1997 Logic Products Printed U.S.A. 1297 SCEA005 Mi

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1997 Logic Products Printed U.S.A. 1297 SCEA005 Mi

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Migration From Power Supplies Logic Devices
1997
Logic Products
Printed U.S.A. 1297
SCEA005
Migration From Power Supplies Logic Devices
1997
Logic Products
Printed U.S.A. 1297
SCEA005
Migration From 3.3-V 2.5-V Power Supplies Logic Devices
SCEA005 December 1997
IMPORTANT NOTICE Texas Instruments (TI) reserves right make changes products discontinue semiconductor product service without notice, advises customers obtain latest version relevant information verify, before placing orders, that information being relied current. warrants performance semiconductor products related software specifications applicable time sale accordance with TI's standard warranty. Testing other quality control techniques utilized extent deems necessary support this warranty. Specific testing parameters each device necessarily performed, except those mandated government requirements. Certain applications using semiconductor products involve potential risks death, personal injury, severe property environmental damage ("Critical Applications"). SEMICONDUCTOR PRODUCTS DESIGNED, INTENDED, AUTHORIZED, WARRANTED SUITABLE LIFE-SUPPORT APPLICATIONS, DEVICES SYSTEMS OTHER CRITICAL APPLICATIONS. Inclusion products such applications understood fully risk customer. products such applications requires written approval appropriate officer. Questions concerning potential risk applications should directed through local sales office. order minimize risks associated with customer's applications, adequate design operating safeguards should provided customer minimize inherent procedural hazards. assumes liability applications assistance, customer product design, software performance, infringement patents services described herein. does warrant represent that license, either express implied, granted under patent right, copyright, mask work right, other intellectual property right covering relating combination, machine, process which such semiconductor products services might used.
Copyright 1997, Texas Instruments Incorporated
Contents
Title Page Introduction Background Technology Features Uniqueness Devices Typical Design Applications Laboratory Testing Results SPICE/IBIS Models Package Information Frequently Asked Questions Conclusion Glossary Bibliography Appendix Available SPICE IBIS Models
Introduction
Powering systems level been standard practice approximately years. Power consumption always concern system design and, because reducing supply voltage yields exponential decrease power consumption, lower supply voltages commonly used. Thus, transition from common power-supply level 3.3-V level occurring. Furthermore, next voltage level which specified switching levels have been defined During this transition, parts system designed lower supply voltage while other parts not. This raises concerns input-voltage tolerance, interfacing translating, level shifting. This application report explores possibilities migrating 3.3-V 2.5-V power supplies discusses implications. Customers successfully using wide range low-voltage, 3.3-V logic devices. These devices within Texas Instruments (TITM) advanced low-voltage CMOS (ALVC), crossbar technology (CBT), crossbar technology with integrated diode (CBTD), low-voltage crossbar technology (CBTLV) low-voltage CMOS revision (LVC-A) logic families. Additionally, plans release level shifter that generates valid 3.3-V 2.5-V signals. transition from 3.3-V logic began with core logic converting first lower power-supply level. Although memory still primarily level, being converted this conversion will continue. same method migration expected with memory logic following core logic several years. main topics this application report are:
Background Technology Features Uniqueness Devices Typical Design Applications Laboratory Testing Results SPICE/IBIS Models Package Information Frequently Asked Questions Conclusion Glossary Bibliography
Background
transition from power-supply level lower driven primarily desire reduce power consumption. approximately last years, power supplies have been standard both core memory logic. However, core logic begun migrate 3.3-V power-supply levels, memory followed. next commonly accepted power-supply level designers beginning incorporate their systems. This sets stage 1.8-V logic, which standard been established.
trademark Texas Instruments Incorporated
each power-supply level, standard exists defining commonly agreed-upon levels input output voltages. Figure shows appropriate switching levels 5-V, 3.3-V, 2.5-V families.
4.44
CMOS Family
Standard
3.3-V Logic Families
2.5-V Logic Families
accordance with JEDEC Standard interface levels
Figure Switching Levels 5-V, 3.3-V, 2.5-V Families
Technology
Table lists logic families produces that operate 3.3-V VCC. process, power-supply level which device designed optimized, whether device operate 3.3-V 2.5-V levels included. Table Logic Family Technology Summary
LOGIC FAMILY ALVC CBTD CBTLV PROCESS CMOS CMOS CMOS CMOS CMOS CMOS OPTIMIZED POWER SUPPLY LEVEL OPERATIONAL OPERATIONAL
LVC-A CBT16232, CBT16233, CBT16390 devices BiCMOS.
