TI SN74ALS870

SN74ALS870
DUAL 16-BY-4 REGISTER FILES
SDAS139A – DECEMBER 1982 – REVISED JANUARY 1995
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DW OR NT PACKAGE
(TOP VIEW)
3-State Buffer-Type Outputs Drive Bus
Lines Directly
Each Register File Has Individual
Write-Enable Controls and Address Lines
Designed Specifically for Multibus
Architecture and Overlapping File
Operations
Prioritized B-Input Port Prevents Write
Conflicts During Dual-Input Mode
Package Options Include Plastic
Small-Outline (DW) Packages and Standard
Plastic (NT) 300-mil DIPs
S0
1A0
1A1
1A2
1A3
1W
S2
DQA1
DQA2
DQA3
DQA4
GND
description
1
24
2
23
3
22
4
21
5
20
6
19
7
18
8
17
9
16
10
15
11
14
12
13
VCC
S1
2A3
2A2
2A1
2A0
2W
S3
DQB4
DQB3
DQB2
DQB1
This device features two 16-word by 4-bit register
files. Each register file has individual write-enable
(1W, 2W) controls and address lines. This device has two 4-bit data I/O ports (DQA1–DQA4 and DQB1–DQB4).
The data I/O ports can output to bus A and bus B, receive input from bus A and bus B, receive input from bus
A and output to bus B, or output to bus A and receive input from bus B. To prevent writing conflicts in the
dual-input mode, the B-input port takes priority. Two select (S0 and S1) lines control which port has access to
which register. S2 determines whether the A ports are in the input or the output modes and S3 does likewise
for the B ports. The address lines (1A0 –1A3 or 2A0 –2A3) are decoded by an internal 1-of-16 decoder to select
which register word is to be accessed. All outputs are 3-state buffer-type outputs designed specifically to drive
bus lines directly.
The SN74ALS870 is characterized for operation from 0°C to 70°C.
FUNCTION TABLE
FILE SELECT
S0
S1
FILE SEL
L
L
1R to A, 1R to B
H
L
2R to A, 1R to B
L
H
1R to A, 2R to B
H
H
2R to A, 2R to B
L
L
A to 1R, 1R to B
H
L
A to 2R, 1R to B
L
H
A to 1R, 2R to B
H
H
A to 2R, 2R to B
L
L
1R to A, B to 1R
H
L
2R to A, B to 1R
L
H
1R to A, B to 2R
H
H
2R to A, B to 2R
L
L
B to 1R
H
L
A to 2R, B to 1R
L
H
A to 1R, B to 2R
H
H
B to 2R
INPUT/OUTPUT
S2
S3
I/O SEL
L
L
A out,
out B out
H
L
in B out
A in,
L
H
A out,
out B in
H
H
A in,
in B in
Copyright  1995, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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1
SN74ALS870
DUAL 16-BY-4 REGISTER FILES
SDAS139A – DECEMBER 1982 – REVISED JANUARY 1995
logic symbol†
1A0
1A1
1A2
1A3
2A0
2A1
2A2
2A3
S0
S1
S2
S3
2
5
19
0
15
3
0
20
21
22
1
23
7
17
18
2W
DQA1
1A
4
6
1W
[REG FILE 16 × 4]
0
3
8
2A
0
15
3
C0/G10
C1/G11
C2 [A in]
EN12 [A out]
C3 [B in]
EN13 [B out]
C4
C5
RAM 16 × 1
[REG 1]
Z6
MUX
12
6
7
8,10
1A,0,2(1/3)4D
1A
1A,1,3,4D
RAM 16 × 1
[REG 2]
9,10
6
7
DQA2
DQA3
DQA4
2A,0,2(1/3)5D
2A
2A,1,3,5D
Z7
13
Z8
8
11
9
11
Z9
9
14
10
15
11
16
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DQB1
MUX
† This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
2
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DQB2
DQB3
DQB4
SN74ALS870
DUAL 16-BY-4 REGISTER FILES
SDAS139A – DECEMBER 1982 – REVISED JANUARY 1995
logic diagram (positive logic)
Decoder
2
1A0
3
1A1
4
1A2
5
1A3
1
S0
S1
S2
S3
1W
2W
Decoder
BIN/Y
1
0 16
2
15
3
16
4
BIN/Y
1
0
2
15 3
4
19
20
21
22
2A0
2A1
2A2
2A3
23
7
17
6
18
REG1
RAM 16×1
0
A 15 A
A,D
DQA1
8
13
DQB1
REG2
RAM 16×1
0
A 15 A
A,D
16
16
Three Identical Channels Not Shown
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Input voltage, VI: All inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
I/O ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 V
Voltage applied to a disabled 3-state output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 V
Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
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SN74ALS870
DUAL 16-BY-4 REGISTER FILES
SDAS139A – DECEMBER 1982 – REVISED JANUARY 1995
recommended operating conditions
MIN
NOM
MAX
4.5
5
5.5
UNIT
VCC
VIH
Supply voltage
VIL
IOH
Low-level input voltage
High-level output current
– 2.6
mA
IOL
tw
Low-level output current
24
mA
tsu
Setup time
High-level input voltage
2
12
Address before write↓
th
Hold time
TA
Operating free-air temperature
V
0.8
Pulse duration, write
V
ns
5
Data before write↑
15
Select before write↓
12
Address before write↓
0
Data before write↑
0
Select before write↓
V
ns
ns
12
0
70
°C
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
PARAMETER
VIK
VOH
VOL
II
Control inputs
DQA and DQB ports
TEST CONDITIONS
VCC = 4.5 V,
VCC = 4.5 V to 5.5 V,
II = – 18 mA
IOH = – 0.4 mA
VCC = 4.5 V,
VCC = 4.5 V,
IOH = – 2.6 mA
IOL = 24 mA
VCC = 5
5.5
5V
VI = 7 V
VI = 5.5 V
1W and 2W
IIH
Other control inputs
Control inputs
DQA and DQB ports‡
VCC – 2
2.4
TYP†
MAX
UNIT
– 1.2
V
V
3.2
0.35
0.5
0.1
0.2
V
mA
20
VCC = 5.5 V,
VI = 2.7 V
DQA and DQB ports‡
IIL
MIN
40
µA
50
VCC = 5
5.5
5V
V,
VI = 0
0.4
4V
– 0.2
– 0.2
mA
IO§
VCC = 5.5 V,
VO = 2.25 V
– 30
– 112
mA
ICC
VCC = 5.5 V
80
110
mA
† All typical values are at VCC = 5 V, TA = 25°C.
