Features: • Single 5 V ± 5% Power Supply
• Fast Access Times: 9/10/12 ns Max
• Byte Writeable via Dual Write Enables
• Internal Input Registers (Address, Data, Control)
• Internally SelfTimed Write Cycle
• ADSP, ADSC, and ADV Burst Control Pins
• Asynchronous Output Enable Controlled ThreeState Outputs
• Common Data Inputs and Data Outputs
• 3.3 V I/O Compatible
• High Board Density 52Lead PLCC Package
• ADSP Disabled with Chip Enable (E) - Supports Address Pipelining
Pinout
Specifications
| PIN NAMES |
A0 A15 . . . . . . . . . . Address Inputs
K . . . . . . . . . . . . . .. . . . . Clock
ADV . . . . .. . . . . Burst Address Advance
LW . . . . . . . . . Lower Byte Write Enable
UW . . . . . . . . . Upper Byte Write Enable
ADSC . . . . . . . Controller Address Status
ADSP . . . . . .. . Processor Address Status
E . . . . . . . .. . . . . . . . Chip Enable
G . . . . . . . . .. . . . . . Output Enable
DQ0 DQ17 . . . . . .. . Data Input/Output
VCC . . . . . ..... . . . + 5 V Power Supply
VSS . . . . . . . . . . . . . . . . . Ground |
DescriptionThe MCM67H618B is a 1,179,648 bit synchronous fast static random access memory designed to provide a burstable, highperformance, secondary cache for the i486E and PentiumE microprocessors. It is organized as 65,536 words of 18 bits, fabricated with Motorola's highperformance silicongate BiCMOS technology. The device integrates input registers, a 2bit 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 (D0 D17), and all control signals except output enable (G) are clock (K) controlled through positive edgetriggered noninverting registers.
Bursts can be initiated with either address status processor ADSP) or address status cache controller (ADSC) input pins. Subsequent burst addresses can be generated internally by the MCM67H618B (burst sequence imitates that of the i486 and Pentium) and controlled by the burst address advance (ADV) input pin. The following pages provide more detailed information on burst controls.
Write cycles are internally selftimed and are initiated by the rising edge of the clock (K) input. This feature eliminates complex offchip
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 MCM67H618B is ideally suited for systems that require wide data bus widths and cache memory. See Figure 2 for applications information.
MCM67H618B Data Sheet
