9–18
Altera Corporation
Stratix II Device Handbook, Volume 2
January 2008
I/O Voltage Support in JTAG Chain
Figure 9–13. JTAG Chain of Mixed Voltages
Table 9–3. Supported TDO/TDI Voltage Combinations
Device
TDI Input Buffer
Power
Stratix II and Stratix II GX TDO VCCIO Voltage Level in I/O Bank 4
VCCIO = 3.3 V
VCCIO = 2.5 V
VCCIO = 1.8 V
VCCIO = 1.5 V
Stratix II and
Stratix II GX
Always VCCPD (3.3V)
level shifter
required
Non-Stratix II
VCC = 3.3 V
level shifter
required
VCC = 2.5 V
level shifter
required
VCC = 1.8 V
v
level shifter
required
VCC = 1.5 V
v
(1)
The TDO output buffer meets VOH (MIN) = 2.4 V.
(2)
The TDO output buffer meets VOH (MIN) = 2.0 V.
(3)
An external 250- pull-up resistor is not required, but recommended if signal levels on the board are not optimal.
(4)
Input buffer must be 3.3-V tolerant.
(5)
Input buffer must be 2.5-V tolerant.
(6)
Input buffer must be 1.8-V tolerant.
3.3 V
VCCIO
Level
Shifter
2.5 V
VCCIO
1.8 V
VCCIO
1.5 V
VCCIO
Tester
TDO
TDI
Must be 3.3 V Tolerant.
Shift TDO to
level accepted
by tester if
necessary.
Must be
1.8 V tolerant.
Must be
2.5 V tolerant.
