®
Using Programmable
I/O Standards
in Mercury Devices
December 2002, ver. 2.1
Introduction
Application Note 134
Programmable logic devices (PLDs) use I/O standards to interface with
memory, microprocessors, backplanes, and peripheral devices. Designers
who want to use these standards with programmable logic need flexible,
high-performance, multi-standard I/O buffers. PLD support for industry
I/O standards improves designers’ time-to-market.
Programmable I/O standards simplify board design. Integrating
dedicated circuitry such as translation buffers, LVDS, LVPECL, and clock
data recovery (CDR) into PLDs saves board space, reduces pin usage, and
improves performance. Altera’s MercuryTM devices offer the highestperformance programmable logic solution with the I/O standards
necessary for the communication and computer industries.
A single Mercury device can simultaneously support multiple I/O
standards, as well as interface with high-speed, low-voltage memory
buses and backplanes. Mercury devices feature source-synchronoussignalling and CDR circuitry that supports data rates up to 1.25 gigabits
per second (Gbps).
This application note provides guidelines for designing with
programmable I/O standards in Mercury devices and covers the
following topics:
■
■
■
■
■
■
I/O Standards
I/O Standards
Mercury I/O Banks
Operating Conditions
Board Termination Schemes
Guidelines for Programmable I/O Standards
Software Support
This section provides an overview of typical applications for the
programmable I/O standards supported by Mercury devices. The
specifications for each I/O standard are also listed.
The Mercury I/O buffers meet the voltage, drive strength, and AC
characteristics necessary to comply with the I/O standards listed in
Table 1.
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Each I/O standard has different voltage reference (VREF), board
termination voltage (VTT), and I/O supply voltage (VCCIO) requirements.
For more information, refer to “Board Termination Schemes” on page 19.
Table 1. I/O Standards Supported in Mercury Devices
I/O Standard
Type
Input
Reference
Voltage
(VREF) (V) (1)
Output
Supply
Voltage
(VCCIO) (V) (1)
Board
Termination
Voltage
(VTT) (V) (1)
LVTTL
Single-ended
N/A
3.3
N/A
LVCMOS
Single-ended
N/A
3.3
N/A
2.5 V
Single-ended
N/A
2.5
N/A
1.8 V
Single-ended
N/A
1.8
N/A
3.3-V PCI (2)
Single-ended
N/A
3.3
N/A
3.3-V PCI-X
Single-ended
N/A
3.3
N/A
AGP 1×
Single-ended
N/A
3.3
N/A
LVDS (3)
Differential
N/A
3.3
N/A
3.3-V LVPECL
Differential
N/A
3.3
N/A
PCML
Differential
N/A
3.3
N/A
GTL+
Voltage referenced
1.0
N/A
1.5
HSTL class I and II
Voltage referenced
0.75
1.5
0.75
HSTL class III and IV
Voltage referenced
0.90
1.5
1.5
SSTL-2 class I and II
Voltage referenced
1.25
2.5
1.25
SSTL-3 class I and II
Voltage referenced
1.5
3.3
1.5
AGP 2×
Voltage referenced
1.32
3.3
N/A
CTT
Voltage referenced
1.5
3.3
1.5
Notes to Table 1:
(1)
(2)
(3)
The values shown for VREF, VCCIO, and VTT are typical values.
PCI: peripheral component interconnect.
The RapidIO packet-switched interconnect, as defined by the RapidIO Trade Association, uses the same electrical
specifications as LVDS and is supported by Mercury devices.
LVTTL
The LVTTL standard is a single-ended, general-purpose standard for
3.3-V applications. The maximum recommended input voltage for
Mercury devices is 4.1 V, which exceeds the 3.9-V requirement of this
specification. This standard requires the output buffer to drive to 2.4 V
(minimum VOH = 2.4 V) but does not require the use of input reference
voltages or termination. The LVTTL interface is defined by JEDEC
Standard JESD 8-A, Interface Standard for Nominal 3.0 V/3.3 V Supply
Digital Integrated Circuits.
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LVCMOS
LVCMOS is a single-ended general-purpose standard used for 3.3-V
applications. The input buffer requirements are the same as the LVTTL
requirements, and the output buffer is required to drive to the rail
(minimum VOH = VCCIO – 0.2 V). This standard requires a 3.3-V I/O
supply voltage (VCCIO), but not the use of input reference voltages or
termination. The LVCMOS standard is defined in JEDEC Standard JESD
8-A, Interface Standard for Nominal 3.0 V/3.3 V Supply Digital Integrated
Circuits.
2.5 V
The 2.5-V standard is similar to LVCMOS but is used for 2.5-V power
supply levels. Mercury devices meet the normal range of this
specification. This standard requires a 2.5-V VCCIO, but not the use of
input reference voltages or termination. The 2.5-V I/O standard is
documented by JEDEC Standard JESD 8-5, 2.5 V ±0.2 V (Normal Range)
and 1.7 V to 2.7 V (Wide Range) Power Supply Voltage and Interface
Standard for Nonterminated Digital Integrated Circuit.
1.8 V
The 1.8-V I/O standard is similar to LVCMOS but is used for 1.8-V power
supply levels and reduced input and output thresholds. Mercury devices
meet the normal range of this specification. This standard requires a 1.8-V
VCCIO , but not the use of input reference voltages or termination. The
1.8-V I/O standard is documented by JEDEC Standard JESD 8-7,
1.8 V ±0.15 V (Normal Range) and 1.2 V to 1.95 V (Wide Range) Power
Supply Voltage and Interface Standard for Nonterminated Digital
Integrated Circuit.
3.3-V PCI
Mercury devices are compliant with PCI Local Bus Specification,
Revision 2.2 for 3.3-V operation. At 3.3 V, the PCI standard supports up to
64-bit bus width operation at 33 or 66 MHz. This standard uses LVTTLtype input and output buffers and requires a 3.3-V VCCIO, but not the use
of input reference voltages or termination.
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PCI-X
An enhanced version of the PCI specification that can support higher
average bandwidth, PCI-X has more stringent requirements than PCI.
PCI-X provides backward compatibility by allowing devices to operate at
conventional PCI frequencies (33 MHz and 66 MHz).
LVDS
The LVDS I/O standard is used for very high-performance, low-powerconsumption data transfer. Two key industry standards define LVDS:
IEEE 1596.3 SCI-LVDS and ANSI/TIA/EIA-644. Both standards have
similar key features, but the IEEE standard supports a maximum data
transfer of 250 megabits per second (Mbps). Mercury devices are designed
to meet the ANSI/TIA/EIA-644 requirements at up to 840 Mbps using
source synchronous mode, and up to 1.25 Gbps in CDR mode. The LVDS
standard requires a 3.3-V VCCIO and a 100-Ω termination resistor between
the two traces at the input buffer. No input reference voltage is required.
