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INTEGRATED CIRCUITS
74F786 4-bit asynchronous bus arbiter
Product specification IC15 Data Handbook 1991 Feb 14
Philips Semiconductors
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
FEATURES
* Arbitrates between 4 asynchronous inputs * Separate grant output for each input * Common output enable * On board 4 input AND gate * Metastable-free outputs * Industrial temperature range available (-40C to +85C)
DESCRIPTION
The 74F786 is an asynchronous 4-bit arbiter designed for high speed real-time applications. The priority of arbitration is determined on a first-come first-served basis. Separate bus grant (BGn) outputs are available to indicate which one of the request inputs is served by the arbitration logic. All BGn outputs are enabled by a common enable (EN) pin. In order to generate a bus request signal a separate 4 input AND gate is provided which may also be used as an independent AND gate. Unused bus request (BR) inputs may be disabled by tying them high.
The 74F786 is designed so that contention between two or more request signals will not glitch or display a metastable condition. In this situation an increase in the BRn to BGn tPHL may be observed. A typical 74F786 has an h = 6.6ns, t = 0.41ns and To = 5sec. Where: h = Typical propagation delay through the device and t and To are device parameters derived from test results and can most nearly be defined as: t = A function of the rate at which a latch in a metastable state resolves that condition. To = A function of the measurement of the propensity of a latch to enter a metastable state. To is also a very strong function of the normal propagation delay of the device. For further information, please refer to the 74F786 application notes. TYPICAL SUPPLY CURRENT (TOTAL) 55mA
TYPE 74F786
TYPICAL PROPAGATION DELAY 6.6ns
ORDERING INFORMATION
ORDER CODE DESCRIPTION 16-pin plastic DIP 16-pin plastic SO COMMERCIAL RANGE VCC = 5V 10%, Tamb = 0C to +70C N74F786N N74F786D INDUSTRIAL RANGE VCC = 5V 10%, Tamb = -40C to +85C I74F786N I74F786D PKG DWG # SOT 38-4 SOT109-1
INPUT AND OUTPUT LOADING AND FAN OUT TABLE
PINS BR0 - BR3 A, B, C, D EN YOUT BG0 - BG3 DESCRIPTION Bus request inputs (active low) AND gate inputs Common bus grant output enable input (active low) AND gate output Bus grant outputs (active low) 74F (U.L.) HIGH/ LOW 1.0/3.0 1.0/1.0 1.0/1.0 150/40 150/40 LOAD VALUE HIGH/ LOW 20A/1.8mA 20A/0.6mA 20A/0.6mA 3.0mA/24mA 3.0mA/24mA
NOTE: One (1.0) FAST unit load is defined as: 20A in the high state and 0.6mA in the low state.
LOGIC SYMBOL
IEC/IEEE SYMBOL
BUS ARBITER 74F786 EN BR0 BR1 BR2 BR3 & 14 BG0 BG1 BG2 BG3 13 12 11 10
4
5
6
7
15
1
2
3
9 4
BR0 BR1 BR2 BR3
A
B
C
D
5 6
6
EN
7 BG0 BG1 BG2 BG3 YOUT 15 1 2 13 12 11 10 14
VCC = Pin 16 GND = Pin 8
3
SF00442
SF00443
February 14, 1991
2
853-1269 01717
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
FUNCTIONAL DESCRIPTION
The BRn inputs have no inherent priority. The arbiter assigns priority to the incoming requests as they are received, therefore, the first BR asserted will have the highest priority. When a bus request is received its corresponding bus grant becomes active, provided that EN is low. If additional bus requests are made during this time they are queued. When the first request is removed, the arbiter services the bus request with the next highest priority. Removing a request while a previous request is being serviced can cause a grant to be changed when arbitrating between three or four requests. For that reason, the user should not remove ungranted requests when arbitrating between three or four requests. This does not apply to arbitration between two requests. If two or more BRn inputs are asserted at precisely the same time, one of them will be selected at random, and all BGn outputs will be held in the high state until the selection is made. This guarantees that an erroneous BGn will not be generated even though a metastable condition may occur internal to the device. When the EN is in the high state the BGn outputs are forced high.
