MCM67M618A
1
MOTOROLA FAST SRAM
Product Preview
64K x 18 Bit BurstRAM
Synchronous Fast Static RAM
With Burst Counter and Self–Timed Write
The MCM67M618A is a 1,179,648 bit synchronous static random access
memory designed to provide a burstable, high–performance, secondary cache
for the MC68040 and PowerPC microprocessors. It is organized as 65,536
words of 18 bits, fabricated using Motorola’s high–performance silicon–gate
BiCMOS technology. The device integrates input registers, a 2–bit counter , high
speed SRAM, and high drive capability outputs onto a single monolithic circuit
for reduced parts count implementation of cache data RAM applications. Synchronous design allows precise cycle control with the use of an external clock (K).
BiCMOS circuitry reduces the overall power consumption of the integrated functions for greater reliability.
Addresses (A0 – A15), data inputs (DQ0 – DQ17), and all control signals,
except output enable (G
), are clock (K) controlled through positive–edge–
triggered noninverting registers.
Bursts can be initiated with either transfer start processor (TSP
) or transfer
start cache controller (TSC
) input pins. Subsequent burst addresses are generated internally by the MCM67M618A (burst sequence imitates that of the
MC68040) and controlled by the burst address advance (BAA
) input pin. The
following pages provide more detailed information on burst controls.
Write cycles are internally self–timed and are initiated by the rising edge of the
clock (K) input. This feature eliminates complex off–chip write pulse generation
and provides increased flexibility for incoming signals.
Dual write enables (LW
and UW) are provided to allow individually writeable
bytes. LW
controls DQ0 – DQ8 (the lower bits), while UW controls DQ9 – DQ17
(the upper bits).
This device is ideally suited for systems that require wide data bus widths and
cache memory.
• Single 5 V ±
5% Power Supply
• Fast Access Times: 9/10/12 ns Max
• Byte Writeable via Dual Write Strobes
• Internal Input Registers (Address, Data, Control)
• Internally Self–Timed Write Cycle
• TSP
, TSC, and BAA Burst Control Pins
• Asynchronous Output Enable Controlled Three–State Outputs
• Common Data Inputs and Data Outputs
• High Board Density 52–PLCC Package
• 3.3 V I/O Compatible
BurstRAM is a trademark of Motorola, Inc.
PowerPC is a trademark of IBM Corp.
This document contains information on a new product under development. Motorola reserves the right to change or discontinue this product without notice.
PIN ASSIGNMENT
10
9
8
DQ9
V
CC
DQ8
12
11
15
14
13
17
16
20
19
18
37
38
34
35
36
42
43
39
40
41
45
46
44
21 22 23 24 25 26 27 28 29 30 31 32 33
7 6 5 4 3 2 1 52 51 50 49 4847
DQ6
DQ7
V
SS
DQ4
DQ5
DQ2
DQ3
V
SS
V
CC
DQ0
DQ1
V
CC
V
SS
V
SS
V
CC
DQ10
DQ11
DQ12
DQ13
DQ14
DQ15
DQ16
DQ17
A6A7E
UW
K
A8A9A10
LW
G
A15
A4A3A2
A1
A13
A14
A12
A11
V
SS
A5
A0
V
CC
BAA
TSC
TSP
All power supply and ground pins must be
connected for proper operation of the device.
PIN NAMES
A0 – A15 Address Inputs. . . . . . . . . . . . . . . .
K Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BAA Burst Address Advance. . . . . . . . . . . .
LW
Lower Byte Write Enable. . . . . . . . . . . .
UW
Upper Byte Write Enable. . . . . . . . . . . .
TSP
, TSC Transfer Start. . . . . . . . . . . . . . . .
E
Chip Enable. . . . . . . . . . . . . . . . . . . . . . . . .
G
Output Enable. . . . . . . . . . . . . . . . . . . . . .
DQ0 – DQ17 Data Input/Output. . . . . . . . . .
V
CC
+ 5 V Power Supply. . . . . . . . . . . . . . . .
V
SS
Ground. . . . . . . . . . . . . . . . . . . . . . . . . .