LVPECL
The LVPECL standard is used in video graphic, telecommunications, and
data communication designs. It is also used for clock distribution.
LVPECL is a differential I/O standard that is similar to LVDS, but with a
different common mode and differential voltage. The LVPECL standard
requires a 3.3-V VCCIO and a 100-Ω termination resistor between the two
traces at the input buffer. No input reference voltage is required.
3.3-V PCML
3.3-V PCML is a differential standard used for high-speed interfacing.
3.3-V PCML requires a 3.3-V VCCIO and a 100-Ω termination resistor
between the two traces at the input buffer. In addition, each input trace
requires a 50-Ω resistor to VTT, and each output trace requires a 100-Ω
resistor to VTT. No input reference voltage is required.
f
4
For more information on CDR mode, refer to Application Note 130 (CDR in
Mercury Devices).
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GTL+
The GTL+ standard is a high-speed bus standard first used by Intel
Corporation for interfacing with the Pentium Pro processor. GTL+ is a
voltage-referenced standard requiring a 1.0-V input VREF and a 1.5-V VTT.
Because GTL+ is an open-drain standard, it does not require a particular
VCCIO supply voltage. GTL+ is often used for processor interfacing or
communication across a backplane.
HSTL Class I, II, III & IV
The HSTL standard is a 1.5-V output buffer supply voltage-based
interface standard for digital integrated circuits. HSTL is a voltagereferenced standard requiring a 0.75-V VREF, a 1.5-V VCCIO, and a
0.75-V VTT. HSTL class III and IV require a 0.9-V VREF, a 1.5-V VCCIO, and
a 1.5-V VTT.The HSTL standard is specified by JEDEC Standard JESD 8-6,
High-Speed Transceiver Logic (HSTL).
SSTL-2 Class I & II
The SSTL-2 standard is a voltage-referenced standard requiring a 1.125-V
VREF, a 2.5-V VCCIO , and a 1.125-V VTT. SSTL-2 is used for high-speed
SDRAM interfaces. The SSTL-2 I/O standard is specified by JEDEC
Standard JESD 8-9, Stub-Series Terminated Logic for 2.5 Volts (SSTL-2).
SSTL-3 Class I & II
The SSTL-3 standard is a voltage-referenced standard requiring a 1.5-V
VREF, a 3.3-V VCCIO , and a 1.5-V VTT. SSTL-3 is used for high-speed
SDRAM interfaces. The SSTL-3 I/O standard is specified by JEDEC
Standard JESD 8-8, Stub-Series Terminated Logic for 3.3 Volts (SSTL-3).
AGP
Mercury devices support the AGP interface in both 1× and 2× modes.
AGP 2× is a voltage-referenced standard requiring a 1.32-V VREF, and a
3.3-V VCCIO. This I/O standard does not require termination. The AGP
standard is specified by the Advanced Graphics Port Interface
Specification Revision 2.0 introduced by Intel Corporation for graphics
applications.
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AN 134: Using Programmable I/O Standards in Mercury Devices
CTT
CTT is a voltage-referenced standard requiring a 1.5-V VREF, a 3.3-V
VCCIO, and a 1.5-V VTT. CTT drivers, when not terminated, are compatible
with the AC and DC specifications for LVCMOS and LVTTL. The CTT
standard is specified by JEDEC Standard JESD 8-4, Center-TapTerminated (CTT) Low-Level, High-Speed Interface Standard for Digital
Integrated Circuits.
Mercury I/O
Banks
Mercury devices contain I/O band rows which are subdivided into I/O
banks. An I/O bank is a group of I/O pins that share common power and
VREF buses. These I/O banks do not cross I/O band row boundaries. One
I/O pin in each bank is designated as the VREF pin for that I/O bank. If
the VREF voltage is not required in that bank, the pin can be used as a
regular I/O pin.
The programmable I/O banks in Mercury devices have individual power
planes with separate VCCIO pins for each I/O bank. The VCCIO supply
supports 3.3-V, 2.5-V, 1.8-V, and 1.5-V levels.
The number of I/O banks in a Mercury device depends on the number of
I/O band rows. The top I/O band row contains four I/O banks
specifically designed for high-speed differential interface (HSDI). These
HSDI I/O banks support LVDS, LVPECL, and 3.3-V PCML I/O
standards. All other I/O band rows contain two I/O banks and support
all other I/O standards. See Table 2.
Table 2. Mercury Device I/O Resources
6
Device
Regular I/O
Rows
Regular I/O
Banks
HSDI Band I/O
Banks
EP1M120
4
8
4
EP1M350
3
6
4
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The HSDI I/O banks can operate in source synchronous or CDR modes.
When used as regular I/O banks, the HSDI transmitter banks support all
the I/O standards shown in Table 1. The HSDI receiver banks support the
I/O output standards and drive strengths, as shown in Table 3.
Table 3. HDSI Receiver I/O Banks Output Standard & Drive Strength Support
Output Standard
LVTTL (3.3 V)
Drive Strength
4 mA
8 mA
12 mA
16 mA
24 mA
LVTTL (2.5 V)
4 mA
8 mA
12 mA
16 mA
LVTTL (1.8 V)
2 mA
4 mA
STTL-3 Class I and II
Minimum
Maximum
STTL-2 Class I and II
Minimum
The following is a list of HSDI receiver I/O banks input standards:
■
■
■
■
■
■
■
■
LVCMOS
LVTTL (3.3 V)
LVTTL (2.5 V)
LVTTL (1.8 V)
GTL+ (3.3 V)
HSTL Class I and II
SSTL-3 Class I and II
SSTL-2 Class I and II
The top I/O banks 1, 2, 3, and 4 only support non-HSDI I/O pins if HSDI
circuitry is unused. If any HSDI channel is used, banks 1, 2, 3, and 4, do
not support regular I/O pins. For more information on CDR mode, refer
to Application Note 130 (CDR in Mercury Devices).
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Operating
Conditions
Tables 4 through 24 list the DC operating specifications for the supported
I/O standards. These tables only list minimal specifications. Mercury
devices may exceed these specifications. Consult the Mercury
Programmable Logic Device Family Data Sheet for details.
