450 MHz QDR II+ SRAM — the buffer engine for high-throughput line cards
The Infineon CY7C1543KV18-450BZI is a 72Mbit synchronous SRAM organised as 4M x 18, built on QDR II+ architecture. It clocks at 450 MHz, delivering back-to-back read and write operations on separate data ports without bus-turnaround dead cycles — exactly what a 40G/100G packet buffer or a network search engine needs to keep the pipeline full. It comes in a 165-ball FBGA (13x15 mm body) that routes out to a 4-layer minimum PCB; the BGA pitch and ball map demand careful via fanout planning.
450 MHz — what the clock rate buys you in system throughput
At 450 MHz each port delivers a data rate of 900 Mbps per pin (double-data-rate on both read and write ports). For the 18-bit-wide data bus that works out to a raw bandwidth of 16.2 Gbps aggregate. The QDR II+ architecture eliminates the idle cycle between read and write that conventional common-I/O SRAMs require, so the controller sees full bus utilisation in mixed-traffic patterns. Timing closure at this speed demands controlled-impedance traces, matched-length routing between the SRAM and the FPGA or ASIC, and a clean 1.8V supply with decoupling within 2 mm of each VDDQ ball.
72Mbit in a 4M x 18 organisation — sizing the lookup table
The 4M x 18 configuration (72Mbit total) maps naturally to 18-bit-wide data paths common in network processors and baseband ASICs. Each word is 18 bits, so an IPv4 forwarding table with 512K entries of 144 bits each fits cleanly across eight devices. The x18 width also suits 18-bit ADC capture buffers or radar pulse-history memories where the extra two bits carry a parity or tag. If the design needs a wider bus, multiple devices can be depth- or width-expanded using the QDR II+ port-select and chip-select signals.
The supply range covers 1.7V to 1.9V, with 1.8V as the nominal operating point. This aligns with the JEDEC standard for QDR II+ core voltage, so a fixed 1.8V rail from a regulator like the Infineon TLV62569 or a TI TPS74801 works directly. The 200 mV margin on each side gives headroom for IR drop across the PCB — important when the SRAM sits 50 mm from the regulator on a 12-layer backplane. The VDD and VDDQ rails are separate in the QDR II+ spec; confirm the PCB decoupling scheme isolates them to avoid supply-induced jitter on the data outputs.
It does not extend to automotive under-hood (125°C) or avionics (125°C+), so if the design targets those environments you are looking at a different temperature grade or a ceramic-packaged variant. At the cold end the 450 MHz PLL may need a longer lock time at power-up; the datasheet's tPLL parameter should be checked against the system reset sequence.
165-ball FBGA — footprint and layout realities
The 165-ball FBGA measures 13x15 mm with a ball pitch of 0.65 mm or 0.8 mm depending on the specific ball map revision. The 1.8V core and I/O supply balls are concentrated on the periphery and centre — plan for at least four decoupling capacitors (two per supply) within 5 mm of the package edge. The MSL rating is typically 3 for this package family; the tray ships moisture-sensitive, so verify the floor life if the reel has been opened.
For the BOM cost engineer, the active status also means Infineon continues to support the part with datasheet revisions and application notes — no orphan-component paperwork needed.