DM74LS670N

DM74LS670N Datasheet

DM74LS670 3-STATE 4-by-4 Register File

Part	Datasheet
DM74LS670N	DM74LS670N (pdf)

PDF Datasheet Preview
DM74LS670 3-STATE 4-by-4 Register File DM74LS670 3-STATE 4-by-4 Register File These register files are organized as 4 words of 4 bits each, and separate on-chip decoding is provided for addressing the four word locations to either write-in or retrieve data. This permits writing into one location, and reading from another word location, simultaneously. Four data inputs are available to supply the word to be stored. Location of the word is determined by the write select inputs A and B, in conjunction with a write-enable signal. Data applied at the inputs should be in its true form. That is, if a high level signal is desired from the output, a high level is applied at the data input for that particular bit location. The latch inputs are arranged so that new data will be accepted only if both internal address gate inputs are HIGH. When this condition exists, data at the D input is transferred to the latch output. When the write-enable input, GW, is HIGH, the data inputs are inhibited and their levels can cause no change in the information stored in the internal latches. When the read-enable input, GR, is HIGH, the data outputs are inhibited and go into the high impedance state. The individual address lines permit direct acquisition of data stored in any four of the latches. Four individual decoding gates are used to complete the address for reading a word. When the read address is made in conjunction with the read-enable signal, the word appears at the four outputs. This entry addressing separate from data read addressing and individual sense line elimi- nates recovery times, permits simultaneous reading and writing, and is limited in speed only by the write time 27 ns typical and the read time 24 ns typical . The register file has a non-volatile readout in that data is not lost when addressed. All inputs except read enable and write enable are buffered to lower the drive requirements to one normal Series DM74LS load, and input clamping diodes minimize switching transients to simplify system design. High speed, double ended AND-OR-INVERT gates are employed for the read-address function and have high sink current, 3-STATE outputs. Up to 128 of these outputs may be wire-AND connected for increasing the capacity up to 512 words. Any number of these registers may be paralleled to provide nbit word length. s For use as: Scratch pad memory Buffer storage between processors Bit storage in fast multiplication designs s Separate read/write addressing permits simultaneous reading and writing s Organized as 4 words of 4 bits s Expandable to 512 words of n-bits s 3-STATE versions of DM74LS170 s Fast access times 20 ns typ Ordering Code: Order Number Package Number Package Description DM74LS670M M16A 16-Lead Small Outline Integrated Circuit SOIC , JEDEC MS-012, Narrow DM74LS670N N16E 16-Lead Plastic Dual-In-Line Package PDIP , JEDEC MS-001, Wide Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code. 2000 Fairchild Semiconductor Corporation DS006436 DM74LS670 Connection Diagram Function Tables Write Table Note 1 Note 2 Read Table Note 3 Write Inputs Word Read Inputs Outputs WB WA GW RB RA GR L Q=D L WOB1 WOB2 WOB3 L H L W1B1 W1B2 W1B3 L W2B1 W2B2 W2B3 H L W3B1 W3B2 W3B3 H = HIGH Level L = LOW Level X = Don’t Care Z = High Impedance OFF Note 1 Q = D = The four selected internal flip-flop outputs will assume the states applied to the four external data inputs. Note 2 Q0 = The level of Q before the indicated input conditions were established. Note 3 WOB1 = The first bit of word 0, etc. Logic Diagram Q4 WOB4 W1B4 W2B4 W3B4 DM74LS670 Absolute Maximum Ratings Note 4 Supply Voltage Input Voltage Operating Free Air Temperature Range 0°C to +70°C Storage Temperature Range −65°C to +150°C Note 4 The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation. Recommended Operating Conditions Parameter Units Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage

PDF Datasheet Preview

DM74LS670 3-STATE 4-by-4 Register File

DM74LS670 3-STATE 4-by-4 Register File

These register files are organized as 4 words of 4 bits each, and separate on-chip decoding is provided for addressing the four word locations to either write-in or retrieve data. This permits writing into one location, and reading from another word location, simultaneously.

Four data inputs are available to supply the word to be stored. Location of the word is determined by the write select inputs A and B, in conjunction with a write-enable signal. Data applied at the inputs should be in its true form. That is, if a high level signal is desired from the output, a high level is applied at the data input for that particular bit location. The latch inputs are arranged so that new data will be accepted only if both internal address gate inputs are HIGH. When this condition exists, data at the D input is transferred to the latch output. When the write-enable input, GW, is HIGH, the data inputs are inhibited and their levels can cause no change in the information stored in the internal latches. When the read-enable input, GR, is HIGH, the data outputs are inhibited and go into the high impedance state.

The individual address lines permit direct acquisition of data stored in any four of the latches. Four individual decoding gates are used to complete the address for reading a word. When the read address is made in conjunction with the read-enable signal, the word appears at the four outputs.

This entry addressing separate from data read addressing and individual sense line elimi-
nates recovery times, permits simultaneous reading and writing, and is limited in speed only by the write time 27 ns typical and the read time 24 ns typical . The register file has a non-volatile readout in that data is not lost when addressed.

All inputs except read enable and write enable are buffered to lower the drive requirements to one normal Series DM74LS load, and input clamping diodes minimize switching transients to simplify system design. High speed, double ended AND-OR-INVERT gates are employed for the read-address function and have high sink current, 3-STATE outputs. Up to 128 of these outputs may be wire-AND connected for increasing the capacity up to 512 words. Any number of these registers may be paralleled to provide nbit word length.
s For use as:

Scratch pad memory

Buffer storage between processors

Bit storage in fast multiplication designs s Separate read/write addressing permits simultaneous
reading and writing s Organized as 4 words of 4 bits s Expandable to 512 words of n-bits s 3-STATE versions of DM74LS170 s Fast access times 20 ns typ
Ordering Code:

Order Number Package Number

Package Description

DM74LS670M

M16A
16-Lead Small Outline Integrated Circuit SOIC , JEDEC MS-012, Narrow

DM74LS670N

N16E
16-Lead Plastic Dual-In-Line Package PDIP , JEDEC MS-001, Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
2000 Fairchild Semiconductor Corporation DS006436

DM74LS670

Connection Diagram

Function Tables

Write Table Note 1 Note 2

Read Table Note 3

Write Inputs

Word

Read Inputs

Outputs

WB WA GW

RB RA GR

L Q=D

L WOB1 WOB2 WOB3

L H L W1B1 W1B2 W1B3

L W2B1 W2B2 W2B3

H L W3B1 W3B2 W3B3

H = HIGH Level

L = LOW Level

X = Don’t Care

Z = High Impedance OFF

Note 1 Q = D = The four selected internal flip-flop outputs will assume the states applied to the four external data inputs.

Note 2 Q0 = The level of Q before the indicated input conditions were established.

Note 3 WOB1 = The first bit of word 0, etc.

Logic Diagram

Q4 WOB4 W1B4 W2B4 W3B4

DM74LS670

Absolute Maximum Ratings Note 4

Supply Voltage

Input Voltage

Operating Free Air Temperature Range 0°C to +70°C

Storage Temperature Range
−65°C to +150°C

Note 4 The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation.

Recommended Operating Conditions

Parameter

Units

Supply Voltage

HIGH Level Input Voltage

LOW Level Input Voltage

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived DM74LS670N Datasheet file may be downloaded here without warranties.

Datasheet ID: DM74LS670N 513807