Table 4. LVTTL Specifications
Symbol
Note (1)
Parameter
Conditions
Minimum
Maximum
Units
V
VCCIO
Output supply voltage
3.0
3.6
VI H
High-level input voltage
2.0
4.1
V
VIL
Low-level input voltage
–0.5
0.8
V
10
µA
II
Input pin leakage current
VIN = 0 V or VCCIO
–10
VOH
High-level output voltage
IOH = –4 to –24 mA
2.4
VOL
Low-level output voltage
IOL = 4 to 24 mA
IO
Output leakage current (when
output is high Z)
GND ≤ VOUT ≤ VCCIO
V
0.45
V
–10
10
µA
Minimum
Maximum
Units
V
Table 5. LVCMOS Specifications
Symbol
Parameter
Conditions
VCCIO
Power supply voltage range
3.0
3.6
VIH
High-level input voltage
2.0
4.1
V
VIL
Low-level input voltage
–0.5
0.8
V
–10
10
µA
II
Input pin leakage current
VIN = 0 V or VCCIO
VOH
High-level output voltage
VCCIO = 3.0,
IOH = –0.1 mA
VOL
Low-level output voltage
VCCIO = 3.0,
IOL = 0.1 mA
IO
Output leakage current (when
output is high Z)
GND ≤ VOUT ≤ VCCIO
8
VCCIO – 0.2
–10
V
0.2
V
10
µA
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Table 6. 2.5-V I/O Specifications
Symbol
Note (1)
Parameter
Conditions
VCCIO
Output supply voltage
VIH
High-level input voltage
VIL
Low-level input voltage
II
Input pin leakage current
VOH
High-level output voltage
VOL
Low-level output voltage
VIN = 0 V or VCCIO
Minimum
Maximum
2.375
2.625
V
1.7
4.1
V
–0.5
0.7
V
10
–10
µA
IOH = –0.1 mA
2.1
V
IOH = –1 mA
2.0
V
IOH = –2 to –16 mA
1.7
Table 7. 1.8-V I/O Specifications
Symbol
V
IOL = 0.1 mA
0.2
V
IOH = 1 mA
0.4
V
IOH = 2 to 16 mA
Output leakage current (when
output is high Z)
IO
Units
GND ≤ VOUT ≤ VCCIO
0.7
V
–10
10
µA
Minimum
Maximum
Units
Note (1)
Parameter
Conditions
VCCIO
Output supply voltage
1.71
1.89
V
VI H
High-level input voltage
0.65 × VCCIO
4.1
V
VIL
Low-level input voltage
–0.5
0.35 × VCCIO
V
II
Input pin leakage current
VIN = 0 V or VCCIO
–10
10
µA
VOH
High-level output voltage
IOH = –2 to –4 mA
VCCIO – 0.45
VOL
Low-level output voltage
IOL = 2 to 4 mA
IO
Output leakage current (when
output is high Z)
GND ≤ VOUT ≤ VCCIO
–10
V
0.45
V
10
µA
Figures 1 and 2 show receiver input and transmitter output waveforms,
respectively, for all differential I/O standards (LVPECL, 3.3-V PCML,
LVDS, and HyperTransportTM technology).
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AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 1. Receiver Input Waveforms for Differential I/O Standards
Single-Ended Waveform
Positive Channel (p) = VIH
±VID
Negative Channel (n) = VIL
VCM
Ground
Differential Waveform
+VID
p−n=0V
VID (Peak-to-Peak)
− VID
Figure 2. Transmitter Output Waveforms for Differential I/O Standards
Single-Ended Waveform
Positive Channel (p) = VOH
±VOD
Negative Channel (n) = VOL
VCM
Ground
Differential Waveform
+VOD
p−n=0V
VOD (Peak-to-Peak)
10
− VOD
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Transmitter Output Waveforms for Differential I/O Standards
Table 8. 3.3-V LVDS I/O Specifications
Symbol
Parameter
Note (2)
Conditions
VCCIO
I/O supply voltage
VOD
Differential output voltage
RL = 100 Ω
∆ VOD
Change in VOD between
high and low
RL = 100 Ω
VOS
Output offset voltage
RL = 100 Ω
∆ VOS
Change in VOS between
high and low
RL = 100 Ω
Minimum
Typical
Maximum
3.135
3.3
3.465
V
450
mV
50
mV
250
1.125
1.25
Units
1.375
V
50
mV
VTH
Differential input threshold VCM = 2.1 V
–100
100
mV
VIN
Receiver input voltage
range
0.0
2.4
V
RL
Receiver differential input
resistor (external to
Mercury devices)
90
100
110
Ω
Minimum
Typical
Maximum
Units
3.135
3.3
3.465
V
0
2,000
mV
mV
Table 9. LVPECL Specifications
Symbol
Parameter
Conditions
VCCIO
I/O supply voltage
VIL
Low-level input voltage
VIH
High-level input voltage
400
2,470
VOL
Low-level output voltage
1,400
1,650
mV
VOH
High-level output voltage
2,275
2,470
mV
VID
Differential input voltage
(3)
400
600
1,200
mV
VOD
Differential output voltage
(3)
525
1,050
1,200
mV
tR
Rise time (20 to 80%) (4)
85
325
ps
tF
Fall time (20 to 80%) (4)
85
325
ps
tDSKEW
Differential skew
25
ps
RL
Receiver differential input
resistor
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100
Ω
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AN 134: Using Programmable I/O Standards in Mercury Devices
Table 10. 3.3-V PCML Specifications
Symbol
Parameter
VCCIO
I/O supply voltage
VIL
Low-level input voltage
Conditions
Minimum
Typical
3.135
3.3
Maximum
Units
3.465
V
VCCIO –
0.3
V
VIH
High-level input voltage
VCCIO
VOL
Low-level output voltage
VCCIO –
0.6
VCCIO –
0.3
V
V
VOH
High-level output voltage
VCCIO
VCCIO –
0.3
V
600
mV
ps
VT
Output termination voltage
VOD
Differential output voltage
VCCIO
tR
Rise time (20 to 80%)
200
tF
Fall time (20 to 80%)
200
ps
tDSKEW
Differential skew
25
ps
RO
Output load
RL
Receiver differential input
resistor
300
450
V
Ω
100
45
50
55
Ω
Minimum
Typical
Maximum
Units
3.0
3.3
3.6
V
Table 11. 3.3-V PCI Specifications
Symbol
Parameter
Conditions
VCCIO
I/O supply voltage
VIH
High-level input voltage
0.5 ×
VCCIO
VCCIO +
0.5
V
VIL
Low-level input voltage
–0.5
0.3 ×
VCCIO
V
II
Input pin leakage current
0 < VIN < VCCIO
–10
10
µA
VOH
High-level output voltage
IOUT = –500 µA
0.9 ×
VCCIO
VOL
Low-level output voltage
IOUT = 1,500 µA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤ VCCIO
12
–10
V
0.1 ×
VCCIO
V
10
µA
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Table 12. PCI-X Specifications
Symbol
Parameter
Conditions
Minimum
Typical
Maximum
Units
VCCIO
I/O supply voltage
3.0
3.6
V
VIH
