Jameco Electronics 3000, 2000 manual Ac Timing Specifications, Memory Access Time

16.AC TIMING SPECIFICATIONS

The Rabbit 3000 processor may be operated at voltages between 1.8 V and 3.6 V, and at temperatures from –40°C to +85°C with use possible use over the extended range -55°C to +105°C. For long life it is desirable not to exceed a die temperature of 125°C. Most users will operate the Rabbit at 3.3 V.

16.1 Memory Access Time

Required memory address and output enable access time for some important typical cases are given in the table below. It is assumed that the clock doubler is used, that the clock spreader is enabled in the normal mode, that the memory early output enable is on, and that the address bus has 60 pF load.

Table 16-1. Memory Requirements at 3.3 V, -40°C to +85°C, Adr Bus 60 pF

Clock	Period	Clock Doubler	Memory Address	Memory Output
Frequency		Nominal Delay	Access	Enable Access
	(ns)
(MHz)		(ns)	(ns)	(ns)
18.43	54	20	97	60
22.11	45	20	78	51
24.00	42	19	72	45
25.80	39	17	66	43
29.49	34	16	56	37
44.24	22.5	10	33.5	22

All important signals on the Rabbit 3000 are output synchronized with the internal clock. The internal clock is closely synchronized with the external clock (CLK) that may be optionally output from pin 2 of the TQFP package. The delay in signal output depends on the capacitive load on the output lines. In the case of the address lines, which are critically important for establishing memory access time requirements, the capacitive loading is usually in the range of 25–100 pF, and the load is due to the input capacitance of the mem- ory devices and PC trace capacitance. Delays are expressed from the waveform midpoint in keeping with the convention used by memory manufacturers.

User’s Manual 215