M
FEATURES
93C66A/B
PACKAGE TYPE
PDIP
CS
CLK
DI
DO
1
8
V
CC
NC
NC
V
SS
4K 5.0V Automotive Temperature Microwire
®
Serial EEPROM
• Single supply 5.0V operation
• Low power CMOS technology
- 1 mA active current (typical)
- 1
µ
A standby current (maximum)
• 512x 8 bit organization (93C66A)
• 256x 16 bit organization (93C66B)
• Self-timed ERASE and WRITE cycles (including
auto-erase)
• Automatic ERAL before WRAL
• Power on/off data protection circuitry
• Industry standard 3-wire serial interface
• Device status signal during ERASE/WRITE
cycles
• Sequential READ function
• 100,000 E/W cycles guaranteed
• Data retention > 200 years
• 8-pin PDIP and SOIC packages
• Available for the following temperature ranges:
- Automotive (E):
-40
°
C to +125
°
C
93C66A/B
2
3
4
7
6
5
SOIC
CS
CLK
DI
DO
1
8
V
CC
NC
NC
V
SS
93C66A/B
2
3
4
7
6
5
BLOCK DIAGRAM
MEMORY
ARRAY
ADDRESS
DECODER
DESCRIPTION
The Microchip Technology Inc. 93C66A/B is a 4K-bit,
low-voltage serial Electrically Erasable PROM. The
device memory is configured as 512 x 8 bits (93C66A)
or 256 x 16 bits (93C66B). Advanced CMOS
technology makes this device ideal for low-power,
nonvolatile memory applications. The 93C66A/B is
available in standard 8-pin DIP and surface mount
SOIC packages.
This device is only recommended
for 5V automotive temperature applications. For all
commercial and industrial temperature applica-
tions, the 93LC66A/B is recommended.
ADDRESS
COUNTER
DATA
REGISTER
DI
MEMORY
DECODE
LOGIC
CLOCK
GENERATOR
V
CC
V
SS
OUTPUT
BUFFER
DO
CS
CLK
Microwire is a registered trademark of National Semiconductor.
©
1998 Microchip Technology Inc.
Preliminary
DS21207B-page 1
93C66A/B
1.0
1.1
ELECTRICAL
CHARACTERISTICS
Maximum Ratings*
TABLE 1-1:
Name
CS
CLK
DI
DO
V
SS
NC
V
CC
PIN FUNCTION TABLE
Function
Chip Select
Serial Data Clock
Serial Data Input
Serial Data Output
Ground
No Connect
Power Supply
V
CC
...................................................................................7.0V
All inputs and outputs w.r.t.
V
SS
................ -0.6V to
V
CC
+1.0V
Storage temperature .....................................-65
°
C to +150
°
C
Ambient temp. with power applied.................-65
°
C to +125
°
C
Soldering temperature of leads (10 seconds) ............. +300
°
C
ESD protection on all pins................................................4 kV
*Notice:
Stresses above those listed under “Maximum ratings” may
cause permanent damage to the device. This is a stress rating only and
functional operation of the device at those or any other conditions
above those indicated in the operational listings of this specification is
not implied. Exposure to maximum rating conditions for extended peri-
ods may affect device reliability.
TABLE 1-2:
DC AND AC ELECTRICAL CHARACTERISTICS
Automotive (E):V
CC
= +4.5V to +5.5VTamb = -40
°
C to +125
°
C
All parameters apply over the
specified operating ranges
unless otherwise noted
Parameter
High level input voltage
Low level input voltage
Low level output voltage
High level output voltage
Input leakage current
Output leakage current
Pin capacitance
(all inputs/outputs)
Operating current
Standby current
Clock frequency
Clock high time
Clock low time
Chip select setup time
Chip select hold time
Chip select low time
Data input setup time
Data input hold time
Data output delay time
Data output disable time
Status valid time
Program cycle time
Endurance
Symbol
V
IH
V
IL
V
OL
V
OH
I
LI
I
LO
C
IN
, C
OUT
I
CC
write
I
CC
read
I
CCS
F
CLK
T
CKH
T
CKL
T
CSS
T
CSH
T
CSL
T
DIS
T
DIH
T
PD
T
CZ
T
SV
T
WC
T
EC
T
WL
—
Min.
2.0
-0.3
—
2.4
-10
-10
—
—
—
—
—
250
250
50
0
250
100
100
—
—
—
—
—
—
100K
Max.