High-level input voltage
0.5 ×
VCCIO
VCCIO +
0.5
V
VIL
Low-level input voltage
–0.5
0.35 ×
VCCIO
V
VIPU
Input pull-up voltage
II
Input leakage current
0 < VIN < V CCIO
–10
VOH
High-level output voltage
IOUT = –500 µA
0.9 ×
VCCIO
VOL
Low-level output voltage
IOUT = 1,500 µA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤ VCCIO
LPIN
Pin inductance
Table 13. GTL+ I/O Specifications
Symbol
Parameter
VTT
Termination voltage
VREF
Reference voltage
VIH
High-level input voltage
0.7 ×
VCCIO
10
µA
V
–10
0.1 ×
VCCIO
V
10
µA
15
nH
Note (1)
Conditions
Minimum
Typical
Maximum
Units
1.35
1.5
1.65
V
0.88
1.0
1.12
VREF + 0.1
VIL
Low-level input voltage
II
Input leakage current
0 < VIN < V CCIO
VOL
Low-level output voltage
IOL = 34 to 46 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤ VCCIO
Altera Corporation
V
–10
–10
V
V
VREF – 0.1
V
10
µA
0.65
V
10
µA
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Table 14. SSTL-2 Class I Specifications
Symbol
Parameter
VCCIO
I/O supply voltage
VTT
Termination voltage
VREF
Reference voltage
VIH
High-level input voltage
Note (1)
Conditions
VIL
Low-level input voltage
II
Input pin leakage current
VOH
High-level output voltage
IOH = –7.6 mA
VOL
Low-level output voltage
IOL = 7.6 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
Table 15. SSTL-2 Class II Specifications
Symbol
Parameter
0 < VIN < VCCIO
Minimum
Typical
Maximum
Units
2.375
2.5
2.625
V
VREF – 0.04
VREF
VREF + 0.04
V
1.15
1.25
1.35
V
VREF + 0.18
3.0
V
–0.3
VREF – 0.18
V
–10
10
µA
VTT – 0.57
V
10
µA
Maximum
Units
VTT + 0.57
V
–10
Note (1)
Conditions
Minimum
Typical
VCCIO
I/O supply voltage
VTT
Termination voltage
VREF
Reference voltage
1.35
V
VIH
High-level input voltage
VREF + 0.18
VCCIO + 0.3
V
VIL
Low-level input voltage
–0.3
VREF – 0.18
V
II
Input pin leakage current
0 < VIN < VCCIO
–10
10
µA
VOH
High-level output voltage
IOH = –15.2 mA
VTT + 0.76
VOL
Low-level output voltage
IOL = 15.2 mA
VTT – 0.76
V
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
10
µA
14
2.375
2.5
2.625
V
VREF – 0.04
VREF
VREF + 0.04
V
1.15
1.25
–10
V
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Table 16. SSTL-3 Class I Specifications
Symbol
Parameter
VCCIO
I/O supply voltage
VTT
Termination voltage
VREF
Reference voltage
VIH
High-level input voltage
Note (1)
Conditions
VIL
Low-level input voltage
II
Input pin leakage current
0 < VIN < V CCIO
VOH
High-level output voltage
IOH = –8 mA
VOL
Low-level output voltage
IOL = 8 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
Table 17. SSTL-3 Class II Specifications
Symbol
Parameter
Minimum
Typical
Maximum
Units
3.0
3.3
3.6
V
VREF – 0.05
VREF
VREF + 0.05
V
1.3
1.5
1.7
V
VREF + 0.2
VCCIO + 0.3
V
–0.3
VREF – 0.2
V
–10
10
µA
VTT – 0.6
V
10
µA
Maximum
Units
VTT + 0.6
V
–10
Note (1)
Conditions
Minimum
Typical
VCCIO
I/O supply voltage
VTT
Termination voltage
3.0
3.3
3.6
V
VREF – 0.05
VREF
VREF + 0.05
V
VREF
Reference voltage
1.7
V
VIH
High-level input voltage
VREF + 0.2
1.3
1.5
VCCIO + 0.3
V
VIL
Low-level input voltage
–0.3
VREF – 0.2
V
II
Input pin leakage current
0 < VIN < V CCIO
–10
10
µA
VOH
High-level output voltage
IOH = –16 mA
VOL
Low-level output voltage
IOL = 16 mA
VTT – 0.8
V
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
10
µA
VT T + 0.8
V
–10
Table 18. 3.3-V AGP 2× Specifications
Minimum
Typical
Maximum
Units
VCCIO
Symbol
I/O supply voltage
Parameter
Conditions
3.15
3.3
3.45
V
VREF
Reference voltage
0.39 × VCCIO
0.41 × VCCIO
V
VIH
High-level input voltage (5)
0.5 × VCCIO
VCCIO + 0.5
V
0.3 × VCCIO
V
VIL
Low-level input voltage (5)
VOH
High-level output voltage
IOUT = –20 µA
VOL
Low-level output voltage
IOUT = 20 µA
II
Input pin leakage current
0 < VI N < VCCIO
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
Altera Corporation
0.9 × VCCIO
3.6
V
0.1 × VCCIO
V
–10
10
µA
–10
10
µA
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AN 134: Using Programmable I/O Standards in Mercury Devices
Table 19. 3.3-V AGP 1× Specifications
Symbol
Parameter
VCCIO
I/O supply voltage
VIH
High-level input voltage (5)
Conditions
Minimum
Typical
3.15
3.3
0.5 × VCCIO
VIL
Low-level input voltage (5)
VOH
High-level output voltage
IOUT = –20 µA
0.9 × VCCIO
Maximum
Units
3.45
V
VCCIO + 0.5
V
0.3 × VCCIO
V
3.6
V
VOL
Low-level output voltage
IOUT = 20 µA
0.1 × VCCIO
V
II
Input pin leakage current
0 < VI N < V CCIO
–10
10
µA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
–10
10
µA
Units
Table 20. 1.5-V HSTL Class I Specifications
Symbol
Parameter
Note (1)
Minimum
Typical
Maximum
VCCIO
I/O supply voltage
1.4
1.5
1.6
V
VREF
Input reference voltage
0.68
0.75
0.9
V
0.7
0.75
0.8
VTT
Termination voltage
VIH (DC)
DC high-level input voltage
Conditions
VREF + 0.1
VIL (DC)
DC low-level input voltage
–0.3
VIH (AC)
AC high-level input voltage
VREF + 0.2
VIL (AC)
AC low-level input voltage
II
Input pin leakage current
0 < VIN < VCCIO
VOH
High-level output voltage
IOH = –8 mA
VOL
Low-level output voltage
IOL = 8 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
16
–10
VREF – 0.1
V
VREF – 0.2
V
10
µA
V
VCCIO – 0.4
–10
V
V
V
0.4
V
10
µA
Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
Table 21. 1.5-V HSTL Class II Specifications
Symbol
Parameter
Note (1)
Conditions
Minimum
Typical
Maximum
Units
VCCIO
I/O supply voltage
1.4
1.5
1.6
V
VREF
Input reference voltage
0.68
0.75
0.9
V
0.7
0.75
0.8
VTT
Termination voltage
VIH (DC)
DC high-level input voltage
