DS1248 Maxim, DS1248 Datasheet - Page 8

• Manufacturer Part Number: DS1248
• Description: The DS1248 1024K NV SRAM with Phantom Clock is a fully static nonvolatile RAM (organized as 128K words by 8 bits) with a built-in real-time clock
• Manufacturer: Maxim

DS1248/DS1248P 1024K NV SRAM with Phantom Clock
ZERO BITS
Registers 1, 2, 3, 4, 5, and 6 contain one or more bits, which will always read logic 0. When writing these
locations, either a logic 1 or 0 is acceptable.
BATTERY LONGEVITY
The DS1248 has a lithium power source that is designed to provide energy for clock activity and clock
and RAM data retention when the V
supply is not present. The capability of this internal power supply
CC
is sufficient to power the DS1248 continuously for the life of the equipment in which it is installed. For
specification purposes, the life expectancy is 10 years at +25°C with the internal clock oscillator running
in the absence of V
power. Each DS1248 is shipped from Maxim with its lithium energy source
CC
disconnected, guaranteeing full energy capacity. When V
is first applied at a level greater than V
, the
CC
PF
lithium energy source is enabled for battery-backup operation. Actual life expectancy of the DS1248 will
be much longer than 10 years since no lithium battery energy is consumed when V
is present.
CC
See “Conditions of Acceptability” at
www.maxim-ic.com/TechSupport/QA/ntrl.htm
CLOCK ACCURACY (DIP MODULE)
The DS1248 is guaranteed to keep time accuracy to within ±1 minute per month at +25°C. The clock is
calibrated at the factory by Maxim using special calibration nonvolatile tuning elements and does not
require additional calibration. For this reason, methods of field clock calibration are not available and not
necessary.
CLOCK ACCURACY (POWERCAP MODULE)
The DS1248P and DS9034PCX are each individually tested for accuracy. Once mounted together, the
module will typically keep time accuracy to within ±1.53 minutes per month (35ppm) at +25°C.
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