IS23SC4428-X2 Просмотр технического описания (PDF) - Integrated Silicon Solution

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IS23SC4428-X2

1-KBYTE EEPROM WITH WRITE PROTECT FUNCTION AND PROGRAMMABLE SECURITY CODE (PSC)

Integrated Silicon Solution 

IS23SC4418

IS23SC4428

ISSI ®

RST

CLK

I/O

012345 6 7012345 6 7012345 6 7

S0 S1 S2 S3 S4 S5 A8 A9 A0 A1 A2 A3 A4 A5 A6 A7 D0 D1 D2 D3 D4 D5 D6 D7

Command

Address

Data

Figure 5. Command Entry Sequence

GENERAL COMMAND DESCRIPTIONS

Read 8-Bits Data

The read 8-bit data command allows the user to specify

the address (A0-A9) of the data byte to be read from the

device. The byte address for the next output data is

automatically incremented after every eight clock pulses.

The data is output in sequential order, with the data from

address n followed by the data from address n+1.

(See Figure 6.)

Read 9-Bits Data with Protect Bit

The read 9-bit data command operates similarly to read 8-

bit data command except that the protect bit for each byte

is output after each 8-bit data and the address for the next

output data is incremented after every nine clock pulses.

(See Figure 7.)

Write/Erase Data Byte without Protect Bit

The write/erase data byte without protect bit command

writes the new data into the specified byte location. There

are three kinds of write/erase operations which are

automatically executed by the device:

1. Erase and subsequent write if 203 clock pulses at

f < 20 KHz are applied. (See Figure 8.)

2. Write only if 103 clock pulses at f < 20 KHz are ap-

plied. This operation is only suitable if single bits of

one byte shall be changed only from 1 to 0. (See

Figure 9.)

3. Erase only if the input data = FFH and 103 clock

pulses at f < 20 KHz are applied. (See Figure 9.)

Note: Erase means 0 → 1. Write means 1 → 0.

If the protect bit of the corresponding byte location is

enabled, the write/erase operation will have no effect on

the content.

Write/Erase Data Byte with Protect Bit

The write/erase data byte with protect bit command

operates similarly to the write/erase data bytewith protect

bit command except that it also writes 0 to the

corresponding protect bit. After the protect bit is set to 0

(write protection enabled), it cannot be changed again.

(See Figures 8 and 9.)

Write Protect Bit with Data Comparison

The write protect bit with data comparison command

writes 0 to the corresponding protect bit only if the input

data and the data in the specified memory location are the

same. After the protect bit is set to 0 (write protection

enabled), it cannot be changed again. (See Figure 9.)

The execution of write/erase commands are terminated

after a given number of clock cycles. When the operation

is done, the device will bring the I/O state to 0. Only RST

transition from 0 to 1 can set the I/O state back to 1.

6

Integrated Silicon Solution, Inc. — 1-800-379-4774

REV. A

11/01/01

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