VREF + 0.1
VIL (DC)
DC low-level input voltage
–0.3
VIH (AC)
AC high-level input voltage
VREF + 0.2
VIL (AC)
AC low-level input voltage
II
Input pin leakage current
0 < VIN < V CCIO
VOH
High-level output voltage
IOH = –16 mA
VOL
Low-level output voltage
IOL = 16 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
Table 22. 1.5-V HSTL Class III Specifications
Symbol
Parameter
V
V
VREF – 0.1
V
VREF – 0.2
V
10
µA
V
–10
VCCIO – 0.4
V
–10
0.4
V
10
µA
Maximum
Units
V
Note (1)
Conditions
Minimum
Typical
VCCIO
I/O supply voltage
1.4
1.5
1.6
VREF
Input reference voltage
0.81
0.9
0.99
V
VTT
Termination voltage
1.4
VCCIO
1.6
V
VIH (DC)
DC high-level input voltage
VREF + 0.1
VIL (DC)
DC low-level input voltage
–0.3
VREF – 0.1
V
VIH (AC)
AC high-level input voltage
VREF + 0.2
VIL (AC)
AC low-level input voltage
VREF – 0.2
V
II
Input pin leakage current
0 < VIN < V CCIO
10
µA
VOH
High-level output voltage
IOH = –8 mA
VOL
Low-level output voltage
IOL = 24 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
Altera Corporation
–10
V
V
VCCIO – 0.4
–10
V
0.4
V
10
µA
17
AN 134: Using Programmable I/O Standards in Mercury Devices
Table 23. 1.5-V HSTL Class IV Specifications
Symbol
Parameter
Note (1)
Conditions
Minimum
Typical
Maximum
Units
VCCIO
I/O supply voltage
1.4
1.5
1.6
V
VREF
Input reference voltage
0.81
0.9
0.99
V
1.4
VCCIO
1.6
V
VTT
Termination voltage
VIH (DC)
DC high-level input voltage
VREF + 0.1
VIL (DC)
DC low-level input voltage
–0.3
VIH (AC)
AC high-level input voltage
VREF + 0.2
VIL (AC)
AC low-level input voltage
II
Input pin leakage current
0 < VIN < VCCIO
VOH
High-level output voltage
IOH = –8 mA
VOL
Low-level output voltage
IOL = 48 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
V
VREF – 0.1
V
VREF – 0.2
V
10
µA
V
–10
VCCIO – 0.4
V
–10
0.4
V
10
µA
Maximum
Units
Table 24. CTT I/O Specifications
Symbol
Parameter
Conditions
Minimum
Typical
VCCIO
I/O supply voltage
3.0
3.3
3.6
V
VTT/VREF
Termination and input
reference voltage
1.35
1.5
1.65
V
VREF – 0.2
V
10
µA
VREF – 0.4
V
10
µA
VIH
High-level input voltage
VIL
Low-level input voltage
VREF + 0.2
II
Input pin leakage current
0 < VIN < VCCIO
VOH
High-level output voltage
IOH = –8 mA
VOL
Low-level output voltage
IOL = 8 mA
IO
Output leakage current
(when output is high Z)
GND ≤ VOUT ≤
VCCIO
–10
V
VREF + 0.4
–10
V
Notes to Tables 4 – 24:
(1)
(4)
(5)
Drive strength is programmable according to values shown in the Mercury Programmable Logic Device Family Data
Sheet.
Mercury devices support the RapidIO interconnect architecture using the source-synchronous LVDS I/O standard
to 500 Mbps.
Peak-to-peak differential voltage is 1,900 mV. Peak-to-peak is the magnitude of subtraction for positive arm (p)
voltage – negative arm (n) voltage.
These parameters meet IEEE Std. 802.3ab Gigabit Ethernet specifications.
VREF specifies the center point of the switching range.
18
Altera Corporation
(2)
(3)
AN 134: Using Programmable I/O Standards in Mercury Devices
Board
Termination
Schemes
The various I/O standards supported by Mercury devices require specific
termination schemes to achieve their high speeds. Each I/O standard has
an individual termination scheme.
Non-Differential I/O Standard Termination Schemes
The diagram in Figure 3 shows the series and parallel termination
resistors that are used with the non-differential I/O standards.
Figure 3. Board Termination Diagram
Driving Device
Receiving Device
VTT
VTT
RT1
RT2
Z = 50 Ω
RS
Altera Corporation
VREF
19
AN 134: Using Programmable I/O Standards in Mercury Devices
Table 25 shows the board termination values and reference voltages each
Mercury I/O standard uses.
Table 25. Board Termination Values
Output Driver
RS (Ω)
RT1 (Ω)
RT2 (Ω)
GTL+
Open-drain
–
50
50
1.0
1.5
SSTL-2 Class I
Push-pull
25
–
50
1.1
1.25
I/O Standard
VREF (V)
VTT (V)
SSTL-2 Class II
Push-pull
25
50
50
1.25
1.25
SSTL-3 Class I
Push-pull
25
–
50
1.5
1.5
SSTL-3 Class II
Push-pull
25
50
50
1.5
1.5
AGP
Push-pull
–
–
–
1.32
CTT
Push-pull
–
–
50
1.5
1.5
HSTL Class I
Push-pull
–
–
50
0.75
0.75
HSTL Class II
Push-pull
–
50
50
0.75
0.75
HSTL Class III
Push-pull
–
–
50
0.90
1.50
HSTL Class IV
Push-pull
–
50
50
0.90
1.50
–
Differential I/O Standard Termination Schemes
There are three I/O standards available for differential termination
schemes: LVDS, LVPECL, and 3.3-V PCML.
1
There are some speed limitations on DC-coupled LVDS. For
more information, refer to AN 130: CDR in Mercury Devices or
AN 159: Using HSDI in Source-Synchronous Mode in Mercury
Devices.
LVDS Termination Schemes
The LVDS I/O standard requires a termination resistor between the
signals at the receiving device as shown in Figure 4. The termination
resistor should match the differential load impedance of the bus (90 to
110 Ω, but typically 100 Ω).
20
Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 4. LVDS Board Termination at the Receiver
Transmitting
Device
Receiving
Device
Z = 50
100 Ω
+
–
Z = 50
LVPECL Termination Schemes
When using DC coupling to transmit from one Mercury device to another
Mercury device, the DC termination scheme is the same as the LVDS
termination scheme. Figure 4 illustrates the LVPECL DC termination
circuit.
When using DC coupling to transmit from a Mercury device to a nonMercury device, termination depends on whether the Mercury device’s
output specifications meet the non-Mercury device’s input specifications.
