OR2C12A

The ORCA Series 2 series of SRAM-based FPGAs are an enhanced version of the ATT2C/2T architecture. The latest ORCA series includes patented architectural enhancements that make functions faster and easier to design while conserving the use of PLCs and routing resources.

The Series 2 devices can be used as drop-in replacements for the ATT2Cxx/ATT2Txx series, respectively,and they are also bit stream compatible with each other. The usable gate counts associated with each series are provided in Table 1. Both series are offered in a variety of packages, speed grades, and temperature ranges.

The ORCA series FPGA consists of two basic elements: programmable logic cells (PLCs) and programmable input/output cells (PICs). An array of PLCs is surrounded by PICs as shown in Figure 1. Each PLC contains a programmable function unit (PFU). The PLCs and PICs also contain routing resources and  configuration RAM. All logic is done in the PFU. Each PFU contains four 16-bit look-up tables (LUTs) and four latches/flip-flops (FFs).

The PLC architecture provides a balanced mix of logic and routing that allows a higher utilized gate/PFU than alternative architectures. The routing resources carry logic signals between PFUs and I/O pads. The routing in the PLC is symmetrical about the horizontal and vertical axes. This improves routability by allowing a bus of signals to be routed into the PLC from any direction.

Some examples of the resources required and the performance that can be achieved using these devices are represented in Table 2.

The FPGA's functionality is determined by internal configuration RAM. The FPGA's internal initialization/configuration circuitry loads the configuration data at powerup or under system control. The RAM is loaded by using one of several configuration modes. The configuration data resides externally in an EEPROM, EPROM, or ROM on the circuit board, or any other storage media. Serial ROMs provide a simple, low pin count method for configuring FPGAs, while the peripheral and JTAG configuration modes allow for easy, in-system programming (ISP).