The following diagram shows the single and burst mode transfer:

The table illustrates the values suggested for capacities C1, C2

Part No.

Crystal Error

Capacity Value

HT1380/HT1381

±10ppm

5pF

10~20ppm

8pF

Operating flowchart

To initiate any transfer of data, REST is taken high and an 8-bit command byte is first loaded into the

control logic to provide the register address and command information. Following the command

word, the clock/calendar data is serially transferred to or from the corresponding register. The REST

pin must be taken low again after the transfer operation is completed. All data enter on the rising

edge of SCLK and outputs on the falling edge of SCLK. In total, 16 clock pulses are needed for a sin-

gle byte mode and 72 for burst mode. Both input and output data starts with bit 0.

In using the HT1380/HT1381, set first the WP and CH to 0 and wait for about 3 seconds, the oscilla-

tor will generate the clocks for internal use. Then, choose either single mode or burst mode to input

the data. The read or write operating flowcharts are shown on the next page.

HT1380/HT1381

7

October 2, 1999

R/ W

A0

A1 A2

0

0

1

0

1

2

3

4

5

6

7

0

1

2

3

4

5

6

7

CO M M A N D B Y T E

D A T A I/ O

S i ngl e b y t e t rans f er

B u rs t m o d e tra n s f e r

SC L K

I/O

01

CO M M A N D B Y T E

DA T A B Y T E 7

DA T A B Y T E 0

R/ W

0

1

2

3

4

5

6

7

11

1

1

1

07

07

SC L K

I/O

RE S T

RE S T

0