ACE24C04.08A_11 参数 Datasheet PDF下载

ACE24C04/08A

Two-wire Serial EEPROM

Page Write

The 4/8K devices are capable of 16-byte page writes.

A page write is initiated the same as a byte write, but the microcontroller does not send a stop

condition after the first data word is clocked in. Instead, after the EEPROM acknowledges receipt of the

first data word, the microcontroller can transmit up to seven more data words. The EEPROM will

respond with a zero after each data word received. The microcontroller must terminate the page write

sequence with a stop condition (refer to Figure 9).

The data word address lower three bits are internally incremented following the receipt of each data

word. The higher data word address bits are not incremented, retaining the memory page row location.

When the word address, internally generated, reaches the page boundary, the following byte is placed

at the beginning of the same page. If more than eight data words are transmitted to the EEPROM, the

data word address will “roll over” and previous data will be overwritten.

Acknowledge Polling

Once the internally timed write cycle has started and the EEPROM inputs are disabled, acknowledge

polling can be initiated. This involves sending a start condition followed by the device address word.

The read/write bit is representative of the operation desired. Only if the internal write cycle has

completed will the EEPROM respond with a zero allowing the read or write sequence to continue.

Read Operations

Read operations are initiated the same way as write operations with the exception that the read/write

select bit in the device address word is set to one. There are three read operations: current address

read, random address read and sequential read.

Current Address Read

The internal data word address counter maintains the last address accessed during the last read or

write operation, incremented by one. This address stays valid between operations as long as the chip

power is maintained. The address “roll over” during read is from the last byte of the last memory page

to the first byte of the first page. The address “roll over” during write is from the last byte of the current

page to the first byte of the same page.

Once the device address with the read/write select bit set to one is clocked in and acknowledged by

the EEPROM, the current address data word is serially clocked out. The microcontroller does not

respond with an input zero but does generate a following stop condition (refer to Figure 10).

Random Read

A random read requires a “dummy” byte write sequence to load in the data word address. Once the

device address word and data word address are clocked in and acknowledged by the EEPROM, the

microcontroller must generate another start condition. The microcontroller now initiates a current

address read by sending a device address with the read/write select bit high. The EEPROM

acknowledges the device address and serially clocks out the data word. The microcontroller does not

respond with a zero but does generate a following stop condition (refer to Figure 11).

VER 1.5

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