PSD835G2-90U

Overview

The PSD835G2-90U 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 Kbit of SRAM. The device provides 52 reconfigurable I/O ports and over 3000 gates of PLD logic. The -90 suffix indicates a maximum access time of 90 ns for both Flash memory and SRAM within the specified voltage range.

Feature Summary

• Dual-bank architecture with concurrent read/write operations between primary and secondary Flash memories
• Integrated CPLD and DPLD logic offering over 3000 gates for address decoding and system control
• In-system programming (ISP) capability via JTAG interface for manufacturing and field updates
• Programmable power management unit supporting automatic power-down modes to minimize standby current

Applications

• Expanding memory space for 8-bit MCUs such as Intel 80C51 family
• Complex address decoding and chip select generation in embedded systems
• In-application programming (IAP) for firmware updates in industrial controllers

Procurement Notes

Verify component status prior to procurement as this part may be obsolete or discontinued. Confirm that the 90 ns speed grade meets the timing requirements of the target 8-bit MCU bus interface. Ensure compatibility with existing PCB footprints for the 80-LQFP package.

Selection Notes

Select the PSD835G2-90U when a 90 ns access time is sufficient for the system clock frequency. Compare against the -70 variant if faster memory access is required. Consider the total memory capacity (4.25 Mbit Flash + 64 Kbit SRAM) against application data storage needs.

Part Context

This component belongs to the PSD835G2 series of Flash PSDs from STMicroelectronics. It serves as a bridge between 8-bit microcontrollers and external memory/peripherals, replacing discrete Flash, SRAM, and PLD chips with a single integrated solution.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation.