Rainbow Electronics DS1339 User Manual
Page 4
DS1339
4 of 18
CLOCK ACCURACY
The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match
between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was
trimmed. Additional error is added by crystal frequency drift caused by temperature shifts. External
circuit noise coupled into the oscillator circuit can result in the clock running fast. Refer to Application
Note 58 “Crystal Considerations with Dallas Real-Time Clocks” for detailed information.
ADDRESS MAP
The address map for the registers of the DS1339 is shown in Figure 2. During a multibyte access, when
the address pointer reaches the end of the register space (10h), it wraps around to location 00h. On a 2-
wire START, STOP, or address pointer incrementing to location 00h, the current time is transferred to a
second set of registers. The time information is read from these secondary registers, while the clock can
continue to run. This eliminates the need to re-read the registers in case of an update of the main registers
during a read.