93AA76_04 Datasheet, PDF (11/22 Pages) Microchip Technology – 8K/16K 1.8V Microwire Serial EEPROM

4.0 PIN DESCRIPTIONS
TABLE 4-1: PIN FUNCTION TABLE
Name
Function
CS
CLK
DI
DO
VSS
ORG
PE
VCC
Chip Select
Serial Data Clock
Serial Data Input
Serial Data Output
Ground
Memory Configuration
Program Enable
Power Supply
4.1 Chip Select (CS)
A high level selects the device. A low level deselects
the device and forces it into Standby mode. However, a
programming cycle which is already initiated will be
completed, regardless of the CS input signal. If CS is
brought low during a program cycle, the device will go
into Standby mode as soon as the programming cycle
is completed.
CS must be low for 250 ns minimum (TCSL) between
consecutive instructions. If CS is low, the internal
control logic is held in a Reset status.
4.2 Serial Clock (CLK)
The Serial Clock is used to synchronize the communi-
cation between a master device and the 93AA76/86.
Opcode, address and data bits are clocked in on the
positive edge of CLK. Data bits are also clocked out on
the positive edge of CLK.
CLK can be stopped anywhere in the transmission
sequence (at high or low level) and can be continued
anytime with respect to clock high time (TCKH) and
clock low time (TCKL). This gives the controlling master
freedom in preparing opcode, address and data.
CLK is a “don't care” if CS is low (device deselected). If
CS is high, but Start condition has not been detected,
any number of clock cycles can be received by the
device without changing its status (i.e., waiting for Start
condition).
CLK cycles are not required during the self-timed write
(i.e., auto erase/write) cycle.
93AA76/86
After detection of a Start condition the specified number
of clock cycles (respectively low-to-high transitions of
CLK) must be provided. These clock cycles are
required to clock in all opcode, address and data bits
before an instruction is executed (see Table 1-2
through Table 1-6 for more details). CLK and DI then
become “don’t care” inputs waiting for a new Start
condition to be detected.
Note:
CS must go low between consecutive
instructions, except when performing a
sequential read (Refer to Section 3.1
“READ” for more detail on sequential
reads).
4.3 Data In (DI)
Data In is used to clock in a Start bit, opcode, address
and data synchronously with the CLK input.
4.4 Data Out (DO)
Data Out is used in the Read mode to output data
synchronously with the CLK input (TPD after the
positive edge of CLK).
This pin also provides Ready/Busy status information
during erase and write cycles. Ready/Busy status infor-
mation is available when CS is high. It will be displayed
until the next Start bit occurs as long as CS stays high.
4.5 Organization (ORG)
When ORG is connected to VCC, the x16 memory
organization is selected. When ORG is tied to VSS, the
x8 memory organization is selected. There is an
internal pull-up resistor on the ORG pin that will select
x16 organization when left unconnected.
4.6 Program Enable (PE)
This pin allows the user to enable or disable the ability
to write data to the memory array. If the PE pin is
floated or tied to VCC, the device can be programmed.
If the PE pin is tied to VSS, programming will be
inhibited. There is an internal pull-up on this device that
enables programming if this pin is left floating.
 2004 Microchip Technology Inc.
DS21130E-page 11