PSD4235G2-70U

Overview

The PSD4235G2-70U is a Flash in-system programmable (ISP) peripheral IC designed for 16-bit microcontrollers with a 5 V supply. It integrates 4 Mbit of Primary Flash memory organized into 8 uniform sectors and 256 Kbit of Secondary Flash memory with 4 sectors, alongside 64 Kbit of SRAM. The device features over 3000 gates of PLD logic, including CPLD and DPLD capabilities, and provides 52 individually configurable I/O pins across 7 ports. It supports concurrent read/erase/write operations and offers a 70 ns access time for both Flash and SRAM components.

Feature Summary

• Dual-bank Flash architecture enabling concurrent operation: reading from one memory block while erasing or writing to the other.
• Integrated PLD with over 3000 gates, comprising 16 output macrocells (OMCs), 24 input macrocells (IMCs), and user-defined internal chip select decoding.
• Supports In-System Programming (ISP) via a built-in JTAG compliant serial port for full-chip programmability.
• Includes an internal page register capable of expanding the microcontroller address space by a factor of 256.

Applications

• Peripheral expansion for 16-bit MCUs such as Intel MCS-96 series (e.g., 80C196KC).
• Motor control driving systems requiring integrated memory and logic.
• Applications necessitating separate program and data spaces with complex memory mapping.

Procurement Notes

Verify component status as the PSD4235G2 family is listed as discontinued in public databases. Confirm availability through authorized distributors or secondary market sources. Ensure the specific -70U suffix corresponds to the 70 ns speed grade and LQFP80 package variant required for the design.

Selection Notes

Select this component when designing with 16-bit MCUs requiring a single-chip solution for memory expansion and logic interfacing. The 70 ns speed grade is suitable for standard 16-bit bus architectures. Ensure the design utilizes a 5 V ± 10% supply voltage. Consider the 80-lead LQFP package dimensions (12x12 mm) for PCB layout constraints.

Part Context

The PSD4235G2 belongs to the Programmable System Device (PSD) family by STMicroelectronics, which combines Flash memory, SRAM, and PLD logic on a single chip. This integration simplifies hardware design by reducing component count compared to discrete memory and logic solutions. The device is specifically optimized for interfacing with 16-bit microcontrollers, providing flexible memory mapping and I/O configuration.

Replacement Considerations

As the PSD4235G2 is discontinued, verify if newer PSD variants or alternative programmable system devices from STMicroelectronics or other manufacturers meet the 4 Mbit Flash and 64 Kbit SRAM requirements. Check for pin-compatible alternatives or assess the need for adapter boards if substituting with different package types.

FAQ

Can the PSD4235G2 perform read and write operations simultaneously?

Yes, the device supports concurrent operation, allowing the system to read from one Flash bank while erasing or writing to the other bank.

How is the microcontroller address space expanded?

The internal page register can expand the microcontroller address space by a factor of 256, facilitating complex memory mapping configurations.

What programming interface is used for in-system programming?

The device features a built-in JTAG compliant serial port that allows full-chip In-System Programmability (ISP).