August 2001, ver. Introduction Although 5.0-V interface been

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Using Altera Devices Multiple-Voltage Systems
August 2001, ver.
Introduction
Although 5.0-V interface been standard decades, move towards advanced process technology requires shift lower voltage levels. today's market, printed circuit boards (PCBs) assembled with mixture 5.0-V, 3.3-V, 2.5-V, 1.8-V devices. accommodate this mixture seamlessly, essential that these devices interface with systems differing supply voltages. Altera's MultiVoltI/O interface meets increasing demand compatibility with devices different voltages. MultiVolt interface separates power supply voltage from output voltage, enabling Altera® devices interface with other devices using different voltage levels same PCB. Altera taken further steps incorporating support hot-socketing, which refers inserting removing cards boards from back plane during operation. Hot-socketing common requirement high-reliability systems. Altera offers variety devices that support hot-socketing. This application note discusses several features that allow implement Altera devices multiple voltage systems without damaging device system, including:
MultiVolt Interface Hot-Socketing Power-Up Sequence Power-On Reset (POR)
MultiVolt Interface
Advanced-process devices require 3.3-V, 2.5-V, 1.8-V power supplies. However, other devices board still 5.0-V 3.3-V supplies. programmable logic device (PLD) must interface with these other devices. future, even lower voltage levels will required smaller process geometries. accommodate need interface with variety devices, Altera developed broadest range MultiVolt interfaces. MultiVolt interface allows devices communicate mixed-voltage design environment. device core pins powered-up with separate supply voltages. VCCINT pins power device core VCCIO pins power buffers most devices. device VCCIO pins that have MultiVolt capability should supplied from same voltage level (e.g., Figure
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A-AN-107-2.0
Using Altera Devices Multiple-Voltage Systems
Figure MultiVolt Interface Feature Altera Devices
Note
5.0-V Device
Altera Device
3.3-V Device
2.5-V Device
Note Figure
Altera device interact with each voltage time, simultaneously (except APEX20KE MAX® 7000B devices, which have different VCCIO levels simultaneously).
5.0-V Device Compatibility
5.0-V devices-FLEX® 10K, 9000, 7000S, 7000, FLEX 8000, 5.0-V FLEX 6000 devices-support interfaces 3.3-V 5.0-V devices.
3.3-V Device Compatibility
When using 3.3-V devices-FLEX 10KA, 3.3-V FLEX 6000, 7000A, 3000A devices-the VCCINT pins must connected 3.3-V power supply. VCCIO pins connected either 2.5-V 3.3-V power supply, depending output requirements. When VCCIO pins connected 3.3-V power supply, output high therefore compatible with 3.3-V 5.0-V systems. device also drive other 3.3-V tolerant, 2.5-V devices. Inputs above devices always driven 2.5-V, 3.3-V, 5.0-V systems, except EPF10K50V EPF10K130V devices, which only driven 3.3-V 5.0-V systems.
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Using Altera Devices Multiple-Voltage Systems
2.5-V Device Compatibility
VCCINT pins 2.5-V APEX 20K, ACEX1K, FLEX 10KE, 7000B devices must connected 2.5-V power supply. VCCIO pins connected either 2.5-V 3.3-V power supply, depending output requirements. When VCCIO pins connected 2.5-V power supply, output levels compatible with 2.5-V systems. When VCCIO pins connected 3.3-V power supply, output high therefore compatible with 3.3-V 5.0-V systems. device also drive other 3.3-V tolerant, 2.5-V devices. APEX device family incorporates wider variety standards. This device family covered Application Note (Using Selectable Standards Altera Devices).
