AT28HC64B PDF 데이터시트 : 부품 기능 및 핀배열

부품번호 AT28HC64B
기능 64K (8K x 8) High-speed Parallel EEPROM
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AT28HC64B 데이터시트, 핀배열, 회로
Fast Read Access Time – 70 ns
Automatic Page Write Operation
– Internal Address and Data Latches for 64 Bytes
Fast Write Cycle Times
– Page Write Cycle Time: 10 ms Maximum (Standard)
2 ms Maximum (Option – Ref. AT28HC64BF Datasheet)
– 1 to 64-byte Page Write Operation
Low Power Dissipation
– 40 mA Active Current
– 100 µA CMOS Standby Current
Hardware and Software Data Protection
DATA Polling and Toggle Bit for End of Write Detection
High Reliability CMOS Technology
– Endurance: 100,000 Cycles
– Data Retention: 10 Years
Single 5 V ±10% Supply
CMOS and TTL Compatible Inputs and Outputs
JEDEC Approved Byte-wide Pinout
Industrial Temperature Ranges
Green (Pb/Halide-free) Packaging Option Only
1. Description
The AT28HC64B is a high-performance electrically-erasable and programmable read-
only memory (EEPROM). Its 64K of memory is organized as 8,192 words by 8 bits.
Manufactured with Atmel’s advanced nonvolatile CMOS technology, the device offers
access times to 55 ns with power dissipation of just 220 mW. When the device is
deselected, the CMOS standby current is less than 100 µA.
The AT28HC64B is accessed like a Static RAM for the read or write cycle without the
need for external components. The device contains a 64-byte page register to allow
writing of up to 64 bytes simultaneously. During a write cycle, the addresses and 1 to
64 bytes of data are internally latched, freeing the address and data bus for other
operations. Following the initiation of a write cycle, the device will automatically write
the latched data using an internal control timer. The end of a write cycle can be
detected by DATA polling of I/O7. Once the end of a write cycle has been detected, a
new access for a read or write can begin.
Atmel’s AT28HC64B has additional features to ensure high quality and manufactura-
bility. The device utilizes internal error correction for extended endurance and
improved data retention characteristics. An optional software data protection mecha-
nism is available to guard against inadvertent writes. The device also includes an
extra 64 bytes of EEPROM for device identification or tracking.
64K (8K x 8)
Page Write and
Software Data

AT28HC64B pdf, 반도체, 판매, 대치품
4.5 Toggle Bit
In addition to DATA Polling, the AT28HC64B provides another method for determining the end
of a write cycle. During the write operation, successive attempts to read data from the device
will result in I/O6 toggling between one and zero. Once the write has completed, I/O6 will stop
toggling, and valid data will be read. Toggle bit reading may begin at any time during the write
4.6 Data Protection
If precautions are not taken, inadvertent writes may occur during transitions of the host system
power supply. Atmel® has incorporated both hardware and software features that will protect
the memory against inadvertent writes.
Hardware Protection
Hardware features protect against inadvertent writes to the AT28HC64B in the following ways:
(a) VCC sense – if VCC is below 3.8 V (typical), the write function is inhibited; (b) VCC power-on
delay – once VCC has reached 3.8 V, the device will automatically time out 5 ms (typical)
before allowing a write; (c) write inhibit – holding any one of OE low, CE high or WE high inhib-
its write cycles; and (d) noise filter – pulses of less than 15 ns (typical) on the WE or CE inputs
will not initiate a write cycle.
Software Data Protection
A software-controlled data protection feature has been implemented on the AT28HC64B.
When enabled, the software data protection (SDP), will prevent inadvertent writes. The SDP
feature may be enabled or disabled by the user; the AT28HC64B is shipped from Atmel with
SDP disabled.
SDP is enabled by the user issuing a series of three write commands in which three specific
bytes of data are written to three specific addresses (refer to the “Software Data Protection
Algorithm” diagram on page 10). After writing the 3-byte command sequence and waiting tWC,
the entire AT28HC64B will be protected against inadvertent writes. It should be noted that
even after SDP is enabled, the user may still perform a byte or page write to the AT28HC64B.
This is done by preceding the data to be written by the same 3-byte command sequence used
to enable SDP.
Once set, SDP remains active unless the disable command sequence is issued. Power transi-
tions do not disable SDP, and SDP protects the AT28HC64B during power-up and power-
down conditions. All command sequences must conform to the page write timing specifica-
tions. The data in the enable and disable command sequences is not actually written into the
device; their addresses may still be written with user data in either a byte or page write
After setting SDP, any attempt to write to the device without the 3-byte command sequence
will start the internal write timers. No data will be written to the device, however. For the dura-
tion of tWC, read operations will effectively be polling operations.
4.7 Device Identification
An extra 64 bytes of EEPROM memory are available to the user for device identification. By
raising A9 to 12 V ±0.5 V and using address locations 1FC0H to 1FFFH, the additional bytes
may be written to or read from in the same manner as the regular memory array.
4 AT28HC64B


AT28HC64B 전자부품, 판매, 대치품
11. Input Test Waveforms and Measurement Level
12. Output Test Load
tR, tF < 5 ns
13. Pin Capacitance
f = 1 MHz, T = 25°C(1)
8 12
1. This parameter is characterized and is not 100% tested.
VIN = 0 V
VOUT = 0 V


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64K (8K x 8) High-speed Parallel EEPROM

ATMEL Corporation
ATMEL Corporation

64K (8K x 8) High Speed Parallel EEPROM

ATMEL Corporation
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