M34D64-R STMICROELECTRONICS [STMicroelectronics], M34D64-R Datasheet - Page 3

• Manufacturer Part Number: M34D64-R
• Description: 64 Kbit Serial I2C Bus EEPROM With Hardware Write Control on Top Quarter of Memory
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

SIGNAL DESCRIPTION
Serial Clock (SCL)
This input signal is used to strobe all data in and
out of the device. In applications where this signal
is used by slave devices to synchronize the bus to
a slower clock, the bus master must have an open
drain output, and a pull-up resistor must be con-
nected from Serial Clock (SCL) to V
indicates how the value of the pull-up resistor can
be calculated). In most applications, though, this
method of synchronization is not employed, and
so the pull-up resistor is not necessary, provided
that the bus master has a push-pull (rather than
open drain) output.
Serial Data (SDA)
This bi-directional signal is used to transfer data in
or out of the device. It is an open drain output that
may be wire-OR’ed with other open drain or open
collector signals on the bus. A pull up resistor must
be connected from Serial Data (SDA) to V
ure 5 indicates how the value of the pull-up resistor
can be calculated).
Chip Enable (E0, E1, E2)
These input signals are used to set the value that
is to be looked for on the three least significant bits
(b3, b2, b1) of the 7-bit Device Select Code. These
inputs must be tied to V
Device Select Code.
Write Control (WC)
The hardware Write Control pin (WC) is useful for
protecting the top quarter of the memory (as
shown in Figure 4) from inadvertent erase or write.
The Write Control signal is used to enable
Figure 5. Maximum R
20
16
12
8
4
0
10
L
CC
Value versus Bus Capacitance (C
or V
SS
, to establish the
C BUS (pF)
CC
100
fc = 400kHz
. (Figure 5
CC
. (Fig-
fc = 100kHz
(WC=V
the top quarter of the memory area. When uncon-
nected, the WC input is internally read as V
write operations are allowed.
Figure 4. Memory Map showing Write Control
Area
BUS
IL
) or disable (WC=V
) for an I
1000
1FFFh
1000h
0000h
1800h
0800h
MASTER
V CC
Write Controlled
2
C Bus
Area
SDA
SCL
IH
) write instructions to
R L
C BUS
R L
AI01665
M34D64
C BUS
AI03114C
IL
, and
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