HT1381 データシートの表示（PDF） - Holtek Semiconductor

部品番号

コンポーネント説明

メーカー

HT1381

Serial Timekeeper Chip

Holtek Semiconductor 

HT1380/HT1381

Symbol

tr

tf

tCC

tCCH

tCWH

tCDZ

Parameter

Test Conditions

VDD Conditions

2V

¾

Clock Rise and Fall Time

5V

¾

Reset to Clock Setup

2V

¾

5V

¾

Clock to Reset Hold

2V

¾

5V

¾

Reset Inactive Time

2V

¾

5V

¾

2V

¾

Reset to I/O High Impedance

5V

¾

Min.

¾

¾

4

1

240

60

4

1

¾

¾

Max.

2000

500

¾

¾

¾

¾

¾

¾

280

70

Unit

ns

us

ns

us

ns

Functional Description

The HT1380/HT1381 mainly contains the fol-

lowing internal elements: a data shift register

array to store the clock/calendar data, com-

mand control logic, oscillator circuit and read

timer clock. The clock is contained in eight

read/write registers as shown below. Data con-

tained in the clock register is in binary coded

decimal format.

Two modes are available for transferring the

data between the microprocessor and the

HT1380/HT1381. One is in single-byte mode

and the other is in multiple-byte mode.

The HT1380/HT1381 also contains two addi-

tional bits, the clock halt bit (CH) and the write

protect bit (WP). These bits control the opera-

tion of the oscillator and so data can be written

to the register array. These two bits should first

be specified in order to read from and write to

the register array properly.

Command byte

For each data transfer, a Command Byte is initiated to specify which register is accessed. This is to

determine whether a read, write, or test cycle is operated and whether a single byte or burst mode

transfer is to occur. Refer to the table shown below and follow the steps to write the data to the chip.

First give a Command Byte of HT1380/HT1381, and then write a data in the register.

This table illustrates the correlation between Command Byte and their bits:

Command Byte

Function Description

C7 C6 C5 C4 C3 C2 C1 C0

Select Read or Write Cycle

R/W

Specify the Register to be Accessed

A2 A1 A0

Clock Halt Flag

C

For IC Test Only

1

0

0

1

x

x

x

1

Select Single Byte or Burst Mode

1

0

1

1

1

1

1

x

Note: ²x² stands for don¢t care

4

September 18, 2000

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