CDP1852 Просмотр технического описания (PDF) - Intersil
Номер в каталоге
Компоненты Описание
Список матч
CDP1852 Datasheet PDF : 9 Pages
| |||
CDP1852, CDP1852C
Application Information
In a CDP1800 series microprocessor-based system where
MRD is used to distinguish between INP and OUT
instructions, an lNP instruction is assumed to occur at the
beginning of every I/O cycle because MRD starts high.
Therefore, at the start of an OUT instruction, which uses the
same 3-bit N code as that used for selection of an input port,
the input device is selected for a short time (see Figure 8).
This condition forces SR low and sets the internal SR latch
(see Figure 3). In a small system with unique N codes for
inputs and outputs, this situation does not arise. Using the
CDP1853 N-bit decoder or equivalent logic to decode the N
lines after TPA prevents dual selection in larger systems
(see Figure 9 and Figure 10).
MRD
N0
N1
N2
SELECT
6D
65
SR
FIGURE 8. EXECUTION OF A “65” OUTPUT INSTRUCTION SHOWING MOMENTARY SELECTION OF INPUT PORT “D”
2
N0
N1 3
14
N2
1 OF 8
DECODER
EN
4
5 OUT 0
OUT 1
6 OUT 2
7 OUT 3
12 OUT 4
11 OUT 5
10 OUT 6
9
OUT 7
TPA
TPB
CE
EN
(NOTE 1)
OUTPUT
FIGURE 9. CDP1853 TIMING WAVEFORMS
NOTE:
1. Output enabled when EN = HIGH. Internal signal shown for ref-
erence only (See Figure 1).
13
CE
CLOCK A 1
Qn
(TPA)
CLOCK B 15
(TPB)
FIGURE10. CDP1853 FUNCTIONAL DIAGRAM
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
9
Share Link: 