CY7C138-15JXC

Memory IC Overview

The CY7C138-15JXC is a 4K x 8 dual-port static RAM manufactured using 0.65-micron CMOS technology. It features fully asynchronous operation with a maximum access time of 15 ns and operates within a commercial temperature range of 0°C to +70°C at a supply voltage of 5V ± 10%. The device includes on-chip arbitration logic, semaphore flags for resource sharing, and interrupt pins for port-to-port communication. It is housed in a 68-pin Pb-Free Plastic Leaded Chip Carrier (PLCC) package.

Memory IC Feature Summary

• True dual-ported memory cells allowing simultaneous reads of the same location
• On-chip arbitration logic with BUSY flags for handling data contention
• Integrated semaphore latches for software handshaking between ports
• Interrupt flags enabling direct communication via specific memory locations

Memory IC Applications

• Interprocessor and multiprocessor designs
• Communications status buffering
• Dual-port video and graphics memory

Memory IC Procurement Notes

Verify that the component matches the exact part number CY7C138-15JXC, specifically confirming the 'JXC' suffix indicates the 68-lead Pb-Free PLCC package. Ensure the speed grade corresponds to the 15 ns access time requirement. Confirm the operating temperature range aligns with commercial specifications (0°C to +70°C). Cross-reference the datasheet revision *B for accurate electrical characteristics.

Memory IC Selection Notes

Select this component when a small-capacity, high-speed dual-port SRAM is required for synchronous or asynchronous multi-processor systems. The 15 ns speed grade suits applications demanding rapid data exchange. Consider the CY7C139 variant if a 9-bit organization is needed instead of 8-bit. Verify that the 68-pin PLCC package fits the board layout constraints and that lead-free compliance is mandatory for the assembly process.

Memory IC Part Context

This component belongs to the Cypress CY7C138/39 family of dual-port SRAMs, now part of the Infineon portfolio following the acquisition of Cypress Semiconductor. These devices are designed for applications requiring independent access from two processors to shared memory without external arbitration logic. The family offers various speed grades and organizations to fit different performance and interface requirements.

Memory IC Replacement Considerations

CY7C138-15JC: Identical electrical performance but in a standard plastic PLCC package rather than Pb-Free.

Memory IC FAQ

How does the device handle simultaneous access to the same memory address?

The device uses on-chip arbitration logic. If both ports attempt to access the same location simultaneously, the BUSY flag asserts on one port to indicate contention, granting access priority based on timing.

What is the function of the SEM pin?

The SEM pin acts as a chip enable for the eight internal semaphore latches. Asserting it LOW allows the port to read or write semaphore states to manage shared resources.

How are interrupts triggered between ports?

Interrupts are triggered by writing to specific memory addresses. Writing to location FFF sets the right port's interrupt flag, while writing to location FFE sets the left port's interrupt flag.