DS1689_05 Datasheet, PDF (3/36 Pages) Dallas Semiconductor – 3V/5V Serialized Real-Time Clocks with NV RAM Control

PIN
SO EDIP
13
13
14, 19 14
15
15
16
16
17
17
18
18
20
20
21
21
22
22
23
—
DS1689/DS1693
NAME
PWR
GND
KS
CS
ALE
WR
RD
PSEL
IRQ
V_BAT
FUNCTION
Active-Low Power-On Interrupt Output. The PWR pin is intended
for use as an on/off control for the system power. With V_CC voltage
removed from the DS1689/DS1693, PWR may be automatically
activated from a kickstart input via the KS pin or from a wake-up
interrupt. Once the system is powered on, the state of PWR can be
controlled via bits in the Dallas registers.
Ground. DC power is provided to the device on this pin.
Active-Low Kickstart Input. When V_CC is removed from the
DS1689/DS1693, the system can be powered on in response to an
active low transition on the KS pin, as might be generated from a
key closure. V_BAUX must be present and auxiliary battery enable bit
(ABE) must be set to 1 if the kickstart function is used, and the KS
pin must be pulled up to the V_BAUX supply. While V_CC is applied, the
KS pin can be used as an interrupt input.
Active-Low Chip Select Input. This signal must be asserted low
during a bus cycle for the RTC portion of the DS1689/DS1693 to be
accessed. CS must be kept in the active state during RD and WR
timing. Bus cycles, which take place with ALE asserted but without
asserting, CS will latch addresses. However, no data transfer will
occur.
Address Strobe Input (Active High). A pulse on the address strobe
pin serves to demultiplex the bus. The falling edge of ALE causes
the RTC address to be latched within the DS1689/DS1693.
Active-Low Write Data Strobe. The WR signal is an active low
signal. The WR signal defines the time period during which data is
written to the addressed register.
Active-Low Read Data Strobe. RD identifies the time period when
the DS1689/DS1693 drives the bus with RTC read data. The RD
signal is an enable signal for the output buffers of the clock.
+3V or +5V Power Select. When PSEL is logic 1, 5V operation is
selected. When PSEL is logic 0 or is floated, the device is in
autosense mode and determines the correct mode of operation based
on the voltage on V_CCI.
Active-Low Interrupt Request Output (Open Drain). The IRQ pin is
an active-low output of the DS1689/DS1693 that can be tied to the
interrupt input of a processor. The IRQ output remains low as long
as the status bit causing the interrupt is present and the
corresponding interrupt-enable bit is set. To clear the IRQ pin, the
application software must clear all enabled flag bits contributing to
IRQ’s active state. When no interrupt conditions are present, the IRQ
level is in the high impedance state. Multiple interrupting devices
can be connected to an IRQ bus. The IRQ pin is an open-drain
output and requires an external pullup resistor.
Battery Input for Any Standard 3V Lithium Cell or Other Energy
Source. Battery voltage must be held between 2.5V and 3.7V for
proper operation.
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