V
CC
+1
0.8
0.4
—
10
10
7
1.5
1
1
2
—
—
—
—
—
—
—
400
100
500
2
6
15
—
Units
V
V
V
V
µ
A
µ
A
pF
mA
mA
µ
A
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ms
ms
ms
cycles
CS = V
SS
(Note 2)
Conditions
I
OL
= 2.1 mA; V
CC
= 4.5V
I
OH
= -400
µ
A; V
CC
= 4.5V
V
IN
= V
SS
to V
CC
V
OUT
= V
SS
to V
CC
V
IN
/V
OUT
= 0 V (Notes 1 & 2)
Tamb = +25
°
C, F
CLK
= 1 MHz
Relative to CLK
Relative to CLK
Relative to CLK
Relative to CLK
C
L
= 100 pF
C
L
= 100 pF (Note 2)
C
L
= 100 pF
ERASE/WRITE mode
ERAL mode
WRAL mode
25
°
C, V
CC
= 5.0V, Block Mode (Note 3)
Note 1:
This parameter is tested at Tamb = 25
°
C and F
CLK
= 1 MHz.
2:
This parameter is periodically sampled and not 100% tested.
3:
This application is not tested but guaranteed by characterization. For endurance estimates in a specific
application, please consult the Total Endurance Model which may be obtained on Microchip’s BBS or web-
site.
DS21207B-page 2
Preliminary
©
1998 Microchip Technology Inc.
93C66A/B
2.0
2.1
PIN DESCRIPTION
Chip Select (CS)
CLK cycles are not required during the self-timed
WRITE (i.e., auto ERASE/WRITE) cycle.
After detecting a START condition, the specified num-
ber of clock cycles (respectively low to high transitions
of CLK) must be provided. These clock cycles are
required to clock in all required opcodes, addresses,
and data bits before an instruction is executed
(Table 2-1 and Table 2-2). 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.
A high level selects the device; a low level deselects the
device and forces it into standby mode. However, a pro-
gramming cycle which is already in progress will be
completed, regardless of the Chip Select (CS) input
signal. If CS is brought low during a program cycle, the
device will go into standby mode as soon as the pro-
gramming cycle is completed.
CS must be low for 250 ns minimum (T
CSL
) between
consecutive instructions. If CS is low, the internal con-
trol logic is held in a RESET status.
2.3
Data In (DI)
2.2
Serial Clock (CLK)
The Serial Clock (CLK) is used to synchronize the com-
munication between a master device and
the 93C66A/B. Opcodes, addresses, 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 the 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 a START condition).
Data In (DI) is used to clock in a START bit, opcode,
address, and data synchronously with the CLK input.
2.4
Data Out (DO)
Data Out (DO) 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 informa-
tion during ERASE and WRITE cycles. READY/BUSY
status information is available on the DO pin if CS is
brought high after being low for minimum chip select
low time (T
CSL
) and an ERASE or WRITE operation
has been initiated. The status signal is not available on
DO, if CS is held low during the entire ERASE or
WRITE cycle. In this case, DO is in the HIGH-Z mode.
If status is checked after the ERASE/WRITE cycle, the
data line will be high to indicate the device is ready.
TABLE 2-1:
Instruction
ERASE
ERAL
EWDS
EWEN
READ
WRITE
WRAL
1
1
1
1
1
1
1
INSTRUCTION SET FOR 93C66A
SB
Opcode
11
00
00
00
10
01
00
A8 A7
1
0
1
0
0
1
X
X
X
Address
A6 A5 A4 A3 A2 A1 A0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Data In
—
—
—
—
—
D7 - D0
D7 - D0
Data Out
(RDY/BSY)
(RDY/BSY)
HIGH-Z
HIGH-Z
D7 - D0
(RDY/BSY)
(RDY/BSY)
Req. CLK Cycles
12
12
12
12
20
20
20
A8 A7 A6 A5 A4 A3 A2 A1 A0
A8 A7
0
1
A6 A5 A4 A3 A2 A1 A0
X
X
X
X
X
X
X
TABLE 2-2:
Instruction
ERASE
ERAL
EWEN
EWDS
READ
WRITE
WRAL
1
1
1
1
1
1
1
INSTRUCTION SET FOR 93C66B
SB
Opcode
11
00
00
00
10
01
00
A7
1
1
0
A7
A7
0
A6
0
1
0
A6
A6
1
A5
X
X
X
A5
A5
X
Address
A4
X
X
X
A4
A4
X
A3
X
X
X
A3
A3
X
A2
X
X
X
A2
A2
X
A1
X
X
X
A1
A1
X
A0
X
X
X
A0
A0
X
Data In
—
—
—
—
—
D15 - D0
D15 - D0
Data Out
(RDY/BSY)
(RDY/BSY)
HIGH-Z
HIGH-Z
D15 - D0
(RDY/BSY)
(RDY/BSY)
Req. CLK Cycles
11
11
11
11
27
27
27
©
1998 Microchip Technology Inc.
Preliminary
DS21207B-page 3
93C66A/B
3.0
FUNCTIONAL DESCRIPTION
3.2
Data In (DI) and Data Out (DO)
Instructions, addresses, and write data are clocked into
the DI pin on the rising edge of the clock (CLK). The DO
pin is normally held in a HIGH-Z state except when
reading data from the device, or when checking the
READY/BUSY status during a programming operation.
