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Details, datasheet, quote on part number:SN54LS348
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| Part: | SN54LS348 |
| Category: | Communication => Network => Encoder/Decoder/Encryption/Decryption |
| Description: | 8-input Priority Encoders With 3-state Outputs |
| Company: | Motorola Semiconductor Products |
| Datasheet: | Download SN54LS348 datasheet File size : 221 kB |
| Request For quote: | Find where to buy SN54LS348
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Datasheet text preview:
8-INPUT PRIORITY ENCODERS WITH 3-STATE OUTPUTS
The SN54 / 74LS348 and the SN54 / 74LS848 are eight input priority encoders which provide the 8-line to 3-line function. The outputs (A0 A2) and inputs (0 7) are active low. The active low input which has the highest priority (input 7 has the highest) is represented on the outputs (output A0 is the lowest bit). An example would be if inputs 1, 2 and 4 were low, then a binary 4 would be represented on the outputs. The GS (Group Signal) output is active low when any of the inputs are low. It serves to indicate when any of the inputs are active. A0, A1 and A2 are three-state outputs. This allows for up to 64 line expansion without the need for special external circuitry. A logical one on the Enable Input (EI) forces A0, A1 ared A2 to the disabled state and outputs GS and EO to the high state. A high on all data inputs (0 7) together with a low on the EI input disables outputs A0, A1, and A2 and forces output GS to the high state and output EO to the low state. Use of the EI input in conjunction with the EO output provides for the capability of having priority encoding of n input signals. The LS848 has special internal circuitry providing for a greatly reduced negative going glitch on the GS (Group Signal) output and on a reduced tendency for the A0, A1 and A2 outputs to become momentarily enabled. Both of these occurrences happen when the EI input goes from a logical one to a logical zero and all data inputs (0 7) are held at logical ones. The internal glitch reduction circuitry does add an additional fan-in of one on all data inputs (compared to that of the LS348).
OUTPUTS VCC 16 EO 15 EO 4 5 1 4 2 5 6 3 6 INPUTS 7 4 7 EI 5 EI A2 6 A2 GS 14 GS 3 13 3 INPUTS 2 12 2 1 11 1 0 10 0 A0 A1 8 GND OUTPUT A0 9
SN54 / 74LS348 SN54 / 74LS848
8-INPUT PRIORITY ENCODERS WITH 3-STATE OUTPUTS
LOW POWER SCHOTTKY
J SUFFIX CERAMIC CASE 620-09
16 1
16 1
N SUFFIX PLASTIC CASE 648-08
16 1
D SUFFIX SOIC CASE 751B-03
ORDERING INFORMATION
SN54LSXXXJ SN74LSXXXN SN74LSXXXD Ceramic Plastic SOIC
7 A1
OUTPUTS
FUNCTION TABLE
INPUTS EI H L L L L L L L L L 0 X H X X X X X X X L 1 X H X X X X X X L H 2 X H X X X X X L H H 3 X H X X X X L H H H 4 X H X X X L H H H H 5 X H X X L H H H H H 6 X H X L H H H H H H 7 X H L H H H H H H H A2 Z Z L L L L H H H H OUTPUTS A1 Z Z L L H H L L H H A0 Z Z L H L H L H L H GS H H L L L L L L L L EO H L H H H H H H H H
H = HIGH Logic Level L = LOW Logic Level X = Irrelevant Z = High Impedance State
FAST AND LS TTL DATA 5-499
SN54 / 74LS348 · SN54/74LS848
BLOCK DIAGRAMS
(5) EI (10) EI 0 (5) (10) (15) EO (14) GS 0 G13 G29 (15) EO (14) GS G1
1
(11)
(11) 1
G2
G9
G31
G30
G14 (12) (9) A0 3 (13) 3 (1) (1) 4 (2) (7) A1 (2) 5 (3) 6 (3) (4) 7 6 (6) A2 (4) 7 G24 G8 G7 G6 (13) (12) 2 G3 (9) A0 G18
2
G15
G4
G16 G17
4
G5
G10
G19 (7) A1 G23
5
G11
G20 G21 G22
G12
G25 G26 G27 G28
(6) A2
SN54 / 74LS348
SN54 / 74LS848
GUARANTEED OPERATING RANGES
Symbol VCC TA IOH IOH IOL IOL Supply Voltage Operating Ambient Temperature Range Output Current -- High Output Current -- High Output Current -- Low Output Current -- Low EO, GS A0, A1, A2 A0, A1, A2 EO, GS A0, A1, A2 A0, A1, A2 Parameter 54 74 54 74 54, 74 54 74 54 74 54 74 Min 4.5 4.75 55 0 Typ 5.0 5.0 25 25 Max 5.5 5.25 125 70 0.4 1.0 2.6 4.0 8.0 12 24 Unit V °C mA mA mA mA
FAST AND LS TTL DATA 5-500
SN54 / 74LS348 · SN54/74LS848
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits Symbol VIH VIL VIK Parameter Input HIGH Voltage 54 Input LOW Voltage 74 Input Clamp Diode Voltage Output HIGH Voltage A0, A1, A2 VOH EO, GS EO, GS VOL Output LOW Voltage EO, GS Output LOW Voltage A0, A1, A2 Output Off Current HIGH Output Off Current LOW Input HIGH Current Input 0, EI -- LS348 Input 0 -- LS848 Other -- LS348 Other -- LS848 IIH Input HIGH Current Input 0, EI -- LS348 Input 0 -- LS848 Other -- LS348 Other -- LS848 Input LOW Current Input 0, EI -- LS348 IIL Input 0 -- LS848 Other -- LS348 Other -- LS848 Short Circuit Current (Note 1) EO, GS A0, A1, A2 Power Supply Current Total, Output HIGH ICC Total, Output LOW 13 25 20 30 12 54, 74 54 74 54, 74 74 54, 74 74 2.4 2.5 2.7 0.65 3.1 3.5 3.5 0.25 0.35 0.25 0.35 0.4 0.5 0.4 0.5 20 20 20 40 40 60 0.1 0.2 0.2 0.3 0.4 0.8 0.8 1.2 120 130 23 mA VCC = MAX, Inputs 7, EI = GND All Others Open 0.8 1.5 V V V V V V V V µA µA µA µA µA µA mA mA mA mA mA mA mA mA mA mA VCC = MAX All Inputs and Outputs Open VCC = MAX, VIN = 0.4 V VCC = MAX, VIN = 7.0 V VCC = MAX, VIN = 2.7 V IOL = 4.0 mA IOL = 8.0 mA IOL = 12 mA IOL = 24 mA VCC = VCC MIN, VIN = VIL or VIH per Truth Table VCC = VCC MIN, VIN = VIL or VIH per Truth Table Min 2.0 0.7 V Typ Max Unit V Test Conditions Guaranteed Input HIGH Voltage for All Inputs Guaranteed Input LOW Voltage for All Inputs VCC = MIN, IIN = 18 mA
VCC = MIN, IOH = MAX, VIN = VIH or VIL per Truth Table
VOL IOZH IOZL
VCC = MAX, VOUT = 2.7 V VCC = MAX, VOUT = 0.4 V
IOS
VCC = MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
FAST AND LS TTL DATA 5-501
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