If the Mercury device’s minimum and maximum VOD, VOH, and VOL
values are within the non-Mercury device’s input specifications, then
termination is the same DC termination scheme as shown in Figure 4. If
the Mercury device’s VOH and VOL specifications are not within the nonMercury device’s specifications, then an AC-coupled termination scheme
is required. A DC restoration circuit is also implemented at the nonMercury device to move the common mode voltage within the destination
device’s specifications. The required common mode voltage determines
the resistor values needed for the DC restoration.
For non-Mercury transmitters with DC coupling, use the LVPECL
termination schemes suggested by the third-party chip vendor.
AC coupling is useful for applications where the common mode voltages
at the receiver and transmitter are different. One example is a system that
has different chassis grounds. When using AC coupling, a DC restoration
circuit is required to restore the common mode voltage. A voltage divider
on each leg adjusts for the common mode voltage required at the receiver.
Figure 5 illustrates the LVPECL AC termination circuit.
Altera Corporation
21
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 5. LVPECL AC Termination Scheme
VCCIO = 3.3 V
R1
Mercury 10 to 100 nF
Transmitter
R1
Mercury
Receiver
Z = 50
+
–
100 Ω
Z = 50
10 to 100 nF
R2
R2
GND GND
Follow these guidelines to calculate appropriate values for R1 and R2:
■
■
■
■
Resistors R1 and R2 should be in the kΩ range.
R1 || R2 || 50 Ω ≈ 50 Ω. In this equation, the 50 Ω value on the left of
the equal sign comes from the fact that 100-Ω differential = 50 Ω to
ground on a positive signal arm or +50 Ω to ground on a negative
signal arm.
R2/(R1 + R2) × 3.3 V = VCM. Calculate R1 and R2 using a value for the
common mode voltage (VCM) in the middle of the Mercury receiver
tolerance. VCM can range from 0 to 0.7 V and from 1.8 to 2.4 V. Altera
recommends that VCM = 2.1 V.
R1 = 5.6 kΩ and R2 = 3.3 kΩ are standard resistor values that meet the
requirements. However, other values are possible.
AC-coupled designs can use an R1/R2 combination that is equivalent to
the circuit in Figure 6 without the 100-Ω termination resistor. The parallel
combination of R1 and R2 acts as two 50-Ω-to-GND terminations
(equivalent to the 100-Ω termination) to replace the common mode
restoration circuit. The disadvantage of this circuit is that the current is
much higher for each receiver signal arm. The current will be
approximately 15 mA instead of less than 0.5 mA. The advantage of using
this circuit is that it requires one less resistor. Figure 6 illustrates this
alternative LVPECL AC termination circuit.
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Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 6. Alternative LVPECL AC Termination Scheme
VCCIO = 3.3 V
R1
Mercury 10 to 100 nF
Transmitter
R1
Mercury
Receiver
Z = 50
+
–
Z = 50
10 to 100 nF
R2
R2
GND GND
Follow these guidelines to calculate values for the R1 and R2 resistors:
■
■
■
■
Resistors R1 and R2 will be in the Ω range.
R1 || R2 ≈ 50 Ω.
R2/(R1 + R2) × 3.3 V = VCM. Calculate R1 and R2 using a value for
VCM in the middle of the Mercury receiver tolerance. VCM can range
from 0 to 0.7 V and from 1.8 to 2.4 V. Altera recommends that
VCM = 2.1 V.
R1= 138 Ω and R2 = 78 Ω are resistor values that meet the
requirements. However, other values are possible.
These AC coupling schemes also apply for receiving AC-coupled signals
from non-Mercury devices. For non-Mercury receiver devices, follow the
third party’s suggested termination scheme.
3.3-V PCML Termination Scheme
The 3.3-V PCML I/O standard requires 100-Ω resistors to VTT on the
signals at the transmitting device, and it requires 50-Ω resistors to VTT on
the signals at the receiving device. Figure 7 shows the termination scheme
for 3.3-V PCML. The termination voltage VTT is the same as the VCCIO
voltage (3.3 V).
Altera Corporation
23
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 7. 3.3-V PCML Board Termination at the Transmitter & Receiver
VTT
50 Ω
Transmitting
Device
50 Ω
50 Ω
50 Ω
Receiving
Device
Z = 50
+
–
Z = 50
Guidelines for
Programmable
I/O Standards
The following guidelines should be used when designing for the
programmable I/O standards in Mercury devices. The guidelines define
which standards are compatible based on input, output, and bidirectional
types within an I/O bank.
■
■
■
No two input pins can be placed in the same I/O bank if their I/O
standards require a different VREF voltage. However, non-voltagereferenced standards can coexist with voltage-referenced standards,
e.g., one bank can support both GTL+ and LVTTL.
No two push-pull standard output pins can be placed in the same I/O
bank if they require a different VCCIO voltage level. GTL+ is an opendrain I/O standard and therefore can be assigned to I/O banks with
a 2.5-V or 3.3-V VCCIO level.
Output pins that can switch while an input is using a VREF have to be
placed two pads away from the VREF pin. Figure 8 illustrates output
pin placement. Although Figures 8 through 10 show the pins as onedimensional, Mercury I/O pads are in an array spread over the
bottom of the die. The pins that are within two pads of the VREF pins
are listed in the Mercury device pin tables on the Altera® web site
(www.altera.com).
Figure 8. Output Pin Placement Guidelines
VREF
Inputs or
Ouputs
24
Inputs
Inputs or
Ouputs
Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
■
Voltage-referenced bidirectional buses that share a single tri-state
control signal can be placed around the VREF pin, as shown in
Figure 9. This placement works because the bus is only operating in
one direction at a time. When the bidirectional pins are driving out,
no inputs are using the VREF pin. When the bidirectional pins are
accepting input signals, no output pins will interfere with the input
pins’ ability to use the VREF level.
Figure 9. Placement of Bidirectional Buses with Single OE Control
VREF
VREF
■
Altera Corporation
An unrelated output pin may be placed within a voltage-referenced
bidirectional bus if the output pin is more than two pads from the
VREF pin, as shown in Figure 10.
25
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 10. Placement of Output Pins Outside the Bidirectional Buses
VREF
Not
Recommended
These outputs affect the inputs
VREF
Recommended
■
■
■
■
■
Even when the HSDI circuitry is not being used, the VCCIO voltage
level of the two HSDI transmitter I/O banks must always be set to the
same voltage level. The two I/O banks each have their own VREF
pins; therefore, I/O standards with different VREF voltages but the
same VCCIO voltage can be used in the two HSDI I/O banks. For
example, the first HSDI I/O bank can support AGP 2×
(VCCIO = 3.3 V, VREF = 1.32 V), while the second HSDI I/O bank can
support SSTL-3 (VCCIO = 3.3 V, VREF = 1.5 V).
When using one or more HSDI channels, non-differential I/O
standards are not allowed in any of the HSDI I/O banks.
