STMicroelectronics PSD834F2-90JI

Overview

PSD834F2-90JI from STMicroelectronics is a Flash in-system programmable (ISP) peripheral IC for 8-bit microcontrollers, integrating dual-bank Flash (1 Mbit primary + 256 Kbit secondary), 256 Kbit SRAM, 27 reconfigurable I/O ports, JTAG ISP interface, and PLD logic (3000+ gates, 16 OMCs/24 IMCs). It operates at 5 V with 90 ns access time and supports concurrent read/erase/write operations in separate memory banks - used in legacy industrial control systems interfacing with 80C51XA or 68HC11 MCUs.

For engineers reviewing the PSD834F2-90JI datasheet, PSD834F2-90JI pinout, PSD834F2-90JI application, or PSD834F2-90JI equivalent, key selection considerations include its dual-bank Flash concurrency, PLD-based chip select decoding, page register–enabled address space expansion, and JTAG-based in-system programming capability for embedded MCU peripheral augmentation.

Technical Context

The PSD834F2-90JI implements a unified peripheral architecture where Flash memory, SRAM, PLD logic, and I/O are tightly coupled to an 8-bit MCU bus via configurable timing and sector-select logic. Its dual-bank Flash enables real-time firmware updates without halting MCU execution - one bank active while the other is erased or programmed.

PLD functionality includes both CPLD (16 output macrocells, 24 input macrocells) and DPLD (user-defined internal chip select decoding), with Turbo Bit acceleration for critical timing paths. The integrated page register expands the MCU's 16-bit address space by factor of 256, enabling access to up to 16 MB of combined memory space.

Key Specifications

Pinout & Package

PSD834F2-90JI is housed in a 52-pin PLCC (Plastic Leaded Chip Carrier) package, designated by suffix 'J' per ST's part numbering scheme (Table 1, Doc ID 7833 Rev 7). This RoHS-compliant ECOPACK® package supports through-hole mounting and offers thermal and mechanical reliability for industrial environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Flash-peripheral-with-PLD applications.

Compared with PSD834F2-90JI, PSD833F2-90JI sacrifices dual-bank concurrency and boot isolation for reduced cost and density, while PSD854F2-90JI trades package compatibility for expanded I/O and memory headroom - making PSD834F2-90JI the optimal balance for retrofitting legacy 52-pin PLCC-based 8-bit systems.

Availability

PSD834F2-90JI is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy MCU-based HMI controllers, and automotive body control modules requiring stable component supply and long-term lifecycle support.

Supply support for PSD834F2-90JI includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in microcontrollers, power management, analog, and automotive ICs - with over 40 years of industrial-grade product development experience.

The PSD8XXFX family was designed specifically to augment 8-bit MCU systems with integrated Flash, SRAM, and programmable logic - targeting cost-sensitive, long-lifecycle industrial and automotive applications where external glue logic and discrete memory were previously required.

FAQ

What MCU families does PSD834F2-90JI natively support?

PSD834F2-90JI is explicitly validated for 80C51XA, 68HC11, 80C251, and 80C31 microcontrollers, with dedicated timing models and bus interface examples provided in Sections 15.5–15.8 of the datasheet. Its control signal mapping (RD/WR/CS) and address/data bus structure align directly with these architectures' external memory interface protocols.

Does PSD834F2-90JI support true concurrent read-while-write operation?

Yes - the dual-bank Flash architecture allows reading from the primary bank while simultaneously erasing or programming the secondary bank, or vice versa. This is implemented at the hardware level with independent bank control logic and verified in Section 6.2 of the datasheet, enabling zero-interrupt firmware updates in real-time systems.

How is Flash memory protected against accidental writes or erases?

Flash protection is enforced via hardware sector-lock bits stored in dedicated Flash Protection and PSD/EE Protection registers (Tables 12–13). Once set, these bits prevent program/erase commands from affecting locked sectors until cleared via JTAG security unlock sequence - a feature confirmed in Section 10.1 and Section 19.3 of the datasheet.

Can the PLD logic be reconfigured independently of Flash contents?

Yes - the CPLD and DPLD logic configurations are stored separately in nonvolatile configuration memory and can be updated via JTAG without altering Flash or SRAM contents. Section 14 details PLD loading procedures, and Table 6 confirms independent programming methods for each functional block including PLD, Flash, and SRAM.