Quality Semiconductor QS72245-25J

The QS722X5 architecture uses a dual-port memory array with independent read and write pointer control. Data enter through D0-D17 under the write clock and leave through Q0-Q17 under the read clock. The QS72245 family member provides 4,096 words of 18 bits, enabling short-term buffering between subsystems that may run at different rates.

• 4K x 18 FIFO organization in the QS722X5 family.
• Separate read and write clocks for independent data streams.
• Full, empty and programmable almost-full/almost-empty status signals.
• Expansion signals for deeper FIFO configurations.
• Enhanced operating-mode controls described in the original QSI application note.

The manufacturer-authored QS722X5 application note describes WCLK/WEN write control, RCLK/REN read control, OE, reset, load and enhanced-mode signals. Its status outputs include FF, EF, PAF and PAE; shared pins also provide expansion or half-full functions according to configuration. Consult the controlled device data sheet for setup/hold limits, flag timing and the exact -25J speed grade.

The QSI AN-26 document depicts the QS722X5 family in a 68-pin PLCC top-view pinout. The local catalog package is blank, and the exact -25J package order-code mapping and registry entry have not been independently confirmed. The local 68-PLCC JPG is missing; do not use this draft as a board-footprint approval.

Assembly checks

• Verify the exact order-code package drawing and pin-one orientation.
• Confirm lead geometry against the intended PCB land pattern or socket.
• Qualify solderability, ESD handling and date-code traceability.

The family pinout names D0-D17 data inputs, Q0-Q17 data outputs, WCLK, WEN, RCLK, REN, OE, RS, LD, FF, EF, PAF and PAE. FL/RT, WXI/WEN2, WXO/HF, RXI/REN2 and RXO/EF2 serve expansion or alternate flag/control roles. Verify the mode-dependent pin definitions in the exact device documentation before wiring.

Do not infer a guaranteed cycle time, voltage tolerance or temperature range solely from the ordering suffix or another manufacturer's 72245 device.

The product database contains QS72245-20J, QS72245-25TF and QS72245-35J. These are same-family comparison candidates, not approved drop-in replacements. Confirm speed, package, pinout, status-flag behavior and temperature grade against controlled manufacturer documents.

Quality Semiconductor's original AN-26, “QS722X5 Family, Designer-Friendly, 18-Bit-Wide Clocked FIFOs” (MAPN-00026-00, July 1995), supports the family architecture, QS72245 depth and 68-pin PLCC family pinout. It is an application note, not a controlled exact-order-code timing or mechanical data sheet. Obtain the exact QS72245-25J ordering and package document before final qualification.

• Temporary buffering between independently clocked logic blocks.
• Rate matching in high-performance digital data paths.
• Expandable FIFO queues in communication and signal-processing systems.

The local catalog lists 598 units at USD 1.00, minimum quantity 11, with no price tiers. An indexed DigiKey/Rochester exact-code offer lists 598 units, minimum order 9, and USD 32.24 at ten; another indexed Quality Semiconductor listing shows 598 units and USD 25.79 at 25 with lower large-quantity tiers. The identical stock quantity does not establish supply-chain identity. These seller claims conflict substantially with the local USD 1.00 price, so inventory and pricing are left unchanged pending procurement verification.

Confirm exact -25J ordering, timing, voltage and temperature limits; validate pin and footprint geometry; then reconcile authenticated inventory and quantity pricing. The package JPG, registry entry and exact-order-code data sheet remain unresolved. Keep this draft in manual review with noindex; do not publish until all checks pass.