PIN CONFIGURATION
B1 C2 D3 BR0 4 BR1 5 BR2 6 BR3 7 GND 8 16 V CC 15 14 13 12 11 10 9 A YOUT BG0 BG1 BG2 BG3 EN
SF00441
PIN DESCRIPTION
SYMBOL BR0 - BR3 A, B, C, D EN BG0 - BG3 YOUT GND VCC PINS 4, 5, 6, 7 15, 1, 2, 3 9 13, 12, 11, 10 14 8 16 TYPE Input Input Input Output Output Ground Power NAME Bus request inputs (active low) Inputs of the 4-input AND gate Enable input Bus grant outputs (active low) Output of the 4-input AND gate ground (0V) Positive supply voltages When low it enables the BG0 - BG3 outputs. These outputs indicate the selected bus request. BG0 corresponds to BR0, BG1 to BR1, etc. FUNCTION The logic of this device arbitrates between these four inputs. Unused inputs should be tied high.
February 14, 1991
3
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
ARBITER FUNCTION TABLE
INPUTS EN L L L L BR0 1 X X X BR1 X 1 X X BR2 X X 1 X X BR3 X X X 1 X BG0 L H H H H BG1 H L H H H OUTPUTS BG2 H H L H H BG3 H H H L H
H X X Notes to mode selection function table H = High-voltage level L = Low-voltage level X = Don't care 1 = First of inputs to go low
ARBITER FUNCTION TABLE
INPUTS A L L L L L L L L H H H H H H H B L L L L H H H H L L L L H H H C L L H H L L H H L L H H L L H D L H L H L H L H L H L H L H L H OUTPUT YOUT L L L L L L L L L L L L L L L H
H H H Notes to AND function table H = High-voltage level L = Low-voltage level
February 14, 1991
4
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
LOGIC DIAGRAM
A B C D BR0 15 1 2 3 4 14 YOUT
13 BR1 5
BG0
BR2
6 12 BG1
BR3
7
11
BG2
10
BG3
VCC = Pin 16 GND = Pin 8
EN
SF00444
ABSOLUTE MAXIMUM RATINGS
(Operation beyond the limit 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 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 Commercial range Industrial range Tstg Storage temperature range PARAMETER RATING -0.5 to +7.0 -0.5 to +7.0 -30 to +5 -0.5 to VCC 48 0 to +70 -40 to +85 -65 to +150 UNIT V V mA V mA
C C C
February 14, 1991
5
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
RECOMMENDED OPERATING CONDITIONS
SYMBOL UNIT VCC VIN 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 Commercial range Industrial range 0 -40 PARAMETER MIN 4.5 2.0 0.8 -18 -1 24 +70 +85 LIMITS NOM 5.0 MAX 5.5 TA = -40 to +85C V V V mA mA mA
C C
DC ELECTRICAL CHARACTERISTICS
(Over recommended operating free-air temperature range unless otherwise noted.) SYMBOL PARAMETER TEST CONDITIONS1 VOH High-level output voltage VCC = MIN, VIL = MAX, VIH = MIN VCC = MIN, VIL = MAX, VIH = MIN VIK II IIH IIL IOS Input clamp voltage Input current at maximum input voltage High-level input current Low-level input current current3 A - D, EN BRn Short-circuit output VCC = MAX -60 VCC = MIN, II = IIK VCC = 0.0V, VI = 7.0V VCC = MAX, VI = 2.7V VCC = MAX, VI = 0.5V IOH = MAX MIN LIMITS TYP2 MAX V 3.3 0.30 0.30 -0.73 0.50 0.50 -1.2 100 20 -0.6 -1.8 -150 V V V V A A mA mA mA UNIT
10%VCC 5%VCC 10%VCC 5%VCC
2.4 2.7
VOL
Low-level output voltage
IOL = MAX
ICC Supply current (total) VCC = MAX 55 80 mA Notes to DC electrical characteristics 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 = 25C. 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.
