PSD835G2-70U

Overview

The PSD835G2-70U is a Flash Programmable System Device (PSD) designed for 8-bit microcontrollers, operating on a single 5 V ±10% supply. It integrates dual-bank flash memory comprising 4 Mbits of primary Flash and 256 Kbits of secondary Flash, alongside 64 Kbits of SRAM. The device features 52 reconfigurable I/O ports and over 3000 gates of PLD logic, supporting CPLD and DPLD configurations. It supports in-system programming via JTAG and offers concurrent read/write operations across memory banks. The component provides high endurance with 100,000 erase/write cycles for Flash and 15-year data retention.

Feature Summary

• Dual-bank Flash architecture: 4 Mbits primary (8 sectors) and 256 Kbits secondary (4 sectors) with concurrent operation capability.
• Integrated 64 Kbit SRAM and over 3000 gates of PLD logic including 16 output macrocells.
• 52 individually configurable I/O ports supporting MCU, PLD, address latch, and special function modes.
• In-system programmability via built-in JTAG serial port using low-cost FlashLINK cables.

Applications

• Expanding program and data memory space for 8-bit MCUs
• Implementing complex address decoding and chip select logic via PLD
• Providing non-volatile storage for configuration data and user parameters

Procurement Notes

This product is officially listed as obsolete by STMicroelectronics. Verification of availability should focus on distributor surplus or secondary market sources rather than direct manufacturer allocation. Ensure the specific suffix '-70U' matches the required 70 ns access time and LQFP80 package form factor for design compatibility.

Selection Notes

Select this component when interfacing with 8-bit MCUs requiring external memory expansion and flexible logic integration without additional discrete components. Verify that the target system operates at 5 V and utilizes an 8-bit multiplexed or non-multiplexed bus interface compatible with the PSD architecture. Confirm that the 70 ns speed grade meets the maximum clock frequency requirements of the host microcontroller.

Part Context

The PSD835G2 belongs to the PSD835G family of Flash Programmable System Devices from STMicroelectronics. These devices are engineered to replace traditional mask-programmed gate arrays and PROMs while providing persistent memory. The -70U designation specifically indicates the 70 nanosecond access speed variant housed in an 80-lead Low Profile Quad Flat Package (LQFP).

Replacement Considerations

As the part is obsolete, no official direct replacement is currently published by STMicroelectronics for this exact specification. Designers may need to evaluate newer generation PSDs or discrete memory/logic combinations if pin-compatible alternatives are not available in the secondary market.