The READY/BUSY status can be verified during an
ERASE/WRITE operation by polling the DO pin; DO
low indicates that programming is still in progress, while
DO high indicates the device is ready. The DO will enter
the HIGH-Z state on the falling edge of the CS.
It is possible to connect the Data In (DI) and Data
Out (DI) pins together. However, with this configuration
it is possible for a “bus conflict” to occur during the
“dummy zero” that precedes the READ operation, if A0
is a logic-high level. Under such a condition the voltage
level seen at DO is undefined and will depend upon the
relative impedances of DO and the signal source driv-
ing A0. The higher the current sourcing capability of A0,
the higher the voltage at the DO pin.
3.1
START Condition
3.3
Data Protection
The START bit is detected by the device if CS and DI
are both high with respect to the positive edge of CLK
for the first time.
Before a START condition is detected, CS, CLK, and DI
may change in any combination (except to that of a
START condition), without resulting in any device oper-
ation (ERASE, ERAL, EWDS, EWEN, READ, WRITE,
and WRAL). As soon as CS is high, the device is no
longer in the standby mode.
An instruction following a START condition will only be
executed if the required amount of opcodes,
addresses, and data bits for any particular instruction is
clocked in.
After execution of an instruction (i.e., clock in or out of
the last required address or data bit) CLK and DI
become don't care bits until a new START condition is
detected.
During power-up, all programming modes of operation
are inhibited until V
CC
has reached a level greater than
3.8V. During power-down, the source data protection
circuitry acts to inhibit all programming modes when
Vcc has fallen below 3.8V at nominal conditions.
The ERASE/WRITE Disable (EWDS) and ERASE/
WRITE Enable (EWEN) commands give additional pro-
tection against accidentally programming during nor-
mal operation.
After power-up, the device is automatically in the
EWDS mode. Therefore, an EWEN instruction must be
performed before any ERASE or WRITE instruction
can be executed.
FIGURE 3-1:
CS
SYNCHRONOUS DATA TIMING
V
IH
V
IL
V
IH
T
CSS
T
CKH
T
CKL
T
CSH
CLK
V
IL
T
DIS
V
IH
T
DIH
DI
V
IL
T
PD
T
PD
T
CZ
DO
(READ)
DO
(PROGRAM)
V
OH
V
OL
T
SV
V
OH
T
CZ
STATUS VALID
V
OL
Note:
AC Test Conditions: V
IL
= 0.4V, V
IH
= 2.4V.
DS21207B-page 4
Preliminary
©
1998 Microchip Technology Inc.
93C66A/B
3.4
ERASE
3.5
Erase All (ERAL)
The ERASE instruction forces all data bits of the spec-
ified address to the logical “1” state. This cycle begins
on the rising clock edge of the last address bit.
The DO pin indicates the READY/BUSY status of the
device if CS is brought high after a minimum of 250 ns
low (T
CSL
). DO at logical “0” indicates that program-
ming is still in progress. DO at logical “1” indicates that
the register at the specified address has been erased
and the device is ready for another instruction.
The Erase All (ERAL) instruction will erase the entire
memory array to the logical “1” state. The ERAL cycle
is identical to the ERASE cycle, except for the different
opcode. The ERAL cycle is completely self-timed and
commences at the rising clock edge of the last address
bit. Clocking of the CLK pin is not necessary after the
device has entered the ERAL cycle.
The DO pin indicates the READY/BUSY status of the
device, if CS is brought high after a minimum of 250 ns
low (T
CSL
) and before the entire ERAL cycle is com-
plete.
FIGURE 3-2:
CS
ERASE TIMING
T
CSL
CHECK STATUS
CLK
DI
1
1
1
A
N
A
N
-1
A
N
-2
•••
A0
T
SV
T
CZ
READY
HIGH-Z
T
WC
DO
HIGH-Z
BUSY
FIGURE 3-3:
CS
ERAL TIMING
T
CSL
CHECK STATUS
CLK
DI
1
0
0
1
0
X
•••
X
T
SV
T
CZ
READY
HIGH-Z
T
EC
DO
HIGH-Z
BUSY
©
1998 Microchip Technology Inc.
Preliminary
DS21207B-page 5
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