Table CMOS process indicates that devices contain solely CMOS circuitry. BiCMOS process indicates that combination bipolar CMOS transistors implemented circuitry.
Features Uniqueness Devices
When discussing interactions between different power-supply levels, distinction between input-voltage tolerance, interfacing translating, level shifting important. Input-voltage tolerance applies when device with lower power supply withstand presence higher voltage without being damaged. example, 3.3-V device drives 2.5-V device without harming receiver. Under this concept, there implication about device being able produce signal compatible with higher power-supply level. Interfacing translating implies that device generate valid input output voltage levels, even though single power-supply level being used. device level shifter when implements power supplies produce signals that conform switching requirements both lower-voltage power supply higher-voltage power supply. devices families listed Table operate function correctly when powered 3.3-V 2.5-V VCC. following paragraphs address devices interact when they operated power-supply level exposed signals from device operated different power-supply level. Figure illustrates that 3.3-V device adequately drive 2.5-V device. VOL(3.3-V logic) (0.4 less than VIL(2.5-V logic) (0.7 which allows 300-mV noise margin. Similarly, VOH(3.3-V logic) (2.4 greater than VIH(2.5-V logic) (1.7 which allows 700-mV noise margin. Table summarizes compatibility between 3.3-V 2.5-V devices when both powered 3.3-V VCC. Table 3.3-V 2.5-V Compatibility When
LOGIC FAMILY ALVC CBTD CBTLV 2.5-V TOLERANT 2.5-V SWITCHING LEVELS GENERATED
LVC-A CBT, CBTD, CBTLV families limited input voltage.
2.5-V device cannot adequately drive 3.3-V device. VOL(2.5-V logic) (0.4 less than VIL(3.3-V logic) (0.8 which allows 400-mV noise margin. However, VOH(2.5-V logic) approximately equal VIH(3.3-V logic) which theoretically allows noise margin. Therefore, 2.5-V devices should used drive 3.3-V devices. Table summarizes compatibility between 2.5-V 3.3-V devices when both powered 2.5-V VCC. Table 2.5-V 3.3-V Compatibility When
LOGIC FAMILY ALVC CBTD CBTLV LVC-A 3.3-V TOLERANT 3.3-V SWITCHING LEVELS GENERATED
Typical Design Applications
When migrating from power supplies 3.3-V power supplies, migration from expected occur stages. Specifically, core logic will make transition while memory I/Os probably will lag. configuration Figure likely will commonplace.
3.3-V 2.5-V 3.3-V Memory
Figure Typical Anticipated 3.3-V/2.5-V Architecture operates 2.5-V must communicate with 3.3-V memory I/O. unidirectional data flow from memory CPU, e.g., reading from memory receiving input from I/O, device that powered 3.3-V acceptable. However, communication data transfer from memory I/O, such address buffering printing, only device with level-shifting capabilities that generate true 3.3-V signals from 2.5-V input should used.
Laboratory Testing
demonstrate ability devices operate both 3.3-V 2.5-V levels, several devices were tested determine typical propagation delay times. Because typical values were desired, ambient temperature 25°C. Tables show conditions under which measurements were taken results obtained.
Results
Data Tables show that under same conditions device's propagation delay increases reduced decreases capacitive load decreased. Table Typical Propagation Delays When
LOGIC FAMILY AHC245 AHC16245 ALVC16245 CBTD CBTLV3245 LVCH245A LVCH16245A DIRECTION <--> <--> <--> <--> <--> <--> CAPACITIVE LOAD (pF) tPLH/tPHL (TYPICAL) 4.3/3.7 4.6/3.9 4.3/3.7 6.8/5.6 1.4/1.7 1.8/2.2 2.7/3.1 2.1/2.2 2.8/2.5
Table Typical Propagation Delays When
LOGIC FAMILY AHC245 AHC16245 ALVCH16245 CBTD CBTLV3245 LVCH245A LVCH16245A DIRECTION <--> <--> <--> <--> <--> CAPACITIVE LOAD (pF) tPLH/tPHL (TYPICAL) 5.6/4.6 5.6/4.5 9.4/7.2 2.4/2.5 3.6/2.8 3.1/3.6 3.1/3.5 2.8/2.7 4.1/3.1
SPICE/IBIS Models
SPICE IBIS models available certain devices. Appendix lists SPICE IBIS models given functions within logic family. SPICE model level-13 model that consists input output stages obtained contacting your local Sales Representative. IBIS model consists input output stages obtained site
Package Information
devices discussed this application report available variety packages, including plastic dual-in-line package (PDIP), quarter-size outline package (QSOP), small-outline integrated circuit (SOIC), small-outline transistor (SOT), shrink small-outline package (SSOP), thin shrink small-outline package (TSSOP), thin very small-outline package (TVSOP). TI's Logic Selection Guide, literature number SDYU001, lists devices packages which they available.
