PF(MAX) to
V_PF(MIN)
t_R
DATA RETENTION (DS17x87 ONLY)
(T_A = +25°C)
PARAMETER
SYMBOL
Expected Data Retention
t_DR
(Note 9)
CONDITIONS
MIN TYP MAX UNITS
20
150
ms
300
µs
0
µs
MIN TYP MAX UNITS
10
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
(Note 10)
C_IO
(Note 10)
CONDITIONS
MIN TYP MAX UNITS
12
pF
12
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:
CONDITIONS
0 to 3.0V
50pF + 1TTL Gate
Input/Output: V_IL max and V_IH min
5ns
WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode can cause loss of
data.
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.
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