AT24C64D-XHM-T Atmel, AT24C64D-XHM-T Datasheet - Page 9

• Manufacturer Part Number: AT24C64D-XHM-T
• Description: EEPROM SERIAL EEPROM 64K 2-WIRE 1.7V
• Manufacturer: Atmel

Specifications of AT24C64D-XHM-T

• Density: 64Kb
• Interface Type: Serial (2-Wire)
• Organization: 8Kx8
• Access Time (max): 550ns
• Frequency (max): 1MHz
• Write Protection: Yes
• Data Retention: 100Year
• Operating Supply Voltage (typ): 1.8/2.5/3.3/5V
• Package Type: TSSOP
• Operating Temp Range: -40C to 85C
• Supply Current: 3mA
• Operating Supply Voltage (min): 1.7V
• Operating Supply Voltage (max): 5.5V
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8717B–SEEPR–6/10
5.
6.
Device Addressing
The 32K/64K EEPROM requires an 8-bit device address word following a start condition to enable the chip for a
read or write operation (see
sequence for the first four most significant bits as shown. This is common to all 2-wire EEPROM devices.
The 32K/64K uses the three device address bits A2, A1, A0 to allow as many as eight devices on the same bus.
These bits must compare to their corresponding hardwired input pins. The A2, A1, and A0 pins use an internal
proprietary circuit that biases them to a logic low condition if the pins are allowed to float.
The eighth bit of the device address is the read/write operation select bit. A read operation is initiated if this bit is
high and a write operation is initiated if this bit is low.
Upon a compare of the device address, the EEPROM will output a zero. If a compare is not made, the device will
return to standby state.
DATA SECURITY: The Atmel
write protect the entire memory when the WP pin is at V
Write Operations
BYTE WRITE: A write operation requires two 8-bit data word addresses following the device address word and
acknowledgment. Upon receipt of this address, the EEPROM will again respond with a zero and then clock in the
first 8-bit data word. Following receipt of the 8-bit data word, the EEPROM will output a zero and the addressing
device, such as a microcontroller, must terminate the write sequence with a stop condition. At this time the
EEPROM enters an internally-timed write cycle, t
write cycle and the EEPROM will not respond until the write is complete (see
PAGE WRITE: The 32K/64K EEPROM is capable of 32-byte page writes.
A page write is initiated the same way 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 31 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 (see
page
The data word address lower five 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 32 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.
11).
Figure 7-1 on page 10
®
AT24C32D/64D has a hardware data protection scheme that allows the user to
WR
). The device address word consists of a mandatory one, zero
, to the nonvolatile memory. All inputs are disabled during this
CC
.
Atmel AT24C32D/64D
Figure 7-2 on page
10).
Figure 7-3 on
9