Quality Semiconductor QS72245-20J

Data enter the FIFO through D0-D17 under write-clock control and leave through Q0-Q17 under read-clock control. Separate read and write pointers address a dual-port memory array. At 4,096 words of 18 bits, the QS72245 family member can decouple digital blocks whose data arrival and consumption rates differ.

• 4K x 18 organization documented for the QS72245 family member.
• Independent read and write control paths.
• Full, empty and programmable almost-full/almost-empty flag support.
• Expansion pins for wider or deeper FIFO systems.
• Enhanced operating-mode options described in the QSI family note.

The manufacturer-authored QS722X5 note identifies WCLK/WEN, RCLK/REN, output enable, reset, load and enhanced-mode functions. FF and EF indicate boundary conditions; PAF and PAE report programmable thresholds. Some pins have expansion, half-full or alternative enable roles. Mode-dependent behavior, setup/hold requirements and the exact -20J speed grade must be checked against the controlled order-code data sheet.

QSI's AN-26 provides a top-view 68-pin PLCC pinout for the QS722X5 family. The local catalog package is blank, while the exact QS72245-20J package drawing and registry mapping have not been verified. The local 68-PLCC JPG is absent. Treat the image path below as a pending asset, not as approved mechanical evidence.

Assembly checks

• Obtain the exact -20J manufacturer package drawing.
• Confirm pin-one orientation and PCB or socket dimensions.
• Verify handling, solderability and lot traceability.

The family drawing labels D0-D17 inputs, Q0-Q17 outputs, WCLK, WEN, RCLK, REN, OE, RS, LD, FF, EF, PAF and PAE. FL/RT, WXI/WEN2, WXO/HF, RXI/REN2 and RXO/EF2 have mode-dependent expansion or control functions. Confirm the exact pin map and operating mode before board-level connection.

The suffix alone is not sufficient evidence for a guaranteed cycle time, supply tolerance or temperature range.

The product database contains QS72245-25J, QS72245-20TF and QS72245-35J. These are family comparison candidates only, not approved drop-in substitutes. Verify clock grade, package, pinout, flag behavior and operating temperature for each exact order code.

Quality Semiconductor's original AN-26, “QS722X5 Family, Designer-Friendly, 18-Bit-Wide Clocked FIFOs” (MAPN-00026-00, July 1995), establishes the QS72245 family architecture, depth and PLCC family pinout. It is an application note rather than a controlled -20J timing or mechanical specification. Obtain the exact device documentation before production qualification.

• Temporary buffering between independently clocked logic.
• Data-rate matching in high-throughput digital paths.
• Depth- or width-expanded FIFO queues.

The local catalog lists 593 units at USD 1.00, minimum quantity 11, with no tiers. An indexed DigiKey/Rochester exact-code offer lists 593 units, minimum order 9 and USD 32.24 at ten. An indexed Quality Semiconductor seller listing shows 593 units, USD 25.79 at 25, USD 24.50 at 100 and lower prices at larger quantities. The matching stock counts do not prove a common supply chain. The local price is not reconciled with these seller claims; inventory and pricing remain unchanged.

Confirm exact QS72245-20J timing, electrical limits, temperature and package drawing before layout or substitution. Resolve package registry and JPG availability; authenticate inventory and quantity pricing. Keep this draft in manual review with noindex and do not publish until all checks pass.