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Part: 74F148
Category:
Logic
-> Encoders/Multiplexers
-> Encoders
Description: 74F148; 8-input Priority Encoder;; Package: SOT109 (SO16), SOT38-1 (DIP16)
Company: Philips Semiconductors
Datasheet: Download 74F148 datasheet File size : 93 kB
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INTEGRATED CIRCUITS
74F148 8-input priority encoder
Product specification IC15 Data Handbook 1990 Mar 01
Philips Semiconductors
Philips Semiconductors
Product specification
8-input priority encoder
74F148
FEATURES
· Code conversions · Multi-channel D/A converter · Decimal-to-BCD converter · Cascading for priority encoding of "N" bits · Input enable capability · Priority encoding-automatic selection of highest priority input line · Output enable-active Low when all inputs are High · Group signal output-active when any input is Low
DESCRIPTION
The 74F148 8-input priority encoder accepts data from eight active-Low inputs and provides a binary representation on the three active-Low outputs. A priority is assigned to each input so that when two or more inputs are simultaneously active, the input with the highest priority is represented on the output, with input line I7 having the highest priority. A High on the Enable Input (EI) will force all outputs to the inactive (High) state and allow new data to settle without producing erroneous information at the outputs. A Group Signal (GS) output and an Enable Output (EO) are provided with the three data outputs. The GS is active-Low when any input is Low: this indicates when any input is active. The EO is active-Low when all inputs are High. Using the Enable Output along with the Enable Input allows priority encoding of N input signals. Both EO and GS are active-High when the Enable Input is High.
PIN CONFIGURATION
I4 I5 I6 I7 EI A2 A1 GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCC EO GS I3 I2 I1 I0 A0
SF00181
TYPE 74F148
TYPICAL PROPAGATION DELAY 6.0ns
TYPICAL SUPPLY CURRENT (TOTAL) 23mA
ORDERING INFORMATION
DESCRIPTION 16-pin plastic DIP 16-pin plastic SO COMMERCIAL RANGE VCC = 5V ±10%, Tamb = 0°C to +70°C N74F148N N74F148D PKG DWG # SOT38-4 SOT109-1
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS I1 I7 I0 EI EO GS A0 A2 DESCRIPTION Priority inputs (active Low) Priority input (active Low) Enable input (active Low) Enable output (active Low) Group select output (active Low) Address outputs (active Low) 74F (U.L.) HIGH/LOW 1.0/2.0 1.0/1.0 1.0/2.0 50/33 50/33 50/33 LOAD VALUE HIGH/LOW 20µA/1.2mA 20µA/0.6mA 20µA/1.2mA 1.0mA/20mA 1.0mA/20mA 1.0mA/20mA
NOTE: One (1.0) FAST unit load is defined as: 20µA in the High state and 0.6mA in the Low state.
March 1, 1990
2
8530345 98994
Philips Semiconductors
Product specification
8-input priority encoder
74F148
LOGIC SYMBOL
10 11 12 13 1 2 3 4
IEC/IEEE SYMBOL
10 10/Z10 11 12 I0 I1 I2 I3 I4 I5 I6 I7 13 EO 5 EI GS A0 A1 A2 14 15 1 2 3 4 5 VCC = Pin 16 GND = Pin 8 9 7 6 11/Z11 2/Z12 3/Z13 4/Z14 5/Z15 6/Z16 7/Z17
HPRI/BIN
0 1 2
9 7 8
EN = /V18
10 11 12 13 14 15 16 17
1
18 15 14
SF00182
SF00183
LOGIC DIAGRAM
EI 5 I7 4 I6 3 I5 2 I4 1 I3 13 I2 12 I1 11 I0 10
9 VCC = Pin 16 GND = Pin 8 A2 A1
9 A0
9
14 GS
15 EO
SF00184
March 1, 1990
3
Philips Semiconductors
Product specification
8-input priority encoder
74F148
FUNCTION TABLE
INPUTS EI H L L L L L L L L L I0 X H X X X X X X X L I1 X H X X X X X X L H I2 X H X X X X X L H H I3 X H X X X X L H H H I4 X H X X X L H H H H I5 X H X X L H H H H H I6 X H X L H H H H H H I7 X H L H H H H H H H GS H H L L L L L L L L A0 H H L H L H L H L H OUTPUTS A1 H H L L H H L L H H A2 H H L L L L H H H H EO H L H H H H H H H H
H = High voltage level L = Low voltage level X = Don't care
APPLICATION
ENABLE LSB MSB
I0 EI EO GS
I1
I2
I3
I4
I5
I6
I7 EI EO GS
I0
I1
I2
I3
I4
I5
I6
I7
A0
A1
A2
A0
A1
A2
A0
A1
A2
A3
FLAG
16-Input Priority Encoder
SF00185
March 1, 1990
4
Philips Semiconductors
Product specification
8-input priority encoder
74F148
ABSOLUTE MAXIMUM RATINGS
(Operation beyond the limits set forth in this table may impair the useful life of the device. Unless otherwise noted these limits are over the operating free-air temperature range.) SYMBOL VCC VIN IIN VOUT IOUT Tamb Tstg Supply voltage Input voltage Input current Voltage applied to output in High output state Current applied to output in Low output state Operating free-air temperature range Storage temperature range PARAMETER RATING 0.5 to +7.0 0.5 to +7.0 30 to +5 0.5 to VCC 40 0 to +70 65 to +150 UNIT V V mA V mA °C °C
RECOMMENDED OPERATING CONDITIONS
LIMITS SYMBOL VCC VIH VIL IIK IOH IOL Tamb Supply voltage High-level input voltage Low-level input voltage Input clamp current High-level output current Low-level output current Operating free-air temperature range 0 PARAMETER MIN 4.5 2.0 0.8 18 1 20 +70 NOM 5.0 MAX 5.5 V V V mA mA mA °C UNIT
DC ELECTRICAL CHARACTERISTICS
(Over recommended operating free-air temperature range unless otherwise noted.) SYMBOL PARAMETER TEST CONDITIONS1 CONDITIONS VCC = MIN, VIL = MAX VIH = MIN, IOH = MAX Low-level output voltage output voltage Input clamp voltage Input current at maximum input voltage High-level input current I0 IIL IOS ICC Low-level input current input current I1 I7, EI Short-circuit output Supply current current3 VCC = MAX, VI = 0 5V MAX 0.5V VCC = MAX VCC = MAX 60 23 VCC = MIN, VIL = MAX VIH = MIN, IOL = MAX VCC = MIN, II = IIK VCC = MAX, VI = 7.0V VCC = MAX, VI = 2.7V ±10%VCC ±5%VCC ±10%VCC ±5%VCC LIMITS MIN 2.5 V 2.7 3.4 0.30 0.30 0.73 0.50 V 0.50 1.2 100 20 0.6 1.2 150 35 V µA µA mA mA mA mA TYP2 MAX UNIT
VOH
High-level output voltage output voltage
VOL VIK II IIH
(total)4
NOTES: 1. For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions for the applicable type. 2. All typical values are at VCC = 5V, Tamb = 25°C. 3. Not more than one output should be shorted at a time. For testing IOS, the use of high-speed test apparatus and/or sample-and-hold techniques are preferable in order to minimize internal heating and more accurately reflect operational values. Otherwise, prolonged shorting of a High output may raise the chip temperature well above normal and thereby cause invalid readings in other parameter tests. In any sequence of parameter tests, IOS tests should be performed last. 4. To measure ICC, outputs must be open, VIN on all inputs = 4.5V.
March 1, 1990
5
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