2010 Microchip Technology Inc. DS21131F-page 11
93LC76/86
4.0 PIN DESCRIPTIONS
TABLE 4-1: PIN FUNCTION TABLE
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 (T
CSL) 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 93LC76/86.
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 (T
CKH) and
clock low time (T
CKL). 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.
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 1-3
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.
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 (T
PD 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 orga-
nization is selected. When ORG is tied to V
SS, 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 V
CC, the device can be programmed.
If the PE pin is tied to V
SS, programming will be
inhibited. There is an internal pull-up on this device that
enables programming if this pin is left floating.
Name Function
CS Chip Select
CLK Serial Data Clock
DI Serial Data Input
DO Serial Data Output
V
SS Ground
ORG Memory Configuration
PE Program Enable
V
CC Power Supply
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).
