1996 Microchip Technology Inc. DS11109H-page 1

FEATURES

• Fast Read Access Time—150 ns
• CMOS Technology for Low Power Dissipation
- 30 mA Active
- 100

m

A Standby
• Fast Byte Write Time—200

m

s or 1 ms
• Data Retention >200 years
• High Endurance - Minimum 100,000



Erase/Write
Cycles
• Automatic Write Operation
- Internal Control Timer
- Auto-Clear Before Write Operation
- On-Chip Address and Data Latches
• Data Polling
• Ready/Busy
• Chip Clear Operation
• Enhanced Data Protection
-VCC

Detector
- Pulse Filter
- Write Inhibit
• Electronic Signature for Device Identification
• 5-Volt-Only Operation
• Organized 8Kx8 JEDEC Standard Pinout
- 28-pin Dual-In-Line Package
- 32-pin PLCC Package
- 28-pin Thin Small Outline Package (TSOP)
8x20mm
- 28-pin Very Small Outline Package (VSOP)
8x13.4mm
• Available for Extended Temperature Ranges:
- Commercial: 0˚C to +70˚C

DESCRIPTION

The Microchip Technology Inc. 28C64A is a CMOS 64K non-
volatile electrically Erasable PROM. The 28C64A is
accessed like a static RAM for the read or write cycles without
the need of external components. During a “byte write”, the
address and data are latched internally, freeing the micropro-
cessor address and data bus for other operations. Following
the initiation of write cycle, the device will go to a busy state
and automatically clear and write the latched data using an
internal control timer. To determine when the write cycle is
complete, the user has a choice of monitoring the Ready/
Busy output or using Data polling. The Ready/Busy pin is an
open drain output, which allows easy configuration in wired-
or systems. Alternatively, Data polling allows the user to read
the location last written to when the write operation is com-
plete. CMOS design and processing enables this part to be
used in systems where reduced power consumption and reli-
ability are required. A complete family of packages is offered
to provide the utmost flexibility in applications

PACKAGE TYPES
BLOCK DIAGRAM
A10
CE
21
20
19
VSS
I/O2
14
13
12
OE
A11
A9
A8
22
23
24
RDY/BSY
A12
A7
1
2
3
4
5
25
26
27
28
6
7
NC
WE
VCC
A6
A5
A4
A3
I/O7
I/O6
I/O5
I/O4
I/O3
I/O1
I/O0

A0
A1
A2
18
17
16
15
11
10
9
8
OE
A11
A9
A8
NC
WE
Vcc

RDY/BSY
A12
A7
A6
A5
A4
A3
A10
CE
I/07
I/06
I/05
I/04
I/03

Vss
I/02
I/01
I/00
A0
A1
A2
1
2
3
4
5
6
7

8
9
10
11
12
13
14
28
27
26
25
24
23
22

21
20
19
18
17
16
15
• Pin 1 indicator on PLCC on top of package
• 1
2
3
4
5
6
7
8
9
10
11
12
13
14

28
27
26
25
24
23
22
21
20
19
18
17
16
15
RDY/BSY
A12
A7
A6
A5
A4
A3
A2
A1
A0
I/O0
I/O1
I/O2
V
Vcc
WE
NC
A8
A9
A11
OE
A10
CE
I/O7
I/O6
I/O5
I/O4
I/O3SS
A6
A5
A4
A3
A2
A1
A0
NC
I/O0
A8
A9
A11
NC
OE
A10
CE
I/O7
I/O6
A7 A12 RDY/BSY NU Vcc WE NC
I/O1 I/O2
Vss
NU
I/O3 I/O4 I/O5
14 15 16 17 18 19 20
4 3 2 1
32 31 30
29
28
27
26
25
24
23
22
21
5
6
7
8
9
10
11
12
13
DIP/SOIC
PLCC
TSOP
VSOP
I/O0 I/O7
Input/Output
Buffers
Chip Enable/
Output Enable
Control Logic
CE
OE
Data Protection
Circuitry
A12
Y Gating
16K bit
Cell Matrix
X
Decoder
Y
Decoder
A0
Data
Poll
Auto Erase/Write
Timing
VCC
VSS
WE
L
a
t
c
h
e
s
Program Voltage
Generation
Rdy/
Busy

28C64A

64K (8K x 8) CMOS EEPROM

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