Table summarizes Altera MultiVolt support. Table Altera MultiVolt Support Device VCCINT
Notes (1), Input Signal
VCCIO
Output Signal
FLEX 10K, FLEX 8000, FLEX 6000 (5.0 7000S, 9000 EPF10K50V, EPF10K130V FLEX 10KA, FLEX 6000 (3.3 7000A, 3000A FLEX 10KE ACEX APEX APEX 20KE (3),
7000B
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Using Altera Devices Multiple-Voltage Systems
Notes Table
FLEX devices support 3.3-V pins with 5.0-V core, except 84-pin plastic J-lead chip carrier (PLCC) 240-pin quad flat pack (QFP) packages. 7000S devices-except EPM7032S EPM7064S devices 44-pin PLCC thin quad flat pack (TQFP) packages-support 3.3-V pins with 5.0-V core. EPF8282V pins 5.0-V tolerant. Altera does recommend driving 5.0-V signals these 3.3-V devices. APEX APEX 20KE pins 5.0-V tolerant. more information APEX 20KE MultiVolt support, Application Note (Using Selectable Standards Altera Devices).
5.0-V Compatibility
Altera 5.0-V tolerant devices 5.0-V compatible. example, 3.3-V device drive 5.0-V device, return, driven 5.0-V device. Additionally, when VCCIO pins 5.0-V device connected pins still driven 5.0-V signals because buffers still 5.0-V tolerant.
5.0-V CMOS Compatibility
Altera's 5.0-V devices with NMOS-only output buffers meet 5.0-V levels. When voltage output exceeds approximately NMOS pull-up transistor goes cut-off mode. Therefore, external pull-up resistor pull signal Figure Figure 5.0-V Altera Device Compatibility with 5.0-V CMOS Devices Note
VCCIO
REXT VOUT 5.0-V CMOS Device
Note Figure
When VOUT transistor cut-off. result, external resistor (REXT) pull output node (VOUT) full rail level
Altera Corporation
Using Altera Devices Multiple-Voltage Systems
make Altera low-voltage device outputs compatible with 5.0-V CMOS devices, configure output pins open-drain pins external pull-up resistor. low-voltage devices have CMOS driver; VOUT VCCIO, PMOS pull-up transistor still conducts driving high, preventing external pull-up resistor from pulling signal (see Figure 5.0-V tolerant, 3.3-V 2.5-V devices also drive 5.0-V CMOS devices. Figure CMOS Output Buffer Altera Low-Voltage Devices
VCCIO
Note
VOUT
REXT 5.0-V CMOS Device
Note Figure
When VOUT VCCIO, current will flow shown above. result, VOUT node cannot pulled
pull output low-voltage device (input high) level 5.0-V CMOS device, open-drain driving trace that pulled through external pull-up resistor (see Figure Choose pull-up resistor that small enough sufficient signal rise time, large enough that does violate (output low) specifications devices driving that trace.
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Using Altera Devices Multiple-Voltage Systems
Figure Low-Voltage Altera Device Compatibility with 5.0-V CMOS Devices Note
VCCIO
Open Drain VOUT
REXT 5.0-V CMOS Device
Note Figure
pull VOUT rail ensure that output open drain. Therefore, external pull-up resistor (REXT) pulls VOUT
open-drain never drives high, only tri-state. When open-drain active, drives low. When open-drain inactive, tri-stated trace pulls external resistor. device operates successfully because 5.0-V input within input specification.
Hot-Socketing
Hot-socketing, hot-swap, plug-in refers inserting removing board device into system board while system power system support hot-socketing, plug-in removal board must damage system interrupt system operation.
Hot-Socketing Altera Devices
following Altera 3.3-V, 2.5-V, 1.8-Vand 1.8-5 devices designed support hot-socketing without special design requirements:
MercuryAPEXII APEX ACEX FLEX 10KA FLEX 10KE (except EPF10K100B devices) 3.3-V FLEX 6000 MAX® 7000AE 7000B 3000A
Altera Corporation
Using Altera Devices Multiple-Voltage Systems
following features have been implemented Altera devices ease hot-socketing process:
Devices driven before power-up with damage device. Devices drive before during power-up. Signal pins drive VCCIO VCCINT power supplies.
