• 1100010111
• 0111100000
• 1110110011
• 0011100101
• 0011100110
• 0000101010
• 0000101011
I/O Voltage for JTAG Operation
The Cyclone V device operating in IEEE Std. 1149.1 BST mode uses four dedicated JTAG pins—
TDI
,
TDO
,
TMS
, and
TCK
. Cyclone V devices do not support the optional
TRST
pin.
The
TCK
pin has an internal weak pull-down resistor, while the
TDI
and
TMS
pins have internal weak pull-up
resistors. The 3.3-, 3.0-, or 2.5-V V
CCPD
supply of I/O bank 3A powers the
TDO
,
TDI
,
TMS
, and
TCK
pins. All
user I/O pins are tri-stated during JTAG configuration.
The JTAG chain supports several different devices. Use the supported
TDO
and
TDI
voltage combinations
listed in the following table if the JTAG chain contains devices that have different V
CCIO
levels. The output
voltage level of the
TDO
pin must meet the specification of the
TDI
pin it drives.
Table 9-3: Supported TDO and TDI Voltage Combinations
The TDO output buffer for V
CCPD
of 3.3 V or 3.0 V meets V
OH
(MIN) of 2.4 V, and the TDO output buffer for V
CCPD
of 2.5 V meets V
OH
(MIN) of 2.0 V.
Cyclone V TDO V
CCPD
TDI Input Buffer
Power (V)
Device
V
CCPD
= 2.5 V
V
CCPD
= 3.0 V
V
CCPD
= 3.3 V
Yes
Yes
Yes
V
CCPD
= 3.3
Cyclone V
Yes
Yes
Yes
V
CCPD
= 3.0
Yes
Yes
Yes
V
CCPD
= 2.5
Yes
Yes
Yes
V
CC
= 3.3
Non-Cyclone V
(22)
Yes
Yes
Yes
V
CC
= 2.5
Yes
Yes
Yes
V
CC
= 1.8
Yes
Yes
Yes
V
CC
= 1.5
Performing BST
You can issue
BYPASS
,
IDCODE
, and
SAMPLE
JTAG instructions before, after, or during configuration without
having to interrupt configuration.
To issue other JTAG instructions, follow these guidelines:
• To perform testing before configuration, hold the
nCONFIG
pin low.
(22)
The input buffer must be tolerant to the TDO V
CCPD
voltage.
Altera Corporation
JTAG Boundary-Scan Testing in Cyclone V Devices
9-7
I/O Voltage for JTAG Operation
CV-52009
2014.01.10