Texas Instruments CY74FCT823ATSOC

Overview

CY74FCT823ATSOC from Texas Instruments is a 9-bit bus-interface register with 3-state outputs, positive-edge-triggered D-type flip-flops, buffered clock-enable (EN) and asynchronous clear (CLR), and TTL-compatible I/O logic levels. It delivers 64 mA sink / 32 mA source drive, 10 ns propagation delay (tPLH/tPHL at CL = 50 pF), and supports partial-power-down via Ioff. It is used in high-performance microprogrammed systems for parity bus interfacing and high-current output port applications.

For engineers reviewing the CY74FCT823ATSOC datasheet, CY74FCT823ATSOC pinout, CY74FCT823ATSOC application, or CY74FCT823ATSOC equivalent, key selection criteria include its 9-bit parallel register architecture, 3-state output control timing (tPZL/tPHZ), Ioff-enabled power-down isolation, edge-rate-controlled noise immunity, and SOIC-24 package compatibility with legacy FCT-family designs.

Technical Context

This device implements nine independent D-type flip-flops synchronized to the rising edge of CP, with shared EN (clock enable) and CLR (asynchronous clear) inputs controlling all bits simultaneously. Output enable (OE) independently places all Y0–Y8 outputs into high-impedance state without affecting internal register state.

Its logic design integrates edge-rate control circuitry to reduce switching noise, matched rise/fall times for clean signal integrity, and Ioff protection that disables outputs when VCC = 0 V-preventing backflow current during partial power-down. Input thresholds (VIH = 2 V, VIL = 0.8 V) and output voltage levels (VOH = 2.4 V min at –15 mA, VOL = 0.55 V max at 64 mA) ensure full TTL interoperability.

Key Specifications

Pinout & Package

Package: SOIC-24 (DW), 7.5 mm × 15.4 mm body, 1.27 mm pitch, RoHS-compliant NIPDAU finish, MSL Level-1 (unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 9-bit bus-interface register applications.

Compared with CY74FCT823CTSOC, CY74FCT823ATSOC trades 4 ns of speed for improved noise characteristics and lower dynamic power; compared with SN74FCT823ATSO, it shares identical performance and layout but reflects TI's CY74-series branding for industrial-grade qualification tracking.

Availability

CY74FCT823ATSOC is available at Aetrix Electronics and suitable for industrial control systems, legacy 5-V bus expansion, and microprogrammed logic applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for CY74FCT823ATSOC 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

Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The CY74FCT family targets high-speed, low-noise 5-V logic interfaces-designed specifically for bus buffering, register expansion, and TTL-compatible system integration in mission-critical industrial equipment.

FAQ

What is the maximum clock frequency supported by CY74FCT823ATSOC?

CY74FCT823ATSOC does not specify a maximum clock frequency in its datasheet; instead, it guarantees timing parameters including 10 ns propagation delay (tPLH/tPHL) and 4 ns minimum setup time (tsu) for data and EN inputs. Based on these values, reliable operation is ensured up to approximately 50 MHz in typical 50-pF load conditions. For higher frequencies, designers must verify timing closure using worst-case propagation, setup, and hold values across temperature and voltage extremes. CY74FCT823ATSOC is optimized for deterministic latching in microprogrammed and control-store applications-not for continuous high-frequency streaming.

Does CY74FCT823ATSOC support hot-swap or live-insertion?

Yes, CY74FCT823ATSOC supports partial-power-down operation via its Ioff feature, which disables outputs when VCC = 0 V and prevents damaging current backflow from live buses into the unpowered device. This makes CY74FCT823ATSOC suitable for hot-swap applications in modular backplanes or field-replaceable units, provided OE is held high during insertion to keep outputs in high-impedance state until VCC stabilizes. The 2000-V HBM ESD rating further enhances robustness during handling and insertion.

Can CY74FCT823ATSOC be used with 3.3-V logic systems?

No, CY74FCT823ATSOC is a 5-V-only device with VCC operating range of 4.75 V to 5.25 V and TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max). Its inputs are not 3.3-V tolerant-applying 3.3-V logic signals directly may result in marginal or incorrect switching due to insufficient VIH margin, and its outputs swing to ~3.3 V (VOH typ) but are not guaranteed to interface reliably with 3.3-V CMOS receivers. To interface with 3.3-V systems, use a dedicated level translator or select a 3.3-V-compatible register such as SN74LVC823A.

What is the purpose of the CLR and EN pins on CY74FCT823ATSOC?

CY74FCT823ATSOC uses CLR (asynchronous clear) to force all Q outputs low immediately, independent of CP or EN state-enabling system-wide reset without waiting for a clock edge. EN (clock enable) provides synchronous control: when EN = H, CP transitions are ignored and Q outputs retain their prior state, effectively pausing register updates. Both inputs are buffered for noise immunity and fanout, and they operate concurrently-CLR takes priority over EN. This dual-control architecture allows CY74FCT823ATSOC to serve as a flexible building block in sequenced control logic and fault-recovery circuits.

Is CY74FCT823ATSOC pin-compatible with older AM29823 devices?

Yes, CY74FCT823ATSOC is explicitly designed to be functionally and pin-compatible with AM29823, as confirmed in its datasheet: "Function, Pinout, and Drive Compatible With FCT, F Logic, and AM29823." All 24 pins-including D0–D8, Y0–Y8, CP, EN, CLR, OE, VCC, and GND-map identically between CY74FCT823ATSOC and AM29823. Electrical characteristics (drive strength, timing, voltage levels) are also aligned, making CY74FCT823ATSOC a direct drop-in replacement for AM29823 in legacy designs, with added benefits including Ioff support and enhanced ESD protection.