‡ For I/O ports, the parameters IIH and IIL include the off-state output current.
§ The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS.
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SN74ALS870
DUAL 16-BY-4 REGISTER FILES
SDAS139A – DECEMBER 1982 – REVISED JANUARY 1995
switching characteristics (see Figure 1)
PARAMETER
ta(A)
ta(S)
(S)
tdi
dis
ten
tpd
FROM
(INPUT)
TO
(OUTPUT)
VCC = 4.5 V to 5.5 V,
CL = 50 pF,
R1 = 500 Ω,
R2 = 500 Ω,
TA = MIN to MAX†
MIN
MAX
Any A
Any DQ
3
19
S0
Any DQA
3
15
S1
Any DQB
3
15
S2
Any DQA
3
14
S3
Any DQB
3
14
S2
Any DQA
3
17
S3
Any DQB
3
17
W
Any DQ
5
23
DQA
DQB
5
26
5
26
DQB
DQA
† For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions.
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UNIT
ns
ns
ns
ns
ns
5
SN74ALS870
DUAL 16-BY-4 REGISTER FILES
SDAS139A – DECEMBER 1982 – REVISED JANUARY 1995
PARAMETER MEASUREMENT INFORMATION
SERIES 54ALS/74ALS AND 54AS/74AS DEVICES
7V
RL = R1 = R2
VCC
S1
RL
R1
Test
Point
From Output
Under Test
CL
(see Note A)
From Output
Under Test
RL
Test
Point
From Output
Under Test
CL
(see Note A)
CL
(see Note A)
LOAD CIRCUIT FOR
BI-STATE
TOTEM-POLE OUTPUTS
LOAD CIRCUIT
FOR OPEN-COLLECTOR OUTPUTS
3.5 V
Timing
Input
Test
Point
LOAD CIRCUIT
FOR 3-STATE OUTPUTS
3.5 V
High-Level
Pulse
1.3 V
R2
1.3 V
1.3 V
0.3 V
0.3 V
Data
Input
tw
th
tsu
3.5 V
1.3 V
3.5 V
Low-Level
Pulse
1.3 V
0.3 V
1.3 V
0.3 V
VOLTAGE WAVEFORMS
SETUP AND HOLD TIMES
VOLTAGE WAVEFORMS
PULSE DURATIONS
3.5 V
Output
Control
(low-level
enabling)
1.3 V
1.3 V
0.3 V
tPZL
Waveform 1
S1 Closed
(see Note B)
tPLZ
[3.5 V
1.3 V
tPHZ
tPZH
Waveform 2
S1 Open
(see Note B)
1.3 V
VOL
0.3 V
VOH
1.3 V
0.3 V
[0 V
3.5 V
1.3 V
Input
1.3 V
0.3 V
tPHL
tPLH
VOH
In-Phase
Output
1.3 V
1.3 V
VOL
tPLH
tPHL
VOH
Out-of-Phase
Output
(see Note C)
1.3 V
1.3 V
VOL
VOLTAGE WAVEFORMS
PROPAGATION DELAY TIMES
VOLTAGE WAVEFORMS
ENABLE AND DISABLE TIMES, 3-STATE OUTPUTS
NOTES: A. CL includes probe and jig capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control.
C. When measuring propagation delay items of 3-state outputs, switch S1 is open.
D. All input pulses have the following characteristics: PRR ≤ 1 MHz, tr = tf = 2 ns, duty cycle = 50%.
E. The outputs are measured one at a time with one transition per measurement.
Figure 1. Load Circuits and Voltage Waveforms
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Copyright  1998, Texas Instruments Incorporated