DS1672

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DETAILED DESCRIPTION

The DS1672 provides a 32-bit counter that increments once-per-second. The counter data is accessible

prevent data corruption. The device switches to the backup supply input, which maintains oscillator and

The block diagram in Figure 4 shows the main elements of the DS1672. As shown, communications to

identification code followed by a register address. Subsequent registers can be accessed sequentially until

a STOP condition is executed.

Figure 4. Block Diagram

Oscillator Circuit

The DS1672 uses an external 32.768kHz crystal. The oscillator circuit does not require any external

resistors or capacitors to operate. Table 1 specifies several crystal parameters for the external crystal.

Figure 4 shows a functional schematic of the oscillator circuit. If using a crystal with the specified

characteristics, the startup time is usually less than one second.

Table 1. Crystal Specifications*

PARAMETER

SYMBOL

MIN

TYP

MAX

UNITS

Nominal Frequency

32.768

kHz

Series Resistance

ESR

45

k

Ω

Load Capacitance

6

pF

*The crystal, traces, and crystal input pins should be isolated from RF generating signals. Refer to Application Note 58:

Crystal Considerations with Dallas Real-Time Clocks.

32-BIT COUNTER

(4 BYTES)

POWER CONTROL

ADDRESS REGISTER

CONTROL LOGIC

1Hz

V

CC

V

BACKUP

GND

SCL

SDA

CONTROL

TRICKLE CHARGER

X1

X2

RST

Dallas

Semiconductor

DS1672

C

L

C

L

N

OSCILLATOR

AND

DIVIDER