DS1689S/T&R Maxim Integrated, DS1689S/T&R Datasheet - Page 7

• Manufacturer Part Number: DS1689S/T&R
• Description: Real Time Clock
• Manufacturer: Maxim Integrated
• Series: DS1689, DS1693r

Specifications of DS1689S/T&R

• Function: Clock, Calendar, NV SRAM Control
• Rtc Bus Interface: Multiplexed
• Date Format: DW
• Time Format: HH
• Rtc Memory Size: 114 B
• Supply Voltage - Max: 5.5 V
• Supply Voltage - Min: 2.7 V
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-28
• Part # Aliases: 90-1689S-TRL

POWER-DOWN/POWER-UP CONSIDERATIONS
The real-time clock function will continue to operate and all of the RAM, time, calendar, and alarm
memory locations remain nonvolatile regardless of the level of the V
the DS1689/DS1693 and reaches a level of greater than V
accessible after t
reset (see Register A). This time period allows the system to stabilize after power is applied.
When PSEL is floating or logic 0, the DS1689 is in autosense mode and 3V or 5V operation is
determined based on the voltage on V
rises above 4.5V for a minimum of t
rise above the level of 4.25V. Selection of the power supply input levels requires 150ms of input stability
before operation can commence.
When 5V operation is selected, the device is fully accessible and data can be written and read only when
V
timekeeping function continues unaffected by the lower input voltage. As V
V
V
When 3V operation is selected and applied within normal limits, the device is fully accessible and data
can be written or read. When V
V
V
from V
When V
SQW pins, all inputs are ignored and all outputs are in a high impedance state.
RTC ADDRESS MAP
The address map for the RTC registers of the DS1689/DS1693 is shown in Figure 2. The address map
consists of the 14-clock/calendar registers. Ten registers contain the time, calendar, and alarm data, and
four bytes are used for control and status. All registers can be directly written or read except for the
following:
1. Registers C and D are read-only.
2. Bit 7 of Register A is read-only.
3. The high order bit of the seconds byte is read-only.
CCI
BAT
BAT
BAT
BAUX
pin or V
is greater than 4.5V. When V
and V
and V
) when V
CCI
CC
to the backup supply when V
falls below V
BAUX
BAUX
BAUX
CCI
, the RAM and timekeeper are switched over to a lithium battery connected either to the
, the power supply is switched from V
REC
pin.
drops below V
, provided that the oscillator is running and the oscillator countdown chain is not in
PF
, the chip is write-protected. With the possible exception of the KS, PWR, and
CCI
PF
. If V
REC
falls below V
CCI
CCI
. However, 3V operation is automatically selected if V
CCI
. Selection of 5V operation is automatically invoked when V
PF
is below 4.5V, read and writes are inhibited. However, the
drops below the larger of V
is greater than V
PF
, access to the device is inhibited. If V
7 of 36
CCI
to the backup supply (the greater of V
PF
BAT
(power fail trip point), the device becomes
and V
BAUX
BAT
CCI
input. When V
and V
, the power supply is switched
CC
falls below the greater of
BAUX
.
CCI
PF
is applied to
CCI
is less than
does not
BAT
and
CCI