AT93C46D View Datasheet(PDF) - Atmel Corporation

Part Name

Description

MFG CO.

AT93C46D

Three-wire Serial EEPROM

Atmel Corporation 

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AT93C46D

Table 1-4. Instruction Set for the AT93C46D

Instruction SB

Op

Code

Address

x8

x 16

READ

1

10

A6 – A0

A5 – A0

EWEN

ERASE

WRITE

ERAL

1

00

11XXXXX 11XXXX

1

11

1

01

A6 – A0

A6 – A0

A5 – A0

A5 – A0

1

00

10XXXXX 10XXXX

Data

x8

x 16

D7 – D0

D15 – D0

WRAL

1

00

01XXXXX 01XXXX

D7 – D0

D15 – D0

EWDS

1

00

00XXXXX 00XXXX

Note: The Xs in the address field represent DON’T CARE values and must be clocked.

Comments

Reads data stored in memory, at

specified address

Write enable must precede all

programming modes

Erases memory location An – A0

Writes memory location An – A0

Erases all memory locations. Valid

only at VCC = 4.5V to 5.5V

Writes all memory locations. Valid

only at VCC = 4.5V to 5.5V

Disables all programming instructions

2. Functional Description

The AT93C46D is accessed via a simple and versatile three-wire serial communication inter-

face. Device operation is controlled by seven instructions issued by the host processor. A valid

instruction starts with a rising edge of CS and consists of a start bit (logic “1”) followed by the

appropriate op code and the desired memory address location.

READ (READ): The Read (READ) instruction contains the address code for the memory loca-

tion to be read. After the instruction and address are decoded, data from the selected memory

location is available at the serial output pin DO. Output data changes are synchronized with the

rising edges of serial clock SK. It should be noted that a dummy bit (logic “0”) precedes the 8- or

16-bit data output string.

ERASE/WRITE ENABLE (EWEN): To assure data integrity, the part automatically goes into the

Erase/Write Disable (EWDS) state when power is first applied. An Erase/Write Enable (EWEN)

instruction must be executed first before any programming instructions can be carried out.

Please note that once in the EWEN state, programming remains enabled until an EWDS instruc-

tion is executed or VCC power is removed from the part.

ERASE (ERASE): The Erase (ERASE) instruction programs all bits in the specified memory

location to the logical “1” state. The self-timed erase cycle starts once the Erase instruction and

address are decoded. The DO pin outputs the Ready/Busy status of the part if CS is brought

high after being kept low for a minimum of 250 ns (tCS). A logic “1” at pin DO indicates that the

selected memory location has been erased and the part is ready for another instruction.

WRITE (WRITE): The Write (WRITE) instruction contains the 8 or 16 bits of data to be written

into the specified memory location. The self-timed programming cycle tWP starts after the last bit

of data is received at serial data input pin DI. The DO pin outputs the Read/Busy status of the

part if CS is brought high after being kept low for a minimum of 250 ns (tCS). A logic “0” at DO

indicates that programming is still in progress. A logic “1” indicates that the memory location at

the specified address has been written with the data pattern contained in the instruction and the

5

5193F–SEEPR–1/08

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