Devices Driven before Power-Up
Devices that support hot-socketing damaged pins driven before device powered-up. Altera devices that support hot-socketing, device pins, dedicated input pins, dedicated clock pins driven before during power-up without damaging device.
Devices Drive before during Power-Up
Devices that support hot-socketing interrupt system operation cause contention driving before during power-up. Altera devices that support hot-socketing, pins tri-stated before during power-up configuration, will drive out.
Signal Pins Cannot Drive
CCIO
CCINT Power Supply
Devices that support hot-socketing powered-up through their signal pins (when plugged into live board) causing power supplies short-out. This irregular power-up damage both driving driven devices disrupt card power-up. Altera devices that support hot-socketing, there current path from I/O, dedicated input, dedicated clock pins VCCIO VCCINT pins before during power-up; therefore, these devices cannot powered-up through pins. Some Altera devices have weak pull-up resistors; these resistors activated device powered VCCIO VCCINT pins. result, Altera devices that support hotsocketing inserted into removed from) powered-up system board without damage without interfering with operation system board. During hot-socketing, these devices will affect signal integrity back plane.
Altera Corporation
Using Altera Devices Multiple-Voltage Systems
operating conditions each device data sheet specify device input leakage current. most devices, this leakage current During hot-socketing, leakage current into higher. Table shows this value Altera devices that support hot-socketing. Table Hot-Socket Leakage Current Altera Devices Device
ACEX FLEX 10KA, FLEX 10KE, FLEX 6000 (3.3 7000AE, 3000A
Condition
5.75
Unit
5.75 (1),
APEX 7000B Notes Table
These devices 5.0-V tolerant. Includes current from weak pull-up resistors cell. GCLRn pins 7000AE 3000A devices driven during hot-socketing. After VCCINT VCCIO reach recommended operating conditions, these pins 5.0-V tolerant. other pins 700AE 3000A devices driven 5.75 during hot-socketing. These 2.5-V devices 3.3-V tolerant.
possible concern regarding hot-socketing potential latch-up. Latch-up occur when electrical subsystems hot-socketed into active system. During hot-socketing, signal pins connected driven active system before power supply provide current device's ground planes. This condition lead latch-up cause low-impedance path from ground within device. result, device expends large amount current, possibly causing electrical damage. Altera devices immune latch-up when operated within device specifications, including hot-socketing.
Power-Up Sequence
Altera devices designed operate multiple-voltage environments where difficult control power sequencing. Therefore, devices designed accommodate possible power-up sequence. following sections address power-up sequence different voltage levels.
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Using Altera Devices Multiple-Voltage Systems
When VCCIO VCCINT supplied from different power sources Altera device, delay between VCCIO VCCINT occur. Normal operation does occur until both power supplies their recommended operating range. When VCCINT powered-up, IEEE Std. 1149.1 Joint Test Action Group (JTAG) circuitry active. connected VCCIO VCCIO powered-up, JTAG signals left floating. Thus, transition cause state machine transition unknown JTAG state, leading incorrect operation when VCCIO finally poweredup. disable JTAG state during power-up sequence, should pulled ensure that inadvertent rising edge does occur TCK. more information, refer Application Note (In-System Programmability Guidelines).
3.3-V, 2.5-V, 1.8-V APEX, FLEX Devices
Because APEX 20K, ACEX FLEX 10KA, FLEX 10KE, 7000B, 3.3-V FLEX 6000, 7000AE, 3000A devices used multi-voltage environment, they designed specifically tolerate possible power-up sequence (where appropriate). VCCINT VCCIO supply power either sequence. 5.0-V, 3.3-V, 2.5-V, 1.8-V input signals drive these devices before VCCINT VCCIO applied without special precautions; only exception that nGCLR pins 7000AE 3000A devices must exceed until VCCIO VCCINT reach recommended operating level. change VCCIO supply voltage from vice-versa while board powered-up. However, must ensure that VCCINT VCCIO power supplies stay within correct device operating conditions. FLEX configuration devices power-up either order, must ensure that nSTATUS CONF_DONE pull-up resistors connected same voltage configuration device. This connection avoids driving signals into configuration device that powered. 2.5-V 1.8-V devices only Altera devices that have VCCIO voltage level higher than VCCINT level.
