DS1689 Datasheet, PDF (20/32 Pages) Dallas Semiconductor – 3-Volt/5-Volt Serialized Real-Time Clock with NV RAM Control

DS1689/DS1693
VRT2 - This status bit gives the condition of the auxiliary battery. It is set to a logic 1 condition when the
external lithium battery is connected to the V_BAUX. If this bit is read as a logic 0, the external battery
should be replaced.
INCR - Increment in Progress status bit. This bit is set to a 1 when an increment to the time/date registers
is in progress and the alarm checks are being made. INCR will be set to a 1 at 122 ms before the update
cycle starts and will be cleared to 0 at the end of each update cycle.
PAB - Power Active Bar control bit. When this bit is 0, the PWR pin is in the active low state. This bit
can be written to a logic 1 or 0 by the user. If either WF AND WIE = 1 OR KF AND KSE = 1, the PAB
bit will be cleared to 0.
RF - Ram Clear Flag - This bit will be set to a logic 1 when a high to low transition occurs on the RCLR
input if RCE=1. The RF bit is cleared by writing it to a logic 0. This bit can also be written to a logic 1 to
force an interrupt condition.
WF – Wake-up Alarm Flag - This bit is set to 1 when a wake-up alarm condition occurs or when the user
writes it to a 1. WF is cleared by writing it to a 0.
KF - Kickstart Flag - This bit is set to a 1 when a kickstart condition occurs or when the user writes it to a
1. This bit is cleared by writing it to a logic 0.
EXTENDED CONTROL REGISTER 4B
MSB
BIT 7
BIT 6
BIT 5
BIT 4
ABE
E32K
CS
RCE
BIT 3
PRS
BIT 2
RIE
BIT 1
WIE
LSB
BIT 0
KSE
ABE - Auxiliary Battery Enable. This bit when written to a logic 1 will enable the V_BAUX pin for
extended functions.
E32K - Enable 32,768 output. This bit when written to a logic 1 will enable the 32,768 Hz oscillator
frequency to be output on the SQW pin provided SQWE=1.
CS - Crystal Select Bit. When CS is set to a 0, the oscillator is configured for operation with a crystal that
has a 6 pF specified load capacitance. When CS=1, the oscillator is configured for a 12.5 pF crystal.
RCE - RAM Clear Enable bit. When set to a 1, this bit enables a low level on pin 4 ( RCLR ) to clear all
114 bytes of user RAM. When RCE = 0, the RAM clear function is disabled.
PRS - PAB Reset Select Bit. When set to a 0 the PWR pin will be set hi-Z when the DS1689 goes into
power-fail. When set to a 1, the PWR pin will remain active upon entering power-fail.
RIE - Ram Clear Interrupt Enable. When RIE is set to a 1, the IRQ pin will be driven low when a RAM
clear function is completed.
WIE – Wake-Up Alarm Interrupt Enable. When V_CC voltage is absent and WIE is set to a 1, the PWR pin
will be driven active low when a wake-up condition occurs, causing the WF bit to be set to 1. When V_CC
is then applied, the IRQ pin will also be driven low. If WIE is set while system power is applied, both
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