MC68340 datasheet(396/441 Pages) FREESCALE

Part #	MC68340

Description	Integrated Processor with DMA User?셲 Manual

PDF	441 Pages

Scroll/Zoom	100%

Manufacturer	FREESCALE [Freescale Semiconductor, Inc]

Direct Link	http://www.freescale.com

Logo

396 / 441 page

MOTOROLA

MC68340 USER’S MANUAL

10-9

OUTPUT2

OUTPUT1

CLKOUT

T/2

td1

t s

Figure 10-13. Skew between Two Outputs

The method for calculating a frequency-adjusted ts is as follows:

ts' = ts + N (Tf'/2 – Tf/2) + (Tf'/2 – td1)

where:

ts' = the frequency-adjusted skew

ts = the skew at full speed

N = the number of full one-half clock periods in ts, if any

Tf'/2 = one-half the new clock period

Tf/2 = one-half the clock period at full speed

td1 = the propagation time for the first output from the clock edge

The following calculation uses a 16.78-MHz port, specification 21, R/

W high to AS

asserted, at 8 MHz as an example:

ts = 15 ns minimum

N = 0

Tf'/2 = 125/2 = 62.5 ns

Tf/2 = 60/2 = 30 ns

td1 = 30 ns maximum

therefore:

ts' = 15 + 0(62.5 – 30) + (62.5 – 30) = 47.5 ns minimum

In this manner, new specifications for lower frequencies can be derived for an MC68340.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

MC68340 Datasheet(PDF) 396 Page - Freescale Semiconductor, Inc