©
1997 Microchip Technology Inc.
Preliminary
DS21172D-page 1
M
93C46B
FEATURES
• Single supply 5.0V operation
• Low power CMOS technology
- 1 mA active current (typical)
- 1
µ
A standby current (maximum)
• 64 x 16 bit organization
• 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
• 1,000,000 E/W cycles guaranteed
• Data retention > 200 years
• 8-pin PDIP/SOIC and 8-pin TSSOP packages
• Available for the following temperature ranges:
BLOCK DIAGRAM
DESCRIPTION
The Microchip Technology Inc. 93C46B is a 1K-bit,
low-voltage serial Electrically Erasable PROM. The
device memory is configured as 64 x 16 bits. Advanced
CMOS technology makes this device ideal for
low-power, nonvolatile memory applications. The
93C46B is available in standard 8-pin DIP, surface
mount SOIC, and TSSOP packages. The 93C46BX are
only offered in a 150 mil SOIC package.
PACKAGE TYPE
- Commercial (C):
0
°
C to
+70
°
C
- Industrial (I):
-40
°
C to
+85
°
C
- Automotive (E):
-40
°
C to
+125
°
C
V
CC
V
SS
DI
CS
CLK
DO
MEMORY
ARRAY
ADDRESS
DECODER
ADDRESS
COUNTER
DATA
REGISTER
OUTPUT
BUFFER
MEMORY
DECODE
LOGIC
CLOCK
GENERATOR
93C46B
CS
CLK
DI
DO
1
2
3
4
8
7
6
5
V
CC
NC
NC
V
SS
CS
CLK
DI
DO
V
CC
NC
NC
V
SS
93C46B
NU
V
CC
CS
CLK
NC
V
SS
DO
DI
93C46BX
93C46B
CS
CLK
DI
DO
1
2
3
4
8
7
6
5
V
CC
NC
NC
V
SS
TSSOP
SOIC
SOIC
1
2
3
4
DIP
8
7
6
5
1
2
3
4
8
7
6
5
1K 5.0V Microwire
®
Serial EEPROM
Microwire is a registered trademark of National Semiconductor Incorporated.
93C46B
DS21172D-page 2
Preliminary
©
1997 Microchip Technology Inc.
1.0
ELECTRICAL
CHARACTERISTICS
1.1
Maximum Ratings*
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 1-1
PIN FUNCTION TABLE
Name
Function
CS
Chip Select
CLK
Serial Data Clock
DI
Serial Data Input
DO
Serial Data Output
V
SS
Ground
NC
No Connect
V
CC
Power Supply
TABLE 1-2
DC AND AC ELECTRICAL CHARACTERISTICS
All parameters apply over the
specified operating ranges
unless otherwise noted
Commercial (C)
V
CC
= +4.5V to +5.5V Tamb = 0
°
C to +70
°
C
Industrial (I)
V
CC
= +4.5V to +5.5V Tamb = -40
°
C to +85
°
C
Automotive (E)
V
CC
= +4.5V to +5.5V Tamb = -40
°
C to +125
°
C
Parameter
Symbol
Min.
Max.
Units
Conditions
High level input voltage
V
IH
2.0
V
CC
+1
V
Low level input voltage
V
IL
-0.3
0.8
V
Low level output voltage
V
OL
—
0.4
V
I
OL
= 2.1 mA; V
CC
= 4.5V
High level output voltage
V
OH
2.4
—
V
I
OH
= -400
µ
A; V
CC
= 4.5V
Input leakage current
I
LI
-10
10
µ
A
V
IN
= V
SS
to V
CC
Output leakage current
I
LO
-10
10
µ
A
V
OUT
= V
SS
to V
CC
Pin capacitance
(all inputs/outputs)
C
IN
, C
OUT
—
7
pF
V
IN
/V
OUT
Tamb = +25
°
C, F
CLK
= 1 MHz
I
CC
read
—
1
mA
Operating current
I
CC
write
—
1.5
mA
Standby current
I
CCS
—
1
µ
A
CS = V
SS
Clock frequency
F
CLK
—
2
MHz
V
CC
= 4.5V
Clock high time
T
CKH
250
—
ns
Clock low time
T
CKL
250
—
ns
Chip select setup time
T
CSS
50
—
ns
Relative to CLK
Chip select hold time
T
CSH
0
—
ns
Relative to CLK
Chip select low time
T
CSL
250
—
ns
Data input setup time
T
DIS
100
—
ns
Relative to CLK
Data input hold time
T
DIH
100
—
ns
Relative to CLK
Data output delay time
T
PD
—
400
ns
C
L
= 100 pF
Data output disable time
T
CZ
—
100
ns
C
L
= 100 pF (Note 2)
Status valid time
T
SV
—
500
ns
C
L
= 100 pF
Program cycle time
T
WC
—
2
ms
ERASE/WRITE mode
T
EC
—
6
ms
ERAL mode
T
WL
—
15
ms
WRAL mode
Endurance
—
1M
—
cycles
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 appli-
cation, please consult the Total Endurance Model which may be obtained on Microchip’s BBS or website.
93C46B
©
1997 Microchip Technology Inc.
Preliminary
DS21172D-page 3
2.0
PIN DESCRIPTION
2.1
Chip Select (CS)
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.
2.2
Serial Clock (CLK)
The Serial Clock (CLK) is used to synchronize the com-
munication between a master device and the 93C46B.
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 the 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 a START condition).
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
2-1). CLK and DI then become don't care inputs
waiting for a new START condition to be detected.
