DS1689SN+ Maxim Integrated, DS1689SN+ Datasheet - Page 4

• Manufacturer Part Number: DS1689SN+
• Description: Real Time Clock
• Manufacturer: Maxim Integrated
• Series: DS1689, DS1693r

Specifications of DS1689SN+

• Rohs: yes
• 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: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-28

SO
24
25
26
27
28
—
PIN
19, 23
EDIP
2, 3,
24
25
26
27
28
NAME
SQW
V
CEO
V
N.C.
CEI
CCO
CCI
Square-Wave Output. The SQW pin can output a signal from one of
13 taps provided by the 15 internal divider stages of the real time
clock. The frequency of the SQW pin can be changed by
programming Register A as shown in Table 2. The SQW signal can
be turned on and off using the SQWE bit in Register B. A 32kHz
SQW signal is output when SQWE = 1, the Enable 32kHz (E32K)
bit in extended register 04BH is logic 1, and V
32kHz square wave is also available when V
E32K = 1, ABE = 1, and voltage is applied to V
External SRAM Power-Supply Output. This pin is internally
connected to V
during power fail, V
(whichever is larger). For 5V operation, switchover from V
backup supply occurs when V
V
occurs at V
than V
occurs when V
+3V or +5V Main Supply. DC power is provided to the device on
these pins. 5V operation is selected when the PSEL pin is at logic 1.
If PSEL is floated or at logic 0, the device is in autosense mode and
determines the correct operating voltage based on the V
level.
Active-Low RAM Chip Enable Output. When power is valid, CEO
will equal CEI. When power is not valid, CEO will be driven high
regardless of CEI.
Active-Low RAM Chip Enable Input. CEI should be driven low to
enable the external RAM.
No Connection
BAUX
. For 3V operation, switchover from V
BAT
and V
PF
if V
CCI
CCI
BAUX
4 of 36
PF
drops below the larger of V
when V
is less than V
CCO
, the switch from V
is internally connected to the V
CCI
FUNCTION
is within nominal limits. However,
CCI
drops below the larger of V
BAT
and V
CCI
BAUX
to the backup supply
CC
CCI
BAT
CC
is less than V
BAUX
. If V
to the backup supply
is above V
and V
.
PF
BAT
CCI
BAUX
is greater
voltage
CCI
or V
PF
.
PF
BAT
. A
to the
if
BAUX
and