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Using Altera Devices Multiple-Voltage Systems
5.0-V FLEX Devices
When VCCIO powers-up, devices drive without core being powered-up. This power-up sequence does damage devices their functionality affected, interfere with function system that contains devices. Because possible interference with system functionality, Altera does recommend driving 5.0-V device input signals relying output device before VCCINT powered-up. FLEX configuration devices power-up either order, must ensure that nSTATUS CONF_DONE pull-up resistors connected same voltage configuration device. This connection avoids driving signals into configuration device that powered.
Power-On Reset
state system power-up important consideration designing circuit. When power applied Altera device, event occurs only reaches recommended operating range within certain period time (specified maximum rise time). event does occur these conditions because slower rise times cause incorrect device initialization functional failure. maximum rise time FLEX 10K, FLEX 8000, FLEX 6000 devices should monotonic (during rise time, slope zero positive). devices, maximum rise time infinite long monotonic. Altera's device registers cleared (MAX 7000AE, 7000B, 3000A devices) during power-on reset. using NOT-Gate Push-Back option Quartusand MAX+PLUS® software, registers power-up active-high. NOT-Gate Push-Back option advanced logic synthesis option, which allows compiler's logic synthesizer module push inversion (i.e., gate) back through register implement that register's input. Once VCCINT power supply reaches specified operating range, must remain that range. VCCINT does remain range, operation guaranteed until VCCINT re-enters specified operating range.
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Using Altera Devices Multiple-Voltage Systems
APEX, ACEX FLEX Devices
Before supply reaches recommended operating range, pins tri-stated, with exception APEX 20K, ACEX FLEX 10KE devices that have pull-up resistors pins. During POR, registers cleared tri-state released. Once power supply reaches stable reliable operating voltage after nCONFIG gone high, actual device configuration begins. During configuration, pins tri-stated.
Devices
Before supply reaches recommended operating range 7000AE, 7000B, 3000A devices, pins tristated. During POR, registers cleared set. After POR, tri-state released pins user mode function programmed device been previously programmed successfully). other 7000-including 7000E, 7000S, 7000A-and 9000 devices, pins undefined until reaches recommended operating range. During POR, registers cleared tri-state released. After POR, pins user mode function programmed. power-up state latches undefined Altera devices except 5000 devices. 5000 devices, latches power-up low.
During POR, device configures pins, clears device registers, releases tri-states.
Conclusion
PCBs often contain 5.0-V, 3.3-V, 2.5-V, 1.8-V devices. MultiVolt interface enables device core specific voltage (5.0 while keeping pins compatible with 5.0-V, 3.3-V, 2.5-V, 1.8-V logic levels. Altera's MultiVolt interface allows incorporate newer generation devices with devices varying voltage levels seamlessly. Altera taken further steps designing devices which allow VCCINT VCCIO power-up either sequence incorporating support hot-socketing.
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Using Altera Devices Multiple-Voltage Systems
Innovation Drive Jose, 95134 (408) 544-7000 http://www.altera.com Applications Hotline: (800) 800-EPLD Customer Marketing: (408) 544-7104 Literature Services: lit_req@altera.com
Altera specific device designations trademarks and/or service marks Altera Corporation United States other countries. Altera acknowledges trademarks other organizations their respective products services mentioned this document. Altera products protected under numerous U.S. foreign patents pending applications, maskwork rights, copyrights. Altera warrants performance semiconductor products current specifications accordance with Altera's standard warranty, reserves right make changes products services time without notice. Altera assumes responsibility liability arising application information, product, service described herein except expressly agreed writing Altera Corporation. Altera customers advised obtain latest version device specifications before relying published information before placing orders products services. Copyright 2001 Altera Corporation. rights reserved.
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