February 14, 1991
6
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
AC ELECTRICAL CHARACTERISTICS
LIMITS Tamb = +25C SYMBOL Tamb = 0C to +70C VCC = +5.0V 10% CL = 50pF, RL = 500 MIN 2.0 2.5 4.5 4.0 2.5 2.5 4.5 MAX 8.5 7.5 10.5 10.0 8.5 8.0 10.5 7.5 7.5 10.0 9.5 8.0 7.5 10.0 Tamb = -40C to +85C VCC = +5.0V 10% CL = 50pF, RL = 500 MIN 2.0 2.5 4.5 4.0 2.5 2.5 4.5 MAX 8.5 7.5 10.5 10.0 8.5 8.0 10.5 ns ns ns ns UNIT
PARAMETER
TEST CONDITION MIN
VCC = +5.0V CL = 50pF, RL = 500 TYP 4.5 4.5 7.0 6.5 5.0 4.5 7.0 MAX 2.5 2.5 5.0 4.5 3.0 2.5 5.0
tPLH tPHL tPLH tPHL tPLH tPHL tPHL
Propagation delay, A, B, C, D to YOUT Propagation delay, BRn to BGn Propagation delay, EN to BGn Propagation delay, BRa to BGb
Waveform 1 Waveform 2 Waveform 2 Waveform 2
AC WAVEFORMS
VM tPLH YOUT VM VM tPHL VM BGa VM BRa VM
A, B, C, D
SF00445
Waveform 1. Propagation delay for AND gate to output
BRb tPHL VM
BGb BRn, EN VM tPHL VM VM tPLH VM
SF00447
Waveform 3. Propagation delay for bus request to bus grant output Notes to AC waveforms 1. For all waveforms, VM = 1.5V. 2. a and b represents any of the bus requests or grants. BGa low-to-high transition and the BGb high-to-low transition occur simultaneously.
BGn
SF00446
Waveform 2. Propagation delay for bus request or enable to bus grant output
February 14, 1991
7
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
TEST CIRCUIT AND WAVEFORMS
VCC NEGATIVE PULSE VIN PULSE GENERATOR RT D.U.T. VOUT 90% VM 10% tTHL (tf ) CL RL tw VM 10% tTLH (tr ) 0V 90% AMP (V)
tTLH (tr ) 90% POSITIVE PULSE VM 10% tw
tTHL (tf ) AMP (V) 90% VM 10% 0V
Test Circuit for Totem-Pole Outputs DEFINITIONS: RL = Load resistor; see AC ELECTRICAL CHARACTERISTICS for value. CL = Load capacitance includes jig and probe capacitance; see AC ELECTRICAL CHARACTERISTICS for value. RT = Termination resistance should be equal to ZOUT of pulse generators.
Input Pulse Definition INPUT PULSE REQUIREMENTS family amplitude VM 74F 3.0V 1.5V rep. rate 1MHz tw 500ns tTLH 2.5ns tTHL 2.5ns
SF00006
February 14, 1991
8
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
DIP16: plastic dual in-line package; 16 leads (300 mil)
SOT38-4
1991 Feb 14
9
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
SO16: plastic small outline package; 16 leads; body width 3.9 mm
SOT109-1
1991 Feb 14
10
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
NOTES
1991 Feb 14
11
Philips Semiconductors
Product specification
4-bit asynchronous bus arbiter
74F786
Data sheet status
Data sheet status Objective specification Preliminary specification Product specification Product status Development Qualification Definition [1] This data sheet contains the design target or goal specifications for product development. Specification may change in any manner without notice. This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips Semiconductors reserves the right to make chages at any time without notice in order to improve design and supply the best possible product. This data sheet contains final specifications. Philips Semiconductors reserves the right to make changes at any time without notice in order to improve design and supply the best possible product.
Production
[1] Please consult the most recently issued datasheet before initiating or completing a design.
Definitions
Short-form specification -- The data in a short-form specification is extracted from a full data sheet with the same type number and title. For detailed information see the relevant data sheet or data handbook. Limiting values definition -- Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability. Application information -- Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or modification.
Disclaimers
Life support -- These products are not designed for use in life support appliances, devices or systems where malfunction of these products can reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application. Right to make changes -- Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless otherwise specified. Philips Semiconductors 811 East Arques Avenue P.O. Box 3409 Sunnyvale, California 94088-3409 Telephone 800-234-7381 (c) Copyright Philips Electronics North America Corporation 1998 All rights reserved. Printed in U.S.A. print code Document order number: Date of release: 10-98 9397-750-05181
Philips Semiconductors
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