Texas Instruments SN74ACT7807-20PAG

Overview

SN74ACT7807-20PAG from Texas Instruments is a 2048-word × 9-bit clocked FIFO memory IC with independent asynchronous read/write clocks, 12 ns access time, 67 MHz data rate, and programmable almost-full/almost-empty flags. It serves as a high-speed data buffering interface between mismatched clock domains in communication controllers and digital signal processing systems.

For engineers reviewing the SN74ACT7807-20PAG datasheet, SN74ACT7807-20PAG pinout, SN74ACT7807-20PAG application, or SN74ACT7807-20PAG equivalent, key selection considerations include its dual-clock synchronization, 64-pin TQFP (PAG) package, 0°C to 70°C operating range, 3-state outputs, and cascading capability for word-width/depth expansion.

Technical Context

The SN74ACT7807-20PAG implements a synchronous dual-port RAM core with independent write-pointer and read-pointer logic, each synchronized to its respective clock domain (WRTCLK and RDCLK). Its status-flag generation-IR synchronized to WRTCLK, OR and HF synchronized to RDCLK-is implemented via internal edge-triggered registers to eliminate metastability in cross-clock-domain signaling.

Flag behavior is fully deterministic: IR goes high on the second rising edge of WRTCLK after reset; OR asserts on the third rising edge of RDCLK after first write; AF/AE supports programmable offsets (X/Y up to 1023) or defaults to 256, with PEN-controlled latching before first write. Reset requires four WRTCLK and four RDCLK edges while RESET is low.

Key Specifications

Pinout & Package

SN74ACT7807-20PAG uses a 64-pin Thin Quad Flat Package (PAG) with 0.5-mm lead pitch and exposed thermal pad. The package supports surface-mount reflow assembly and provides thermal impedance of 58°C/W (θ_JA).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FIFO memory applications.

Compared with SN74ACT7807-20FN and SN74ACT7807-25PAG, the SN74ACT7807-20PAG uniquely delivers 67 MHz performance in the 64-pin TQFP form factor-enabling higher-density routing and better EMI containment than FN, while outperforming -25PAG in bandwidth-critical capture and streaming roles.

Availability

SN74ACT7807-20PAG is available at Aetrix Electronics and suitable for telecom infrastructure, digital audio subsystems, industrial PLC backplanes, and automated test equipment requiring stable component supply across extended production lifecycles.

Supply support for SN74ACT7807-20PAG 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 specializing in analog, embedded processing, and logic solutions, with decades of heritage in high-reliability interface and memory products.

The SN74ACT7807-20PAG belongs to TI's Advanced CMOS Logic FIFO family, engineered specifically for deterministic, low-latency data buffering in mixed-clock-domain systems such as communications infrastructure and real-time control.

FAQ

What is the maximum clock frequency supported by the SN74ACT7807-20PAG?

The SN74ACT7807-20PAG supports a maximum clock frequency of 67 MHz for both WRTCLK and RDCLK inputs. This rating is validated under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C) with CL = 50 pF. Timing parameters including setup/hold and propagation delays are guaranteed to meet specification at this rate, enabling use in high-throughput data acquisition and packet buffering applications where sub-15 ns latency is critical. The SN74ACT7807-20PAG achieves this performance using low-power advanced CMOS process technology.

How does the programmable AF/AE flag function in the SN74ACT7807-20PAG?

The AF/AE flag in the SN74ACT7807-20PAG indicates either almost-empty (≤X words) or almost-full (≥2048–Y words) states, with X and Y programmable up to 1023. Programming occurs post-reset and before the first write: with PEN low, the value on D0–D8 and WRTEN1/DP9 is latched as X on the first WRTCLK rising edge and as Y on the second. If PEN remains high, default offsets of X = Y = 256 apply. The SN74ACT7807-20PAG uses this dual-threshold mechanism to support adaptive flow control without external logic or software polling.

Is the SN74ACT7807-20PAG pin-compatible with other variants in the same family?

Yes, the SN74ACT7807-20PAG shares identical pinout and electrical behavior with other PAG-package variants including SN74ACT7807-25PAG and SN74ACT7807-40PAG. All PAG versions use the same 64-pin TQFP footprint, terminal functions, and timing architecture-only maximum clock frequency and associated AC parameters differ. However, it is not pin-compatible with the 44-pin FN-package variant (e.g., SN74ACT7807-20FN), which has different pin count, assignment, and thermal characteristics. The SN74ACT7807-20PAG maintains full functional compatibility across speed grades within the PAG family.

What are the reset requirements for the SN74ACT7807-20PAG?

The SN74ACT7807-20PAG requires an asynchronous active-low RESET signal asserted for at least four complete cycles of both WRTCLK and RDCLK to fully initialize internal pointers and flags. During reset, IR, OR, and HF are driven low, while AF/AE is set high. The first valid write to empty memory causes OR to assert on the third rising edge of RDCLK. Power-up reset is mandatory: the SN74ACT7807-20PAG will not operate correctly unless RESET is applied per this timing sequence, as internal synchronization registers depend on clock-edge detection during reset assertion.

Does the SN74ACT7807-20PAG support cascading for increased memory depth or width?

Yes, the SN74ACT7807-20PAG supports both word-depth and word-width cascading. For depth expansion (e.g., 4096×9), two devices are connected with shared clocks and enables, while chaining IR/OR flags and using HF to coordinate handshaking. For width expansion (e.g., 2048×18), multiple units share WRTCLK/RDCLK/RESET/PEN and route D0–D8 and Q0–Q8 across devices, with WRTEN1/DP9 repurposed as data bit 9. Cascading preserves all flag functionality and timing guarantees, and the SN74ACT7807-20PAG datasheet provides verified schematics for both configurations in Figures 9 and 10.