
6-47
March 1997
CDP1826C
CMOS 64-Word x 8-Bit
Static RAM
Features
Ideal for Small, Low-Power RAM Memory Require-
ments in Microprocessor and Microcomputer Applica-
tions
Interfaces with CDP1800-Series Microprocessors
Without Additional Address Decoding
Daisy Chain Feature to Further Reduce External
Decoding Needs
Multiple Chip-Select Inputs for Versatility
Single Voltage Supply
No Clock or Precharge Required.
Pinout
CDP1826C (PDIP)
TOP VIEW
Description
The CDP1826C is a general purpose, fully static, 64-word x
8-bit random-access memory, for use in CDP1800-series or
other microprocessor systems where minimum component
count and/or price performance and simplicity in use are
desirable.
The CDP1826C has 8 common data input and data-output
terminals with three-state capability for direct connection to a
standard bidirectional data bus. Two chip-select inputs - CS1
and CS2 - are provided to simplify memory-system expan-
sion. An additional select pin, CS/A5, is provided to enable
the CDP1826C to be selected directly from the CDP1800
multiplexed address bus without additional latching or
decoding. In an 1800 system, the CS/A5 pin can be tied to
any MA address line from the CDP1800 processor. A TPA
input is provided to latch the high-order bit of this address
line as a chip-select for the CDP1826C. If this CS/A5 input is
latched high, and if CS = 1 and CS2 = 0 at the appropriate
time in the memory cycle, the CDP1826C will be enabled for
writing or reading. In a non-1800 system, the TPA pin can be
tied high, and the CS/A5 pin can be used as a normal
address input.
The six input-address buffers are gated with the chip-select
function to reduce standby current when the device is dese-
lected, as well as to provide for a simplified power down
mode by reducing address buffer sensitivity to long fall times
from address drivers which are being powered down.
Two memory control signals, MRD and MWR, are provided
for reading from the writing to the CDP1826C. The logic is
designed so that MWR overrides MRD, allowing the chip to
be controlled from a single R/W.
A CHIP ENABLE OUTPUT is provided for daisy-chaining to
additional memories or I/O devices. This output is high
whenever the chip-select function selects the CDP1826C,
which deselects any other chip which has its CS input con-
nected to the CDP1826C CEO output. The connected chip is
selected when the CDP1826C is deselected and the MRD
input is low. Thus, the CEO is only active for a read cycle
and can be setup so that a CEO of another device can feed
the MRD of the CDP1826C, which in turn selects a third chip
in the daisy chain.
The CDP1826C has a recommended operating voltage of
4.5V to 5.5V and is supplied in 22 lead dual-in-line plastic
packages (E suffix). The CDP1826C is also available in chip
form (H suffix).
Ordering Information
PACKAGE
TEMP. RANGE
-40
o
C to +85
o
C
PART NUMBER
PKG.
NO.
PDIP
CDP1826CE
E22.4
1
11
10
9
8
7
6
5
3
2
4
22
12
13
14
15
16
17
18
19
21
20
BUS 1
BUS 2
BUS 3
BUS 4
BUS 5
BUS 6
CS1
BUS 7
CS2
V
SS
A0
A1
A2
A3
CS/A5
A4
TPA
MRD
MWR
CEO
BUS 0
V
DD
File Number
1311.2
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Intersil Corporation 1999