Frequently Asked Questions
Question: Answer: reconcile differences between 3.3-V part system 2.5-V part? When designing with multiple power-supply levels single system, ensure that devices that powered with lower-voltage power supply damaged when interfacing with part system that powered higher-voltage power supply. This accomplished ensuring that devices voltage tolerant other devices. purposes this application report, 2.5-V device must 3.3-V tolerant ensure that damage occurs 2.5-V device. With logic family, could interface part system with 3.3-V part system adding diode between external output-enable terminals. similar method with CBTLV family interface between 3.3-V part 2.5-V part system? drive CBTLV output levels fully rail, PMOS transistor added circuitry. This PMOS associated circuitry prevent CBTLV family devices from level translating between However, family capable performing this function. Please item bibliography. copy SPICE IBIS models? SPICE models obtained contacting your local Sales Representative. IBIS models obtained
Question:
Answer:
Question: Answer:
Conclusion
systems migrate from 3.3-V 2.5-V power supplies, issues input-voltage tolerance, interfacing translating, level shifting must addressed. 3.3-V device drive 2.5-V device, 2.5-V device cannot drive 3.3-V device switching-level incompatabilities. offers variety logic families that capable operating 3.3-V 2.5-V levels.
Glossary
ALVC CBTLV IBIS LVC-A LVTTL PDIP QSOP SOIC SPICE SSOP TSSOP TVSOP Advanced High-Speed CMOS Advanced Low-Voltage CMOS Crossbar Technology Low-Voltage Crossbar Technology Central Processing Unit Buffer Information Specification Input/Output Low-Voltage CMOS Revision Low-Voltage Transistor-Transistor Logic Plastic Dual-In-line Package Quarter-Size Outline Package Small-Outline Integrated Circuit Small-Outline Transistor Simulation Program With Integrated-Circuit Emphasis Shrink Small-Outline Package Texas Instruments Thin Shrink Small-Outline Package Thin Very Small-Outline Package
Bibliography
3.3-V 2.5-V Translation with Texas Instruments Crossbar Technology, literature number SCDA004 Advanced Interface SPICE Models, 1995, literature number SCBD004A AHC/AHCT, HC/HCT, CMOS Logic Data Book, 1996, literature number SCLD004 Switches, Crossbar Technology Data Book, 1996, literature number SCDD001A Logic Selection Guide, literature number SDYU001 (revised quarterly) Low-Voltage CMOS Logic Data Book, 1997, literature number SCBD152 Low-Voltage Logic Data Book, 1996, literature number SCBD003B Semiconductor Group Package Outlines Reference Guide, literature number SSYU001
Appendix Available SPICE IBIS Models
LOGIC FUNCTION '112 '125 '126 '137 '138 '139 '157 '158 '240 '241 '244 '245 '257 '258 '373 '374 '540 '541 '543 '544 '573 '574 '646 '652 '821 '823 '827 '828 LOGIC FAMILY ALVC LVC-A LOGIC FUNCTION '841 '843 '861 '863 '2952 '16233 '16240 '162240 '16241 '16244 '162244 '16245 '162245 '16260 '162260 '162268 '16269 '162269 '16270 '16271 '16272 '16280 '162280 '16282 '162282 '16334 '162334 '16344 '162344 '16373 '162373 '16374 '162374 '16409 '162409 '16500 '16501 LOGIC FAMILY ALVC LVC-A
SPICE model exists; IBIS model exists; applicable, indicating that device does exist that particular family; neither SPICE IBIS model exists.
Available SPICE IBIS Models (Continued)
LOGIC FUNCTION '16524 '16525 '16540 '162540 '16541 '162541 '16543 '16600 '16601 '162601 '16646 '16652 '16721 '162721 '16820 '162820 '16821 '16823 '16825 LOGIC FAMILY ALVC LVC-A LOGIC FUNCTION '16827 '162827 '16828 '16830 '162830 '16831 '162831 '16832 '162832 '16835 '162835 '16836 '162836 '16841 '162841 '16843 '16863 '16901 '16952 LOGIC FAMILY ALVC LVC-A
SPICE model exists; IBIS model exists; applicable, indicating that device does exist that particular family; neither SPICE IBIS model exists.

1997 Logic Products Printed U.S.A. 1297 SCEA005 Mi

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