m34d64-w STMicroelectronics, m34d64-w Datasheet - Page 8

• Manufacturer Part Number: m34d64-w
• Description: 64 Kbit Serial I2c Bus Eeprom With Hardware Write Control On Top Quarter Of Memory
• Manufacturer: STMicroelectronics

Signal description
2
2.0.1
2.0.2
2.1
2.2
2.3
8/28
Chip Enable (E0, E1, E2)
Write Control (WC)
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 connected from Serial Clock
(SCL) to V
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
the value of the pull-up resistor can be calculated).
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
or V
floating), these inputs are read as low (0,0,0).
Figure 3.
The hardware Write Control pin (WC) is useful for protecting the top quarter of the memory
(as shown in
(WC = V
When unconnected, the WC input is internally read as V
V
V
SS
SS
SS
is the reference for the V
ground
, to establish the device select code as shown in
IL
) or disable (WC = V
CC
Device select code
.
Figure
(Figure 5
4.) from inadvertent write. The Write Control signal is used to enable
indicates how the value of the pull-up resistor can be calculated). In
CC
IH
) write instructions to the top quarter of the memory area.
supply voltage.
E i
M24xxx
V CC
V SS
E i
M24xxx
V CC
V SS
Ai12806
Figure
IL
, and write operations are allowed.
3. When not connected (left
CC
.
(Figure 5
indicates how
M34D64
CC