Power Control

The power-control function is provided by a precise,

temperature-compensated voltage reference and a

device is fully accessible and data can be written and

after RST goes high (Figure 1).

Address Map

Table 3 shows the address map for the DS1374 regis-

ters. During a multibyte access, the address pointer

wraps around to location 00h when it reaches the end of

address pointer incrementing to location 00h, the current

time is transferred to a second set of registers. These

secondary registers read the time information, while the

clock continues to run. This eliminates the need to reread

the registers in case of an update of the main registers

during a read.

Time-of-Day Counter

The time-of-day counter is a 32-bit up counter that

increments once per second when the oscillator is run-

ning. The contents can be read or written by accessing

the address range 00h–03h. When the counter is read,

the current time of day is latched into a register, which

is output on the serial data line while the counter contin-

ues to increment.

Note: Writing to any TOD register will reset the 1Hz

square wave output.

Trickle Charger and Reset Input/Output

10

____________________________________________________________________

SUPPLY CONDITION

READ/WRITE

ACCESS

POWERED

BY

No

No

Yes

Yes

Table 2. Power Control

ADDRESS

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

FUNCTION

00H

TOD Counter Byte 0

Time-of-Day Counter

01H

TOD Counter Byte 1

Time-of-Day Counter

02H

TOD Counter Byte 2

Time-of-Day Counter

03H

TOD Counter Byte 3

Time-of-Day Counter

04H

WD/ALM Counter Byte 0

Watchdog/Alarm Counter

05H

WD/ALM Counter Byte 1

Watchdog/Alarm Counter

06H

WD/ALM Counter Byte 2

Watchdog/Alarm Counter

07H

EOSC

WACE

WD/ALM

BBSQW

WDSTR

RS2

RS1

AIE

Control

08H

OSF

0

0

0

0

0

0

AF

Status

09H

TCS3

TCS2

TCS1

TCS0

DS1

DS0

ROUT1

ROUT0

Trickle Charger

Table 3. Address Map

Note: Unless otherwise specified, the state of the registers is not defined when power is first applied.