Issue link: https://resources.pcb.cadence.com/i/1180526
PSpice User Guide Digital device modeling October 2019 381 Product Version 17.4-2019 © 1999-2019 All Rights Reserved. The format for digital primitives is similar to that for analog devices. One difference is that most digital primitives require two models instead of one: ■ The timing model, which specifies propagation delays and timing constraints such as setup and hold times. ■ The I/O model, which specifies information specific to the device's input/output characteristics. The reason for having two models is that, while timing information is specific to a device, the input/output characteristics are specific to a whole logic family. Thus, many devices in the same family reference the same I/O model, but each device has its own timing model. The Figure 7-1 on page 384 presents an overview of a digital device definition in terms of its primitives and underlying model attributes. These models are discussed further on Timing model on page 387 and Input/Output model on page 393. Memory ROM RAM read-only memory random access read-write memory Multi-Bit A/D & D/A Converters ADC DAC multi-bit A/D converter multi-bit D/A converter Behavioral LOGICEXP PINDLY CONSTRAINT logic expression pin-to-pin delay constraint checking Table 7-1 Digital primitives summary Type Description