2.3
Data In (DI)
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 posi-
tive edge of CLK).
This pin also provides READY/BUSY status information
during ERASE and WRITE cycles. READY/BUSY sta-
tus 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.
Note:
CS must go low between consecutive
instructions.
TABLE 2-1
INSTRUCTION SET FOR 93C46B
Instruction
SB
Opcode
Address
Data In
Data Out
Req. CLK Cycles
ERASE
1
11
A5
A4
A3
A2
A1
A0
—
(RDY/BSY)
9
ERAL
1
00
1
0
X
X
X
X
—
(RDY/BSY)
9
EWDS
1
00
0
0
X
X
X
X
—
HIGH-Z
9
EWEN
1
00
1
1
X
X
X
X
—
HIGH-Z
9
READ
1
10
A5
A4
A3
A2
A1
A0
—
D15 - D0
25
WRITE
1
01
A5
A4
A3
A2
A1
A0
D15 - D0
(RDY/BSY)
25
WRAL
1
00
0
1
X
X
X
X
D15 - D0
(RDY/BSY)
25
93C46B
DS21172D-page 4
Preliminary
©
1997 Microchip Technology Inc.
3.0
FUNCTIONAL DESCRIPTION
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.
3.1
START Condition
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.
3.2
Data In (DI) and Data Out (DO)
It is possible to connect the Data In (DI)and Data Out
(DO) pins together. However, with this configuration, if
A0 is a logic-high level, it is possible for a “bus conflict”
to occur during the “dummy zero” that precedes the
READ operation. 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.
3.3
Data Protection
During power-up, all programming modes of operation
are inhibited until Vcc 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/SRITE Disable (EWDS) and ERASE/
WRITE Enable (EWEN) commands give additional pro-
tection against accidental programming during normal
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:
SYNCHRONOUS DATA TIMING
CS
V
IH
V
IL
V
IH
V
IL
V
IH
V
IL
V
OH
V
OL
V
OH
V
OL
CLK
DI
DO
(READ)
DO
(PROGRAM)
T
CSS
T
DIS
T
CKH
T
CKL
T
DIH
T
PD
T
CSH
T
PD
T
CZ
STATUS VALID
T
SV
T
CZ
Note:
AC test conditions: V
IL
= 0.4V, V
IH
= 2.4V
93C46B
©
1997 Microchip Technology Inc.
Preliminary
DS21172D-page 5
3.4
ERASE
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.
3.5
Erase All (ERAL)
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
complete.
FIGURE 3-2:
ERASE TIMING
FIGURE 3-3:
ERAL TIMING
CS
CLK
DI
DO
T
CSL
CHECK STATUS
1
1
1
A
N
A
N
-1
A
N
-2
•••
A0
T
SV
T
CZ
BUSY
READY
HIGH-Z
T
WC
HIGH-Z
CS
CLK
DI
DO
T
CSL
CHECK STATUS
1
0
0
1
0
X
•••
X
T
SV
T
CZ
BUSY
READY
HIGH-Z
T
EC
HIGH-Z
93C46B
DS21172D-page 6
Preliminary
©
1997 Microchip Technology Inc.
3.6
ERASE/WRITE Disable and Enable
(EWDS/EWEN)
The device powers up in the ERASE/WRITE Disable
(EWDS) state. All programming modes must be pre-
ceded by an Erase/Write Enable (EWEN) instruction.
Once the EWEN instruction is executed, programming
remains enabled until an EWDS instruction is executed
or Vcc is removed from the device. To protect against
accidental data disturbance, the EWDS instruction can
be used to disable all ERASE/WRITE functions and
should follow all programming operations. Execution of
a READ instruction is independent of both the EWDS
and EWEN instructions.
3.7
READ
The READ instruction outputs the serial data of the
addressed memory location on the DO pin. A dummy
zero bit precedes the 16-bit output string. The output
data bits will toggle on the rising edge of the CLK and
are stable after the specified time delay (T
PD
). Sequen-
tial read is possible when CS is held high. The memory
data will automatically cycle to the next register and
output sequentially.
FIGURE 3-4:
EWDS TIMING
FIGURE 3-5:
EWEN TIMING
FIGURE 3-6:
READ TIMING
CS
CLK
DI
1
0
0
0
0
X
•••
X
T
CSL
1
X
CS
CLK
DI
0
0
1
1
X
T
CSL
•••
CS
CLK
DI
DO
1
1
0
An
•••
A0
HIGH-Z
0
Dx
•••
D0
Dx
•••
D0
•••
Dx
D0
93C46B
©
1997 Microchip Technology Inc.
Preliminary
DS21172D-page 7
3.8
WRITE
The WRITE instruction is followed by 16 bits of data,
which are written into the specified address. After the
last data bit is clocked into the DI pin, the self-timed
auto-erase and programming cycle begins.
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 write cycle is complete.
DO at logical “0” indicates that programming is still in
progress. DO at logical “1” indicates that the register at
the specified address has been written with the data
specified and the device is ready for another instruc-
tion.
3.9
Write All (WRAL)
The Write All (WRAL) instruction will write the entire
memory array with the data specified in the command.
The WRAL cycle is completely self-timed and com-
mences at the rising clock edge of the last data bit.
Clocking of the CLK pin is not necessary after the
device has entered the WRAL cycle. The WRAL com-
mand does include an automatic ERAL cycle for the
device. Therefore, the WRAL instruction does not
require an ERAL instruction, but the chip must be in the
EWEN status.
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
).
FIGURE 3-7:
WRITE TIMING
FIGURE 3-8: