March 1999
NM34C02
2K-Bit Standard 2-Wire Bus Interface
Designed with Permanent Write-Protection for First 128 Bytes for Serial Presence
Detect Application on Memory Modules
General Description
Features
The NM34C02 is 2048 bits of CMOS non-volatile electrically
erasable memory. It is designed to support Serial Presence
Detect circuitry in memory modules. This communications proto-
col uses CLOCK (SCL) and DATA I/O (SDA) lines to synchro-
nously clock data between the master (for example a micropro-
cessor) and the slave EEPROM device(s).
■ Extended Operating Voltage: 2.7V-5.5V
■ Write-Protection for first 128 bytes
■ 200 µA active current typical
– 10 µA standby current typical
– 1.0 µA standby current typical (L)
– 0.1 µA standby current typical (LZ)
The contents of the non-volatile memory allows the CPU to
determine the capacity of the module and the electrical character-
istics of the memory devices it contains. This will enable "plug and
play" capability as the module is read and PC main memory
resources utilized through the memory controller.
■ IIC compatible interface
– Provides bidirectional data transfer protocol
■ Sixteen byte page write mode
– Minimizes total write time per byte
The first 128 bytes of the memory of the NM34C02 can be
permanentlyWriteProtectedbywritingtothe"WRITEPROTECT"
Register. Write Protect implementation details are described
under the section titled Addressing the WP Register.
■ Self timed write cycle
- Typical write cycle time of 6ms
■ Endurance: 1,000,000 data changes
■ Data retention greater than 40 years
The NM34C02 is available in a JEDEC standard TSSOP package
for low profile memory modules for systems requiring efficient
space utilization such as in a notebook computer. Two options are
available: L - Low Voltage and LZ - Low Power, allowing the part
to be used in systems where battery life is of primary importance.
■ Packages available: 8-pin TSSOP and 8-pin SO
Block Diagram
V
CC
V
SS
H.V. GENERATION
TIMING &CONTROL
START CYCLE
START
STOP
SDA
LOGIC
CONTROL
LOGIC
SLAVE ADDRESS
REGISTER &
COMPARATOR
2
E
PROM
16
ARRAY
16 x 16 x 8
XDEC
SCL
LOAD
INC
A2
A1
A0
WORD
ADDRESS
COUNTER
0/1/2/3
4
16
4
R/W
YDEC
Device Address Bits
8
Write Protect
Register
CK
D
OUT
DATA REGISTER
D
IN
DS012821-1
1
© 1999 Fairchild Semiconductor Corporation
NM34C02 Rev. D.2
www.fairchildsemi.com