DS1689_05 Datasheet, PDF(21/36 Page) Dallas Semiconductor – 3V/5V Serialized Real-Time Clocks with NV RAM Control

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DS1689_05 Datasheet, PDF (21/36 Pages) Dallas Semiconductor – 3V/5V Serialized Real-Time Clocks with NV RAM Control

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DS1689/DS1693

EXTENDED CONTROL REGISTERS

Two extended control registers are provided to supply controls and status information for the extended

features offered by the DS1689/DS1693. These are designated as extended control registers A and B and

are located in register bank 1, locations 04AH and 04BH, respectively. The functions of the bits within

these registers are described as follows.

Extended Control Register 4A

MSB

BIT 7

BIT 6

BIT 5

BIT 4

VRT2

INCR

BIT 3

PAB

BIT 2

BIT 1

LSB

BIT 0

*Reserved bits. These bits are reserved for future use by Dallas Semiconductor. They can be read and written, but have no effect on

operation.

Bit 7: 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 VBAUX. If this bit is read as logic 0, the external

battery should be replaced.

Bit 6: INCR (Increment in Progress Status). This bit is set to 1 when an increment to the time/date

registers is in progress and the alarm checks are being made. INCR is set to 1 at 122Âµs before the update

cycle starts and is cleared to 0 at the end of each update cycle.

Bit 4: PAB (Power Active Bar Control). When this bit is 0, the PWR pin is in the active-low state. The

user can write this bit to logic 1 or logic 0. If either [WF and WIE = 1] or [KF and KSE = 1], the PAB bit

is cleared to 0.

Bit 2: RF (RAM Clear Flag). This bit is set to 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 logic 0. This bit can also be written to logic 1 to

force an interrupt condition.

Bit 1: 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 1. WF is cleared by writing it to 0.

Bit 0: KF (Kickstart Flag). This bit is set to 1 when a kickstart condition occurs or when the user writes

it to 1. This bit is cleared by writing it to logic 0.

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