Infineon Technologies CY37256P208-125NXI

Overview

CY37256P208-125NXI from Cypress Semiconductor is a 256-macrocell In-System Reprogrammable (ISR™) Complex Programmable Logic Device (CPLD) in the Ultra37000 family, operating at 5V with 125 ns maximum propagation delay (tPD), 154 MHz maximum frequency (fMAX), and 192 I/O pins in a 208-pin PQFP package. It features four synchronous clocks, programmable bus-hold on all I/Os, and JTAG-compliant ISR for field reconfiguration without pinout or timing changes. Used in legacy industrial control logic replacement and PCI-compliant interface glue logic.

For engineers reviewing the CY37256P208-125NXI datasheet, CY37256P208-125NXI pinout, CY37256P208-125NXI application, or CY37256P208-125NXI equivalent, key selection criteria include macrocell count, I/O count per package variant, tPD/fMAX speed bin, VCCO voltage flexibility (3.3V/5V I/O support), and JTAG boundary-scan compliance for system-level testability.

Technical Context

The device implements a modular architecture with multiple logic blocks interconnected via a fully global Programmable Interconnect Matrix (PIM), eliminating route-dependent delays. Each logic block contains a 72×87 product term array, intelligent allocator supporting 0–16 product terms per macrocell, and 16 macrocells-some configured as I/O, others as buried registers.

It supports flexible clocking: four global synchronous clocks (CLK0–CLK3) with polarity control, plus an asynchronous product-term clock (PTCLK); all macrocells accept any of these clocks. Dedicated inputs include four clock-capable pins and one general-purpose input, enabling precise timing control in synchronous state machines and bus interface logic.

Key Specifications

Pinout & Package

CY37256P208-125NXI is housed in a 208-pin Plastic Quad Flat Pack (PQFP) with 0.5 mm lead pitch, JEDEC MS-026 standard footprint, and exposed thermal pad (non-electrical). Package supports surface-mount reflow assembly and provides mechanical stability for high-vibration industrial environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar CPLD-based logic replacement applications.

Compared with XC95288XL-10TQ144I and ATF1508AS-15JU208, CY37256P208-125NXI uniquely balances 5V operation, PCI compliance, JTAG ISR, and 192 I/Os - making it irreplaceable in legacy industrial and telecom systems where voltage compatibility and field update capability are mandatory.

Availability

CY37256P208-125NXI is available at Aetrix Electronics and suitable for industrial PLC upgrades, PCI add-in card refurbishment, and automotive body control module production requiring stable component supply through extended lifecycle management.

Supply support for CY37256P208-125NXI 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

Cypress Semiconductor (now part of Infineon Technologies) is a U.S.-based semiconductor company specializing in programmable logic, memory, and mixed-signal solutions for industrial, automotive, and communications markets.

The Ultra37000 CPLD family was designed specifically for high-reliability, field-upgradable logic replacement in legacy systems - emphasizing pinout stability, JTAG-based reprogrammability, and mixed-voltage I/O interoperability.

FAQ

Is CY37256P208-125NXI compatible with 3.3V I/O buses?

Yes. The device supports 3.3V I/O levels when VCCO pins are connected to 3.3V; outputs meet 3.3V JEDEC CMOS standards and are 5V-tolerant. Core logic operates at 5V, and ISR programming requires 5V on VCC. This dual-voltage capability enables seamless integration into mixed-signal boards without level-shifting circuitry.

Does this CPLD support in-system programming without removing it from the board?

Yes. CY37256P208-125NXI implements Cypress's In-System Reprogrammable (ISR™) feature via IEEE 1149.1 JTAG interface. Programming and configuration data are shifted in through TDI and out through TDO while the device remains soldered in-circuit, enabling firmware updates and design iterations without physical access or board rework.

What is the purpose of the four dedicated clock inputs (CLK0–CLK3)?

CLK0–CLK3 provide globally routed synchronous clocks to all logic blocks. Each clock supports programmable polarity (rising/falling edge), allowing independent clock domain assignment for different functional blocks - such as separating control logic timing from data path timing or implementing PCI-compliant clocking schemes with precise setup/hold margins.

Can unused I/O pins be left unconnected?

Yes. All I/O pins feature user-programmable bus-hold circuitry - a weak latch that maintains the last driven logic state when the pin enters high-impedance mode. This eliminates floating inputs, reduces system noise, and permits unconnected pins during prototyping or in low-pin-count configurations without external pull resistors.