DS1685_10 Datasheet, PDF (18/34 Pages) Maxim Integrated Products – 3V/5V Real-Time Clocks

DS1685/DS1687 3V/5V Real-Time Clocks
Figure 5. DS1685/DS1687 Register Map and Extended Register Bank Definition
BANK 0 DV0
MSB
=0
LSB
00
TIMEKEEPING AND CONTROL
0D
0E
50 BYTES-USER RAM
3F
64 BYTES-USER RAM
MSB
00
0D
0E
3F
40
41
42
43
44
45
46
47
48
49
4A
4B
4C
4D
4E
4F
50
51
52
53
54
BANK 1 DV0 =
1
LSB
TIMEKEEPING AND CONTROL
50 BYTES-USER RAM
MODEL NUMBER BYTE
1^ST BYTE SERIAL NUMBER
2^ND BYTE SERIAL NUMBER
3^RD BYTE SERIAL NUMBER
4^TH BYTE SERIAL NUMBER
5^TH BYTE SERIAL NUMBBER
6^TH BYTE SERIAL NUMBER
CRC BYTE
CENTURY BYTE
DATE ALARM
EXTENDED CONTROL REG 4A
EXTENDED CONTROL REG 4B
RESERVED
RESERVED
RTC ADDRESS-2
RTC ADDRESS-3
EXTENDED RAM ADDRESS
RESERVED
RESERVED
EXTENDED RAM DATA PORT
RESERVED
EXTENDED
RAM
128 x 8
7F
7F
When bank 1 is selected, the clock/calendar registers and the original 50 bytes of user RAM still appear as bank 0.
However, the registers that provide control and status for the extended functions are accessed in place of the
additional 64 bytes of user RAM. The major functions controlled by the extended registers are listed below:
1) 64-Bit Silicon Serial Number
2) Century counter
3) Date Alarm
4) Auxiliary Battery Control/Status
5) Wake Up
6) Kickstart
7) RAM Clear Control/Status
8) 128 Bytes Extended RAM Access
The bank selection is controlled by the state of the DV0 bit in register A. To access bank 0, the DV0 bit should be
written to a 0. To access bank 1, DV0 should be written to a 1. Register locations designated as reserved in the
bank 1 map are reserved for future use by Maxim. Bits in these locations cannot be written and return a 0 if read.
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