The PCI clamp diode affects input tolerance. When the PCI clamp
diode is turned on, an I/O pin is clamped to VCCIO. For example, a
2.5-V VCCIO bank without the clamp diode is tolerant to 3.3-V inputs.
However, when the clamp diode is turned on, the 2.5-V VCCIO bank
is not 3.3-V tolerant. An LVTTL input that does not have its clamp
diode turned on can be placed in a bank that has a VCCIO level below
3.3 V.
Bidirectional pins have to satisfy both input and output guidelines.
All output drivers per pair of VCCIO/GND pins should not sink more
current than 570 mA in total. There is a maximum of 15 pins per
power pin pair.
Pins in I/O banks using the 1.8-V or 1.5-V VCCIO levels are never
current-limited. Use the following equation to calculate total current
for I/O standards with 3.3-V or 2.5-V VCCIO levels:
² [(IMAX for standard) × (number of I/O pins of that standard)] <
570mA
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Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
Table 26 shows the IMAX values.
Table 26. IMAX Values
IMAX (mA)
I/O Standard
3.3-V VCCIO
2.5-V VCCIO
LVTTL
22
15
PCI, PCI-X, AGP
21
–
GTL+
46
44
SSTL-3
30
–
SSTL-2, class I
–
17
SSTL-2, class II
–
25
In practice, this rule applies only to GTL+ pins, which may sink more
than 45 mA per output pin. For other standards, every pin in an I/O
bank can be used without violating this requirement.
1
Software
Support
Refer to the Mercury pin tables on the Altera web site
(www.altera.com) to view the grouping of I/O pins to
power pin pairs.
The Altera Quartus® II software provides software support for the
programmable I/O standards. This section shows how to implement and
view the programmable I/O standards for Mercury devices in the
Quartus II software and give placement and assignment guidelines,
including:
■
■
■
■
■
Device and Pin Options Dialog Box
Pin Assignments Dialog Box
Representation of I/O banks and I/O standards in the Floorplan
Editor
HSDI and general PLL paired pin labeling
Automatic placement
Device & Pin Options Dialog Box
The Voltage tab in the Device & Pin Options dialog box which is
available from the Compiler Settings dialog box (Processing menu)
contains a Default I/O standard drop-down menu, used to set the default
I/O standard for a device. All I/O pins without a specific I/O standard
assignment will default to the I/O standard specified in this drop-down
menu. Figure 11 shows the Device & Pin Options dialog box when
targeting a Mercury device.
Altera Corporation
27
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 11. Voltage Tab in the Device & Pin Options Dialog Box
Assign Pins Dialog Box
In the Assign Pins dialog box, shown in Figure 12, designers can make pin
assignments, specify I/O standards, and view the settings made to each
pin.
The Number column in the Available Pins & Existing Assignments list
corresponds with the pin number on the specified package. The Name
column contains the user-specified pin name in the design. The I/O Bank
column displays the number of the bank in which the pin resides, and the
I/O Standard column displays the current I/O standard assignment for
the pin. The Type column displays the following pin types: I/O, VREF,
reserved, dedicated clock, and dual-purpose pin names. The Available
Pins & Existing Assignments list can be sorted on any column by clicking
on the column heading. Drop-down menus are available for making I/O
standard and reserved pin assignments on a pin-by-pin basis.
28
Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 12. Assign Pins Dialog Box
The Quartus II software automatically assigns VREF pins when the
designer assigns I/O pins to an I/O standard that requires a reference
voltage. For example, if a designer assigns an I/O pin in Bank 8 to be an
SSTL-2 type I/O pin, the predetermined VREF pin of Bank 8 will
automatically be assigned. The predetermined VREF pins are shown in the
Type column as regular I/O pins with VREF as a secondary function.
The designer can also choose to manually assign the predetermined VREF
pins. VREF pins are assigned the same way as reserved pins. To select the
I/O standard for I/O and VREF pins, choose an I/O standard from the
I/O Standards drop-down menu. To assign a VREF pin, enter a pin name
in the Pin name box (reserve pin names are not declared in the design file),
check the Reserve pin box, and select Reserve as VREF from the dropdown menu.
Follow the steps below to make pin assignments, designate I/O standard
types, and reserve pins. Designers should reserve I/O pins that may be
needed in the future.
Altera Corporation
1.
Open or create the project to modify.
2.
Choose Compiler Settings (Processing menu).
29
AN 134: Using Programmable I/O Standards in Mercury Devices
3.
Click the Chips & Devices tab.
4.
Select the target device in the Available devices list.
5.
Click Assign Pins.
6.
In the Assign Pins dialog box, to show the pins for which you
cannot assign a node name in the Available Pins & Existing
Assignments list, turn on Show no connect pins.
7.
In the Available pins & existing assignments list, select the pin
number for the pin to which you want to assign, change, or delete a
node name assignment.
8.
If there is an existing assignment to the selected pin, click Delete
under Assignment to delete the node name assignment from the pin.
9.
To assign a new node name to the pin, or change the existing node
name assignment for the pin, under Assignment, type a node name
in the Pin name box or copy the node name to the Assign Pins
dialog box with the Node Finder.
10. If you added or changed the node name assignment for the pin and
you want to assign an I/O standard to the pin, under Assignment,
select a standard from the I/O Standard list.
11. If you added or changed the node name assignment or I/O standard
and you want to reserve the pin for future use or reserve a pin that
does not yet exist in the design file, under Assignment, turn on
Reserve pin. Select As input tri-stated, As output driving ground,
As output driving an unspecified signal, or As VREF from the
Reserve pin menu.
12. To save a new assignment and add the assignment to the Available
pins & existing assignments list, under Assignment, click Add.
13. To save the changed assignment and add the assignment to the
Available pins & existing assignments list, under Assignment, click
Change.
14. Repeat steps 7 to 13 for each additional assignment you want to
make, change, or delete.
15. Click OK.
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Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
In addition to the Assign Pins dialog box, I/O standards can be assigned
through the Assignment Organizer dialog box (Tools menu). The
advantage to using the Assign Pins dialog box is that pin assignments and
I/O standard assignments can be set in one dialog box. To make an I/O
standard assignment without assigning the node to a pin, use the
Assignment Organizer dialog box.
I/O Banks & Standards in the Floorplan Editor
The Floorplan Editor supports many features in Mercury devices,
including multiple I/O standards, PLLs, and the HSDI circuitry. The
Floorplan Editor shows membership in I/O banks by using a unique
background fill color around each pin for each I/O bank. In addition, the
bank number is shown. The Floorplan Editor has two package views
(Package Top, Package Bottom) and two internal views (Interior LABs
and Interior Cells). In the package views, the I/O bank number is labeled
above the pin. In the interior views, the I/O bank is outside the package
as a background around the pin name.
Only I/O and VCCIO pins have a colored background; GNDINT, GNDIO,
and VCCINT pins do not. Figure 13 shows the coloring in the Floorplan
Editor for the EP1M120FC484 device in package view. The figure shows
portions of two I/O banks of the device.
