36 Mbit QDR II+ at 400 MHz — what it buys you
QDR II+ means the read and write data buses are independent and double-data-rate on each edge, so the effective bandwidth is 400 MT/s per port. This part is aimed at high-throughput buffer and look-aside applications in networking switches, base-station line cards, and test equipment where the bus turnaround penalty of a common-I/O SRAM would cost a clock cycle.
Industrial temperature range — field-fit check
The 85°C ceiling is the standard industrial limit; if your design must sustain junction temperatures above 95°C, you are outside this part's specified operating range.
165-FBGA — layout and rework realities
The 165-ball FBGA (13x15 mm body, 1.0 mm ball pitch typical for this class) demands controlled-impedance routing on a multi-layer PCB, X-ray inspection after reflow, and a hot-air rework station with a preheater for any ball replacement. The package is surface-mount only; no socketed or through-hole variant exists.
Infineon lists this part as Obsolete. That means the factory last-time-buy window has closed, and new production is not available. The only supply route is surplus inventory held by independent distributors. No factory lead time applies; the stock is what is physically on the shelf.