HT93LC56 データシートの表示（PDF） - Holtek Semiconductor

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HT93LC56

2K 3-Wire CMOS Serial EEPROM

Holtek Semiconductor 

Timing Diagrams

HT93LC56

Functional Description

The HT93LC56 is accessed via a three-wire serial

communication interface. The device is arranged

into 128 words by 16 bits or 256 words by 8 bits

depending whether the ORG pin is connected to

VCC or VSS. The HT93LC56 contains seven in-

structions: READ, ERASE, WRITE, EWEN,

EWDS, ERAL and WRAL. When the user se-

lectable internal organization is arranged

into 128×16 (256×8), these instructions are all

made up of 11(12) bits data: 1 start bit, 2 op code

bits and 8(9) address bits.

By using the control signal CS, SK and data

input signal DI, these instructions can be given

to the HT93LC56. These serial instruction data

presented at the DI input will be written into

the device at the rising edge of SK. During the

READ cycle, DO pin acts as the data output and

during the WRITE or ERASE cycle, DO pin

indicates the BUSY/READY status. When the

DO pin is active for read data or as a

BUSY/READY indicator the CS pin must be

high; otherwise DO pin will be in a high-imped-

ance state. For successful instructions, CS must

be low once after the instruction is sent. After

power on, the device is by default in the EWDS

state. And, an EWEN instruction must be per-

formed before any ERASE or WRITE instruc-

tion can be executed. The following are the

functional descriptions and timing diagrams of

all seven instructions.

READ

The READ instruction will stream out data at a

specified address on the DO pin. The data on

DO pin changes during the low-to-high edge of

SK signal. The 8 bits or 16 bits data stream is

preceded by a logical “0” dummy bit. Irrespec-

tive of the condition of the EWEN or EWDS

instruction, the READ command is always

valid and independent of these two instruc-

tions. After the data word has been read the

internal address will be automatically incre-

mented by 1 allowing the next consecutive data

word to be read out without entering further

address data. The address will wrap around

with CS High until CS returns to LOW.

EWEN/EWDS

The EWEN/EWDS instruction will enable or

disable the programming capabilities. At both

the power on and power off state the device auto-

matically entered the disable mode. Before a

WRITE, ERASE, WRAL or ERAL instruction is

given, the programming enable instruction

EWEN must be issued, otherwise the

ERASE/WRITE instruction is invalid. After the

EWEN instruction is issued, the programming

enable condition remains until power is turned off

or a EWDS instruction is given. No data can be

written into the device in the programming dis-

abled state. By so doing, the internal memory

data can be protected.

5

6th May ’99

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