DS1670

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POWER-UP/POWER-DOWN CONSIDERATIONS

The DS1670 was designed to operate with a power supply of 3.3 volts. When 3.3 volts are applied within

drops below the lower of 2.7 volts (typical) or the battery voltage, the device is switched over to the

backup power supply.

for 250 ms (typical) to allow the power supply and microprocessor to stabilize.

ADDRESS/COMMAND BYTE

The command byte for the DS1670 is shown in Figure 2. Each data transfer is initiated by a command

byte. Bits 0 through 6 specify the addresses of the registers to be accessed. The MSB (bit 7) is the

Read/Write bit. This bit specifies whether the accessed byte will be read or written. A read operation is

selected if bit 7 is a 0 and a write operation is selected if bit 7 is a 1. The address map for the DS1670 is

shown in Figure 3.

ADDRESS/COMMAND BYTE Figure 2

76

54

3

2

1

0

RD

WR

A6

A5

A4

A3

A2

A1

A0

DS1670 ADDRESS MAP Figure 3

BIT 7

BIT 0

00

0

10 SECONDS

SECONDS

01

0

10 MINUTES

MINUTES

10 HR

02

0

12

24

A/P

10 HR

HOURS

03

0

0

0

0

0

DAY

04

0

0

10 DATE

DATE

05

0

0

0

10

MO.

MONTH

06

10 YEAR

YEAR

07

M

10 SEC ALARM

SECONDS ALARM

08

M

10 MIN ALARM

MINUTES ALARM

10 HR

09

M

12

24

A/P

10 HR

HOUR ALARM

0A

M

0

0

0

DAY ALARM

0B

CONTROL REGISTER

0C

STATUS REGISTER

0D

WATCHDOG REGISTER

0E

ADC REGISTER

0F

7F

RESERVED