Altera Corporation
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AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 13. Device Package View
Under the View menu in the Floorplan Editor, the Show I/O Banks option
turns on the I/O bank color display in the two interior views. This
command also turns on the display of both the I/O bank colors and bank
numbers in the two package views.
The Floorplan Editor Color Legend, which is located under the View
menu, has an entry for each I/O pin color.
HSDI & General PLL Paired Pin Labeling
Information on the dual-purpose paired HSDI pins are displayed in the
same text string as the other information on a pin, similar to other pins
that have secondary functions, such as INIT_DONE. For example, in
Figure 12 on page 29, I/O pin A16 is now shown as I/O, HSDI_RX1p.
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Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
HSDI pin names all begin with the prefix HSDI. The next two characters
for data pins indicate whether they belong to the receiver (RX) or
transmitter (TX), followed by the two-digit channel <number> ranging
from 01 to 18. The last character at the end of the pin name indicates
polarity: p for positive and n for negative polarity.
Table 27 summarizes all of the HSDI pin names. The dedicated clock pins
(HSDI_CLK1p and HSDI_CLK2p) support HSDI and have optional dualpurpose negative polarity pins associated with them. The PLL feedback
pins (CLKLK_FB1p, CLKLK_FB2p) and the general PLL output pins
(CLKLK_OUT1p, CLKLK_OUT2p) follow the same convention as the
dedicated clock pins.
Table 27. HSDI & General PLL Pin Naming Convention
Pin Name
Altera Corporation
Function
HSDI_RX<number>p
Receiver positive data pin
HSDI_RX<number>n
Receiver negative data pin
HSDI_TX<number>p
Transmitter positive data pin
HSDI_TX<number>n
Transmitter negative data pin
HSDI_CLK1p
HSDI PLL 1 input clock positive pin
HSDI_CLK1n
HSDI PLL 1 input clock negative pin
HSDI_CLK2p
HSDI PLL 2 input clock positive pin
HSDI_CLK2n
HSDI PLL 2 input clock negative pin
HSDI_TXCLKOUTp
Transmitter output clock positive pin
HSDI_TXCLKOUTn
Transmitter output clock negative pin
CLK<number>p
Dedicated clock positive pin
CLK<number>n
Dedicated clock negative pin
CLKLK_FB<number>p
Dual-purpose ClockLockTM feedback positive pin
(general PLL)
CLKLK_FB<number>n
Dual-purpose ClockLock feedback negative pin
(general PLL)
CLKLK_OUT<number>p
Dual-purpose ClockLock output positive pin
(general PLL)
CLKLK_OUT<number>n
Dual-purpose ClockLock output negative pin
(general PLL)
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AN 134: Using Programmable I/O Standards in Mercury Devices
Figure 14 shows an HSDI receiver channel in the Floorplan Editor. The
receiver data channel, represented by the HSDI_RX01p and HSDI_RX01n
pins, feeds the dedicated HSDI circuitry. The HSDI circuitry for each
channel is represented by two horizontal rectangles. The top rectangle
represents the clock recovery unit (CRU) and the deserializer. The bottom
rectangle represents the synchronizer first-in first-out (FIFO) buffer. The
HSDI clock (HSDI_CLK1p, HSDI_CLK1n) drives HSDI_PLL1, which is
represented as a diamond in Figure 14.
Figure 14. Logic Cell View Showing the HSDI Circuitry
Automatic Placement & Verification of Programmable I/O
Standards With the Quartus II Software
The Quartus II software verifies correct placement of all I/O and VREF
pins, following the rules outlined in “Guidelines for Programmable I/O
Standards” on page 24. The Quartus II software:
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Automatically places I/O pins of different VREF standards without
pin assignments in separate I/O banks and enables the VREF pins of
these I/O banks.
Altera Corporation
AN 134: Using Programmable I/O Standards in Mercury Devices
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Verifies that no two voltage-referenced I/O pins requiring different
VREF levels are placed in one bank.
Does not allow placement of an output pin within two pins of a VREF
pin.
Reports an error message if the current limit is exceeded for a
Mercury power bank, as determined by the equation documented in
“Guidelines for Programmable I/O Standards” on page 24.
Reserves the unused HSDI channels and regular user I/O pins in the
HSDI banks when any of the HSDI channels are being used.
Conclusion
The Mercury devices’ programmable I/O features and standards simplify
board design by minimizing the number of devices used to interface with
memory, microprocessors, and backplanes. Mercury devices support a
wide spectrum of programmable I/O standards, including LVDS,
LVPECL, 3.3-V PCML, and LVTTL, allowing customization for a wide variety
of applications. Input, output, and bidirectional pins of different I/O
standards can be intermixed within I/O banks for additionally flexibility.
Mercury devices also offer increased I/O performance with features like
CDR (1.25-Gbps data transfer), double data rate I/O (DDRIO),
programmable delays, and fast Mercury I/O pins.
References
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Altera Corporation
Interface Standard for Nominal 3 V/3.3 V Supply Digital Integrated
Circuits, JESD8-A, Electronic Industries Association, June 1994.
Stub-Series Terminated Logic for 3.3 Volts (SSTL-3), EIA/JESD8-8,
Electronic Industries Association, August 1996.
Stub-Series Terminated Logic for 2.5 Volts (SSTL-2), EIA/JESD8-9,
Electronic Industries Association, September 1998.
Electrical Characteristics of Low Voltage Differential Signaling
(LVDS) Interface Circuits, ANSI/TIA/EIA-644, American National
Standards Institute/Telecommunication Industry
Association/Electronic Industries Association.
2.5 V ±0.2 V (Normal Range) and 1.7 V to 2.7 V (Wide Range) Power
Supply Voltage and Interface Standard for Nonterminated Digital
Integrated Circuit, EIA/JESD8-5, Electronic Industries Association,
October 1995.
1.8 V ±0.15 V (Normal Range) and 1.2 V to 1.95 V (Wide Range) Power
Supply Voltage and Interface Standard for Nonterminated Digital
Integrated Circuit, EIA/JESD8-7, Electronic Industries Association,
February 1997.
PCI Local Bus Specification, Revision 2.2, PCI Special Interest Group,
December 1998.
35
AN 134: Using Programmable I/O Standards in Mercury Devices
Revision
History
The information contained in AN 256: Implementing Double Data Rate
I/O Signaling in Cyclone Devices version 1.1 supersedes information
published in previous versions.
Version 2.1
The following changes were made to AN 134: Using Programmable I/O
Standards in Mercury Devices version 2.1:
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Change the VCM value in Table 8 from 1.2 V to 2.1 V.
Updated text to Note (2) under Table 24.
Updated GTL+ values in Table 25.
Updated Figure 7.
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